We ran into a problem this morning that I'm struggling with. We have 2 POPs connected together via fiber (75 miles or so). Along the way is series of non-Cisco broadband aggregation routers. We do not want to interface with the agg routers via OSPF. They are outside of our administrative control and would be more trouble than it would be worth to try and make it happen. We had these agg routers set up to carry a number of VLANs across the ring of agg routers to the other POP and a few ancillary sites in the middle. We met them with a trunk on each end, allowed VLANs, native for the local broadband traffic, etc. This part works alright.
The problem we discovered yesterday is that the agg routers are stripping out IS-IS packets. I could ping across the interface IPs (connected route) but I could not see any IS-IS packets. The only solution we had to work around that problem was a GRE tunnel. This worked and IS-IS worked right away. However this introduced a MTU problem in the backbone of the ISP. Web surfing worked but not that well. Larger downloads failed miserably. Etc. I can not find a way to raise the MTU on the tunnel. We requested that the MTU on all GigE interfaces on the agg routers be maxed out at 9216. I've already changed the MTU on our physical interfaces and associated SVIs. POP1 has a pair of 7600s running SRB. POP2 has a pair of ME6524s. The first router in each pair is supposed to connect via a VLAN to the first in the other pair and the same for the other pair of routers on another VLAN. By all account it should look like 2 separate paths between POPs. I'm trying to find another option for either raising the MTU on the GRE tunnel or perhaps switching to another tunnel type such as L2TPv3 and carrying the VLANs across myself. I am short on L2TP knowledge though. Any other ideas would be welcomed as well. Before it's suggested, no I can not eliminate the agg routers in the middle. We have get through them somehow. I already rolled back the changes but I do have a link up to test with. Thanks Justin _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
