From: Danny Cox (dandermanuk@gmail.com)
Date: Sat Nov 12 2005 - 11:15:50 GMT-3
On 11/11/05, dusth@comcast.net <dusth@comcast.net> wrote:
> Hi all, I need some clarification on how does bgp know to traverse inside the tunnel and what parameter of the tunnel interface tell that for bgp end points? I do not have access to the lab right now so I can not verify the config.
> Here is the example:
> r1:
> interface tunnel 14
> ip unnumber loopback 0
> tunnel source 1.1.1.1
> tunnel destination 4.4.4.4
> bgp 10
> nei 4.4.4.4 remote-as 10
> nei 4.4.4.4 update-source loopback0
> Does the ip unnumber of the tunnel or the tunnel source & destination tell router that bgp traffic need to traverse inside the tunnel?
As Leigh said in another post, this won't work because the BGP traffic
will just follow the route given by the IGP. If you manage to get the
IGP to indicate that it should go down the tunnel, then that's the
route which GRE will try to use and the tunnel will be like a snake
eating its own tail.
On the other hand, if you use policy routing you can do this. Set the
next-hop to be 4.4.4.4 for BGP traffic only, specified using a route
map and an ACL. That way the GRE traffic will follow the IGP route,
but BGP traffic will go down the tunnel.
Hope that helps?
cheers
Danny
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