[c-nsp] as-override

[Peter Rathlev]

Hi Gary,

The as-override only works if the AS being overridden (from R1) is the
same as the AS of the neighbor (R3), in which case it is replaced with
the providers AS (R2). When they're differente ASses (no pun!) it won't
have any effect.

Removing the AS from R1 would defeat the loop-prevention in BGP. What if
R3 were to announce routes to R1 by other means? So forgive my asking:
Why do you want to remove the AS when sending prefixes to R3? :-)

Regards,
Peter

On Fri, 2008-04-11 at 13:30 +0100, Gary Roberton wrote:
> I have a router that is receiving updates from a site router with an AS I
> want to replace.  I have used remove-private-as and this works but I need to
> see it I can get as-override working.  I have the following;
> Router 1 (10.5.5.1) > Router 2 (10.5.5.2) > Router 3 (10.35.3.74)
> 
> Router 2 is to remove the AS of Router 1.   I have the following config in
> Router 2
> 
>  router bgp 2856
>  no synchronization
>  bgp router-id 10.5.5.2
>  bgp log-neighbor-changes
>  no auto-summary
>  !
>  address-family ipv4 vrf cc
>   redistribute connected
>   redistribute static
>   neighbor 10.5.5.1 remote-as 64537
>   neighbor 10.5.5.1 activate
>   neighbor 10.35.3.74 remote-as 64603
>   neighbor 10.35.3.74 update-source FastEthernet0/1
>   neighbor 10.35.3.74 activate
>   neighbor 10.35.3.74 as-override
>   no synchronization
>  exit-address-family
> 
> I have tried the as-override on both neighbor statments and neith works.  I
> have two questions,
> 1. On which neighbor statement do I put as-override
> 2. Is there anything missing?
> 
> Thanks
> 
> Regards
> 
> Gary
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