11-03-2009 09:39 AM - edited 03-18-2019 10:46 AM
there are 2 ways to configure a port that connects a phone and piggy backs a PC.
1)
switchport access vlan 1
switchport voice vlan 2
2)
switchport trunk encap dot1q
switchport mode trunk
switchport trunk native vlan 1
switchport voice vlan 2
which is best way... is there a doc?
11-03-2009 10:00 AM
Hi Joel,
The Trunk mode setup was a Cisco "best practice" on the older 3500XL Switches (like the 3550).
The switchport mode trunk method was the only way to go, but on all newer versions (like the 2960/2970/3750)the need for Switchport mode Trunk is not necessary..
I do know that it is unnecessary to configure the switchport in Trunk mode because when you use the Voice VLAN (with an "Access" vlan) command a "special" dot1q trunk is automatically setup. The reasons I have seen to support this setup are many and vary from minimizing Trunking overhead to ease of configuration and everything in between :)
Here is one of the better threads I have ever read on this issue (with some Tac links as well). There are some great answers from Mahesh,Paolo Sankar and others here.
http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Unified Communications and Video&topic=IP Telephony&CommCmd=MB?cmd=pass_through&location=outline@^1@@.1ddd5905/14#selected_message
Hope this helps!
Rob
11-03-2009 02:16 PM
thanks
11-03-2009 03:15 PM
I think that "switchport voice vlan" depends on the the phone supporting CDP? Someone, please correct me if I am wrong about this. In case you used non-Cisco phones assuming they have VLAN ability, you could use this:
switchport trunk encapsulation dot1q
switchport mode trunk
switchport trunk native vlan DVLAN
switchport access vlan VVLAN
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