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QoS config for 7920 IP phones

Hi,

I have a network with some AP1100 with 12.2(11)JA, in the document "Wireless IPT Design Guide for the Cisco 7920 IP Phone" I can read:

"The Cisco 7920 IP Phones support a QoS similar to EDCF for upstream (toward the AP) traffic. In additional, the Cisco 7920 dynamically announces its presence with the Cisco Aironet AP to ensure its downstream traffic is placed into the high priority queue on the AP. This dynamic announcement is done through Cisco Discovery Protocol (CDP). The CDP packets are sent from the Cisco 7920 to the AP and identify the phone so that the AP can place all traffic to the phone in the high priority queue.

If we have the CDP enable in the Wireless VLAN

do I need to apply any QoS, or this is done by the AP automatically? because of the sentence: "the AP can place all traffic TO the phone in the high priority queue" besides this having the "QoS Element for Wireless Phones setting" which maps to the IOS command dot11 phone is mandatory?.

Well my last question is that we have configured in the switch ports (Catalyst 2950 EI) where tere are APs connected, as the document recommends:

interface FastEthernet0/9

switchport access vlan 2

switchport voice vlan 6

no ip address

mls qos trust cos

auto qos voip trust

spanning-tree portfast

And I can read that the IP phone uses cos 6 for all its voice packets. Is this transmitted through the Fast Ethernet Interface of the wireless point? and we don't change it in any policy in the APs; in this case I think that we musn't apply "auto qos voip trust" which automatically generates "mls qos trust cos" because all the Cisco Catalyst LAN is configured for carrying voice which enters with cos 5. Is this correct?

Regards

2 REPLIES
Bronze

Re: QoS config for 7920 IP phones

The config should be like this.

conf t

mls qos <-- enable qos globally

interface fast x/x <-- for all the interfaces connected to IP phone

auto qos voip cisco-phone

interface fast x/x <-- for the uplink interface connected tothe router

auto qos voip trust

Re: QoS config for 7920 IP phones

That doesn't work I have captured packets ans obviously doesn't work, the packets that came from the IP phone have CoS 0 and IP DSCP 0.

In your config when you have the the command "auto qos voip cisco-phone" in the interfece, the COS of the 802.1q is only trusted when the Catalyst detect a Cisco IP phone directly connected to the port.

I also tried to apply a policy out in the Fastethernet port of the AP and set all the packets for the voice VLAN to 5 and this doesn't work either.

Anyoune has other suggestion?

Regards.

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