We are currently struggling with an issue which appears to exist between our Extreme edge switches and certain models of VoIP phones.
Basically, despite having ELRP configured, if a user creates a loop by plugging both the PC and LAN ports on the back of a phone into the same switch the switch does not detect it.
We have carried out packet captures. With a laptop plugged directly into the switch, we see the ELRP packets every 2 seconds. If we put one of these phones in between (with the laptop plugged into the phones PC port) the ELRP packets do not arrive.
This suggests that the phones are stripping/filtering the packets in some way.
Any suggestions are welcome.