Voice VLANs

[nelson.garcia]

Not sure if this is the right thread or if I should put this under LAN switching, but here it goes.

I know that with Catalyst switches you can issue the "switchport voice vlan #" command to separate voice and data traffic by utilizing CDP to communicate with a Cisco IP phone connected to that port.

My question is, what is the best practice for separating voice and data traffic on the same port with non-Cisco IP phones?

Thanks guys.

[Leo Laohoo]

Depends on the manufacturer, I guess.  We use the same config when we had Nortel VoIP phones.

[nelson.garcia]

You used the voice vlan command with Nortel phones? Do they support CDP or what? How did the switch know which packets were voice.

[William Bell · Accepted solution]

Well, that depends on the hardware and software you are dealing with for end point and switch.

Clearly, best practice is to keep voice and data separate.  The question is whether you can do this manually or dynamically via a protocol like CDP.  For the dynamic option you would be looking for your switch and endpoints to support LLDP-Med:

http://www.cisco.com/en/US/technologies/tk652/tk701/technologies_white_paper0900aecd804cd46d.html

http://en.wikipedia.org/wiki/Link_Layer_Discovery_Protocol

You will want to research this and test it out before going to production.

HTH.

Regards,
Bill

Please remember to rate helpful posts.

[nelson.garcia]

Ahh, I think I read about LLDP somewhere, isn't this the successor to CDP?

Also, what is the manual way of going about this?

[William Bell]

Successor?  No, not really.   LLDP is just a standardized approach.  CDP isn't the only proprietary method for exchanging data at the logical  link layer.  There are others.

The manual method would be dictated by your endpoint manufacturer.  You would have to configure VLAN separation on the phone directly.  Essentially, the phone will participate in a dot1q trunk with the switch.  You may even need to configure the switch port as a trunk (or auto?).  Something you would need to play with to find out what works best for your switch and phone combo.

HTH.

Regards,
Bill

Please remember to rate helpful posts.

[nelson.garcia]

Perfectly clear, thanks for the awesome link, and yes I read that LLDP is a stanardized approach and not a successor. Looks like the 6757i Aastra phones we use support LLDP.

Thanks again.