best practice for voice vlan - access or trunk

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Rob Huffman Tue, 11/03/2009 - 10:00
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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

Brandon Svec Tue, 11/03/2009 - 15:15
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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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