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Re: OpenBGPD incorrect gateway problem in rib and fib
- To: misc_(_at_)_openbsd_(_dot_)_org
- Subject: Re: OpenBGPD incorrect gateway problem in rib and fib
- From: Andrew Veitch <ajv-openbsd-misc_(_at_)_erkle_(_dot_)_org>
- Date: Thu, 18 Nov 2004 16:45:42 +0000 (GMT)
On Thu, 18 Nov 2004, Claudio Jeker wrote:
To add a little more confusion, set nexthop sets the exit nexthop (which
is announced via bgpd) whereas "bgpctl show ip bgp" shows the true nexthop
which is the same as "netstat -rnfinet" shows.
In my test scenario, I have a couple of routers as follows:
rtr1: IP A.A.A.A
BGP session to rtr2 (B.B.B.B)
rtr2: IP B.B.B.B
BGP session to rtr1 (A.A.A.A)
BGP session to upstream router (C.C.C.C)
In my current configuration, the gateway/nexthop for all non-upstream
traffic is being set to the IP address of the upstream router (C.C.C.C)
where is should be set to the IP address of rtr1 (A.A.A.A).
I attempt to rectify this by using "set nexthop A.A.A.A" in the relevant
neighbor configuration on rtr2. However, this doesn't seem to affect
the gateway/nexthop used.
From your comment above, I attempted to "set nexthop A.A.A.A" in the
neighbor configuration on rtr1 - so that rtr1 would announce routes
with the appropriate nexthop set, but still rtr2 seems to want to use
Should I be looking to use the filters to set the appropriate
gateway/nexthop for traffic from rtr2? I'm wary as the configuration
changes I've attempted don't seem to be having any effect at all, and
when I tried this on my main system, it resulted in traffic which
should have been passed internally (as a result of an iBGP session)
traversing one upstream to reach another, even though there was a
better route available via another "internal" router.
Basically, what I'm looking at is what I need to put in the configuration
file to affect the gateway/nexthop that is displayed (and used) by
the "bgpctl show ip bgp" and "netstat -rnfinet" commands for routes
pertaining to a particular neighbo(u)r's peering session.
Andrew Veitch mailto:ajv_(_at_)_erkle_(_dot_)_org http://erkle.org/
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