CUCM MTP Sizing

[Ahmed Abd El-Baky]

Hi Everyone

Do you have an idea on how to size maximum Media Termination Point (MTP) session that a Cisco Call Manager cluster can manage without impacting overall performance

I currently have a 3 node CUCM cluster , version 11.5 , anticipated concurrent SIP MTP sessions is 1200 call.

Many Thanks

Ahmed

[Jitender Bhandari · Accepted solution]

Hi Ahmed,

If it is a dedicated media server you can go full monty on it

Media Termination Point (MTP) Parameters

Call Count:	This parameter specifies the maximum total number of call parties that the media termination point will support. Each media termination point that is allocated for use will have resources for 2 call parties so that the total number of available media termination point resources will be half the value of this setting. If you increase this value substantially you should consider using a dedicated media streaming node (with Cisco IP Voice Media Streaming Application activated and without Cisco CallManager activated) to prevent interference between streaming and call processing.
	This is a required field.
	Default: 48
	Minimum:  0
	Maximum:  512

If it is not a dedicated media server it is ideally not advised to increase the count to a high number.

But why you want to increase MTP?

(Rate if it helps)

JB

[Ahmed Abd El-Baky]

Hi JB, 

Many thanks for the fast reply, It is just a workaround for a security limitation that enforces me to use the CUCM as an MTP to enforce using it's IP address as a source address instead of the IP phones IP addresses.

i can also increase the MTP throttling percentage to increase resource usage capacity.

So this means that if i used a dedicated MTP node i can scale up to 512 concurrent MTP sessions ?

Best Regards

Ahmed 

[Jitender Bhandari]

Hi Ahmed,

Yes, the maximum number you can go to is 512.

I am not sure if this would serve the purpose or not, but why don't you go for software IOS MTP, as they are much more scalable in nature.

(Rate if it helps)

JB

[Ahmed Abd El-Baky]

Hi JB, 

What is the sizing guidelines for doing MTP on an IOS ISR using PVDM3 ?

Best Regards

Ahmed 

[Jitender Bhandari]

Hi Ahmed,

beauty of using software IOS MTP is it does not require DSP, so no added hardware cost.

(Rate if it helps)

JB

[Ahmed Abd El-Baky]

HI JB, 

Many thanks , i found an article covering that issue:

https://supportforums.cisco.com/discussion/11948661/how-many-software-mtp-sessions-isr-g2-router-can-support

Thanks for your help .

Ahmed 

[Jitender Bhandari]

Hi Ahmed,

That is good info you found.

Happy to help.

JB

[Jaime Valencia]

Do bear in mind that the numbers that are shown are reference numbers, for an ISR not doing anything else, besides being an IOS SW MTP resource, they do use CPU/memory from the ISR for the packet processing, that otherwise you'd do with the DSP's.

Make sure to properly size the ISR platform given those numbers, and the resources you're already using in them.

[Ahmed Abd El-Baky]

Hi Jaime, 

Thanks for the valuable insights , So how to take into consideration sizing both the SIP Concurrent sessions & the MTP function to define the ISR's expected actual utilization.

Many Thanks

Ahmed 

[Jaime Valencia]

Most usually the numbers are based on 75% CPU usage, G711 and no VAD enabled, you'll need to do the math based on current CPU usage to find out what would be the theoretical maximum number of MTP's you could use without going above 75% CPU usage.

[Ahmed Abd El-Baky]

Hi Jiame, 

the VE team informed me that using the MTP function beside the SIP sessions processing will decrease the overall SIP concurrent sessions capacity to half.

This is in aligned with the 75 % CPU usage rule.

Referencing to your reply , will the PVDMs be used in this scenario or just the router's CPU.

Thanks

Ahmed