Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

Location Call Admission Control in CCM

I've read that Location CAC is supposed to be utilized in a hub and spoke topology. However, I can't find any documentation that states what specifically happens if CAC is utilizes in a non hub and spoke topolgy. What are the effects?


Re: Location Call Admission Control in CCM

The effects are that it will not work correctly and you could end up with bad audio. When a call is made from one location to another, bandwidth is deducted from each bandwidth value that is given for that location. That is not actual bandwidth. If your calls from site a to b goes through site c, site c's bandwidth value will not be effected. If you go through more sites, you will have this problem compounded. Since the numbers will not be accurate, it cannot guarantee the QOS you have setup for voice on WAN links will be overutilized. You could also end up with calls being blocked b/c it may think that b/w is being used that is not being used. Bottom line is, there is not a way to have CAC work correctly with a non hub and spoke topology. You will have incorrect bandwidth and possibly bad audio/blocked calls.



Re: Location Call Admission Control in CCM

Can you clarify a little? If my CM resides at a central location, but my sites are connected via MPLS, will that cause issues? I've got a central sip trunk at the main location with CM that all sites use.

Sent from Cisco Technical Support iPhone App

Re: Location Call Admission Control in CCM

Just to add to Steven Post

with UC CAC you can use one of the bellow options

1- location based CUCM CAC

2- IOS CAC using GK

3-CUCM  location based CAC with RSVP ( topology aware CAC )

so the question you ask here which one you use best for your your network and the answer is it depends on the UC an CUCM design

for example:

1- Simple Hub-and-Spoke Topologies

- Centralized Unified CM Deployments

In multisite WAN deployments with centralized call processing in a simple hub-and-spoke topology, use Unified CM static locations for implementing call admission control

Distributed Unified CM Deployments

For distributed call processing deployments on a simple hub-and-spoke topology, you can implement call admission control with a Cisco IOS gatekeeper

or you can use mix in the type of topology

2- Two-Tier Hub-and-Spoke Topologies

This scenario requires that you deploy topology-aware call admission control, which for a single Unified CM cluster means using RSVP-enabled locations

-- about your MPLS connected sites it will be easy to use location based unless you have a multi tier design where there a site and under each site there are branches

however for flat MPLS cloud you just need to consider the amount of voice calls to be sent over the MPLS ( LLQ in QoS ) and consider this in the location design with regard to the codec being used between sites

and the bellow link to CUCM SRND will help you understand each casein more details

Design Considerations for Call Admission Control


if helpful Rate

Location Call Admission Control in CCM

from the same link for your MPLS topology

MPLS IP WAN from a Service Provider, and Its Topology Equivalent

Based on these considerations, it is easy to see that, from a call admission control perspective, a service-provider IP WAN service based on MPLS is in reality equivalent to a hub-and-spoke topology without a hub site


if helpful Rate

CreatePlease to create content