[c-nsp] as-override

[Gary Roberton]

Peter

Thanks for your reply.  Why can't Cisco put it as simply as that.

I am only trying to replace the AS as the one being advertised by R1 is used
again by another part of the network.  i.e. R5 also uses the same AS
number.  I need my network to be advertised through to R5 and R5 would drop
the updates if it saw its own AS number inthe path, therefore I am trying to
find various options to 'hide' the AS of R1.  This was one of the potential
options but not now as it doesnt do what I want it to do.

Hope this makes sense.

Gary

On Fri, Apr 11, 2008 at 4:29 PM, Peter Rathlev <peter at rathlev.dk> wrote:

> 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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