Switch configuration to trunk voice and data vlan

Unanswered Question
Jul 14th, 2009


I have 2 switches, 2 vlans/switch, vlan 10 (voice vlan) vlan 20 (data vlan) , 1 MCS with CUCM 7.0.

I want to configure trunking between 2 switches but keep the qos of voice vlan.

This is my interface gigabitethernet 0/1 configuration.

interface gigabitethernet 0/1

switchport mode acces

swtchport acces vlan 20

switchport voice vlan 10

spanning-tree portfast

How i configure gigabitethernet 0/24 to trunk voice and data vlan and keep the qos of voice vlan.


I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Marwan ALshawi Tue, 07/14/2009 - 13:57

on the tunk link between the tow switches

int gig0/5

switchport trunk encapsulation dot1q

switchport mode trunk

mls qos trust dscp

this on both side of the switches

also make sure that cos 5 map to dscp 46]by issuing show mls map cos-dscp

this will preserve the qos marking is tat wha you looking for

my question here if you have only tow switches i think qos not an issue unless you have remote sites over a WAN link

anyway good luck


ioan_ploscariu Wed, 07/15/2009 - 07:36

I have more switches, more locations, but all in a campus switched network.In this moment i don't have voip over WAN link.

commands - show mls map cos-dscp - map cos 5 to dscp 40?it's ok?


Marwan ALshawi Wed, 07/15/2009 - 14:26

no it has to to be 46

enter the following command it will fix it to u

mls qos map cos-dscp 0 8 16 24 32 46 48 56

by the way al these config to keep the marking

if you want some sort of prioritization tell me what switches model you are usig and i will try to send you some commands to help in this

good luck

Rui Carlos Antunes Mon, 07/20/2009 - 02:42

On the port connecting to the Cisco IP Phone, try the Cisco macro/command "auto qos voip cisco-phone".

On the 802.1Q trunk use the "auto qos voip trust".

This is usually enough to provide QoS for Cisco IP Phone voice traffic.


This Discussion