simple way to trace the l2 path across multiple nexus 7k,5k,2k and 6500

[cnicules]

Hello,
i have for a client to identify the forwarding path over a local lan build with nexus switches.
a fairly simple architecture: n7k as core, a couple of n5k and each n5k with a couple of n2k.
6500 as routing, firewall point. all the equipment are dual homed with vPC. some n5k and n2k are with multiple uplinks.
there is a big mix of interfaces, 40G, 10G, 1G fiber, copper....

there are some strange behaviors of slow performance on some flows, no apparent interfaces errors or drops.
started to do "sh port-channel load-balance forwarding-path int port-channel 1 ...." but it's a pain.

is there a tool that can trace and ideally track in real time if the path change for a particular flow?

Thanks,

Ciprian

[Paul Chapman]

Hi Ciprian -

I've seen some marketing material from LiveAction for this type of analysis, but I can't speak to it from personal experience.

Just be aware that Nexus platforms will use cut-through switching for traffic that ingresses and egresses through interfaces running at the same speed (particularly 10G and higher and some variation for 1G).  The resulting behavior is that damaged L2 frames will not be dropped by the platform and increment counters.  If you have a bad fiber module in the path somewhere, it will take a bit of troubleshooting to flush out. (This is from personal experience.)

PSC