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"auto QoS voip cisco-phone" on Catalyst switch

with auto QoS configuration like this:

interface GigabitEthernet0/4

switchport access vlan 12

switchport mode access

switchport voice vlan 15

srr-queue bandwidth share 10 10 60 20

srr-queue bandwidth shape 10 0 0 0

queue-set 2

mls qos trust device cisco-phone

mls qos trust cos

auto qos voip cisco-phone

spanning-tree portfast

I am sure PC behind IP phones will be on vlan 12 with dscp/cos reset to zero by IP phones.

but...

what about a PC connecting to this port G0/4 directly without IP phone?

will the switch detect it via CDP (it's not IP phone!) then reset COS to zero?

or blindly trust incoming COS from this user PC?

thanks!

2 REPLIES

Re: "auto QoS voip cisco-phone" on Catalyst switch

The IP phone is detected via CDP. If there is no Ip phone, the traffic will not be trusted.

Traffic will flow via the access-vlan (12) with dscp & cos both reset to zero.

Regards,

Leo

New Member

Re: "auto QoS voip cisco-phone" on Catalyst switch

thanks!

We also have C6500 SUP32 running IOS without AutoQoS support.

L2S19(config-if)#mls qos trust ?

cos cos keyword

dscp dscp keyword

extend extend keyword

ip-precedence ip-precedence keyword

is it even possible to configure the SAME function fo Auto QoS manually?

you can not specify "mls qos trust device" any more

I think no because switch won't check with CDP discovery (IP phone or not) and determine trust boundry.

let me know!

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