[c-nsp] GRE tunnels between Cisco ME3600X

[Gert Doering]

Hi,

On Tue, Apr 17, 2012 at 01:40:46PM +0100, paul.magee at agencyport.com wrote:
> I have a GRE tunnel established between two of these things, they show
> up in each other's CDP neighbours, a BGP session is established between
> them, and they are exchanging routes. BGP learned routes are inserted
> into the routing table but it doesn't seem to actually route through the
> tunnel, as though for some reason, the route in the routing table is
> ignored. If I add a static route to the remote tunnel address, both it &
> the learned route are immediately dropped from the routing table. On a
> probably related note there is no arp entry for the remote tunnel
> address on either router...

This sounds like "the control plane knows how to do GRE, but the
forwarding plane does not".  

So your BGP and CDP speaker can insert packets into the tunnel, but 
the hardware forwarding engine has no idea how to handle that - and
while it could give the packet to the CPU to handle it, it sanely
decides to not do that.

But that's just guesswork.

gert
-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 305 bytes
Desc: not available
URL: <https://puck.nether.net/pipermail/cisco-nsp/attachments/20120417/051f0172/attachment.sig>