Installed VSS 6800 pair with 3 IA groups for a customer in a pretty small network. This 6800 is core and four wan routers terminate into IA's for branches, Internet etc. Transitioned them off a pair of 4507's with a trunk between the two networks and using HSRP migrated everyone over.
Now that EVERY device is running on the 6800's and 4500's to totally empty its time to allow hsrp values to change and move the active gateway to 6800's to take over layer 3 and turn down the 4500's. When we do so the network comes to a crawl. I put the cable back in for the 4507 router on a stick and speed comes right back. I can find no errors, no reasons for this to happen checking everything so many times. They have a few static routes and rest are eigrp neighbor routes from the wan routers mentioned. Traceroutes show same paths as computers are all in IA's going to one router or another for destination. From switch I see no latency to computer 1, nor to computer 2, but computer 1 and computer 2 can hardly speak to each other its so slow. At any time routing goes back to 4507 where all traffic must hairpin out and back in the speed is very fast, lose that hairpin "router on a stick" and business crashes. This is final step to get 4500's out of production and cpu remains around 22%, no bad stats on interfaces, no drops etc. no syslog errors whatsoever, eigrp routes and statics, infact config matches 4507 but for IA's in place. Very small network with 4 routers, plus core, 3 IA "IDF" stacks, 2 for users 1 is on core for data center routers. No acl's and only default qos is enabled, traffic numbers are very very low but when hsrp standby goes active on 6800X it crawls despite how little traffic. It all dies at single vlan 4, but that vlan is where ALL layer 3 happens as its home to all routers. No line cards in 6800's so IA ports are used which is not what I like to do but Cisco markets and sells them as fully capable so customer ran with that. All inf ports are dual 10GB port-channels, dual 10GB to each of 3 fex stacks, dual 10GB VSL links, all other ports are 1Gb IA terminated pc's and routers.
Anyone aware of layer3 forwarding issues ?? tonight was last straw, rebooted vss pair and still does same thing, can recreate at will, just have to allow a hsrp standby IP to go active... and yes also removed hsrp standby's and changed IP to .1 on SVI as its not needed once the 4500 is offline.. leaving as without 4500 business cannot run.
thanks in advance,
dave
