TelePresence endpoints - call rate explanation needed

[carstenlp]

Hi,

I'm fairly new to TelePresence endpoints and I need some clarification regarding the call rate between endpoints.

I have a CUCM 10.5 with MX300 G2 endpoints registered and by default the call rate in all endpoints is 6000 kbps when placing a call. This will result in error when A calls B which has audio and video both ways but when A invites C for a conference there's only audio between A and C because all available bandwidth (6000 kbps.) was used between A and B.

The immediate solution is to reduce the call rate in the endpoint configuration to something lower say 1920 kbps. However if the endpoints is restarted or unregistered from the CUCM the call rate reverts back to 6000 kbps. I've tinkered with the location bandwidth settings in the CUCM but that doesn't appear what to have an influence on the call rate settings in the endpoints.

How do I permanently change the default call rate in the endpoints so it's remembered even when the endpoints are restarted or reregistered?

Thank you and have a nice day.

/Carsten

[Wayne DeNardi]

It's highly likely that the second call is Audio only as you don't have a Multi-Site licence installed on your "A" unit, so the 2nd call to the "C" device will always be audio only as the endpoint isn't licenced to make a multi-site video call.

Wayne
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[carstenlp]

Hi Wayne,

Sorry for not replying before now. I'm using the Conductor and a TelePresence Server for the "multisite" configuration. Hence the endpoints do not need the Multi-Site option key.

Thanks and have a nice day.

[Christian Arroyo Castillo]

Hello, 

I tested from my lab and one of my endpoints remained through multiple reboots. Let me know if you are pushing configuration templates to it from TMS or not.

[carstenlp]

Hi Christian,

Thanks for your reply. I don't have a TMS so from your tests it seems like the TMS is pushing the value to the codec at bootup which would be ideal.

Have a nice day.

[Jens Didriksen]

"How do I permanently change the default call rate in the endpoints so it's remembered even when the endpoints are restarted or reregistered?"

Specify the rate in the codec itself which is found at

Configuration/System Configuration/Conference/DefaultCall\Rate

/jens

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[carstenlp]

Hi Jens,

Thanks for the suggestion. I did change it in the web interface of the codec however it's reverted back to default if the codec is switched off or unregistrered and registrered again.

Have a nice day.

[Matt Barber · Accepted solution]

Hey,

Maybe late to the party with this but hopefully someone will find this useful. We've changed the default behaviour for TC endpoints if the unit registers to Communications Manager. That's because if UCM controls the call, the region settings determine the call bandwidth, not the endpoint. That's why the endpoint reverts to 6000 on reboot, it's by design if it's registering to UCM.

If for some reason you did want to lock the unit down to something else, you can create a startup script with the configuration to change the setting. However, if you're making calls across a UCM, just set the region bandwidth to the value you require. Then make a call, check the Call Info in Call Control when logged into the endpoint - you'll see the endpoint use the value defined in UCM regions, not in the endpoint config.

Cheers
Matt

[Aaron Wilson]

The problem with this you are making "default call rate" now the "max call rate". I have my systems and phonebook entries set to 1.5M as the default call rate, however if someone wants to bump up to 3M, 4M, etc, for better experience they are welcome to. We just default to 1.5M so everyone is respecful of the bandwidth and novices do not make 6M calls on a 6M MPLS link.

[carstenlp]

Hi Matt,

Thanks for your reply. I've tested with an EX90 by creating a startup script which changes the default call rate to 768 kbps. When I run the script the call rate is indeed changed but when the unit is reset from the CUCM the call rate is reverted to 6000 kbps so the script does not run even if it's activated.

In my opinion this is a design flaw. As of right now users are unable to create a multiparty conference because all of the available bandwidth has been used in one call. In order to create a multiparty conference users have to manually adjust the call rate to a lower value in order to have enough bandwidth available. This has to be done per call.

I've created a TAC case in order to find a permanent solution. I'll post the results here when a solution has been found.

Cheers
Carsten

[Justin Ferello]

Carsten,

Did you find anything?

Thanks,
Justin

[carstenlp]

Hi everyone,

I finally found a solution.

The key to the bandwidth management in CUCM is the Region Configuration. Here you define how much bandwidth is allocated to each voice and video call. I've tinkered with this before as I was quite sure these were the settings to modify. However I didn't notice any change on the endpoints themselves and it turns out the CUCM will indeed throttle the calls to the maximum bandwith specified without actually changing the settings in the endpoint configuration.

Please observe the attached screenshot. I have a Region called R_Video. Right now the Maximum Session Bit Rate for Video Calls is set to 6000 kbps. This means that depending on the codec type a video call will be made at maximum kbps. This leaves no bandwidth available for another call. If you modify this setting to say 1000 kbps each call placed from the endpoint would consume a maximum 1000 kbps which allows for multiple calls per endpoint.

I mistakenly thought that the Default Call Rate in the endpoint configuration would actually change depending on the settings in CUCM but that's not the case. Default Call Rate will always show the maximum kbps again depending on the endpoint type.

I hope the above clarifies the issue.

Have a nice day.

[Matt Barber]

Carsten,

Thank you for following up on this thread with your findings. Exactly right - if we provision an endpoint from UCM, and UCM acts as the call agent, then it's UCM that defines bandwidth exchange in the SDP.

Therefore in each logical region, UCM manages bandwidth for all devices in that region.

The call rate is actually pushed down to the endpoint by UCM, it's in the CNF file retrieved on registration from the UCM TFTP server. This contains the 6000 value. This just allows the device to make such a high bandwidth call, in the eventuality the region settings are set so high and the UCM SDP negotiates this bandwidth.

If you see unexpected things happen when setting up calls registered to UCM, a good place to start is the UCM SDL trace and observe the SIP exchange. In there you get the real picture of what the call control agent wants the endpoints to do. Then go from there out to the endpoints.

Cheers
Matt

[Aaron Wilson]

I'm still going to argue this is not a solution. The region setting does define the max callrate for a given call, but this is MAX rate, not default rate.

The VC systems have a default call rate option for a reason, its the starting point. They also have a max call rate option to do just that, provide a max rate.

The two problems I see are:

1) CUCM is sending a 6000 value for default call rate without giving a way to override. If you register to a VCS it does not overwrite the user defined value, so CUCM should not overwrite or provide a way to specify.

2) Just because a sites LAN/WAN pipe is large enough to handle 6M calls doesn't mean you want that to be the default call rate. Nor does it mean you want to limit calls strictly to 1.5M max.

In my scenario I have TMS specfying all phonebook contacts to 1.5M as default, but users can override when placing the call. The issue lies with manually entered far sites, those default to 6M unless a user changes it.

The regional and location settings I have in CUCM restrict what a specific site can do in total. So if I have a site with a small 10M WAN link, I limit their region to 1.5M, but my large fat sites on a 200M link have unrestricted region calling (10M limit is the device max). However, just because a site has a big fat pipe doesnt mean I want all calls to default to 6M. I want *all* defaults from TMS, user entered, etc, to be 1.5M. *Then* if a user says "make it a 4M call", and the CUCM region/location allows it, place the call at 4M.

With CUCM becoming the better option for VC registration we really need to preserve features we have had and not write silly values with no way to override.