From: Gregg Malcolm (greggm@xxxxxxxxxxxxx)
Date: Tue Mar 12 2002 - 17:03:04 GMT-3
Michael,
One trick I've found extremely useful is "sh ip bgp x.x.x.x" where x.x.x.x
is a route that is not being advertised in BGP. Anytime you are doing IBGP
(which of course includes RR's and Confeds) you will have next hop issues.
I find the IBGP/EBGP next hop rule somewhat confusing. So, anytime I can't
get an IBGP route to appear in a neighbors BGP routing table, I show the bgp
route on the speaker that should be advertising it. If you have a next hop
issue, you will see a "not advertised to any peer" statement because the
next hop is not reachable. NHS on the appropriate router will fix. Just an
easy way to fix IBGP problems w/o memorizing the various IBGP/EBGP next hop
rules.
Gregg
----- Original Message -----
From: "Michael Snyder" <msnyder@ldd.net>
To: "'Tshon'" <tshon@netzero.net>
Cc: <ccielab@groupstudy.com>
Sent: Tuesday, March 12, 2002 11:04 AM
Subject: RE: Route Reflection vs. Next Hop Self, Answered.
> I agree. Thanks for everyone that answered my question. I believe my
> confusion came from working with a two router pod where split horizon
> wasn't an issue.
>
>
> Yes, this to have to functional differences. A router reflector
> overcomes the IBGP split horizon rule:
>
> If I learn it via IBGP I will not pass it to my IBGP neighbors.
>
> Next-hop-self:
>
> Overcomes the next hop propogation problem. If the next hop being
> advertised for a given route
> is not reachable, I can't use that route, so I set the Next hop to be
> the router who advertised it to me,
> instead of the next hop EBGP router that my internal router might not
> have knowledge of.
>
> Michael Snyder wrote:
>
>
> I've been reading up on BGP lately, and have come up with a question.
>
>
>
>
>
> Is there a functional difference between setting a neighbor as a route
>
>
> reflector client, or setting a neighbor as next hop self? Assuming 'no
>
>
> sync', to my mind these commands seem to do the same thing. The same
>
>
> network topology and limits seem to apply to each command.
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