From: James Ventre (messageboard@ventrefamily.com)
Date: Thu Jun 01 2006 - 08:09:33 ART
Scott Morris wrote:
>The voice vlan command is used to modify a field in CDP frames so that
>the Cisco IP phone can read what the voice vlan (or auxilliary vlan if
>you've been around a while!) is to help it "discover" itself. But
>otherwise, doesn't really dictate anything.
>The trunking portion really isn't covered in there at all because both
>Cisco's IP phones and the 3550 work with dynamic trunking protocols to
>magically figure things out! If you are running on a different
switch >(or NM-16ESw), you'll need:
What do you mean by "dictate anything"? Using this config sets up a
trunk with 2 Vlans (despite being configured as an access port) and it
works without any negotiation happening:
interface FastEthernet0/1
switchport access vlan 227
switchport mode access
switchport voice vlan 209
service-policy input IP-Telephony
no logging event link-status
no logging event power-inline-status
spanning-tree portfast
spanning-tree bpduguard enable
spanning-tree guard root
end
The first VLAN on the trunk is the untagged vlan (configured with the
access vlan), and the second is the voice vlan. This voice is the
tagged vlan. There is no trunking negotiation taking place - it's
plugged into an AVAYA telephone, and I can assure you, it works (I just
received a telephone call a few minutes ago). I notify the telephone of
the tagged vlanid by offering it via DHCP.
IPTel-2nd-Floor-1>show int trunk module 1
Port Mode Encapsulation Status Native vlan
Fa0/1 off negotiate not-trunking 1
[SNIP]
Port Vlans allowed on trunk
Fa0/1 209,227
[SNIP]
Port Vlans in spanning tree forwarding state and not pruned
Fa0/1 209,227
Fa0/2 none
[SNIP]
Note that despite the status of "non-trunking", the Vlans are in the
forwarding mode.
James
This archive was generated by hypermail 2.1.4 : Sat Jul 01 2006 - 07:57:31 ART