Re: bgp peering+RR posted 10/11/2007
- Subject: Re: bgp peering+RR
- From: "Joseph Saad" <joseph.samir.saad@xxxxxxxxx>
- Date: Fri, 12 Oct 2007 00:30:19 +0400
- Cc: "Cisco certification" <ccielab@xxxxxxxxxxxxxx>
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whether R1 and R4 Loopbacks still reachable by R4 and R1 respectively.
Independent of Route reflection, if reachability is maintained via other
means (e.g. via R3) the R1 eBGP-learnt routes will be advertised to R4 via
the direct iBGP peering between R1 and R4. in Summary, the iBGP peering is
not broken in the first place.
If not, then you need to consider the Route-reflection rules.
Jeff Dolye Page 137: RFC 1966 defines three rules that the RR uses to
determine who the route is advertised to, depending on how the route was
l If the route was learned from a non-client IBGP peer, it is reflected to
l If the route was learned from a client, it is reflected to all nonclients
and clients, except for the originating client.
l If the route was learned from an EBGP peer, it is reflected to all clients
with R3 as the route-reflector, it has learnt the route via a non-client
iBGP peer (from R1), hence it will be reflected to clients only (R2 & R%).
Which means R4 shouldn't receive it.
Hope this helps.
On 10/10/07, slevin kremera < slevin.kremera@xxxxxxxxx> wrote:
> / \
> / \
> / \ / \
> / \ / \
> r2 r5 r2
> here all the routers are in as100. r1-r3-r4 are full meshed and peering
> lo0. r2 and r5 are peering with r3 and r4..I am planning to make r2 and r5
> as rr-clients for r3 and r4
> .The question here is if the link between r1 and r4 is broken and r1
> recieves an ebgp updates from outside..will it fwd it to R4??
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