Re: ip route statement [7:43001]
One reason to add that null 0 hold down route is so you always have it in your route table. For instance if you are running BGP and anouncing a /20 to a provider and you have instability in your IGP you may lose the route in your table and not anounce that to your provider. If your provider sees the route flapping it can dampen your /20. With the hold down route you can always anounce the /20 cause it will be in your route table. Mike F. Michael L. Williams wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Also, to supplement (or create) summary routes... Mike W. Ladrach, Daniel E. wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... The Null interface is typically used for preventing routing loops. Daniel Ladrach CCNA, CCNP WorldCom -Original Message- From: Stanfast Preye [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 01, 2002 2:34 PM To: [EMAIL PROTECTED] Subject: ip route statement [7:43001] Dear Group, Why is it necessary to configure all routers in a network with ip route xxx.xxx.xxx.xxx null 0 statement before implementing migrating to a new IP address scheme and DHCP service in the network. Somebody please help Regards, Preye. - Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43099t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ip route statement [7:43001]
Can it be used as a default-gateway for hosts in LANs when migrating from one class of IP Address to another. Example: Host configuration (default-gateway=128.100.10.32) Router global configuration (ip route 128.100.10.32 null 0) Can somebody explain how this works? Kind regards, Preye. Patrick Ramsey wrote: I've never done this before... I've migrated countless networks to new ip schemes. But you have not given us a whole lot of info to go by. check out this link. Is this what you are trying to accomplish? http://www.cisco.com/warp/public/105/52.html#subfirstone There are other reasons to route to null as well. What are your goals? -Patrick Stanfast Preye 05/01/02 02:34PM Dear Group, Why is it necessary to configure all routers in a network with ip route xxx.xxx.xxx.xxx null 0 statement before implementing migrating to a new IP address scheme and DHCP service in the network. Somebody please help Regards, Preye. - Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax Confidentiality Disclaimer This email and any files transmitted with it may contain confidential and /or proprietary information in the possession of WellStar Health System, Inc. (WellStar) and is intended only for the individual or entity to whom addressed. This email may contain information that is held to be privileged, confidential and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any unauthorized access, dissemination, distribution or copying of any information from this email is strictly prohibited, and may subject you to criminal and/or civil liability. If you have received this email in error, please notify the sender by reply email and then delete this email and its attachments from your computer. Thank you. Do You Yahoo!? Yahoo! Health - your guide to health and wellness Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43105t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ip route statement [7:43001]
How a Null route can prevent a routing loop. If you have, for example, 4 networks behind you router. 10.1.0.0\24 10.1.1.0\24 10.1.2.0\24 10.1.3.0\24 And to reduce the size of the routing tables in the upstream routers you summarize those networks to one network. 10.1.0.0\26 and you have a default route point to the upstream router. All is good, until you lose one of your networks. Now you don't have 10.1.2.0\24 in your routing table, **^$#! So you send it to the upstream router, your gateway of last resort. The upstream router has your summary route so the packet is routed back to you, %^$^%^%*! And around it goes... In come the null route to save the day. Add a null route to your summary address and when you have the route in your routing table, more specific prefix, you route it accordingly. However, when a more specific route disappears packets destined to the missing route will match the null route, thus stopping the loop. Hope that explains at least one case. Philip -Original Message- From: Chuck [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 01, 2002 10:18 PM To: [EMAIL PROTECTED] Subject: Re: ip route statement [7:43001] can you provide an example of what circumstance might require the use of a null route to prevent a loop? My lack of imagination is preventing me from deriving my own example. Ladrach, Daniel E. wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... The Null interface is typically used for preventing routing loops. Daniel Ladrach CCNA, CCNP WorldCom -Original Message- From: Stanfast Preye [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 01, 2002 2:34 PM To: [EMAIL PROTECTED] Subject: ip route statement [7:43001] Dear Group, Why is it necessary to configure all routers in a network with ip route xxx.xxx.xxx.xxx null 0 statement before implementing migrating to a new IP address scheme and DHCP service in the network. Somebody please help Regards, Preye. - Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43123t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
ip route statement [7:43001]
Dear Group, Why is it necessary to configure all routers in a network with ip route xxx.xxx.xxx.xxx null 0 statement before implementing migrating to a new IP address scheme and DHCP service in the network. Somebody please help Regards, Preye. - Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43001t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ip route statement [7:43001]
I've never done this before... I've migrated countless networks to new ip schemes. But you have not given us a whole lot of info to go by. check out this link. Is this what you are trying to accomplish? http://www.cisco.com/warp/public/105/52.html#subfirstone There are other reasons to route to null as well. What are your goals? -Patrick Stanfast Preye 05/01/02 02:34PM Dear Group, Why is it necessary to configure all routers in a network with ip route xxx.xxx.xxx.xxx null 0 statement before implementing migrating to a new IP address scheme and DHCP service in the network. Somebody please help Regards, Preye. - Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax Confidentiality Disclaimer This email and any files transmitted with it may contain confidential and /or proprietary information in the possession of WellStar Health System, Inc. (WellStar) and is intended only for the individual or entity to whom addressed. This email may contain information that is held to be privileged, confidential and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any unauthorized access, dissemination, distribution or copying of any information from this email is strictly prohibited, and may subject you to criminal and/or civil liability. If you have received this email in error, please notify the sender by reply email and then delete this email and its attachments from your computer. Thank you. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43006t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ip route statement [7:43001]
I'm not sure what you mean by implementing migrating. The cammand that you mentioned is a easy efficient access-list alternative. Essentially it tells the router to drop all packets destined for the specified network. It's easier to setup than an access-list, and more efficent in terms of processor time. Putting that on every router would essentially kill that address space on the network, but you could also do that by changing the IP addresses on the interfaces. Perhaps you could explain a little further what it is you want to accomplish. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43007t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ip route statement [7:43001]
Never knew it was. Where does it say this is necessary?? I use routes to null to generate a route or send packets to a bit bucket. Dave Stanfast Preye wrote: Dear Group, Why is it necessary to configure all routers in a network with ip route xxx.xxx.xxx.xxx null 0 statement before implementing migrating to a new IP address scheme and DHCP service in the network. Somebody please help Regards, Preye. - Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax -- David Madland Sr. Network Engineer CCIE# 2016 Qwest Communications Int. Inc. [EMAIL PROTECTED] 612-664-3367 Emotion should reflect reason not guide it Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43011t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ip route statement [7:43001]
The Null interface is typically used for preventing routing loops. Daniel Ladrach CCNA, CCNP WorldCom -Original Message- From: Stanfast Preye [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 01, 2002 2:34 PM To: [EMAIL PROTECTED] Subject: ip route statement [7:43001] Dear Group, Why is it necessary to configure all routers in a network with ip route xxx.xxx.xxx.xxx null 0 statement before implementing migrating to a new IP address scheme and DHCP service in the network. Somebody please help Regards, Preye. - Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43026t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ip route statement [7:43001]
Hi Preye The Null interface is also used to filter the private network from the Internet. does this give u some clue ??? - Original Message - From: Ladrach, Daniel E. To: Sent: Wednesday, May 01, 2002 1:09 PM Subject: RE: ip route statement [7:43001] The Null interface is typically used for preventing routing loops. Daniel Ladrach CCNA, CCNP WorldCom -Original Message- From: Stanfast Preye [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 01, 2002 2:34 PM To: [EMAIL PROTECTED] Subject: ip route statement [7:43001] Dear Group, Why is it necessary to configure all routers in a network with ip route xxx.xxx.xxx.xxx null 0 statement before implementing migrating to a new IP address scheme and DHCP service in the network. Somebody please help Regards, Preye. - Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43040t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ip route statement [7:43001]
Hi Preye The Null interface is also used to filter the private network from the Internet. does this give u some clue ??? - Original Message - From: Ladrach, Daniel E. To: Sent: Wednesday, May 01, 2002 1:09 PM Subject: RE: ip route statement [7:43001] The Null interface is typically used for preventing routing loops. Daniel Ladrach CCNA, CCNP WorldCom -Original Message- From: Stanfast Preye [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 01, 2002 2:34 PM To: [EMAIL PROTECTED] Subject: ip route statement [7:43001] Dear Group, Why is it necessary to configure all routers in a network with ip route xxx.xxx.xxx.xxx null 0 statement before implementing migrating to a new IP address scheme and DHCP service in the network. Somebody please help Regards, Preye. - Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43049t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ip route statement [7:43001]
can you provide an example of what circumstance might require the use of a null route to prevent a loop? My lack of imagination is preventing me from deriving my own example. Ladrach, Daniel E. wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... The Null interface is typically used for preventing routing loops. Daniel Ladrach CCNA, CCNP WorldCom -Original Message- From: Stanfast Preye [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 01, 2002 2:34 PM To: [EMAIL PROTECTED] Subject: ip route statement [7:43001] Dear Group, Why is it necessary to configure all routers in a network with ip route xxx.xxx.xxx.xxx null 0 statement before implementing migrating to a new IP address scheme and DHCP service in the network. Somebody please help Regards, Preye. - Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43068t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ip route statement [7:43001]
Also, to supplement (or create) summary routes... Mike W. Ladrach, Daniel E. wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... The Null interface is typically used for preventing routing loops. Daniel Ladrach CCNA, CCNP WorldCom -Original Message- From: Stanfast Preye [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 01, 2002 2:34 PM To: [EMAIL PROTECTED] Subject: ip route statement [7:43001] Dear Group, Why is it necessary to configure all routers in a network with ip route xxx.xxx.xxx.xxx null 0 statement before implementing migrating to a new IP address scheme and DHCP service in the network. Somebody please help Regards, Preye. - Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=43070t=43001 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
