Bandwidth Requirements between CUCM Cluster and distributed Unity Connection

Unanswered Question
Feb 7th, 2010

Hi,  We have a centralised CUCM cluster and need to install Unity Connection on a remote site. The design guides show this is supported but I can't find any minimum bandwidth requirements for the WAN between CUCM and UCN other than the standard min 150ms one way delay.

Does anyone know what these requirements are before we go ahaead and deploy?

many thanks,  Keith.

I have this problem too.
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Tommer Catlin Wed, 02/10/2010 - 12:41

If you place Unity Connection at a remote location, and you are not using AXL connections, Unity will operate fine at the remote location.  The only bandwidth consideration to figure out is how many voicemail ports to/from CUCM you will need.

For example, if you have 48 ports for CUC to/from CUCM, this could potentially be 48 G.711/G.729 calls at one time going on.  You need to provision this bandwith, set the QOS in your WAN and it should be fine.

Your other consideration would be if you are using IMAP connections or Personal Assistant to log into the webpage of CUC.  This will increase your data traffic, but not your voice traffic.

For rough calcs:   G.711 is 80kb   G.729 is 30kb.

Multiple this by the number of ports

G.711 codec 80kbs

48 ports

= 3840  or 3.8megs (maybe a little less, but better to over estimate the requirements)

Hope this helps

kallan Thu, 02/11/2010 - 10:47

Hi,  Thank you for your response.  All voice traffic will be local to the remote site as it will have its own voice gateway. Any calls coming in the remote gateway will go voicemail on teh remote unity Connection server. I'm concerned that you mention we could have up 48 x G.711 calls across the WAN.  The only traffic across the WAN should be the control traffic for Unity Connection ports.  This was the bandwidth I was trying to work out.  Regards,  Keith.

Tommer Catlin Thu, 02/11/2010 - 11:22

I understand, the Unity server is for that site only, no cross wan traffic.   I was trying to find an SS7 document that states the bandwidth required for this, but I cant seem to find it. I thought I saw one with regards to Gatekeepers at one time.   Basically, every call will have SS7 happening. With this traffic, although small if I recall, does require bandwidth.  And to be even more precise, it should have QOS applied to it to keep the traffic prioritized in the WAN.  Any delay in the call setup or tear down will busy out channels, etc.

I keep thinking its 8kb, but I cant recall.  Maybe someone else has input on this.


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