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3850 - auto qos voip cisco-phone

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Dec 13th, 2013
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I am having an issue where it appears that the "auto qos voip cisco-phone" command is marking down my voice packets COS and DSCP values to 0.  Anyone else notice this?  I am connecting Cisco 7945 phone to the interfaces with this command applied to the interface.  I verified that the IP Phone is sending COS = 5 and DSCP = ef to the switchport.  I verified the packets inbound to the switchport and the packets outbound as they transit to the destination IP Phone's switchport.

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Rasika Nayanajith Sat, 12/14/2013 - 11:25
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Hi joshua,


What is the IOS-XE version you are running on your 3850 ?


Post your switchport configuration (7945 phone connected)


Here is 3.3 QoS config guide & I noticed it says something like below qouted. So make sure this trust device command is there & your port is configured for standard VoIP port connectivity.(like voice vlan, etc)

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/3se/consolidated_guide/configuration_guide/b_consolidated_3850_3se_cg/b_consolidated_3850_3se_cg_chapter_01101000.html#reference_8A1C35AB2874498F90C4F5600301BE9D


"The trust device device_type interface configuration command is only supported in an auto-QoS configuration, and not as a stand-alone command on the switch. When using the trust device device_type interface configuration command in an auto-QoS configuration, if the connected peer device is not a corresponding device (defined as a device matching your trust policy), both CoS and DSCP values are set to "0" and any input policy will not take effect"



HTH

Rasika


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Joshua Fontenot Mon, 12/16/2013 - 06:18
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I am running 03.03.01SE.


Here is the config of a typical port:

interface GigabitEthernet1/0/1

switchport access vlan 100

switchport mode access

switchport voice vlan 1000

trust device cisco-phone

auto qos voip cisco-phone

spanning-tree portfast

service-policy input AutoQos-4.0-CiscoPhone-Input-Policy

service-policy output AutoQos-4.0-Output-Policy


It's as if the COS value of the phone is not being trusted on the ingress of the switchport.

Joshua Fontenot Mon, 12/16/2013 - 08:10
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I worked with Cisco TAC and this appears to be a new bug.  The work around is to remove the "trust device cisco-phone" command under the interface.

Rasika Nayanajith Mon, 12/16/2013 - 08:55
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Thanks for that info. If you get to know the bug-id please post it here for others benefit.


Rasika

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