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Hi,The same configurations of regular IP over GRE should be applied over physical interfaces, once the tunnel get ip, establish your routing protocol and LDP over the tunnel interface, based on the MPLS application you gone use decied the maximum number of labels will be included in one packet (4 bytes per label) then add the 24 GRE header and adjust your MTU.Best Regards,Mounir Mohamed
I understand. But, I really don't know how can I configure. I tray something but it isn't working. I cannot establish the MP-BGP session over my GRE tunnel. I made the GRE tunnel and I put the GRE interface into one VRF. I'm a little bit lost and I need a configuration example to have a starting point.Thanks, Alexandru Nitulescu
Hello alexandru,one thing is to have a GRE tunnel as a VRF access link, another different matter is to use the GRE tunnel as your backbone link between PE routers.in a few words to support MPLS forwarding and signaling you enable MPLS into the tunnel interface with mpls ip command.PE1 interface tunnel 12tunnel source <local PE pub ip address>tunnel destination < remote PE pub ip address >ip address 10.x.y.1 255.255.255.252mpls ip! some mtu fixing may be necessaryinterface loop5ip address 172.16.12.1 255.255.255.255an IGP running over 10.x.y.0/30 + mpls ldp router-id loop5 or change mpls source on the tunnelrouter ospf 12network 10.x.y.0 0.0.0.3 area 0network 172.16.12.1 0.0.0.0 area 0!router bgp 12address-family vpnv4 neighbor 172.16.12.2 activateneighbor 172.16.12.2 update-source loop5neigh 172.16.12.2 send-community bothConstraint:the public ip addresses are different from 10.x.y.0/30 and 172.16.12.x and must be known / advertisedpublic ip addresses mustn't be advertised over IGP running over GRE tunnel (try and see what happens ...)hope to helpGiuseppe