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CCM server QoS

Answered Question
Oct 25th, 2006
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Is CCM server capable of QoS marking signalization packets that sends to phones?


When snnifing traffic, it`s visible that packets going from my phone to CCM are marked (ToS 3), but packets going from CCM to phone are not marked (default 0).


thx


Correct Answer by Aaron Harrison about 10 years 10 months ago

Hi


Yes - as I mentioned before, your CCM port must be configured to trust DSCP 'qos trust dscp' not trust COS.


COS is a marking in the dot1q or ISL header of a packet - as the CallManager is not on a trunked port like phones are, it can NOT mark COS on packets.


Also you wouldn't normally have 'switchport voice vlan' on the port to CallManager as it is an access port in that VLAN.


Regards


Aaron


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Brandon Buffin Wed, 10/25/2006 - 06:42
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Be default CCM does mark its signalling packets. Take a look at the following link for confirmation.


http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a00801ffe28.shtml


This can be changed in CCM admin -> System -> Enterprise Parameters. You might check there to see if the values have been changed. Also, make sure that these packets are not being remarked somewhere else in the network.


Hope this helps. If so, please rate the post.


Brandon

Aaron Harrison Wed, 10/25/2006 - 07:06
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Hi


Also if you are sniffing at the downstream (phone) end it would be worth verifying that you have both enabled qos and set the port trust state on the port the CM is attached to to 'trust DSCP'.


Regards


Aaron


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darijohorvat Wed, 10/25/2006 - 23:43
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thanks for your answers.


In Ent. Par. Conf. DSCP marking of packets is set, and this is QoS configuration of switch that CCM is attached to (WS-C4506):


qos dbl

qos map dscp 24 25 26 27 28 29 30 31 to tx-queue 4

qos map dscp 32 33 34 35 36 37 38 39 to tx-queue 4

qos map cos 3 to dscp 26

qos map cos 5 to dscp 46

qos


interface GigabitEthernet6/45

switchport access vlan 10

switchport mode access

switchport voice vlan 10

service-policy output autoqos-voip-policy

qos trust cos

auto qos voip trust

tx-queue 3

priority high

shape percent 33


Is there something that must be changed in cofiguration?


thx







Correct Answer
Aaron Harrison Wed, 10/25/2006 - 23:55
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Hi


Yes - as I mentioned before, your CCM port must be configured to trust DSCP 'qos trust dscp' not trust COS.


COS is a marking in the dot1q or ISL header of a packet - as the CallManager is not on a trunked port like phones are, it can NOT mark COS on packets.


Also you wouldn't normally have 'switchport voice vlan' on the port to CallManager as it is an access port in that VLAN.


Regards


Aaron


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