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Setting Qos for the Cisco C20plus codec endpoints.

My company has implemented a cisco video conferencing system using the Cisco C20plus codecs as H323 endpoints.

We currently utilise the Optus evolve network (MPLS) for our WAN

Our network WAN utilises Qos per VLAN settings.
For example, phones are in their own VLANs per site and the video conferencing system has its own VLAN.

We policy map ACLs to the following Qos classes specified by Optus in order of priority (Highest to lowest):

Cisco recommend that Gold-RT is reserved for audio (phones) so I would like to set the C20plus video and audio traffic in the Gold-NRT class.
This class has the DSCP bits set to af42 which is more than ample priority for the video conferencing traffic.

Can anyone tell me what ports I need to specify in a permit statement in the Gold-NRT ACL to apply dscp af42 to the video and audio traffic please?

All C20plus endpoints RTP ports range are set to 2326 - 2486 so I will need a UDP permit statement for those ports for the C20plus endpoint ip address.

Are these the only ports that I need add to the Gold-NRT ACL?

Everyone's tags (1)
Cisco Employee

Hi, To get the answer to your



To get the answer to your question, I advise you to post this question in TelePresence community to get the Cisco C20 experts to respond. This community is only for Cisco WebEx Meetings Server and Cisco Unified MeetingPlace products.


Thank you.


VIP Purple

As Dejan has said, this

As Dejan has said, this question would be better placed in the TelePresence section of the forums where endpoints such as the C20 are discussed.

In any case, if you set your switch ports to trust the DSCP markings on the packets, the tags themselves can be applied on the endpoint.

If you go to the web interface of the C20 and log in, then go to Configuration > System Configuration > Network.

Scroll down near the bottom and you'll find the QoS section.  Here you can set the Mode to "Diffserv" and set each of the individual values as required, ie, if you want AF42, enter 36 in the field (see the Assured Forwarding table on wikipedia for other value mappings).

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