What I've done in the past is port-mirroring, where you can even mirror a port to a remote-port, meaning your wireshark/whatever probe can site on a completely different switch.
The other option is to tcpdump locally ON the switch. Yes, there's a packet capture command! Of course you may not want to keep that running forever - the switch does have limited space...
I usually just need to troubleshoot things and capture a few minutes of traffic, then tftp the captured file to a server and read it through wireshark after the capture. You could possibly even script that (capture this much data, stop, transfer file, erase file, start capturing again, rinse-repeat)
https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-perform-a-local-packet-capture-on-a...
https://gtacknowledge.extremenetworks.com/articles/How_To/Perform-a-packet-capture-in-the-EXOS-CLI-u... That's the one I usually go by.
Sorry, wanted to reply 2 days ago...
Frank