nanog mailing list archives
Re: GRE Tunnels and MPLS
From: Shimol Shah <shimshah () cisco com>
Date: Thu, 04 Nov 2010 16:49:55 -0400
Do you have recir enabled ? If not, good one to enable and check for status of issue.
http://www.cisco.com/en/US/docs/ios/mpls/command/reference/mp_m1.html#wp1012208"If you do not enable tunnel-MPLS recirculation, the IPv4 and IPv4-tunneled packets that need to be labeled (for example, the packets that are encapsulated with an MPLS header) will be corrupted when they are transmitted from the Cisco 7600 series router."
Shimol On 11/4/10 4:00 PM, Rettke, Brian wrote:
Beginning work on our implementation of MPLS for the backbone network. I've run into difficulty with our GRE tunnels. The GRE Tunnel sits on our co-lo router (a Cisco 7600), and it uses a route-map to push our 10.x modem traffic to our DHCP servers. This is because the backbone is not complete and DHCP traffic needs to traverse the internet. What I have found is that when I enable basic MPLS on the co-location interfaces that head back to the individual systems, DHCP traffic still works, but ICMP and other 10.x traffic dies. There is also an intermittent problem with DHCP when it is enabled, where not all DISCOVERS are answered. I've tried everything I can think of, including adjusting MTU and TCP MSS. It only seems to impact when the co-location router has a GRE tunnel on one buffer, which it terminates, and then it has to encapsulate traffic with an MPLS tag before sending out of the other buffer. Theoretically, it should work, but I can't figure out if there is some prob
lem with MPLS' interaction with the tunnel. Has anyone encountered something similar?
Sincerely, Brian A . Rettke RHCT, CCDP, CCNP, CCIP Network Engineer, CableONE Internet Services
Current thread:
- GRE Tunnels and MPLS Rettke, Brian (Nov 04)
- Re: GRE Tunnels and MPLS Shimol Shah (Nov 04)
- <Possible follow-ups>
- Re: GRE Tunnels and MPLS Rettke, Brian (Nov 08)
- Re: GRE Tunnels and MPLS Shimol Shah (Nov 08)
- RE: GRE Tunnels and MPLS Rettke, Brian (Nov 09)
- Re: GRE Tunnels and MPLS Shimol Shah (Nov 10)
- RE: GRE Tunnels and MPLS Rettke, Brian (Nov 10)
- Re: GRE Tunnels and MPLS Shimol Shah (Nov 08)