Hey, Has anyone seen issues with the load balancing on port-channels going to hosts connected to FEX's attached to Nexus 7k's?
We have a few hosts that are connected via port-channels to either a 2248 or 2232 FEX. The FEX's are hanging off of a 7k. This is working as far as I can tell, in that all of the ports appear to be operational in the port-channel. On the switch though, I'm seeing 99.99% of the traffic being sent out of one of the links in the 4 port port-channels (with "show port-channel traffic"). Some of the port-channels show 100% of traffic over one link, a few are just 99.99% or something like 99.92%. I'm seeing reasonably balanced stats for received traffic. One of the 7k's is using L3+L4 hashing, one is using just L3. With "show port-channel load-balance forwarding-path", I can see that if I change one of the source IP's, the 7k says that it will choose a different link in the port-channel. I'm still waiting on one of the server guys to let me know what IP's are connecting to these servers, but it seems somewhat implausible to me that this is caused by there just being a very small number of large flows that happen to get hashed onto the same link. I'm seeing this on all of the host facing port-channels that we have off of the FEX's, and I see this historically looking through our monitoring system, as well as right now. These are 7k's running 5.2(3a). I'm noticing this on two different 7k's, with both 2248 and 2232 FEX's, and across 10+ different port-channels to hosts. I'm not seeing this on any of the routed L3 port-channels to other network devices though. The load balancing on the port-channels between the 7k and the FEX's themselves also looks reasonable. Thanks, Oliver ------------------------------------- Oliver Garraux Check out my blog: blog.garraux.net Follow me on Twitter: twitter.com/olivergarraux _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
