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Dennis Mink
Advisor

Video region/locations bandwidth allocation CUCM

I am struggling to understand the following,  (CUCM10.0.x. ) 

 

I have 2 phones, each in their own location and region, say A and B.  using G729 and 384kbps Video as the settings between the two regions.  When I make the call and check the available video bandwidth (for instance through RTMT performance monitoring ), I see that 500 kbps is deducted from the Location bandwidth to make that single video call happen. 

 

The 10.x SRND clearly states:

 

For example, assume that the link configuration for the location Branch 1 to Hub_None allocates 256 kbps of available audio bandwidth and 384 kbps of available video bandwidth. In this case the path from Branch 1 to Hub_None can support up to three G.711 audio calls (at 80 kbps per call) or ten G.729 audio calls (at 24 kbps per call), or any combination of both that does not exceed 256 kbps. The link between locations can also support different numbers of video calls depending on the video and audio codecs being used (for example, one video call requesting 384 kbps of bandwidth or three video calls with each requesting 128 kbps of bandwidth).

 

Well that is not what I am seeing, in fact, when I bring the location's video bandwidth to 499 kbps, I get no video 

 

anyone seeing the same, and what mechanism am I overlooking here?

 

 

 

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Dennis Mink
Advisor

everything leads me to believe this is a bug

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Hi,

 

If I understand correctly, you meant to say that video calls aren't happening if your inter-location bandwidth is less than 500 kbps. Is this correct?

 

What endpoint is initiating the video call?

That is correct, if I set video bandwidth to anything under 500, it degrades to audio only.

 

this is between two 8941 phones.

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Hi,

 

Are you using the phones as SIP or SCCP?

SIP on latest firmware

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Hi,

 

In this case what you are facing isn't a bug. 8941 SIP phones support minimum resolution of W360p (640x360) @ 30fps. This resolution translates to 475 kbps of bandwidth. Since you are using G729 as well then the audio bandwidth is 24 kbps. Adding both video + audio = 499 kbps.

 

As you know for video calls the bandwidth for video and audio is deducted from video locations/links. In this case, your video locations/links should at least have 500 kbps to allow video calls.

 

Hope it is clear now.

I ran a test call from an sx20 into a 8941 and am seeing the following resolution (352x288) and channel rate  (on the receive side of the screen capture). so that doesnt seem to add up.

 

 

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Hi,

 

Try to start the call in the other direction (from 8941 to SX). Also, check 8941 datasheet as the resolution is listed in the datasheet.

Meanwhile I have upgrade the cluster to 10.5.2.

but I am still seeing the same behaviour.

so

500kbps location deduction for a 384kbps Video + G729 call 

2500kbps locations deduction for a 2300kbps call between SX20's

102kbps for a single G711 or G729 audio only call.

I guess I can work with this if  I get my summs right, I just dont understand these numbers, is anyone seeing the same?

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Expected Behaviour.

~Avinash

Avinash how is this expected behaviour. It would be nice if you can explain the details..

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Long back, I had asked for CCM traces.

Please provide the detailed CCM + LBM traces for an example call. Provide the call details. I will explain you what is happening and why.

~Avinash

Avinash,

here is a test call i traced:


SDL_002_100_0004466 @ 9:34:03.010

from +61736383932 (77232) to +61383360935 (33935)


: SIP/2.0/TCP 10.61.2.82:5060;branch=z9hG4bK1008c323e64f8c
From: "Eagle F test 77232" <sip:+61736383932@10.61.2.82>;tag=6936762~1b5af941-cea2-4a00-a0bd-15a532224d7d-52418193
To: <sip:+61383360935@10.61.2.82>

call established according to region settings: 384kbps video and G729

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Dennis,

Since our friend avinsrid89 has decided nit to share his expertise on this subject, I had a look at the traces and then looked up a few documentation. This indeed incorrect according to the documentation. Cisco clearly states that the bandwidth cant exceed the region settings.

Cisco Unified Communications Manager uses the following rules to determine the amount of bandwidth to allocate to a specific call:

  • When Cisco Unified Communications Manager receives an Offer or Answer from an endpoint, it checks whether there is a session level bandwidth modifier in the SDP:

    • If there is a session level bandwidth modifier, Cisco Unified Communications Manager retrieves the bandwidth value from the modifier. If there is more than one modifier type, it retrieves the modifier in the following order of preference: Transport Independent Application Specific (TIAS), Application Specific (AS), Conference Total (CT).

    • If there is no session level bandwidth modifier, Cisco Unified Communications Manager retrieves the bandwidth value from the sum of the media level bandwidth modifiers.

  • The allocated bandwidth is the maximum of what the two endpoints support up to the maximum value of the Region setting. The allocated bandwidth cannot exceed the region setting.

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