Aastra VOIP phone and ELRP

[Mykhaylo_Skrypk]

Hi All,

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.

Thank you,
Mykhaylo

[Mykhaylo_Skrypk]

One of our senior engineers was doing troubleshooting in the lab. Results below:

As you could see from our tests in your lab , the other phones tested with ELRP operated as expected as does a direct cable loop ( using Loop vlan with all ports tagged ).

It is only the old phones 4422 that present this unexpected behaviour.

As we have already discussed ELRP uses a Multicast packet.. It would appear that the version of phone at your site , block these packets.

So we have basically 2 answers from an Extreme hardware point of view:

1:
The 4422 version of phone are being replaced, if so you could priorities those units that are connected to Extreme edge switches .

2:
Configure a basic STP configuration which as demonstrated will block the port ( led still active ) when a loop is detected .
SH STPD S0 detail , active port will be forwarding , other (looped ) port is shown as Blocked.

Thank you all for your input on this,

Mykhaylo