Tagging Issue

[marksgt]

Customer of mine has a Cisco 3560 switch with multiple vlans defined. We are setting up a 3Com voip system on its own vlan. The 3Com NBX supports vlan tagging. If we set the NBX to tag and the switch port that it is connected to as an access port only, the port runs errors and phones do not work properly. The phones support tagging. We have this set up identically in many other customer sites. We know the issue is with the switch not 3Com configuration, however we do not know why the switch is tossing the tags. Any insight will be appreciated.

Mark Sargent
sargent@getadvanced.net

http://www.getadvanced.net

 

[vipergg]

Did you set the cisco up for trunking for the correct vlan that supports the voip.

 

[marksgt]

Yes we did.... We finally set two ports as access ports in a totally separate vlan from the data. Plugged the phone system into one of the ports and a phone into the other. The phone still would not work. The port that the phone system was plugged into would run errors (the system supports tagging and was set to tag). As soon as we would turn off tagging on the system it would work just fine.

Mark Sargent
msargent@getadvanced.net

http://www.getadvanced.net

 

[voltron1011]

Make sure that you have the ports of the switch set for 'dot1q' trunking. Cisco has their own proprietary tagging method (ISL) that is used on some of their switches.