GRE over MPLS

bruno.hodge · ‎05-03-2010

Hello people,

im facing problem trying to establish a GRE tunnel over mpls. The topology goes as follows:

(server) ----CE1(6500)-----PE1(6500)----vrf cloud-----CE2(6500)--FW

-server needs to establish a gre tunnel with FW.

-server receives a default route from CE1 via OSPF.

-CE1 has an default static route pointing to the next hop which is an interface VLAN (in a vrf) on PE1.

- PE1 receives a default route generated by CE2 (via mpbgp).

In this situation the GRE tunnel wouldnt come up.The only way i got the GRE to work was replacing the default static route on CE1 with a more specific static route.

On both cases (default AND specific static routes) the connectivity(ping) from end to end was there.

Has anybody seen anything alike?

thanks,

Bruno

jan.nielsen · ‎05-05-2010

I'm sorry i don't understand your setup, what kinda server supports GRE ?

bruno.hodge · ‎05-05-2010

Actually it is an GGSN.

jan.nielsen · ‎05-06-2010

You could be looking at some recursive routing throug the GRE interface, so the second it comes up it will try to put the GRE packets through the GRE tunnel, this creating a loop. Are you using a dynamic routing protocol to get network info over the GRE tunnel or a static route if so, how is it setup ?