QoS setup - Include tag

[Rolando Valenzuela]

Hello Community!

I have a simple question for most of you, how can I add the tag 46 to my VoIP traffic for following interface? Our provider rejects others tags but 46.

interface FastEthernet4/0/17
 description D017
 switchport access vlan 2
 switchport mode access
 switchport nonegotiate
 switchport voice vlan 3
 srr-queue bandwidth share 10 10 60 20
 priority-queue out
 mls qos trust device cisco-phone
 mls qos trust cos
 energywise level 10 recurrence importance 80 at 45 2 * * *
 energywise level 0 recurrence importance 80 at 30 20 * * *
 energywise importance 80
 energywise role CiscoPhone
 energywise name Brazil
 auto qos voip cisco-phone
 spanning-tree portfast
 spanning-tree bpduguard enable
 service-policy input AutoQoS-Police-CiscoPhone

Thank you!

Rolando Valenzuela.

[Mark Malone · Accepted solution]

Hi from what I see there EF46 would already be in place as your using auto qos voip cisco-phone which would trust the end device as its obviously a Cisco phone.Cisco phones by default mark at the source of traffic themselves with rtp being tagged as 46 , as well your also trusting cos which again would be marked by phone as 5 and converted by switch to 46 in dscp mapping

span the port using wiresharkand you should see your voice packets with marking of 46 DSCP EF

make sure this in in your global config and your uplink is marked with mls qos trust dscp

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

[Rolando Valenzuela]

Hi Mark!

Thanks for the reply, and how do I know which tags is using my auto-settings on the switch? 

This is what I got:

switch1#show run | i mls qos map
mls qos map policed-dscp  24 26 46 to 0
mls qos map cos-dscp 0 8 16 24 32 46 48 56

Should be fine?

Rolando Valenzuela.

[Mark Malone]

Ye that's fine , you have told your switchport mls qos trust cos , the phone sends a marking of cos 5  and dscp 46 which are equal , depending what the port is set to it trusts the marking

Then mls qos map cos-dscp  maps the cos 5 to dscp of 46 and passes it on that's why on the uplink you should trust the dscp rather than cos , from what I remember dscp supports both layer2 and 3 while cos is layer 2 only, so where possible always trust dscp but some older switches are only capable of trusting cos at access layer

[Rolando Valenzuela]

Awesome!!

Thanks Mark!!!