How many BGP neighbor specific distance commands can be configured?

[sal-mahmood1]

How many BGP neighbor specific distance commands can be configured? I am using Cat6500 with IOS.

[Julio E. Moisa]

Hi

Could you please provide more details about the question?

[sal-mahmood1]

I have one cat6500 bgp-router with 4 ebgp neighbors and admin-distance modification (for external-routes) command to make this router as backup path as below:

router bgp 100
neighbor 1.1.1.1 remote-as 200
neighbor 2.2.2.2 remote-as 300
neighbor 3.3..3.3 remote-as 400
neighbor 4.4.4.4 remote-as 500
address-family ipv4
distance bgp 200 200 200

This distance command applies to all neighbors. Now I want to change this router to be the primary path for neighbor 2.2.2.2. So I am thinking of deleting this command and use neighbor specific distance commands for other neighbors (excluding 2.2.2.2).

[Julio E. Moisa]

Hi

You can also use BGP attributes to create backup, now you could use the following command before to delete the distance statement

router bgp 100
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 300
distance bgp 200 200 200
distance <administrative distance> <source IP it can be the neighbor 2.2.2.2> <wildcard should be 0.0.0.0> <ACL to match, example 1>

Sintaxis

distance <administrative distance 1-255> <source IP> <wildcard> <ACL>

example:

access-list 7 permit 192.168.1.0 0.0.0.255

access-list 7 permit host 172.16.1.77

distance 19 2.2.2.2 0.0.0.0 7

So if you are receiving the networks includedo into the ACL 7 and advertised by the source address 2.2.2.2  it will apply the administrative distance of 19 for the networks into the ACL 7.

You could try that. 

[sal-mahmood1]

So the neighbor-specific distance statement will have higher priority right?

[Georg Pauwen]

You mean when you have both:

distance bgp 200 200 200

and

distance 15 2.2.2.2 0.0.0.0

in your BGP configuration ? Yes, distance 15 2.2.2.2 0.0.0.0 will take precedence...

[sal-mahmood1]

Thanks a lot for your help. I will try it in few days.

[Georg Pauwen]

Hello,

in addition to Julio's post (hopefully I am not saying the exact same thing), and that is I think what you are trying to do, you can simply set the distance for neighbor 2.2.2.2 to something lower like the default (20 for EBGP):

distance 15 2.2.2.2 0.0.0.0

You don''t need to set the distance for the other neighbors, since the default is higher than 15.

[sal-mahmood1]

Thanks a lot for your help.

[Julio E. Moisa]

You are welcome, please keep us posted.

:-)

[Georg Pauwen · Accepted solution]

Credits go to Julio. I was just trying to elaborate and clarify...