Hello. In ios-xr the mtu is the L2 mtu while in vanilla ios the mtu is L3 mtu. This gives that XR is including L2 headers in the mtu setting. So in reality you have matching MTUs at present but when you configure XR with an mtu of 1500 you get a mismatch. How is the etherchannel configured? Is the 6509 routing anything or are you using it as a switch?
Bästa hälsningar / Best regards, Gustav Uhlander Senior Communication & Infrastructure Engineer Steria AB Kungsbron 13 Box 169 SE-101 23 Stockholm Sweden Tel: +46 8 622 42 15 Fax: +46 8 622 42 23 Mobile: +46 70 962 71 03 gustav.ulan...@steria.se www.steria.se -----Original Message----- From: cisco-nsp [mailto:cisco-nsp-boun...@puck.nether.net] On Behalf Of Lee Starnes Sent: den 20 maj 2014 23:00 To: cisco-nsp@puck.nether.net Subject: [c-nsp] MTU packet loss problem 12410 XR and 6509 Hello everyone, A strange MTU issue has popped up and for the life of me I am unable to figure out why. This seems to only affect one Metro-E carrier and only when the traffic passes between the 6500 and the 12410. ME Carrier A ---> 10G 6509 ----bundle-ether1(4G)--->12410A ME Carrier B ---/ \-----bundle-ether2(4G)--->12410B ME Carrier C --/ Traffic that passes from either 12410 to customer links on ME carrier A are seeing MTU issues and packet loss. Traffic across those same links for carriers B and C have no issue. To test this, we can ping from from the 12410 to a site on ME carrier A with 1500byte packet size and get packet loss. The same test to clients on ME carrier B and C have no issues. Now, since no changes were made on our end and the carrier states no changes were made on their end, we are at a standstill. However, I did see that the MTU size on the 12410's is by default 1514 and the MTU on the 6500 is 1500. Changing this to match 1500 on both sides causes no traffic to pass. I'm not sure why both sides of the bundle-ether interfaces matching MTU causes 100% packet loss. Anybody have any ideas on why matching MTU size would cause no traffic to pass? Ultimately the carrier will need to fix their issue, but I would like to understand why this problem of matched MTU sizes causes no traffic. Thanks. -Lee _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4570 / Virus Database: 3950/7522 - Release Date: 05/19/14 _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
