From: Scott O'Donnell (scotto@xxxxxxxxxxxx)
Date: Fri Oct 15 1999 - 11:24:06 GMT-3
Ben,
Check the IGP routing table on R2, I think you will find that a route to
the loopback
in question is not present. The whole "Sync" thing was VERY hard for me
to grasp but
here goes an attempt at an explanation.
R2 is an IBGP peer to R3 and for a IBGP update to be accepted, the route
needs to be
validated by an IGP.
I would guess that R1 doesn't learn about it as an EBGP neighbor because
R2 will not
send it out in an update to a EBGP neighbor until it can guarantee the
route is
legitimate within it's own AS.
I would think if you do one of the two following, things should start to
look right.
1.) Allow R2 to learn the loopback route via an IGP like RIP, EIGRP,
etc.
2.) Use "no Sync" on R2 and bypass the requirement for R2 to validate
the update from R3 via an IGP
I'm no expert (yet) but I think I'm on target.
Anyone out there see anything I missed?
Best of luck on #3
Scott
> Ben Rife wrote:
>
> Hi guys,
>
> Question:
> I have an AS 300 which has 2 routers, both running BGP. One of the
> routers is connected to another AS 100 as follows:
>
> ======== =========
> ROUTER1----------------ROUTER2
> |
> ======== |
> AS100 ROUTER3
> =========
> AS300
>
> On router 3, I have created a loopback interface and given it an
> address. I want to advertise it to Router1/2. In order for Router 3 to
> advertise it to Router 2, I have to turn off synchronization on 2 and
> 3. Why? How does the rule of synchronization affect things here?
>
> Thanks for all your help,
> TRy #3 (Dec 5-6, RTP)
>
> Benjy Rife
> MCSE, CNE, CCIE Candidate
> brife@bignet.net
> www.bignet.net/~brife
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