From: Scott Morris (swm@emanon.com)
Date: Tue Oct 03 2006 - 20:59:47 ART
Are you restricted from using an IP address in the tunnel (e.g. why did you
choose to use unnumbered?)??? If you had something unique there it would
make life MUCH easier. :)
Like any method of route recursion, it will go for the best path to get to
whatever the next-hop happens to be. When you say you have a static route
there, how specific is it? (is ospf more specific?) What's the AD.
Put yourself in the router's shoes. You know how BGP sessions are setup,
it's simply TCP. So walk your brain through it step by step (on each
router, by the way, 'cause each one makes its own decisions), and trace how
the packet would move, and what each device decides as it gets passed along.
These types of exercises will reinforce a lot in your head about stuff like
this, and can more readily answer these questions for you! The router makes
very basic decisions. We just need to understand them first!
Cheers,
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-J
IPExpert VP - Curriculum Development
IPExpert Sr. Technical Instructor
smorris@ipexpert.com
http://www.ipexpert.com
_____
From: Chris Broadway [mailto:midatlanticnet@gmail.com]
Sent: Tuesday, October 03, 2006 6:13 PM
To: swm@emanon.com; ccielab@groupstudy.com
Cc: bmcgahan@internetworkexpert.com
Subject: Re: ibgp tunnel sample config needed
Brian and Scott,
I think the main confusion I am having is the neighbor statement in BGP.
R1 (bgp)--------R2 (Non bgp)-------R3(BGP)
tunnel====================tunnel
The Tunnel config on R1 would look something like this:
R1
tunnel 1
ip unnumbered eth 0/1 (R2 facing interface)
tunnel source 192.168.1.1 <http://192.168.1.1/> (R2 facing interface)
tunnel destination 172.168.1.1 <http://172.168.1.1/> (R2 facing interface
on R3)
R3
tunnel 1
ip unnumbered eth 0/1 (R2 facing interface)
tunnel source 172.168.1.1 <http://172.168.1.1/> (R2 facing interface)
tunnel destination 192.168.1.1 <http://192.168.1.1/> (R2 facing interface
on R1)
There is ospf runing on R1, R2 and R3. R1 can reach R3 and vice verse. The
tunnel comes up and I can send traffic from R1 to a loop interface on R3
using static routes.
I am messing up on the BGP configuration. If I use the e0/1 interfaces on
R1 and R3 as the neighbor statements, it will use the route learned through
ospf instead of the tunnels to form the adjacency. Am I using the correct
interfaces for neighbors and tunnels? If so, How do I force the neighbor
adjacency to form through tunnels?
-Broadway
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