Solved: QoS configuration 4507R - Does "qos trust device cisco-phone" annulls an input service policy?

aedamasceno · ‎01-13-2015

Hello all,

We have a 4507R as the Access switch for our network.

I took one of its ports configuration as an example:

Interface FastEthernet 3/30

switchport voice vlan 100

switchport mode access

switchport access vlan 200

service-policy input VOIP-QOS

qos trust device cisco-phone

qos trust cos

Does the command qos trust device cisco-phone annuls the command service-policy input VOIP-QOS when a Cisco phone is inserted?

Also, if I may ask another situation as well, where the config is:

Interface FastEthernet 3/32

switchport voice vlan 100

switchport mode access

switchport access vlan 200

service-policy input VOIP-QOS

qos trust dscp

That config is being used with a Cisco Phone attached. The network team says the packets are being marked correctly. In that service-policy we have treatment for voice signaling and rtp. I am suggesting we use the configuration shown above. What do you guys suggest?

Thanks for the help

Cisco Freak · ‎01-13-2015

Hi aedamasceno,

service-policy input VOIP-QOS

qos trust device cisco-phone

qos trust cos

This configuration tell the switch interface to trust the CoS marking from the device connected at the interface. Also its take one step extra step to make sure that it will trust the marking only if it comes from a cisco IP phone connected there. For example, if there is a PC connected to that port and its sending CoS tagged frames to interface, the switchport will NOT trust the CoS marking from the PC.

The interface will make use of Cisco CDP protocol to detect if its connected to a Cisco IP phone.

Please share the config of the policy-map VOIP-QOS see how its configured.

CF

View solution in original post

Cisco Freak · ‎01-13-2015

Hi aedamasceno,

service-policy input VOIP-QOS

qos trust device cisco-phone

qos trust cos

This configuration tell the switch interface to trust the CoS marking from the device connected at the interface. Also its take one step extra step to make sure that it will trust the marking only if it comes from a cisco IP phone connected there. For example, if there is a PC connected to that port and its sending CoS tagged frames to interface, the switchport will NOT trust the CoS marking from the PC.

The interface will make use of Cisco CDP protocol to detect if its connected to a Cisco IP phone.

Please share the config of the policy-map VOIP-QOS see how its configured.

CF

aedamasceno · ‎01-14-2015

I don't have access to the configuration, and the network guy who was supposed to be with me didn't come today. I will be posting the config in the near future. I appreciate your explanation, it actually confirmed what I was thinking. I was a little unsure.

Thanks again.