QoS for Video Calls

[Leonardo Santana]

Hello,

I have a client complaying about the video quality of a C20 through an MPLS Link.

When i see the call statiscs i see packet loss and jitter.

These are the requirements for Video:

• Interactive-Video traffic should be marked to DSCP AF41; excess videoconferencing traffic can be marked down by a policer to AF42 or AF43.

• Loss should be no more than 1 percent.

• One-way latency should be no more than 150 ms.

• Jitter should be no more than 30 ms.

• Assign Interactive-Video to either a preferential queue or a second priority queue (when supported); when using Cisco IOS LLQ, overprovision the minimum-priority bandwidth guarantee to the size of the videoconferencing session plus 20 percent. (For example, a 384-kbps videoconferencing session requires 460 kbps of guaranteed priority bandwidth.)

On the MPLS link they need to mark the traffic according to these requiremens correct?

Other whats is the resolution when i have a call with 384 kbps:

• 720p30 from 768 kbps
• 720p60 from 1152 kbps
• 1080p30 from 1472 kbps

Regards

Leonardo Santana

[George Thomas]

Correct, you will have to priortize AF41 traffic. You will have to make sure that QoS is turned on in the LAN, WAN, MPLS. Also make sure that the AF41 marking is preserved end to end else it wont help you. This will also include trusting the uplink to the C20.

As far as resolution, if i were to venture a guess I would say 360p but it all depends on how dynamic the participants are in the call, lighting etc. 

[Leonardo Santana]

Thanks George,

Whats is the minimum bandwith for a video call? 384 kbps?

[George Thomas]

Correct, that what I have seen atleast.

[Wayne DeNardi]

The minimum bandwidth for a video call would be 128k (64k for audio, 64k for video).  This can often be seen on legacy ISDN devices with a single ISDN BRI connected.

The quality at this bandwidth isn't great which is why it's usually recommended to use more if you can.