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]
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: 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]
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: 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]
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]
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]
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]
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]
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: 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]
