Re: Loopback Interface [7:73305]
You've got it! They can be used for iBGP, DNS resolution, GRE tunnel endpoints, OSPF/BGP Router IDs, route summarization...the list goes on. Robert Edmonds 8/5/03 3:26:35 PM So, if I understand correctly, aside from OSPF router ID's and the like, just use a loopback interface when you want an always up/up interface. That's pretty simple. John Neiberger wrote in message news:[EMAIL PROTECTED] Exactly right. Sometimes it's nice to have a virtual interface whose status is not tied directly to a physical interface. We've mentioned several configurations where this is the case. From the routers perspective it may have a couple of special properties, since it's virtual, but it's still just another interface, as Dave said. MADMAN 8/5/03 1:25:25 PM I think your thinking way too hard about this;) A loobback is nothing more than a logical interface as opposed to a physical interface. As far as the routing process is concerned it's just another interface. Don't know how to articulate it any further. Dave Robert Edmonds wrote: You gentlemen have pointed out some good uses for loopback interfaces. However, my dilema still remains that I have yet to have somebody solidly explain loopback interfaces in a way that my simple mind can understand. I have also been unsuccessful in finding any website that accomplish this. Any takers? Robert p b wrote in message news:[EMAIL PROTECTED] terminate iBGP sessions on **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 Government can do something for the people only in proportion as it can do something to the people. -- Thomas Jefferson **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73566t=73305 -- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Re: Loopback Interface [7:73305]
Dom wrote: OK Let me have a go at this - A router by definition has at least two interfaces, in most cases it has many more. How do we define the ip address of the router? Is it an Ethernet (LAN facing) interface or a (for example) Serial, HSSI or other WAN facing interface? If any of these interfaces goes down (fails) then we cannot get to the router. This is why we set a loopback interface address - nothing to do with routing or metrics etc, just making sure that we can reach the router You won't get to the router no matter how many loopbacks you have if your phyical connection/s fail!!! :) Dave Best regards, Dom Stocqueler SysDom Technologies Visit our website - www.sysdom.org -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of MADMAN Sent: 05 August 2003 19:47 To: [EMAIL PROTECTED] Subject: Re: Loopback Interface [7:73305] I think your thinking way too hard about this;) A loobback is nothing more than a logical interface as opposed to a physical interface. As far as the routing process is concerned it's just another interface. Don't know how to articulate it any further. Dave Robert Edmonds wrote: You gentlemen have pointed out some good uses for loopback interfaces. However, my dilema still remains that I have yet to have somebody solidly explain loopback interfaces in a way that my simple mind can understand. I have also been unsuccessful in finding any website that accomplish this. Any takers? Robert p b wrote in message news:[EMAIL PROTECTED] terminate iBGP sessions on **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 Government can do something for the people only in proportion as it can do something to the people. -- Thomas Jefferson Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73562t=73305 -- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Re: Loopback Interface [7:73305]
Rusty, was there a URL here that was truncated? If so, I would very much like to see it. n_guide_chapter09186a0080087da4.html#3302 Wilmes, Rusty wrote in message news:[EMAIL PROTECTED] n_guide_chapter09186a0080087da4.html#3302 -Original Message- From: Robert Edmonds [mailto:[EMAIL PROTECTED] Sent: Tuesday, August 05, 2003 9:47 AM To: [EMAIL PROTECTED] Subject: Re: Loopback Interface [7:73305] You gentlemen have pointed out some good uses for loopback interfaces. However, my dilema still remains that I have yet to have somebody solidly explain loopback interfaces in a way that my simple mind can understand. I have also been unsuccessful in finding any website that accomplish this. Any takers? Robert p b wrote in message news:[EMAIL PROTECTED] terminate iBGP sessions on **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73635t=73305 -- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
RE: Loopback Interface [7:73305]
n_guide_chapter09186a0080087da4.html#3302 -Original Message- From: Robert Edmonds [mailto:[EMAIL PROTECTED] Sent: Tuesday, August 05, 2003 9:47 AM To: [EMAIL PROTECTED] Subject: Re: Loopback Interface [7:73305] You gentlemen have pointed out some good uses for loopback interfaces. However, my dilema still remains that I have yet to have somebody solidly explain loopback interfaces in a way that my simple mind can understand. I have also been unsuccessful in finding any website that accomplish this. Any takers? Robert p b wrote in message news:[EMAIL PROTECTED] terminate iBGP sessions on **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73568t=73305 -- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
RE: Loopback Interface [7:73305]
Thanks Dave, I know - but if you are relying on just the address of just an interface on a router with many WAN/LAN connections, you may have another way of reaching it. Which was the point I was trying to make. When monitoring a network do not assume a router is down just because a link/interface is down. All the best. Dom Dom wrote: OK Let me have a go at this - A router by definition has at least two interfaces, in most cases it has many more. How do we define the ip address of the router? Is it an Ethernet (LAN facing) interface or a (for example) Serial, HSSI or other WAN facing interface? If any of these interfaces goes down (fails) then we cannot get to the router. This is why we set a loopback interface address - nothing to do with routing or metrics etc, just making sure that we can reach the router You won't get to the router no matter how many loopbacks you have if your phyical connection/s fail!!! :) Dave Best regards, Dom Stocqueler SysDom Technologies Visit our website - www.sysdom.org -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of MADMAN Sent: 05 August 2003 19:47 To: [EMAIL PROTECTED] Subject: Re: Loopback Interface [7:73305] I think your thinking way too hard about this;) A loobback is nothing more than a logical interface as opposed to a physical interface. As far as the routing process is concerned it's just another interface. Don't know how to articulate it any further. Dave Robert Edmonds wrote: You gentlemen have pointed out some good uses for loopback interfaces. However, my dilema still remains that I have yet to have somebody solidly explain loopback interfaces in a way that my simple mind can understand. I have also been unsuccessful in finding any website that accomplish this. Any takers? Robert p b wrote in message news:[EMAIL PROTECTED] terminate iBGP sessions on **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 Government can do something for the people only in proportion as it can do something to the people. -- Thomas Jefferson Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73565t=73305 -- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Re: Loopback Interface [7:73305]
So, if I understand correctly, aside from OSPF router ID's and the like, just use a loopback interface when you want an always up/up interface. That's pretty simple. John Neiberger wrote in message news:[EMAIL PROTECTED] Exactly right. Sometimes it's nice to have a virtual interface whose status is not tied directly to a physical interface. We've mentioned several configurations where this is the case. From the routers perspective it may have a couple of special properties, since it's virtual, but it's still just another interface, as Dave said. MADMAN 8/5/03 1:25:25 PM I think your thinking way too hard about this;) A loobback is nothing more than a logical interface as opposed to a physical interface. As far as the routing process is concerned it's just another interface. Don't know how to articulate it any further. Dave Robert Edmonds wrote: You gentlemen have pointed out some good uses for loopback interfaces. However, my dilema still remains that I have yet to have somebody solidly explain loopback interfaces in a way that my simple mind can understand. I have also been unsuccessful in finding any website that accomplish this. Any takers? Robert p b wrote in message news:[EMAIL PROTECTED] terminate iBGP sessions on **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 Government can do something for the people only in proportion as it can do something to the people. -- Thomas Jefferson **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73561t=73305 -- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
RE: Loopback Interface [7:73305]
It's very simple. A loopback interface provides a connection point on a router that is not tied to a physical interface. It is very useful in many situations, for basically the same reason. Take OSPF for example. Without a loopback it will use the address of one of its physical interfaces for the routerID (unless you force it). If that interface was to go down, then the OSPF process would burp, and you'd have problems. Using a loopback interface will ensure the same routerID no matter what the physical interfaces were doing. Take management traffic for example. Typical management applications use SNMP to poll the router for interface statistics, etc. If you polled on the primary WAN interface, for example a T1 line, and that T1 went down, then you would not be able to retrieve any statistics at all, even if you had a backup ISDN line on the router. Fred Reimer - CCNA Eclipsys Corporation, 200 Ashford Center North, Atlanta, GA 30338 Phone: 404-847-5177 Cell: 770-490-3071 Pager: 888-260-2050 NOTICE; This email contains confidential or proprietary information which may be legally privileged. It is intended only for the named recipient(s). If an addressing or transmission error has misdirected the email, please notify the author by replying to this message. If you are not the named recipient, you are not authorized to use, disclose, distribute, copy, print or rely on this email, and should immediately delete it from your computer. -Original Message- From: Robert Edmonds [mailto:[EMAIL PROTECTED] Sent: Tuesday, August 05, 2003 12:47 PM To: [EMAIL PROTECTED] Subject: Re: Loopback Interface [7:73305] You gentlemen have pointed out some good uses for loopback interfaces. However, my dilema still remains that I have yet to have somebody solidly explain loopback interfaces in a way that my simple mind can understand. I have also been unsuccessful in finding any website that accomplish this. Any takers? Robert p b wrote in message news:[EMAIL PROTECTED] terminate iBGP sessions on **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73550t=73305 -- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Re: Loopback Interface [7:73305]
Exactly right. Sometimes it's nice to have a virtual interface whose status is not tied directly to a physical interface. We've mentioned several configurations where this is the case. From the routers perspective it may have a couple of special properties, since it's virtual, but it's still just another interface, as Dave said. MADMAN 8/5/03 1:25:25 PM I think your thinking way too hard about this;) A loobback is nothing more than a logical interface as opposed to a physical interface. As far as the routing process is concerned it's just another interface. Don't know how to articulate it any further. Dave Robert Edmonds wrote: You gentlemen have pointed out some good uses for loopback interfaces. However, my dilema still remains that I have yet to have somebody solidly explain loopback interfaces in a way that my simple mind can understand. I have also been unsuccessful in finding any website that accomplish this. Any takers? Robert p b wrote in message news:[EMAIL PROTECTED] terminate iBGP sessions on **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 Government can do something for the people only in proportion as it can do something to the people. -- Thomas Jefferson **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73553t=73305 -- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
RE: Loopback Interface [7:73305]
OK Let me have a go at this - A router by definition has at least two interfaces, in most cases it has many more. How do we define the ip address of the router? Is it an Ethernet (LAN facing) interface or a (for example) Serial, HSSI or other WAN facing interface? If any of these interfaces goes down (fails) then we cannot get to the router. This is why we set a loopback interface address - nothing to do with routing or metrics etc, just making sure that we can reach the router Best regards, Dom Stocqueler SysDom Technologies Visit our website - www.sysdom.org -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of MADMAN Sent: 05 August 2003 19:47 To: [EMAIL PROTECTED] Subject: Re: Loopback Interface [7:73305] I think your thinking way too hard about this;) A loobback is nothing more than a logical interface as opposed to a physical interface. As far as the routing process is concerned it's just another interface. Don't know how to articulate it any further. Dave Robert Edmonds wrote: You gentlemen have pointed out some good uses for loopback interfaces. However, my dilema still remains that I have yet to have somebody solidly explain loopback interfaces in a way that my simple mind can understand. I have also been unsuccessful in finding any website that accomplish this. Any takers? Robert p b wrote in message news:[EMAIL PROTECTED] terminate iBGP sessions on **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 Government can do something for the people only in proportion as it can do something to the people. -- Thomas Jefferson **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73559t=73305 -- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Re: Loopback Interface [7:73305]
You gentlemen have pointed out some good uses for loopback interfaces. However, my dilema still remains that I have yet to have somebody solidly explain loopback interfaces in a way that my simple mind can understand. I have also been unsuccessful in finding any website that accomplish this. Any takers? Robert p b wrote in message news:[EMAIL PROTECTED] terminate iBGP sessions on Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73538t=73305 -- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Re: Loopback Interface [7:73305]
I think your thinking way too hard about this;) A loobback is nothing more than a logical interface as opposed to a physical interface. As far as the routing process is concerned it's just another interface. Don't know how to articulate it any further. Dave Robert Edmonds wrote: You gentlemen have pointed out some good uses for loopback interfaces. However, my dilema still remains that I have yet to have somebody solidly explain loopback interfaces in a way that my simple mind can understand. I have also been unsuccessful in finding any website that accomplish this. Any takers? Robert p b wrote in message news:[EMAIL PROTECTED] terminate iBGP sessions on **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 Government can do something for the people only in proportion as it can do something to the people. -- Thomas Jefferson Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73552t=73305 -- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
RE: Loopback Interface [7:73305]
terminate iBGP sessions on Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73339t=73305 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Loopback Interface [7:73305]
I know the loopback interface is useful for assigning the router ID. Is there any other purpose? Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73305t=73305 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback Interface [7:73305]
when doing unnumbered interfaces routing via loopbacks. Virtual templates, dialer interfaces etc... I use loopbacks for many testing reasons. load balancing and redundancy via BGP use as peer in DLSW for redundancy/stability generate routes Those are a couple I can think of off the top of me noodle Dave DeVoe, Charles (PKI) wrote: I know the loopback interface is useful for assigning the router ID. Is there any other purpose? -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 Government can do something for the people only in proportion as it can do something to the people. -- Thomas Jefferson Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73315t=73305 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Loopback Interface [7:73305]
To monitor the router, since its up/up if the router is up. Larry Letterman Cisco Systems -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of DeVoe, Charles (PKI) Sent: Thursday, July 31, 2003 12:16 PM To: [EMAIL PROTECTED] Subject: Loopback Interface [7:73305] I know the loopback interface is useful for assigning the router ID. Is there any other purpose? Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73317t=73305 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Loopback Interface [7:73305]
1) It's an interface that never goes down. 2) It has a neat use in a situation where you have a VPN router-to-router and are using NAT. You may have a server that uses a static NAT to allow access from outside. To allow traffic from the server to traverse the VPN tunnel - use a route-map to bounce the VPN traffic off an address in the subnet of the loopback interface (which has no NAT statements). 3) In labs a small router can source many routes. -Original Message- From: DeVoe, Charles (PKI) [mailto:[EMAIL PROTECTED] Sent: Thursday, July 31, 2003 2:16 PM To: [EMAIL PROTECTED] Subject: Loopback Interface [7:73305] I know the loopback interface is useful for assigning the router ID. Is there any other purpose? Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73316t=73305 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Loopback Interface [7:73305]
our remote routers are configured to do ddr through the loopback interface. -Original Message- From: Larry Letterman [mailto:[EMAIL PROTECTED] Sent: Thursday, July 31, 2003 1:40 PM To: [EMAIL PROTECTED] Subject: RE: Loopback Interface [7:73305] To monitor the router, since its up/up if the router is up. Larry Letterman Cisco Systems -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of DeVoe, Charles (PKI) Sent: Thursday, July 31, 2003 12:16 PM To: [EMAIL PROTECTED] Subject: Loopback Interface [7:73305] I know the loopback interface is useful for assigning the router ID. Is there any other purpose? Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73321t=73305 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Loopback Interface [7:73305]
Loopbacks are handy for use with ip unnumbered. If you have a multipoint interface using subinterfaces you could give every subinterface the same address and keep everything on the same subnet. They're also handy for DNS. If your router hostname resolves to its loopback address you'll be able to reach the router using the hostname as long as there is at least one real interface up. If you were to resolve the name to an actual interface address you wouldn't be able to reach the router at all of that interface were down. John Wilmes, Rusty 7/31/03 4:49:11 PM our remote routers are configured to do ddr through the loopback interface. -Original Message- From: Larry Letterman [mailto:[EMAIL PROTECTED] Sent: Thursday, July 31, 2003 1:40 PM To: [EMAIL PROTECTED] Subject: RE: Loopback Interface [7:73305] To monitor the router, since its up/up if the router is up. Larry Letterman Cisco Systems -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of DeVoe, Charles (PKI) Sent: Thursday, July 31, 2003 12:16 PM To: [EMAIL PROTECTED] Subject: Loopback Interface [7:73305] I know the loopback interface is useful for assigning the router ID. Is there any other purpose? Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=73324t=73305 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Crypto Map in Loopback interface [7:39744]
You have to apply crypto map on real interface, otherwise phase I won't kick off in case of crypto acl match. You can configure isakmp identity and peer ip to loopback, provided you use the command crypto map mymap local-address. -Keyur Shah- CCIE# 4799 (Security; Routing and Switching) CISSP,CCSA,css1,scsa,scna,mct,mcse,cni,mcne Hello Computers Say Hello to Your Future! http://www.hellocomputers.com Toll-Free: 1.877.794.3556 -Original Message- From: Lidiya White [mailto:[EMAIL PROTECTED]] Sent: Thursday, March 28, 2002 11:37 AM To: [EMAIL PROTECTED] Subject: RE: Crypto Map in Loopback interface [7:39744] Yes, you can apply crypto may on the loopback, tunnel or Ethernet interfaces. Just make sure that routing is setup correctly and use crypto map mymap local-address lo0. You can create tunnel between loopback interfaces or use on one router loopback interface and on another use physical interface for peers. --- Lidiya White -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, March 28, 2002 7:43 AM To: [EMAIL PROTECTED] Subject: Crypto Map in Loopback interface [7:39744] Hi All, Can I apply a crypto map to loopback interface or Ethernet Interface...? (Currently the VPN tunnel is working fine with the crypto map applied to Serial interface of the internet edge router) IF yes, can I create a tunnel between loopback interfaces in peers...? Can I create a tunnel between physical interface and the loopback interface? Thiyagu This e-mail and any files transmitted with it are for the sole use of the intended recipient(s) and may contain confidential and privileged information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. Any unauthorised review, use, disclosure, dissemination, forwarding, printing or copying of this email or any action taken in reliance on this e-mail is strictly prohibited and may be unlawful. Visit us at http://www.cognizant.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=39977t=39744 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Crypto Map in Loopback interface [7:39744]
Hi All, Can I apply a crypto map to loopback interface or Ethernet Interface...? (Currently the VPN tunnel is working fine with the crypto map applied to Serial interface of the internet edge router) IF yes, can I create a tunnel between loopback interfaces in peers...? Can I create a tunnel between physical interface and the loopback interface? Thiyagu This e-mail and any files transmitted with it are for the sole use of the intended recipient(s) and may contain confidential and privileged information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. Any unauthorised review, use, disclosure, dissemination, forwarding, printing or copying of this email or any action taken in reliance on this e-mail is strictly prohibited and may be unlawful. Visit us at http://www.cognizant.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=39744t=39744 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Crypto Map in Loopback interface [7:39744]
Yes, you can apply crypto may on the loopback, tunnel or Ethernet interfaces. Just make sure that routing is setup correctly and use crypto map mymap local-address lo0. You can create tunnel between loopback interfaces or use on one router loopback interface and on another use physical interface for peers. --- Lidiya White -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, March 28, 2002 7:43 AM To: [EMAIL PROTECTED] Subject: Crypto Map in Loopback interface [7:39744] Hi All, Can I apply a crypto map to loopback interface or Ethernet Interface...? (Currently the VPN tunnel is working fine with the crypto map applied to Serial interface of the internet edge router) IF yes, can I create a tunnel between loopback interfaces in peers...? Can I create a tunnel between physical interface and the loopback interface? Thiyagu This e-mail and any files transmitted with it are for the sole use of the intended recipient(s) and may contain confidential and privileged information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. Any unauthorised review, use, disclosure, dissemination, forwarding, printing or copying of this email or any action taken in reliance on this e-mail is strictly prohibited and may be unlawful. Visit us at http://www.cognizant.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=39829t=39744 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
loopback interface range for ospf bgp [7:38628]
what range do people generally use? also.. if people use /32 masks and advertise all of the loopback networks via an igp doesn't that add a crap-load of discontiguous routes to the ole route-table? i guess what i am looking for is a case-study for a large bgp/ospf installation, and how they treated their loopback interfaces/router id's thanks __ Do You Yahoo!? Yahoo! Sports - live college hoops coverage http://sports.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=38628t=38628 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
loopback interface range for ospf bgp [7:38628]
Well, our network is made up of a lot of remote sites, in a sort of three-level tree. Each site has a range of networks that can be summarised. The loopback(s) for a site are part of that range, so once the site's networks are summarised, it doesn't add any extra to the route table. You don't want to know about the actual addressing - suffice to say it does not follow recommended addressing guidelines, but it's like that for historical reasons and we've never found a compelling reason to do the work required to change it. JMcL - Forwarded by Jenny Mcleod/NSO/CSDA on 19/03/2002 02:05 pm - Eric Waguespack Sent by: [EMAIL PROTECTED] 18/03/2002 07:49 pm Please respond to Eric Waguespack To: [EMAIL PROTECTED] cc: Subject:loopback interface range for ospf bgp [7:38628] what range do people generally use? also.. if people use /32 masks and advertise all of the loopback networks via an igp doesn't that add a crap-load of discontiguous routes to the ole route-table? i guess what i am looking for is a case-study for a large bgp/ospf installation, and how they treated their loopback interfaces/router id's thanks __ Do You Yahoo!? Yahoo! Sports - live college hoops coverage http://sports.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=38750t=38628 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
function of loopback interface [7:27181]
From what I've read the functions/benefits of the loopback interface includes that it provides an entry point for console based telnet sessions in the event that all physical interfaces are down. Why is this a benefit? You can always connect through the console to configure the router even if you do not have a loopback interface defined, can't you? So exactly, what are the profits that this can be done telnet-based? A practical example would be great. TIA, Henk Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=27181t=27181 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Loopback interface [7:20949]
Hi all, What is the default speed of a loopback interface on a Cisco router? Thanks, Albert Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=20949t=20949 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface [7:20949]
In a message dated 9/24/01 7:15:36 PM Central Daylight Time, [EMAIL PROTECTED] writes: Subj: Loopback interface [7:20949] Date: 9/24/01 7:15:36 PM Central Daylight Time From: [EMAIL PROTECTED] (Albert Y. Pak) Sender:[EMAIL PROTECTED] Reply-to: [EMAIL PROTECTED] (Albert Y. Pak) To:[EMAIL PROTECTED] 8000 MB Hi all, What is the default speed of a loopback interface on a Cisco router? Thanks, Albert Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=20951t=20949 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Loopback interface [7:20949]
Ah, cool, thanks! Actually, I just found out the answer myself as well. Loopback0 is up, line protocol is up Hardware is Loopback Internet address is 10.1.11.6/32 MTU 1514 bytes, BW 800 Kbit, DLY 5000 usec, reliability 255/255, txload 1/255, rxload 1/255 Thanks again. Albert -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of [EMAIL PROTECTED] Sent: Monday, September 24, 2001 9:46 PM To: [EMAIL PROTECTED] Subject: Re: Loopback interface [7:20949] In a message dated 9/24/01 7:15:36 PM Central Daylight Time, [EMAIL PROTECTED] writes: Subj: Loopback interface [7:20949] Date: 9/24/01 7:15:36 PM Central Daylight Time From: [EMAIL PROTECTED] (Albert Y. Pak) Sender:[EMAIL PROTECTED] Reply-to: [EMAIL PROTECTED] (Albert Y. Pak) To:[EMAIL PROTECTED] 8000 MB Hi all, What is the default speed of a loopback interface on a Cisco router? Thanks, Albert [GroupStudy.com removed an attachment of type application/ms-tnef which had a name of winmail.dat] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=20952t=20949 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Loopback Interface [7:16174]
Would you please explain me in simple terms what is loopback interface? One of the techs from our ISP told me to config my router for loopback interface instead of multilink interface so that he would push the config to my router. He also told me that multilink requires high CPU usage. Would you please give me your opinion on this. Thanks Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=16174t=16174 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback Interface [7:16174]
16.htm#xtocid1566416 From CCO: You can specify a software-only interface called a loopback interface that emulates an interface that is always up. A loopback interface is a virtual interface that allows BGP and RSRB sessions to stay up even if the outbound interface is down, and is supported on all platforms. You can use the loopback interface as the termination address for BGP sessions, for RSRB connections, or for establishing a Telnet session from the communication server's console to its auxiliary port when all other interfaces are down. In applications where other communication servers will attempt to reach this loopback interface, you should configure a routing protocol to distribute the subnet assigned to the loopback address. Packets routed to the loopback interface are rerouted back to the box and processed locally. IP packets routed out the loopback interface but not destined to the loopback interface are dropped. This means the loopback interface also serves as the Null 0 interface. -- Kevin Would you please explain me in simple terms what is loopback interface? One of the techs from our ISP told me to config my router for loopback interface instead of multilink interface so that he would push the config to my router. He also told me that multilink requires high CPU usage. Would you please give me your opinion on this. Thanks Nondisclosure violations to [EMAIL PROTECTED] http://www.siliconsamurai.net - This email was sent using SquirrelMail. Webmail for nuts! http://squirrelmail.org/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=16187t=16174 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback Interface [7:16174]
In a message dated 8/15/01 8:45:34 AM Central Daylight Time, [EMAIL PROTECTED] writes: Subj: Loopback Interface [7:16174] Date: 8/15/01 8:45:34 AM Central Daylight Time From: [EMAIL PROTECTED] (khramov) Sender:[EMAIL PROTECTED] Reply-to: [EMAIL PROTECTED] (khramov) To:[EMAIL PROTECTED] A loopback interface is a virtual interface you can configure on any router and has an 'always-up characteristic as recognized by the router itself. This makes it the most stable route of choice to be advertised by, say, OSPF, which, as a rule advertises the route with the highest physical # , or, if there are loopback interfaces that are configured and can be used, it ALWAYS uses loopback interfaces because of their stability and dependability on carrying the route advertisement. Hth, Rob H. Would you please explain me in simple terms what is loopback interface? One of the techs from our ISP told me to config my router for loopback interface instead of multilink interface so that he would push the config to my router. He also told me that multilink requires high CPU usage. Would you please give me your opinion on this. Thanks Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=16189t=16174 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
I can simply use the quote from Michael Williams' message above to answer your question... 1. A loopback is a logical interface that never goes down. It's used for various reasons (for setting up various kinds of tunnels, for setting who is the DR/BDR in OSPF, etc). 2. Many people use the subnet mask 255.255.255.255 because that's the only way to assign a single IP to the lookback instead of using more than 1 IP address. Therefore, you normally won't see /24s on loopback interfaces. Richard Sim, CT (Chee Tong) wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I have seems some routers with many lookback interfaces configured. May I know what is the purpose to have so many lookback? I thought one loopback can help us to troubleshoot the connectivity Besides, I am interested about question 5 from Richard, you said the lookback IPs within same network can be configured on different router. Does it mean that if we configured many lookback interfaces, those IPs must be in different network. for example 192.168.101.101/24 192.168.102.102/24. But Any one know what is the reason?? 5) If I configured A's loopback IP to be 192.168.0.1/24, can we still configured B's loopback to be 192.168.0.2/24? Note: there are in same network. Sure you can since they are in two different routers. I won't recommend doing this though... The point is, there is no magic behind a loopback interface as you still need physical interface and routing entries if you need access. Richard -Original Message- From: Richard Chang [mailto:[EMAIL PROTECTED]] Sent: Thursday, June 28, 2001 1:51 AM To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] See lines below. Susan Stone wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi.. Sorry, I need a few more questions to verify whether my understanding on loopback is correct or not? Pls answer it. 1) If I have two router A (loopback=192.168.0.1/32) and B (loopback192.168.0.2/32), Router A's S1 int 100.100.100.1/24 is connected to Router B's S1 100.100.100.2/24. There are no more other connection. If S1 of B is down. Can I still telnet from A to B using B's loopback address. No. 2) If Router A and B have another connection. Router A's S2 int 100.200.100.1/24 is connected to Router B's S2 100.200.100.2/24. If S1 of B is down. Can I still telnet from A to B using B's loopback address? Yes, if you have correct routing entries. 3) If Router A doesn't have loopback int configured. Can we still telnet from A to B? Of course you can simply telnet into any physical interface that's still up. 4) Whether the loopback IP address need to be in order or same network? Let say Router A's loopback is 192.168.0.1/32 and Router B's loopback is 20.20.20.1/8. Can we still telnet from A to B? Again, yes, if you have correct routing entries. 5) If I configured A's loopback IP to be 192.168.0.1/24, can we still configured B's loopback to be 192.168.0.2/24? Note: there are in same network. Sure you can since they are in two different routers. I won't recommend doing this though... The point is, there is no magic behind a loopback interface as you still need physical interface and routing entries if you need access. Richard _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. == De informatie opgenomen in dit bericht kan vertrouwelijk zijn en is uitsluitend bestemd voor de geadresseerde. Indien u dit bericht onterecht ontvangt wordt u verzocht de inhoud niet te gebruiken en de afzender direct te informeren door het bericht te retourneren. == The information contained in this message may be confidential and is intended to be exclusively for the addressee. Should you receive this message unintentionally, please do not use the contents herein and notify the sender immediately by return e-mail. == Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=10422t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: what is loopback interface for ? [7:9493]
I have seems some routers with many lookback interfaces configured. May I know what is the purpose to have so many lookback? I thought one loopback can help us to troubleshoot the connectivity Besides, I am interested about question 5 from Richard, you said the lookback IPs within same network can be configured on different router. Does it mean that if we configured many lookback interfaces, those IPs must be in different network. for example 192.168.101.101/24 192.168.102.102/24. But Any one know what is the reason?? 5) If I configured A's loopback IP to be 192.168.0.1/24, can we still configured B's loopback to be 192.168.0.2/24? Note: there are in same network. Sure you can since they are in two different routers. I won't recommend doing this though... The point is, there is no magic behind a loopback interface as you still need physical interface and routing entries if you need access. Richard -Original Message- From: Richard Chang [mailto:[EMAIL PROTECTED]] Sent: Thursday, June 28, 2001 1:51 AM To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] See lines below. Susan Stone wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi.. Sorry, I need a few more questions to verify whether my understanding on loopback is correct or not? Pls answer it. 1) If I have two router A (loopback=192.168.0.1/32) and B (loopback192.168.0.2/32), Router A's S1 int 100.100.100.1/24 is connected to Router B's S1 100.100.100.2/24. There are no more other connection. If S1 of B is down. Can I still telnet from A to B using B's loopback address. No. 2) If Router A and B have another connection. Router A's S2 int 100.200.100.1/24 is connected to Router B's S2 100.200.100.2/24. If S1 of B is down. Can I still telnet from A to B using B's loopback address? Yes, if you have correct routing entries. 3) If Router A doesn't have loopback int configured. Can we still telnet from A to B? Of course you can simply telnet into any physical interface that's still up. 4) Whether the loopback IP address need to be in order or same network? Let say Router A's loopback is 192.168.0.1/32 and Router B's loopback is 20.20.20.1/8. Can we still telnet from A to B? Again, yes, if you have correct routing entries. 5) If I configured A's loopback IP to be 192.168.0.1/24, can we still configured B's loopback to be 192.168.0.2/24? Note: there are in same network. Sure you can since they are in two different routers. I won't recommend doing this though... The point is, there is no magic behind a loopback interface as you still need physical interface and routing entries if you need access. Richard _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. == De informatie opgenomen in dit bericht kan vertrouwelijk zijn en is uitsluitend bestemd voor de geadresseerde. Indien u dit bericht onterecht ontvangt wordt u verzocht de inhoud niet te gebruiken en de afzender direct te informeren door het bericht te retourneren. == The information contained in this message may be confidential and is intended to be exclusively for the addressee. Should you receive this message unintentionally, please do not use the contents herein and notify the sender immediately by return e-mail. == Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=10361t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
Hi.. Sorry, I need a few more questions to verify whether my understanding on loopback is correct or not? Pls answer it. 1) If I have two router A (loopback=192.168.0.1/32) and B (loopback192.168.0.2/32), Router A's S1 int 100.100.100.1/24 is connected to Router B's S1 100.100.100.2/24. There are no more other connection. If S1 of B is down. Can I still telnet from A to B using B's loopback address. 2) If Router A and B have another connection. Router A's S2 int 100.200.100.1/24 is connected to Router B's S2 100.200.100.2/24. If S1 of B is down. Can I still telnet from A to B using B's loopback address? 3) If Router A doesn't have loopback int configured. Can we still telnet from A to B? 4) Whether the loopback IP address need to be in order or same network? Let say Router A's loopback is 192.168.0.1/32 and Router B's loopback is 20.20.20.1/8. Can we still telnet from A to B? 5) If I configured A's loopback IP to be 192.168.0.1/24, can we still configured B's loopback to be 192.168.0.2/24? Note: there are in same network. _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=10080t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
See lines below. Susan Stone wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi.. Sorry, I need a few more questions to verify whether my understanding on loopback is correct or not? Pls answer it. 1) If I have two router A (loopback=192.168.0.1/32) and B (loopback192.168.0.2/32), Router A's S1 int 100.100.100.1/24 is connected to Router B's S1 100.100.100.2/24. There are no more other connection. If S1 of B is down. Can I still telnet from A to B using B's loopback address. No. 2) If Router A and B have another connection. Router A's S2 int 100.200.100.1/24 is connected to Router B's S2 100.200.100.2/24. If S1 of B is down. Can I still telnet from A to B using B's loopback address? Yes, if you have correct routing entries. 3) If Router A doesn't have loopback int configured. Can we still telnet from A to B? Of course you can simply telnet into any physical interface that's still up. 4) Whether the loopback IP address need to be in order or same network? Let say Router A's loopback is 192.168.0.1/32 and Router B's loopback is 20.20.20.1/8. Can we still telnet from A to B? Again, yes, if you have correct routing entries. 5) If I configured A's loopback IP to be 192.168.0.1/24, can we still configured B's loopback to be 192.168.0.2/24? Note: there are in same network. Sure you can since they are in two different routers. I won't recommend doing this though... The point is, there is no magic behind a loopback interface as you still need physical interface and routing entries if you need access. Richard _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=10120t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
what is loopback interface for ? [7:9493]
Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9493t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
A loopback is a logical interface that never goes down. It's used for various reasons (for setting up various kinds of tunnels, for setting who is the DR/BDR in OSPF, etc). It can be set to any valid IP in your network, not just private. Many people use the subnet mask 255.255.255.255 because that's the only way to assign a single IP to the lookback instead of using more than 1 IP address. Mike W. Susan Stone wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9498t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
A loopback interface may be used for many purposes. You may use it as the end of a tunnel on a VPN configuration or you may configure it just to have a stable router-id for OSPF, for instance. You don't need to configure it. They are optional and you may use any address you want. If loopback intfs are following a specific address scheme in your network, then they must be planned for some specific function by who designed the network. You should not change it before knowing what function is this (what may be achieved by analyzing your configuration carefully). The subnet mask used on a loopback intf isn't also necessarily /24. This is frequently used though, to economize address space, since you don't need to differentiate network and host on this segment. In this case, host and network are the same and routing is performed with no problem. ER CCNA - Original Message - From: Susan Stone To: Sent: Friday, June 22, 2001 7:22 AM Subject: what is loopback interface for ? [7:9493] Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9531t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
Sorry, Just a correction: the mask usually used for a loopback intf is /32 (255.255.255.255) and not /24 (255.255.255.0). Rgards, ER CCNA - Original Message - From: Ednilson Rosa To: Sent: Friday, June 22, 2001 1:20 PM Subject: Re: what is loopback interface for ? [7:9493] A loopback interface may be used for many purposes. You may use it as the end of a tunnel on a VPN configuration or you may configure it just to have a stable router-id for OSPF, for instance. You don't need to configure it. They are optional and you may use any address you want. If loopback intfs are following a specific address scheme in your network, then they must be planned for some specific function by who designed the network. You should not change it before knowing what function is this (what may be achieved by analyzing your configuration carefully). The subnet mask used on a loopback intf isn't also necessarily /24. This is frequently used though, to economize address space, since you don't need to differentiate network and host on this segment. In this case, host and network are the same and routing is performed with no problem. ER CCNA - Original Message - From: Susan Stone To: Sent: Friday, June 22, 2001 7:22 AM Subject: what is loopback interface for ? [7:9493] Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9542t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
Sue, In addition to what ER had to say, the main purpose of loopback address is actually contained in your question.loopback interface is always up/up, and this helps you to possibly get into the router when there is problem and all interfaces fail, now you can see what is going on and troubleshoot after you have telneted into the router inno/ccnp --- Ednilson Rosa wrote: Sorry, Just a correction: the mask usually used for a loopback intf is /32 (255.255.255.255) and not /24 (255.255.255.0). Rgards, ER CCNA - Original Message - From: Ednilson Rosa To: Sent: Friday, June 22, 2001 1:20 PM Subject: Re: what is loopback interface for ? [7:9493] A loopback interface may be used for many purposes. You may use it as the end of a tunnel on a VPN configuration or you may configure it just to have a stable router-id for OSPF, for instance. You don't need to configure it. They are optional and you may use any address you want. If loopback intfs are following a specific address scheme in your network, then they must be planned for some specific function by who designed the network. You should not change it before knowing what function is this (what may be achieved by analyzing your configuration carefully). The subnet mask used on a loopback intf isn't also necessarily /24. This is frequently used though, to economize address space, since you don't need to differentiate network and host on this segment. In this case, host and network are the same and routing is performed with no problem. ER CCNA - Original Message - From: Susan Stone To: Sent: Friday, June 22, 2001 7:22 AM Subject: what is loopback interface for ? [7:9493] Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. [EMAIL PROTECTED] __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail http://personal.mail.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9552t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: what is loopback interface for ? [7:9493]
Looback interface is a logical interface on your router such that when your router interface(s) goes down your loopback interface still stays up up. the subnet mask normally assigned is 255.255.255.0 not 255.255.255.255 and this is done so that only one Ip address can be assigned to the loobak interface. It's normally used is ospf networks to configure your router(s) as designated or backup designated router(s). Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9553t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
Can you explain to me how you can telnet into the router if all interfaces fail with the exception of the loopback interface? If ALL interfaces fail, the only way you can get to the router is via console or AUX. And you call yourself a CCNP. No wonder the value of Cisco certification value (with the exception of the CCIE) is becoming less desirable these days. Kevin Juniper Network Certified Internet Expert (JNCIE) Qwest Communiations From: Inno. Ama Reply-To: Inno. Ama To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] Date: Fri, 22 Jun 2001 14:57:53 -0400 Sue, In addition to what ER had to say, the main purpose of loopback address is actually contained in your question.loopback interface is always up/up, and this helps you to possibly get into the router when there is problem and all interfaces fail, now you can see what is going on and troubleshoot after you have telneted into the router inno/ccnp --- Ednilson Rosa wrote: Sorry, Just a correction: the mask usually used for a loopback intf is /32 (255.255.255.255) and not /24 (255.255.255.0). Rgards, ER CCNA - Original Message - From: Ednilson Rosa To: Sent: Friday, June 22, 2001 1:20 PM Subject: Re: what is loopback interface for ? [7:9493] A loopback interface may be used for many purposes. You may use it as the end of a tunnel on a VPN configuration or you may configure it just to have a stable router-id for OSPF, for instance. You don't need to configure it. They are optional and you may use any address you want. If loopback intfs are following a specific address scheme in your network, then they must be planned for some specific function by who designed the network. You should not change it before knowing what function is this (what may be achieved by analyzing your configuration carefully). The subnet mask used on a loopback intf isn't also necessarily /24. This is frequently used though, to economize address space, since you don't need to differentiate network and host on this segment. In this case, host and network are the same and routing is performed with no problem. ER CCNA - Original Message - From: Susan Stone To: Sent: Friday, June 22, 2001 7:22 AM Subject: what is loopback interface for ? [7:9493] Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. [EMAIL PROTECTED] __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail misconduct and Nondisclosure violations to [EMAIL PROTECTED] Get your FREE download of MSN Explorer at http://explorer.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9555t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
The last mail I read before my response was about a sarcastic remark from somebody on this list, somebody actually took this up with his boss because he had a signature just like Kevin. My question is, is this what this board has come to? Ok, lets ignorantly agree that you are right, is this the best way to put it across to me? I believe you are a great engineer for Quest and that you are a juniper expert, could this be the difference between cisco and juniper boxes? I have learnt alot from this group, I will not allow you to change my perception of the well cultured members of this group. --- kevin jones wrote: Can you explain to me how you can telnet into the router if all interfaces fail with the exception of the loopback interface?nbsp; If ALL interfaces fail, the only way you can get to the router is via console or AUX.nbsp; And you call yourself a CCNP.nbsp; No wonder the value of Cisco certification value (with the exception of the CCIE) is becoming less desirable these days. Kevin Juniper Network Certified Internet Expert (JNCIE) Qwest Communiations nbsp; gt;From: Inno. Ama gt;Reply-To: Inno. Ama gt;To: [EMAIL PROTECTED] gt;Subject: Re: what is loopback interface for ? [7:9493] gt;Date: Fri, 22 Jun 2001 14:57:53 -0400 gt; gt;Sue, gt; gt;In addition to what ER had to say, the main purpose of gt;loopback address is actually contained in your gt;question.loopback interface is always up/up, and gt;this helps you to possibly get into the router when gt;there is problem and all interfaces fail, now you can gt;see what is going on and troubleshoot after you have gt;telneted into the router gt; gt;inno/ccnp gt;--- Ednilson Rosa wrote: gt; gt; Sorry, gt; gt; gt; gt; Just a correction: the mask usually used for a gt; gt; loopback intf is /32 gt; gt; (255.255.255.255) and not /24 (255.255.255.0). gt; gt; gt; gt; Rgards, gt; gt; gt; gt; ER gt; gt; CCNA gt; gt; gt; gt; - Original Message - gt; gt; From: Ednilson Rosa gt; gt; To: gt; gt; Sent: Friday, June 22, 2001 1:20 PM gt; gt; Subject: Re: what is loopback interface for ? gt; gt; [7:9493] gt; gt; gt; gt; gt; gt; A loopback interface may be used for many purposes. gt; gt; You may use it as the gt; gt; end of a tunnel on a VPN configuration or you may gt; gt; configure it just to have gt; gt; a stable router-id for OSPF, for instance. gt; gt; gt; gt; You don't need to configure it. They are optional gt; gt; and you may use any gt; gt; address you want. If loopback intfs are following a gt; gt; specific address scheme gt; gt; in your network, then they must be planned for some gt; gt; specific function by who gt; gt; designed the network. You should not change it gt; gt; before knowing what function gt; gt; is this (what may be achieved by analyzing your gt; gt; configuration carefully). gt; gt; gt; gt; The subnet mask used on a loopback intf isn't also gt; gt; necessarily /24. This is gt; gt; frequently used though, to economize address space, gt; gt; since you don't need to gt; gt; differentiate network and host on this segment. In gt; gt; this case, host and gt; gt; network are the same and routing is performed with gt; gt; no problem. gt; gt; gt; gt; ER gt; gt; CCNA gt; gt; gt; gt; - Original Message - gt; gt; From: Susan Stone gt; gt; To: gt; gt; Sent: Friday, June 22, 2001 7:22 AM gt; gt; Subject: what is loopback interface for ? [7:9493] gt; gt; gt; gt; gt; gt; Hi, gt; gt; gt; gt; I always wonder what is loopback interface for? Can gt; gt; anyone explained its gt; gt; function? Can we don't configure the loopback gt; gt; interface. Our WAN Lookback gt; gt; always start with 192.168.X.X why? Must we use gt; gt; private IP? I found I can gt; gt; telnet to a remote router using its loopback IP. gt; gt; But I wonder How I route gt; gt; as it always have the subnet mask of gt; gt; 255.255.255.255. Then which is the gt; gt; network and which the host gt; gt; gt; gt; Susan gt; gt; gt;_ gt; gt; Get Your Private, Free E-mail from MSN Hotmail at gt; gt; http://www.hotmail.com. gt;[EMAIL PROTECTED] gt; gt; gt;__ gt;Do You Yahoo!? gt;Get personalized email addresses from Yahoo! Mail gt;http://personal.mail.yahoo.com/ gt; gt; gt; gt; gt;FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html gt;Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Get your FREE download of MSN Explorer at http://explorer.msn.com __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail http://personal.mail.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9570t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Re: what is loopback interface for ? [7:9493]
Nope. 255.255.255.0 (/24) is the standard class C mask. It allows 254 host addresses instead of just one. By using this mask you will be wasting your address space. If IP address availability is not an issue to you then go ahead. Otherwise it's better to use a /32 (255.255.255.255) mask which only permits one single address. ER CCNA - Original Message - From: FELIX KISSIEDU To: Sent: Friday, June 22, 2001 4:21 PM Subject: RE: what is loopback interface for ? [7:9493] Looback interface is a logical interface on your router such that when your router interface(s) goes down your loopback interface still stays up up. the subnet mask normally assigned is 255.255.255.0 not 255.255.255.255 and this is done so that only one Ip address can be assigned to the loobak interface. It's normally used is ospf networks to configure your router(s) as designated or backup designated router(s). Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9577t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
I don't understand your statement the subnet mask normally assigned is 255.255.255.0 not 255.255.255.255 and this is done so that only one Ip address can be assigned to the loobak interface.Using the subnet mask 255.255.255.0 will waste IP addresses. You would use the 255.255.255.255 subnet mask to make it so it only uses 1 IP address. Although the loopback can be used to sway the DR/BDR election, it's also used as endpoints in DLSw, STUN and BSTUN tunnels as well as for administrative purposes as a way to reach a router no matter which particular interface is up or down. Also they are commonly used as a source of an IP address for IP unnumbered interfaces, since they never go down. Mike W. FELIX KISSIEDU wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Looback interface is a logical interface on your router such that when your router interface(s) goes down your loopback interface still stays up up. the subnet mask normally assigned is 255.255.255.0 not 255.255.255.255 and this is done so that only one Ip address can be assigned to the loobak interface. It's normally used is ospf networks to configure your router(s) as designated or backup designated router(s). Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9581t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
I had this huge post typed out ready to flame you for your response, but I don't want to lower myself to that level. I would hope that you are not an indication of the quality of people that Qwest hires. What an ass! Mike W. kevin jones wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Can you explain to me how you can telnet into the router if all interfaces fail with the exception of the loopback interface? If ALL interfaces fail, the only way you can get to the router is via console or AUX. And you call yourself a CCNP. No wonder the value of Cisco certification value (with the exception of the CCIE) is becoming less desirable these days. Kevin Juniper Network Certified Internet Expert (JNCIE) Qwest Communiations From: Inno. Ama Reply-To: Inno. Ama To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] Date: Fri, 22 Jun 2001 14:57:53 -0400 Sue, In addition to what ER had to say, the main purpose of loopback address is actually contained in your question.loopback interface is always up/up, and this helps you to possibly get into the router when there is problem and all interfaces fail, now you can see what is going on and troubleshoot after you have telneted into the router inno/ccnp --- Ednilson Rosa wrote: Sorry, Just a correction: the mask usually used for a loopback intf is /32 (255.255.255.255) and not /24 (255.255.255.0). Rgards, ER CCNA - Original Message - From: Ednilson Rosa To: Sent: Friday, June 22, 2001 1:20 PM Subject: Re: what is loopback interface for ? [7:9493] A loopback interface may be used for many purposes. You may use it as the end of a tunnel on a VPN configuration or you may configure it just to have a stable router-id for OSPF, for instance. You don't need to configure it. They are optional and you may use any address you want. If loopback intfs are following a specific address scheme in your network, then they must be planned for some specific function by who designed the network. You should not change it before knowing what function is this (what may be achieved by analyzing your configuration carefully). The subnet mask used on a loopback intf isn't also necessarily /24. This is frequently used though, to economize address space, since you don't need to differentiate network and host on this segment. In this case, host and network are the same and routing is performed with no problem. ER CCNA - Original Message - From: Susan Stone To: Sent: Friday, June 22, 2001 7:22 AM Subject: what is loopback interface for ? [7:9493] Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. [EMAIL PROTECTED] __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail misconduct and Nondisclosure violations to [EMAIL PROTECTED] Get your FREE download of MSN Explorer at http://explorer.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9584t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: what is loopback interface for ? [7:9493]
I wouldn't worry too muchHe's got enough trouble trying to find employment with that Juniper Certification! Haha! -Original Message- From: Michael L. Williams [mailto:[EMAIL PROTECTED]] Sent: Friday, June 22, 2001 6:43 PM To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] I had this huge post typed out ready to flame you for your response, but I don't want to lower myself to that level. I would hope that you are not an indication of the quality of people that Qwest hires. What an ass! Mike W. kevin jones wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Can you explain to me how you can telnet into the router if all interfaces fail with the exception of the loopback interface? If ALL interfaces fail, the only way you can get to the router is via console or AUX. And you call yourself a CCNP. No wonder the value of Cisco certification value (with the exception of the CCIE) is becoming less desirable these days. Kevin Juniper Network Certified Internet Expert (JNCIE) Qwest Communiations From: Inno. Ama Reply-To: Inno. Ama To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] Date: Fri, 22 Jun 2001 14:57:53 -0400 Sue, In addition to what ER had to say, the main purpose of loopback address is actually contained in your question.loopback interface is always up/up, and this helps you to possibly get into the router when there is problem and all interfaces fail, now you can see what is going on and troubleshoot after you have telneted into the router inno/ccnp --- Ednilson Rosa wrote: Sorry, Just a correction: the mask usually used for a loopback intf is /32 (255.255.255.255) and not /24 (255.255.255.0). Rgards, ER CCNA - Original Message - From: Ednilson Rosa To: Sent: Friday, June 22, 2001 1:20 PM Subject: Re: what is loopback interface for ? [7:9493] A loopback interface may be used for many purposes. You may use it as the end of a tunnel on a VPN configuration or you may configure it just to have a stable router-id for OSPF, for instance. You don't need to configure it. They are optional and you may use any address you want. If loopback intfs are following a specific address scheme in your network, then they must be planned for some specific function by who designed the network. You should not change it before knowing what function is this (what may be achieved by analyzing your configuration carefully). The subnet mask used on a loopback intf isn't also necessarily /24. This is frequently used though, to economize address space, since you don't need to differentiate network and host on this segment. In this case, host and network are the same and routing is performed with no problem. ER CCNA - Original Message - From: Susan Stone To: Sent: Friday, June 22, 2001 7:22 AM Subject: what is loopback interface for ? [7:9493] Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. [EMAIL PROTECTED] __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail misconduct and Nondisclosure violations to [EMAIL PROTECTED] Get your FREE download of MSN Explorer at http://explorer.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9589t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
Kevin, I believe what was being sted was that in a router with multiple ints, if some go down and some go up, routing info can still be exchanged. It is often the neighbor specified in a bgp config. Brian Sonic Whalen Success = Preparation + Opportunity On Fri, 22 Jun 2001, kevin jones wrote: Can you explain to me how you can telnet into the router if all interfaces fail with the exception of the loopback interface? If ALL interfaces fail, the only way you can get to the router is via console or AUX. And you call yourself a CCNP. No wonder the value of Cisco certification value (with the exception of the CCIE) is becoming less desirable these days. Kevin Juniper Network Certified Internet Expert (JNCIE) Qwest Communiations From: Inno. Ama Reply-To: Inno. Ama To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] Date: Fri, 22 Jun 2001 14:57:53 -0400 Sue, In addition to what ER had to say, the main purpose of loopback address is actually contained in your question.loopback interface is always up/up, and this helps you to possibly get into the router when there is problem and all interfaces fail, now you can see what is going on and troubleshoot after you have telneted into the router inno/ccnp --- Ednilson Rosa wrote: Sorry, Just a correction: the mask usually used for a loopback intf is /32 (255.255.255.255) and not /24 (255.255.255.0). Rgards, ER CCNA - Original Message - From: Ednilson Rosa To: Sent: Friday, June 22, 2001 1:20 PM Subject: Re: what is loopback interface for ? [7:9493] A loopback interface may be used for many purposes. You may use it as the end of a tunnel on a VPN configuration or you may configure it just to have a stable router-id for OSPF, for instance. You don't need to configure it. They are optional and you may use any address you want. If loopback intfs are following a specific address scheme in your network, then they must be planned for some specific function by who designed the network. You should not change it before knowing what function is this (what may be achieved by analyzing your configuration carefully). The subnet mask used on a loopback intf isn't also necessarily /24. This is frequently used though, to economize address space, since you don't need to differentiate network and host on this segment. In this case, host and network are the same and routing is performed with no problem. ER CCNA - Original Message - From: Susan Stone To: Sent: Friday, June 22, 2001 7:22 AM Subject: what is loopback interface for ? [7:9493] Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. [EMAIL PROTECTED] __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail misconduct and Nondisclosure violations to [EMAIL PROTECTED] Get your FREE download of MSN Explorer at http://explorer.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9598t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
Did you guys read what happened to me when i freaked at someone like that? Take a look at the thread how to track down unused ports on a switch and then stop ripping on people who flame you for saying something stupid. or. stop saying stupid things. or just keep your mouth shut if you cant say anything useful. BTW, d0rk, i can establish an IP connection to the AUX interface via the AUX interface/PPP. isnt that an interface? if all the interfaces fail that wouldnt work either. stop being dicks. Love, Peter Slow. To: Sent: Friday, June 22, 2001 6:42 PM Subject: Re: what is loopback interface for ? [7:9493] I had this huge post typed out ready to flame you for your response, but I don't want to lower myself to that level. I would hope that you are not an indication of the quality of people that Qwest hires. What an ass! Mike W. kevin jones wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Can you explain to me how you can telnet into the router if all interfaces fail with the exception of the loopback interface? If ALL interfaces fail, the only way you can get to the router is via console or AUX. And you call yourself a CCNP. No wonder the value of Cisco certification value (with the exception of the CCIE) is becoming less desirable these days. Kevin Juniper Network Certified Internet Expert (JNCIE) Qwest Communiations From: Inno. Ama Reply-To: Inno. Ama To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] Date: Fri, 22 Jun 2001 14:57:53 -0400 Sue, In addition to what ER had to say, the main purpose of loopback address is actually contained in your question.loopback interface is always up/up, and this helps you to possibly get into the router when there is problem and all interfaces fail, now you can see what is going on and troubleshoot after you have telneted into the router inno/ccnp --- Ednilson Rosa wrote: Sorry, Just a correction: the mask usually used for a loopback intf is /32 (255.255.255.255) and not /24 (255.255.255.0). Rgards, ER CCNA - Original Message - From: Ednilson Rosa To: Sent: Friday, June 22, 2001 1:20 PM Subject: Re: what is loopback interface for ? [7:9493] A loopback interface may be used for many purposes. You may use it as the end of a tunnel on a VPN configuration or you may configure it just to have a stable router-id for OSPF, for instance. You don't need to configure it. They are optional and you may use any address you want. If loopback intfs are following a specific address scheme in your network, then they must be planned for some specific function by who designed the network. You should not change it before knowing what function is this (what may be achieved by analyzing your configuration carefully). The subnet mask used on a loopback intf isn't also necessarily /24. This is frequently used though, to economize address space, since you don't need to differentiate network and host on this segment. In this case, host and network are the same and routing is performed with no problem. ER CCNA - Original Message - From: Susan Stone To: Sent: Friday, June 22, 2001 7:22 AM Subject: what is loopback interface for ? [7:9493] Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. [EMAIL PROTECTED] __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail misconduct and Nondisclosure violations to [EMAIL PROTECTED] Get your FREE download of MSN Explorer at http://explorer.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9600t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is loopback interface for ? [7:9493]
People who send flames or retorts to flames are just like people who blow themselves up in terrorist attacks: they think they're getting revenge, when really they're the cause of the problem. If it ain't Cisco-related, keep it private. 'Nuff said. - Original Message - From: Peter I. Slow To: [EMAIL PROTECTED] Sent: Friday, June 22, 2001 10:03 PM Subject: Re: what is loopback interface for ? [7:9493] Did you guys read what happened to me when i freaked at someone like that? Take a look at the thread how to track down unused ports on a switch and then stop ripping on people who flame you for saying something stupid. or. stop saying stupid things. or just keep your mouth shut if you cant say anything useful. BTW, d0rk, i can establish an IP connection to the AUX interface via the AUX interface/PPP. isnt that an interface? if all the interfaces fail that wouldnt work either. stop being dicks. Love, Peter Slow. To: Sent: Friday, June 22, 2001 6:42 PM Subject: Re: what is loopback interface for ? [7:9493] I had this huge post typed out ready to flame you for your response, but I don't want to lower myself to that level. I would hope that you are not an indication of the quality of people that Qwest hires. What an ass! Mike W. kevin jones wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Can you explain to me how you can telnet into the router if all interfaces fail with the exception of the loopback interface? If ALL interfaces fail, the only way you can get to the router is via console or AUX. And you call yourself a CCNP. No wonder the value of Cisco certification value (with the exception of the CCIE) is becoming less desirable these days. Kevin Juniper Network Certified Internet Expert (JNCIE) Qwest Communiations From: Inno. Ama Reply-To: Inno. Ama To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] Date: Fri, 22 Jun 2001 14:57:53 -0400 Sue, In addition to what ER had to say, the main purpose of loopback address is actually contained in your question.loopback interface is always up/up, and this helps you to possibly get into the router when there is problem and all interfaces fail, now you can see what is going on and troubleshoot after you have telneted into the router inno/ccnp --- Ednilson Rosa wrote: Sorry, Just a correction: the mask usually used for a loopback intf is /32 (255.255.255.255) and not /24 (255.255.255.0). Rgards, ER CCNA - Original Message - From: Ednilson Rosa To: Sent: Friday, June 22, 2001 1:20 PM Subject: Re: what is loopback interface for ? [7:9493] A loopback interface may be used for many purposes. You may use it as the end of a tunnel on a VPN configuration or you may configure it just to have a stable router-id for OSPF, for instance. You don't need to configure it. They are optional and you may use any address you want. If loopback intfs are following a specific address scheme in your network, then they must be planned for some specific function by who designed the network. You should not change it before knowing what function is this (what may be achieved by analyzing your configuration carefully). The subnet mask used on a loopback intf isn't also necessarily /24. This is frequently used though, to economize address space, since you don't need to differentiate network and host on this segment. In this case, host and network are the same and routing is performed with no problem. ER CCNA - Original Message - From: Susan Stone To: Sent: Friday, June 22, 2001 7:22 AM Subject: what is loopback interface for ? [7:9493] Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. [EMAIL PROTECTED] __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail misconduct and Nondisclosure violations to [EMAIL PROTECTED] Get your FREE download of MSN Explorer at http://explorer.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9602t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report mi
Re: what is loopback interface for ? [7:9493]
I'm not really wanting to get into the sarcasm part of this thread but I am wondering about the JNCIE. I recently got email from a Juniper guy in Canada (who works for Juniper Canada) and he signed it JNCIE #0005 (or maybe 0015), in any event a very very low number. I showed the email to a few buddies thinking that it would be cool to have such a low number. I just thought that anybody with that cert, who would use it in his email signature - would quote his number just like the CCIE. just an off topic type of thought Kevin Wigle - Original Message - From: CiscoG To: Sent: Friday, 22 June, 2001 19:16 Subject: RE: what is loopback interface for ? [7:9493] I wouldn't worry too muchHe's got enough trouble trying to find employment with that Juniper Certification! Haha! -Original Message- From: Michael L. Williams [mailto:[EMAIL PROTECTED]] Sent: Friday, June 22, 2001 6:43 PM To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] I had this huge post typed out ready to flame you for your response, but I don't want to lower myself to that level. I would hope that you are not an indication of the quality of people that Qwest hires. What an ass! Mike W. kevin jones wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Can you explain to me how you can telnet into the router if all interfaces fail with the exception of the loopback interface? If ALL interfaces fail, the only way you can get to the router is via console or AUX. And you call yourself a CCNP. No wonder the value of Cisco certification value (with the exception of the CCIE) is becoming less desirable these days. Kevin Juniper Network Certified Internet Expert (JNCIE) Qwest Communiations Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9605t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: what is loopback interface for ? [7:9493]
dickhead -Original Message- From: kevin jones [mailto:[EMAIL PROTECTED]] Sent: Friday, June 22, 2001 3:47 PM To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] Can you explain to me how you can telnet into the router if all interfaces fail with the exception of the loopback interface? If ALL interfaces fail, the only way you can get to the router is via console or AUX. And you call yourself a CCNP. No wonder the value of Cisco certification value (with the exception of the CCIE) is becoming less desirable these days. Kevin Juniper Network Certified Internet Expert (JNCIE) Qwest Communiations From: Inno. Ama Reply-To: Inno. Ama To: [EMAIL PROTECTED] Subject: Re: what is loopback interface for ? [7:9493] Date: Fri, 22 Jun 2001 14:57:53 -0400 Sue, In addition to what ER had to say, the main purpose of loopback address is actually contained in your question.loopback interface is always up/up, and this helps you to possibly get into the router when there is problem and all interfaces fail, now you can see what is going on and troubleshoot after you have telneted into the router inno/ccnp --- Ednilson Rosa wrote: Sorry, Just a correction: the mask usually used for a loopback intf is /32 (255.255.255.255) and not /24 (255.255.255.0). Rgards, ER CCNA - Original Message - From: Ednilson Rosa To: Sent: Friday, June 22, 2001 1:20 PM Subject: Re: what is loopback interface for ? [7:9493] A loopback interface may be used for many purposes. You may use it as the end of a tunnel on a VPN configuration or you may configure it just to have a stable router-id for OSPF, for instance. You don't need to configure it. They are optional and you may use any address you want. If loopback intfs are following a specific address scheme in your network, then they must be planned for some specific function by who designed the network. You should not change it before knowing what function is this (what may be achieved by analyzing your configuration carefully). The subnet mask used on a loopback intf isn't also necessarily /24. This is frequently used though, to economize address space, since you don't need to differentiate network and host on this segment. In this case, host and network are the same and routing is performed with no problem. ER CCNA - Original Message - From: Susan Stone To: Sent: Friday, June 22, 2001 7:22 AM Subject: what is loopback interface for ? [7:9493] Hi, I always wonder what is loopback interface for? Can anyone explained its function? Can we don't configure the loopback interface. Our WAN Lookback always start with 192.168.X.X why? Must we use private IP? I found I can telnet to a remote router using its loopback IP. But I wonder How I route as it always have the subnet mask of 255.255.255.255. Then which is the network and which the host Susan _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. [EMAIL PROTECTED] __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail misconduct and Nondisclosure violations to [EMAIL PROTECTED] Get your FREE download of MSN Explorer at http://explorer.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=9606t=9493 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface for OSPF [7:4802]
By the way, cisco has new command can control the router id under ospf router configuration. router-id x.w.y.z (in ip address format) Vincent Chong Brad McConnell There's not much point in putting the loopbacks in their own area unless you're in a lab scenario and trying to make a bigger, more complicated network. ..At least not that I can think of. However, there is definitely a usefulness for loopback interfaces in OSPF -- use them to set your RIDs (used to indentify the router in OSPF LSA's) to controllable, meaningfull addresses. This doesn't even require that the loopbacks be part of the OSPF domain, just that they be configured and up. Highest loopback IP on the router will be the OSPF RID of any LSA's generated by that router (as shown in commands such as show ip ospf neighbor, etc)... -Brad McConnell Vincent Chong wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi; For OSPF implementation, an area can be configured in the Loopback interface. But what purpose, when should I do it? TIA Vincent Chong FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=4817t=4802 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface for OSPF [7:4802]
Couple off the top of my head: OSPF Area router ID If you're running OSPF as your IGP in a hub/spoke type topology, you'd want BGP sourced on an interface that doesn't have a potential to go down. Phil - Original Message - From: Vincent Chong To: Sent: Thursday, May 17, 2001 1:16 AM Subject: Loopback interface for OSPF [7:4802] Hi; TIA Vincent Chong FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=4825t=4802 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface for OSPF [7:4802]
At 01:16 AM 5/17/01 -0400, Vincent Chong wrote: Hi; For OSPF implementation, an area can be configured in the Loopback interface. But what purpose, when should I do it? TIA Vincent Chong Well, somewhat off topic, but the router id will lock on to the loopback address, which might stabilize the network more. However, I think you even wrote to the list an email about that so that probably is not what you are asking. Now why would you want to advertise a loopback interface using OSPF or any IGP? To teach the IGP how to get their later on for redistribution into BGP. Basically only used if you need to use an AS as a transit AS. You have basically two choices. IBGP (full mesh) to the ASBRs of the transit AS. Or, you can redistribute the transit route through an IGP instead. They tend to use loopback interfaces to help the transit ASs achieve more stability to avoid flappage. I am somewhat new on this, so if I am wrong, I will happily defer to someone with more experience, but this is my take on it from what I have read. -Carroll Kong Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=4836t=4802 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface for OSPF [7:4802]
You're pretty much there. To clarify, transit AS's use only fully meshed IBGP (assuming scalability techniques like Route Reflection and Confederations also in use) and usually peer internally via loopback addresses for stability and as you correctly point out, use the IGP to distribute reachability information for those loopbacks. Using IGP only routers for transit might have worked at some point years ago, but simply doesn't cut it anymore due to the sheer volume of paths in the internet. *** REPLY SEPARATOR *** On 5/17/2001 at 10:04 AM Carroll Kong wrote: At 01:16 AM 5/17/01 -0400, Vincent Chong wrote: Hi; For OSPF implementation, an area can be configured in the Loopback interface. But what purpose, when should I do it? TIA Vincent Chong Well, somewhat off topic, but the router id will lock on to the loopback address, which might stabilize the network more. However, I think you even wrote to the list an email about that so that probably is not what you are asking. Now why would you want to advertise a loopback interface using OSPF or any IGP? To teach the IGP how to get their later on for redistribution into BGP. Basically only used if you need to use an AS as a transit AS. You have basically two choices. IBGP (full mesh) to the ASBRs of the transit AS. Or, you can redistribute the transit route through an IGP instead. They tend to use loopback interfaces to help the transit ASs achieve more stability to avoid flappage. I am somewhat new on this, so if I am wrong, I will happily defer to someone with more experience, but this is my take on it from what I have read. -Carroll Kong FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=4863t=4802 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Fw: Loopback interface for OSPF [7:4802]
If you want to be able to address the router as a whole (rather than a particular interface), for example for SNMP, telnet, etc, then using a loopback address is a good way to do it.Of course, if you do this, your loopback address needs to be included in OSPF (or whatever routing protocol you're running) so that it is visible throughout your network. JMcL -- Forwarded by Jenny Mcleod/NSO/CSDA on 18/05/2001 09:22 am --- CCNP @groupstudy.com on 17/05/2001 04:20:38 pm Please respond to CCNP Sent by: [EMAIL PROTECTED] To: [EMAIL PROTECTED] cc: Subject: Fw: Loopback interface for OSPF [7:4802] - Original Message - From: CCNP To: Sent: Thursday, May 17, 2001 11:19 AM Subject: Re: Loopback interface for OSPF [7:4802] Brad is very correct on the use of Loopback interface in OSPF. 1. Loopback interface is more stable than any other physical interface. Catch here is OSPF will continue to use a RID learned from a physical interface even if the interface subsequently fails. So nothing great about this advantage. 2. Admin's can assign RID in a more controlled way because RID's can belong to same network/subnet across the entire OSPF domain. This is the main advantage of using Loopback interface in OSPF. Brijesh - Original Message - From: Brad McConnell To: Sent: Thursday, May 17, 2001 10:50 AM Subject: Re: Loopback interface for OSPF [7:4802] There's not much point in putting the loopbacks in their own area unless you're in a lab scenario and trying to make a bigger, more complicated network. ..At least not that I can think of. However, there is definitely a usefulness for loopback interfaces in OSPF -- use them to set your RIDs (used to indentify the router in OSPF LSA's) to controllable, meaningfull addresses. This doesn't even require that the loopbacks be part of the OSPF domain, just that they be configured and up. Highest loopback IP on the router will be the OSPF RID of any LSA's generated by that router (as shown in commands such as show ip ospf neighbor, etc)... -Brad McConnell Vincent Chong wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi; For OSPF implementation, an area can be configured in the Loopback interface. But what purpose, when should I do it? TIA Vincent Chong FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=4928t=4802 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Loopback interface for OSPF [7:4802]
Hi; For OSPF implementation, an area can be configured in the Loopback interface. But what purpose, when should I do it? TIA Vincent Chong Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=4802t=4802 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface for OSPF [7:4802]
There's not much point in putting the loopbacks in their own area unless you're in a lab scenario and trying to make a bigger, more complicated network. ..At least not that I can think of. However, there is definitely a usefulness for loopback interfaces in OSPF -- use them to set your RIDs (used to indentify the router in OSPF LSA's) to controllable, meaningfull addresses. This doesn't even require that the loopbacks be part of the OSPF domain, just that they be configured and up. Highest loopback IP on the router will be the OSPF RID of any LSA's generated by that router (as shown in commands such as show ip ospf neighbor, etc)... -Brad McConnell Vincent Chong wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi; For OSPF implementation, an area can be configured in the Loopback interface. But what purpose, when should I do it? TIA Vincent Chong FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=4803t=4802 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface for OSPF [7:4802]
Brad is very correct on the use of Loopback interface in OSPF. 1. Loopback interface is more stable than any other physical interface. Catch here is OSPF will continue to use a RID learned from a physical interface even if the interface subsequently fails. So nothing great about this advantage. 2. Admin's can assign RID in a more controlled way because RID's can belong to same network/subnet across the entire OSPF domain. This is the main advantage of using Loopback interface in OSPF. Brijesh - Original Message - From: Brad McConnell To: Sent: Thursday, May 17, 2001 10:50 AM Subject: Re: Loopback interface for OSPF [7:4802] There's not much point in putting the loopbacks in their own area unless you're in a lab scenario and trying to make a bigger, more complicated network. ..At least not that I can think of. However, there is definitely a usefulness for loopback interfaces in OSPF -- use them to set your RIDs (used to indentify the router in OSPF LSA's) to controllable, meaningfull addresses. This doesn't even require that the loopbacks be part of the OSPF domain, just that they be configured and up. Highest loopback IP on the router will be the OSPF RID of any LSA's generated by that router (as shown in commands such as show ip ospf neighbor, etc)... -Brad McConnell Vincent Chong wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi; For OSPF implementation, an area can be configured in the Loopback interface. But what purpose, when should I do it? TIA Vincent Chong FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=4808t=4802 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Fw: Loopback interface for OSPF [7:4802]
- Original Message - From: CCNP To: Sent: Thursday, May 17, 2001 11:19 AM Subject: Re: Loopback interface for OSPF [7:4802] Brad is very correct on the use of Loopback interface in OSPF. 1. Loopback interface is more stable than any other physical interface. Catch here is OSPF will continue to use a RID learned from a physical interface even if the interface subsequently fails. So nothing great about this advantage. 2. Admin's can assign RID in a more controlled way because RID's can belong to same network/subnet across the entire OSPF domain. This is the main advantage of using Loopback interface in OSPF. Brijesh - Original Message - From: Brad McConnell To: Sent: Thursday, May 17, 2001 10:50 AM Subject: Re: Loopback interface for OSPF [7:4802] There's not much point in putting the loopbacks in their own area unless you're in a lab scenario and trying to make a bigger, more complicated network. ..At least not that I can think of. However, there is definitely a usefulness for loopback interfaces in OSPF -- use them to set your RIDs (used to indentify the router in OSPF LSA's) to controllable, meaningfull addresses. This doesn't even require that the loopbacks be part of the OSPF domain, just that they be configured and up. Highest loopback IP on the router will be the OSPF RID of any LSA's generated by that router (as shown in commands such as show ip ospf neighbor, etc)... -Brad McConnell Vincent Chong wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi; For OSPF implementation, an area can be configured in the Loopback interface. But what purpose, when should I do it? TIA Vincent Chong FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=4811t=4802 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface IP address
Though I do not have an in-depth knowledge in loopback interface. I would like to add on a bit of my experience working on it. I have tried to configure a loopback interface for NAT kind of config (For Internet access ) with the interface as ip nat outside. It did not work. Eventually, I have to remove it and put the nat outside statement into my E0.(E1 is my ip nat inside)Surprising that works!! I was told that loopback interface is only for intranet configuration. Is this really true, I am not so sure?? :)Well that's was my experience regards "Alex Lee" [EMAIL PROTECTED] wrote in message 9ai0a7$7fb$[EMAIL PROTECTED]">news:9ai0a7$7fb$[EMAIL PROTECTED]... Group, I was looking at some documents at CCO, and noticed that sometimes their examples use /32 IP address like : interface loopback 0 ip address 172.16.254.3 255.255.255.255 Can someone help me to understand reason behind in using this type of address in the configuration ? _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface IP address
Group, I was looking at some documents at CCO, and noticed that sometimes their examples use /32 IP address like : interface loopback 0 ip address 172.16.254.3 255.255.255.255 Can someone help me to understand reason behind in using this type of address in the configuration ? _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface IP address
Reasons. Plural. 1. This is a loopback interface. It is always up. Which means, if you statically or dynamically make this /32 host route accessible via anywhere in the network, you can connect via IP to this address instead of each regular interface (serial and ethernet interfaces go down). So as long as one of your regular interfaces are up, you can reach the router via this loopback address. This could be especially useful for telnet/ssh remote access, snmp, and icmp testing/troubleshooting/managing of a router. 2. Router-id in routing protocols is determined by the highest loopback address (assuming that one is configured). 3. You can use `ip unnumbered' to a loopback address. I'm sure there are other reasons, but those three are good enough for me. -dre ""Alex Lee"" [EMAIL PROTECTED] wrote in message 9ai0a7$7fb$[EMAIL PROTECTED]">news:9ai0a7$7fb$[EMAIL PROTECTED]... Group, I was looking at some documents at CCO, and noticed that sometimes their examples use /32 IP address like : interface loopback 0 ip address 172.16.254.3 255.255.255.255 Can someone help me to understand reason behind in using this type of address in the configuration ? _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Fw: Loopback interface IP address
- Original Message - From: "Alex Lee" [EMAIL PROTECTED] Newsgroups: groupstudy.cisco To: [EMAIL PROTECTED] Sent: Thursday, April 05, 2001 6:34 AM Subject: Re: Loopback interface IP address Group, I was looking at some documents at CCO, and noticed that sometimes their examples use /32 IP address like : interface loopback 0 ip address 172.16.254.3 255.255.255.255 Can someone help me to understand reason behind in using this type of address in the configuration ? _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Loopback interface IP address
A loopback interface is basically ina network of it's own. it is not connected to another Interface nor does it particcipate in the transport of data (in it's normal form atleast.) However it is used (specially in a dynamic routing enviro) as a "reliable Interface" since it would be available as long as at least one interface on the unit is up. Now for the /32 mask. Well why waste more IPs than needed. All you need is 1 is this "broadcast domain" there is nothing else connected to this interface physically. -Original Message- From: perryb To: [EMAIL PROTECTED] Sent: 4/5/2001 9:28 AM Subject: Fw: Loopback interface IP address - Original Message - From: "Alex Lee" [EMAIL PROTECTED] Newsgroups: groupstudy.cisco To: [EMAIL PROTECTED] Sent: Thursday, April 05, 2001 6:34 AM Subject: Re: Loopback interface IP address Group, I was looking at some documents at CCO, and noticed that sometimes their examples use /32 IP address like : interface loopback 0 ip address 172.16.254.3 255.255.255.255 Can someone help me to understand reason behind in using this type of address in the configuration ? _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Loopback interface IP address
A loopback interface is basically ina network of it's own. it is not connected to another Interface nor does it particcipate in the transport of data (in it's normal form atleast.) However it is used (specially in a dynamic routing enviro) as a "reliable Interface" since it would be available as long as at least one interface on the unit is up. Now for the /32 mask. Well why waste more IPs than needed. All you need is 1 is this "broadcast domain" there is nothing else connected to this interface physically. OSPF has special treatment for /32 host routes, so I tend not to use them for loopbacks -- the entries in the link state database can look weird otherwise. I've also seen some weirdnesses with /30, so I'm apt to use a /29 subnet. I wouldn't want my loopback addresses accessible from the public internet, so I will use private space -- and am not very worried about conserving it. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
loopback interface adsressing
Hello, I had heard a lot about using the loopback interface for router ID for OSPF, etc... because it never goes down. However, my question is about the addressing of this interface, and whether I can assign an IP from the same subnet to a loopback interface on a neighboring router, or I have to assign a separate subnet on each router? and then how would this subnet be reachable? I mean how would I advertise it in the routing protocol?? Thank you Regards, - Hossam El-Ashkar [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: loopback interface adsressing
Hello, I had heard a lot about using the loopback interface for router ID for OSPF, etc... because it never goes down. However, my question is about the addressing of this interface, and whether I can assign an IP from the same subnet to a loopback interface on a neighboring router, or I have to assign a separate subnet on each router? Yes. I'm conservative, and will assign it a prefix no longer than /29 to avoid odd effects if a routing protocol makes assumptions about point-to-point or hsot interfaces. /32 should work, but doesn't in all releass. Since you don't want your routers to be reachable from the outside world, use private address space for the loopbacks. Address conservation then doesn't become an issue. I frequently start numbering loopback addresses in 192.198.255.0/24 and work down. and then how would this subnet be reachable? I mean how would I advertise it in the routing protocol?? Just like any other subnet. Thank you Regards, - Hossam El-Ashkar [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Loopback Interface
just create a virtual interface and give it an ip address and mask. Not you should be able to ping it etc. command to do this: router(config)#interface loopback number where number is 0 - big number router(config-if)#ip address address subnet_mask -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of norsyam ariffin Sent: Friday, March 09, 2001 3:28 AM To: [EMAIL PROTECTED] Subject: Loopback Interface Hi, Could we use loopback interface for troubleshooting purposes and how? Thanks in advance. Syam _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface
The loopback interface is used within OSPF configurations to enable an administrator to control the Router ID's. OSPF bases it's DR and BDR elections and other aspects of configuration on the Highest Router ID assigned within an AS. By choosing to assign a higher RID, which in this case is simply an IP address, to a loopback interface, OSPF will choose the loopback, if it exists, over any physical interface no matter if the RID is higher on the physical interface. --- mak [EMAIL PROTECTED] wrote: !doctype html public "-//w3c//dtd html 4.0 transitional//en" html Hi, pWhen I saw some sample configurations, there is a loopback interface. brWhat is this interface use for? Should I always configure it? pThanks brnbsp; pRegards, brmak/html _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] = Chris from Chicago MasterCNE, 5.x CNE, ICNE, 4.x CNE, CCNA, MCP __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail - only $35 a year! http://personal.mail.yahoo.com/ _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Loopback interface
!doctype html public "-//w3c//dtd html 4.0 transitional//en" html Hi, pWhen I saw some sample configurations, there is a loopback interface. brWhat is this interface use for? Should I always configure it? pThanks brnbsp; pRegards, brmak/html _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Loopback interface
There is some info about the loopback interface in this document. http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/inter _c/iclogint.htm#xtocid119671 watch for word wrap. Jason Fletcher mak wrote in message [EMAIL PROTECTED]... !doctype html public "-//w3c//dtd html 4.0 transitional//en" html Hi, pWhen I saw some sample configurations, there is a loopback interface. brWhat is this interface use for? Should I always configure it? pThanks brnbsp; pRegards, brmak/html _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: deleting of my loopback interface
no int loopback # -Original Message- From: suaveguru [mailto:[EMAIL PROTECTED]] Sent: Thursday, February 08, 2001 4:38 AM To: [EMAIL PROTECTED] Subject: deleting of my loopback interface Sorry anyone knows how to delete a loopback interface if it is incorrectly created? regards, suaveguru __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail - only $35 a year! http://personal.mail.yahoo.com/ _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
deleting of my loopback interface
Sorry anyone knows how to delete a loopback interface if it is incorrectly created? regards, suaveguru __ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail - only $35 a year! http://personal.mail.yahoo.com/ _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Router ID/Loopback interface
Inorder to reflect the new router ID without rebooting ,You can shutdown your serial 2/1 interface and then bring it up by no shutdown. Thangavel - Original Message - From: Erick B. [EMAIL PROTECTED] To: Louie Belt [EMAIL PROTECTED]; 'Ejay Hire' [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED] Sent: Wednesday, October 18, 2000 5:22 PM Subject: RE: OSPF Router ID/Loopback interface Some minor corrections. The OSPF process will use the *highest* loopback IP address if a loopback interface is configured. Otherwise, it uses the *highest* IP address on a physical interface. To configure OSPF (router ospf x) you need a interface with IP to be in a up/up state. You can reboot to have the router ID reflected or you can remove the OSPF process and add it back. --- Louie Belt [EMAIL PROTECTED] wrote: It will take the loopback address as it's ID, even if it is not the highest IP address on the router. Loopbacks take precedence over higher IP's with respect to Router ID's for OSPF. You will have to reboot your router for this change to be reflected. Once an ID is chosen, it will keep that ID regardless of changes until the router is rebooted. Louie -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Ejay Hire Sent: Wednesday, October 18, 2000 1:50 PM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: OSPF Router ID/Loopback interface No, It's the highest Ip on the router. Original Message Follows From: "John Deatherage" [EMAIL PROTECTED] Reply-To: "John Deatherage" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: OSPF Router ID/Loopback interface Date: Wed, 18 Oct 2000 11:15:27 -0700 If I add a loopback interface to a router, when will the router take it as the router ID? Here's a scenario: Serial2/1 is the current router ID: 209.1.1.1 I add Loopback0, which is 10.0.0.1 Shouldn't the router take this as its router ID? When does this happen? Doing: clear ip ospf process Still shows the old router ID. Is there any way to force the router to take the ID from the loopback interface? On another router, I couldn't get it to change until after reload. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] __ Do You Yahoo!? Yahoo! Messenger - Talk while you surf! It's FREE. http://im.yahoo.com/ _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF Router ID/Loopback interface
If I add a loopback interface to a router, when will the router take it as the router ID? Here's a scenario: Serial2/1 is the current router ID: 209.1.1.1 I add Loopback0, which is 10.0.0.1 Shouldn't the router take this as its router ID? When does this happen? Doing: clear ip ospf process Still shows the old router ID. Is there any way to force the router to take the ID from the loopback interface? On another router, I couldn't get it to change until after reload. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Router ID/Loopback interface
No, It's the highest Ip on the router. Original Message Follows From: "John Deatherage" [EMAIL PROTECTED] Reply-To: "John Deatherage" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: OSPF Router ID/Loopback interface Date: Wed, 18 Oct 2000 11:15:27 -0700 If I add a loopback interface to a router, when will the router take it as the router ID? Here's a scenario: Serial2/1 is the current router ID: 209.1.1.1 I add Loopback0, which is 10.0.0.1 Shouldn't the router take this as its router ID? When does this happen? Doing: clear ip ospf process Still shows the old router ID. Is there any way to force the router to take the ID from the loopback interface? On another router, I couldn't get it to change until after reload. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF Router ID/Loopback interface
It will take the loopback address as it's ID, even if it is not the highest IP address on the router. Loopbacks take precedence over higher IP's with respect to Router ID's for OSPF. You will have to reboot your router for this change to be reflected. Once an ID is chosen, it will keep that ID regardless of changes until the router is rebooted. Louie -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Ejay Hire Sent: Wednesday, October 18, 2000 1:50 PM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: OSPF Router ID/Loopback interface No, It's the highest Ip on the router. Original Message Follows From: "John Deatherage" [EMAIL PROTECTED] Reply-To: "John Deatherage" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: OSPF Router ID/Loopback interface Date: Wed, 18 Oct 2000 11:15:27 -0700 If I add a loopback interface to a router, when will the router take it as the router ID? Here's a scenario: Serial2/1 is the current router ID: 209.1.1.1 I add Loopback0, which is 10.0.0.1 Shouldn't the router take this as its router ID? When does this happen? Doing: clear ip ospf process Still shows the old router ID. Is there any way to force the router to take the ID from the loopback interface? On another router, I couldn't get it to change until after reload. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF Router ID/Loopback interface
Some minor corrections. The OSPF process will use the *highest* loopback IP address if a loopback interface is configured. Otherwise, it uses the *highest* IP address on a physical interface. To configure OSPF (router ospf x) you need a interface with IP to be in a up/up state. You can reboot to have the router ID reflected or you can remove the OSPF process and add it back. --- Louie Belt [EMAIL PROTECTED] wrote: It will take the loopback address as it's ID, even if it is not the highest IP address on the router. Loopbacks take precedence over higher IP's with respect to Router ID's for OSPF. You will have to reboot your router for this change to be reflected. Once an ID is chosen, it will keep that ID regardless of changes until the router is rebooted. Louie -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Ejay Hire Sent: Wednesday, October 18, 2000 1:50 PM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: OSPF Router ID/Loopback interface No, It's the highest Ip on the router. Original Message Follows From: "John Deatherage" [EMAIL PROTECTED] Reply-To: "John Deatherage" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: OSPF Router ID/Loopback interface Date: Wed, 18 Oct 2000 11:15:27 -0700 If I add a loopback interface to a router, when will the router take it as the router ID? Here's a scenario: Serial2/1 is the current router ID: 209.1.1.1 I add Loopback0, which is 10.0.0.1 Shouldn't the router take this as its router ID? When does this happen? Doing: clear ip ospf process Still shows the old router ID. Is there any way to force the router to take the ID from the loopback interface? On another router, I couldn't get it to change until after reload. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] __ Do You Yahoo!? Yahoo! Messenger - Talk while you surf! It's FREE. http://im.yahoo.com/ _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Loopback Interface
loopback interface is an always up interface and it will not go down since it is a virtual interface unlike physical interfaces which may be physically down sometimes. It is not necessary to use loopback for a point-to-point connection but you are advised to use probably because it will be more reliable to map frame-relay dlci no to loopback ip addresses since that will guarantee that the frame-relay map is always reliable Jason -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of NRS Hariharan Sent: Saturday, September 23, 2000 5:12 AM To: [EMAIL PROTECTED] Subject: Loopback Interface Hi all, What is a Loopback Interface and what is it's use ?.. Can anyone help me out.. In configuring FrameRelay for point-to-point connection, loopback inetrface is been advised why ?? thanks in advance . hari Get free email and a permanent address at http://www.netaddress.com/?N=1 **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Loopback Interface
Hi all, What is a Loopback Interface and what is it's use ?.. Can anyone help me out.. In configuring FrameRelay for point-to-point connection, loopback inetrface is been advised why ?? thanks in advance . hari Get free email and a permanent address at http://www.netaddress.com/?N=1 **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Route-Map To Loopback Interface
On Fri, 28 Jul 2000, Adrian Chew wrote: I've seen this in some configurations where traffic is sent via a route-map to an IP address that is on the same subnet as a router's loopback interface. Eg. interface ethernet 0 ip address 192.168.1.1 255.255.255.0 ip policy route-map abc interface loopback 0 ip address 192.168.255.1 255.255.255.0 access-list 100 permit ip 192.168.1.0 0.0.0.255 192.168.2.0 0.0.0.255 route-map abc permit 10 match ip address 100 set ip next-hop 192.168.255.2 Could anyone explain how having traffic routed via a loopback interface might help in certain situations? load balacing for one. For example: R1 ip cef int loopback 0 ip address 10.1.1.1 255.255.255.0 int ethernet 0 ip address 192.168.2.1 255.255.255.0 int serial 0 ip address 192.168.1.1 255.255.255.252 ip load-sharing per-packet int serial 1 ip address 192.168.1.5 255.255.255.252 ip load-sharing per-packet ip route 10.1.2.1 255.255.255.0 192.168.1.2 ip route 10.1.2.1 255.255.255.0 192.168.1.6 ip route 0.0.0.0 0.0.0.0 10.1.2.1 R2 ip cef int loopback 0 ip address 10.1.2.1 255.255.255.0 int serial 0 ip address 192.168.1.2 255.255.255.252 ip load-sharing per-packet int serial 1 ip address 192.168.1.6 255.255.255.252 ip load-sharing per-packet ip route 10.1.1.1 255.255.255.0 192.168.1.1 ip route 10.1.1.1 255.255.255.0 192.168.1.5 ip route 192.168.2.0 255.255.255.0 10.1.1.1 You could save yourself some configuring and whatnot by using an IGP to get the dual routes injected instead of declaring them statically here, but I did static here to illustrate Brian Thanks. Regards, Adrian ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] --- Brian Feeny, CCNA, CCDA [EMAIL PROTECTED] Network Administrator ShreveNet Inc. (ASN 11881) ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Route-Map To Loopback Interface
Brian, Thanks for the example - hitting the loopbacks on REMOTE routers is easy to understand (as is loopback interfaces for BGP connections and OSPF Router IDs). However, I've seen traffic being routed to an IP address on the same subnet as the router's loopback interface is on. Eg. E0 R1 Loop 0 R1 S0 R2 E0 IP destination The actual destination IP address might be a subnet on some other remote router but the traffic is first directed to an IP address on the same subnet as the router's own loopback address. I believe its done to avoid some sort of traffic from hitting NAT on the way out, but having an access-list definition for NAT traffic should already take care of this. Take a look at the initial route-map configuration I gave - traffic from E0 bound for network 192.168.2.0/24 (not a destination on the router's own connected interfaces) is set for next-hop IP address of 192.168.255.2 (the router's loopback IP address is 192.168.255.1 with a /24 mask). Regards, Adrian "Brian" [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... On Fri, 28 Jul 2000, Adrian Chew wrote: I've seen this in some configurations where traffic is sent via a route-map to an IP address that is on the same subnet as a router's loopback interface. Eg. interface ethernet 0 ip address 192.168.1.1 255.255.255.0 ip policy route-map abc interface loopback 0 ip address 192.168.255.1 255.255.255.0 access-list 100 permit ip 192.168.1.0 0.0.0.255 192.168.2.0 0.0.0.255 route-map abc permit 10 match ip address 100 set ip next-hop 192.168.255.2 Could anyone explain how having traffic routed via a loopback interface might help in certain situations? load balacing for one. For example: R1 ip cef int loopback 0 ip address 10.1.1.1 255.255.255.0 int ethernet 0 ip address 192.168.2.1 255.255.255.0 int serial 0 ip address 192.168.1.1 255.255.255.252 ip load-sharing per-packet int serial 1 ip address 192.168.1.5 255.255.255.252 ip load-sharing per-packet ip route 10.1.2.1 255.255.255.0 192.168.1.2 ip route 10.1.2.1 255.255.255.0 192.168.1.6 ip route 0.0.0.0 0.0.0.0 10.1.2.1 R2 ip cef int loopback 0 ip address 10.1.2.1 255.255.255.0 int serial 0 ip address 192.168.1.2 255.255.255.252 ip load-sharing per-packet int serial 1 ip address 192.168.1.6 255.255.255.252 ip load-sharing per-packet ip route 10.1.1.1 255.255.255.0 192.168.1.1 ip route 10.1.1.1 255.255.255.0 192.168.1.5 ip route 192.168.2.0 255.255.255.0 10.1.1.1 You could save yourself some configuring and whatnot by using an IGP to get the dual routes injected instead of declaring them statically here, but I did static here to illustrate Brian Thanks. Regards, Adrian ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] --- Brian Feeny, CCNA, CCDA [EMAIL PROTECTED] Network Administrator ShreveNet Inc. (ASN 11881) ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] --- ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Route-Map To Loopback Interface
The only thing I can think of is with that setup you have, any traffic from source .1.0 to destination 2.0 will be routed via the loopback and thus droppedCan't think of anything else Kenny "Adrian Chew" [EMAIL PROTECTED] wrote in message 8lskht$quq$[EMAIL PROTECTED]">news:8lskht$quq$[EMAIL PROTECTED]... Brian, Thanks for the example - hitting the loopbacks on REMOTE routers is easy to understand (as is loopback interfaces for BGP connections and OSPF Router IDs). However, I've seen traffic being routed to an IP address on the same subnet as the router's loopback interface is on. Eg. E0 R1 Loop 0 R1 S0 R2 E0 IP destination The actual destination IP address might be a subnet on some other remote router but the traffic is first directed to an IP address on the same subnet as the router's own loopback address. I believe its done to avoid some sort of traffic from hitting NAT on the way out, but having an access-list definition for NAT traffic should already take care of this. Take a look at the initial route-map configuration I gave - traffic from E0 bound for network 192.168.2.0/24 (not a destination on the router's own connected interfaces) is set for next-hop IP address of 192.168.255.2 (the router's loopback IP address is 192.168.255.1 with a /24 mask). Regards, Adrian "Brian" [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... On Fri, 28 Jul 2000, Adrian Chew wrote: I've seen this in some configurations where traffic is sent via a route-map to an IP address that is on the same subnet as a router's loopback interface. Eg. interface ethernet 0 ip address 192.168.1.1 255.255.255.0 ip policy route-map abc interface loopback 0 ip address 192.168.255.1 255.255.255.0 access-list 100 permit ip 192.168.1.0 0.0.0.255 192.168.2.0 0.0.0.255 route-map abc permit 10 match ip address 100 set ip next-hop 192.168.255.2 Could anyone explain how having traffic routed via a loopback interface might help in certain situations? load balacing for one. For example: R1 ip cef int loopback 0 ip address 10.1.1.1 255.255.255.0 int ethernet 0 ip address 192.168.2.1 255.255.255.0 int serial 0 ip address 192.168.1.1 255.255.255.252 ip load-sharing per-packet int serial 1 ip address 192.168.1.5 255.255.255.252 ip load-sharing per-packet ip route 10.1.2.1 255.255.255.0 192.168.1.2 ip route 10.1.2.1 255.255.255.0 192.168.1.6 ip route 0.0.0.0 0.0.0.0 10.1.2.1 R2 ip cef int loopback 0 ip address 10.1.2.1 255.255.255.0 int serial 0 ip address 192.168.1.2 255.255.255.252 ip load-sharing per-packet int serial 1 ip address 192.168.1.6 255.255.255.252 ip load-sharing per-packet ip route 10.1.1.1 255.255.255.0 192.168.1.1 ip route 10.1.1.1 255.255.255.0 192.168.1.5 ip route 192.168.2.0 255.255.255.0 10.1.1.1 You could save yourself some configuring and whatnot by using an IGP to get the dual routes injected instead of declaring them statically here, but I did static here to illustrate Brian Thanks. Regards, Adrian ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] --- Brian Feeny, CCNA, CCDA [EMAIL PROTECTED] Network Administrator ShreveNet Inc. (ASN 11881) ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] --- ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] --- ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Route-Map To Loopback Interface
I've seen this in some configurations where traffic is sent via a route-map to an IP address that is on the same subnet as a router's loopback interface. Eg. interface ethernet 0 ip address 192.168.1.1 255.255.255.0 ip policy route-map abc interface loopback 0 ip address 192.168.255.1 255.255.255.0 access-list 100 permit ip 192.168.1.0 0.0.0.255 192.168.2.0 0.0.0.255 route-map abc permit 10 match ip address 100 set ip next-hop 192.168.255.2 Could anyone explain how having traffic routed via a loopback interface might help in certain situations? Thanks. Regards, Adrian ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
