[c-nsp] Believing iBGP over eBGP?

[Daniel Roesen]

On Wed, Aug 11, 2004 at 03:13:42AM -0500, Patrick Bohannon wrote:
> BorderA is also getting just a default route from its eBGP peer, which is
> probably implied here already.  Shouldn't the administrative distance of 20
> associated with eBGP-learned routes supercede the administrative distance of
> 200 associated with iBGP-learned routes?

No, AS_PATH length rules. Your default route from Upstream B has a
4-hop AS_PATH of "4279 4279 4279 7132" while your Upstream A default
route has just one single AS (4323).

> borderB#sh ip bgp 0.0.0.0 
> BGP routing table entry for 0.0.0.0/0, version 128
> Paths: (3 available, best #3, table Default-IP-Routing-Table)
>   Not advertised to any peer
>   4279 4279 4279 7132
>     x.x.x.x (borderB's eBGP peer) from x.x.x.x (borderB's eBGP peer)
> (x.x.x.x)
>       Origin IGP, localpref 100, valid, external
>   7132, (received-only)
>     x.x.x.x (borderB's eBGP peer) from x.x.x.x (borderB's eBGP peer)
> (x.x.x.x)
>       Origin IGP, localpref 100, valid, external
>   4323
>     x.x.x.x (borderA's eBGP peer) (metric 20) from x.x.x.x (borderA)
> (x.x.x.x)
>       Origin IGP, localpref 100, valid, internal, best

Given from that output, it seems that you are prepending in the ingress
route-map applied to RouterB's EBGP peer with your own AS4279. This
makes the default route worse compared to the other default route from
Time Warner AS4323


Best regards,
Daniel