6.4 Local Conference Bridge Implementation

This topic describes how you can implement local conference bridges at remote sites to keep voice streams local when all members of the conference are located at the same site.

Considerations When Deploying Local Media Resources at Remote Sites

  • Traffic stays off the IP WAN when remote site devices require a media resource—for example, conference bridges.
  • Local media resources require appropriate hardware at remote site (e.g., DSPs in gateway).
  • Considerations:
    1. Number of devices at remote site and likelihood of using a feature or application that requires the media resource
    2. Ease of adding required resources
    3. Available bandwidth toward central site
    4. Audio only or audio and video

When local conference bridges or MTPs are deployed at each site, traffic does not have to cross the IP WAN if all endpoints are located at the same site. You can implement local media resources such as conference bridges and MTPs by providing appropriate hardware, for example by adding DSPs at the routers that are located at the remote sites.

Whether the extra cost for providing local conference resources is worthwhile depends on several factors:

  • Cost of adding conference resources: Is it sufficient to add DSPs to an existing router, or do you have to replace the whole platform?
  • Number of devices at the remote site and the likelihood of using applications or features that require access to the media resource that is considered to be locally deployed: How many phones are located at the remote site? How often do the phones use features that require a media resource that is currently available only over the IP WAN? What is the maximum number of devices that require access to the media resource at the same time?
  • Available bandwidth and cost of additional bandwidth: Is there enough bandwidth (or can additional bandwidth be provisioned) to accommodate the requirements that are determined by the preceding factors? How does the cost of adding bandwidth compare to the cost of deploying local DSPs?
  • Type of conference bridges: Do you want to provide conference services only to audio calls or also to video calls?

Example: Implementing Local Conference Bridges at Two Sites

The figure shows a sample scenario for deploying local conference bridge resources at a remote site.

Phones at the remote site should use a local conference bridge when creating a conference.

The figure shows a main site with software and hardware conference resources. At the remote site, hardware conference resources are added to the remote site gateway. As a result, the remote site phones can set up conferences by using local resources instead of accessing the conference resources that are located at the main site. For conferencing remote site members only, traffic is not sent across the IP WAN.

Note

When an ad hoc conference includes members of separate sites, a separate voice stream for each remote member must be sent across the IP WAN. However, if a Meet-Me conference is set up, the users that are located at the remote site could first establish an ad hoc conference (by using a media resource that is local to the remote users) and then add a call to the remote Meet-Me conference to their local ad hoc conference. In this case, there is only a single voice stream that is sent across the IP WAN connecting the two conferences.

The figure illustrates how MRGs and MRGLs are used to ensure that headquarters phones use the conference resources at the headquarters and that remote site phones use the remote site conference resource when establishing a conference.

These three MRGs are created:

  • HQ_HW-MRG: This MRG includes the hardware conference bridge that is provided by the voice gateway that is located at the headquarters.
  • HQ_SW-MRG: This MRG includes the software conference bridge that is provided by a Cisco Unified Communications Manager server that is located at the headquarters.
  • BR_HW-MRG: This MRG includes the hardware conference bridge that is provided by the voice gateway that is located at the remote site.

The HQ_HW-MRG is the first entry of the MRGL, which is called HQ_MRGL; the HQ_SW-MRG is the next entry. Headquarters phones are configured with the HQ_MRGL. Because MRGs are used in a prioritized way, headquarters phones that invoke a conference will first use the available hardware conference resources; when all of the hardware resources are in use, the software conference resources are accessed.

At the remote site, all phones refer to the BR_MRGL, which includes only the BR_HW-MRG. This configuration allows remote phones to use their local conference bridge when they invoke conferences instead of accessing conference resources that are located across the IP WAN.