switchport voice vlan vs. normal vlan trunk configuration

Unanswered Question
Dec 1st, 2008
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Hello,

it would be fine if somebody could tell me what are the differences between the following two ways to configure a switchport to connect a phone with a pc behind it.


1.

int fa0/1

switchmode access

switchport voice vlan 22

switchport access vlan 33


2.

int fa0/1

switchport mode trunk

switchport trunk native vlan 33

switchport trunk allowed vlan 22,33


Both solutions work but I'm interested what are the differences in detail.


Best Regards,

Thorsten Steffen

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Chris Deren Mon, 12/01/2008 - 18:46
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    2017 IP Telephony, Contact Center, Unified Communications

Depending on the switch you are connecting to (older generation i.e. 3524) you were forced to use trunking (second example), it will still work on newer switches, but there is absolutely no reason to do this. Phones will automatically select the specified voice vlan and apply the data vlan to the PC port.

So, use 1st example unless your switch prevents you from it.


HTH,


Chris

thorsten.steffen Mon, 12/01/2008 - 23:41
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Hello Chris,

thanks for your quick answer.

So am I right that from switch view both examples work exactly similar which means building a trunk with one tagged vlan (voice) and one untagged native vlan (pc)?

When I used the "switchport voice vlan" configuration I did not get any output from the "show int trunk" command, is that correct? In my eyes it's still a vlan trunk.


Best Regards,

Thorsten

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