Location and CAC via CUSP

[mnour401917_2]

Hi All,

I'm wondering if anyone have idea on this.

We have the following scenario where i need to maintain location and CAC support after i have implemented CUSP between the ingress gateway and CUCM.

PSTN===>Gateway====CUSP=====CUCM=== IP PHones

I will have a SIP trunk from Gateway to CUSP and CUCM to CUSP.

Some of the remote locations have slow links and having the location and CAC configuration is a must.

CUCM need to be able to know where the call is originating from and set the correct CAC.

Any idea how to achieve  this?

Thanks

Nour

[Vivek Batra]

As you have mentioned that some of the remote location have slow links, you need to share full topology for us to assist you better.

Also share on which version of CUCM you're since there are significant changes in CAC from V9 onwards.

- Vivek

[mnour401917_2]

Hi Vivek,

Please see attached.

CUCM version is 10.5

Thanks.

[Vivek Batra]

Attached figure doesn't tell how many sites are there, so I assume there is only 1 site and you want to restrict the number of calls from IP phone to PSTN.

You have a choice to restrict it in IOS too using max-conn command otherwise you can use location as well.

Let say you have 256 Kbps of bandwidth between IP phone and PSTN gateway and you are using G711 codec. This will roughly allow 3 simultaneous calls. Region settings between IP Phone and SIP Trunk will choose the codec to be used for such calls.

You should have atleast two locations, one for IP Phones and other for SIP Trunk.

Location IP Phone - location_phone

Location SIP Trunk - location_pstn

Set inter location bandwidth between location_phone and location_pstn to 240 Kbps (80Kbps per call). Please note that the bandwidth you configure under location settings is only for call counting purpose and doesn't account the actual bandwidth being used.

Assign location_phone to all Phones and location_pstn to SIP Trunk.

Doing so, CUCM will restrict the number of calls between IP Phones and PSTN as per relevant configurations made.

- Vivek

[mnour401917_2]

Hi Vivek,

There are about 5 remote sites with different link speeds.

What you said above is correct if the ingress gateway have a Trunk directly to CUCM. The Gateways have SIP Trunks to CUSP not CUCM.  CUSP then forwards the calls to CUCM.

On your response above you did not mention how CUSP fits on this and what CUSP need to be able to do in order for CUCM to identify original gateway and apply correct CAC.

I have updated the diagram.

Thanks.

[Vivek Batra]

How is your MPLS network look plays an important role in designing locations CAC.

As I can see there are in total of 5 sites (A, B, C, D, E), so all sites are directly connected OR is in hub/spoke? For instance, when there is a packet flow between A and B, does it only utilize the bandwidth of A and B OR packet may also flow through other site as well?

Other point, all sites have local PSTN gateway with couple of IP Phones?

- Vivek