12.7 Links

This topic describes the functions of links in the Cisco TelePresence Video Communication Server (VCS).

Links are logical connections between subzones or zones. Links are created automatically among the default subzone, traversal subzones, and default zone, but they can be deleted.

You can freely configure links for any subzones and zones. Calls between endpoints that are located in two different zones or subzones are only possible if there is a path between the two zones or subzones. The path does not have to be a direct link between the two zones or subzones. It can involve multiple zones or subzones and links. You should configure subzones and links so that they match the physical layout of your network. The subzones and links are similar to locations and links between locations in the Cisco Unified Communications System. In the Cisco VCS, however, they are not only used for CAC, but also for call routing, because calls are only possible if the two endpoints have a path that is configured between their zones or subzones.

Zone Bandwidth Restrictions: Within

This section shows an example of the bandwidth restriction for a call that is placed within a subzone.

The figure shows an example of a call where the Within bandwidth restriction parameter applies.

Endpoint 3 calls endpoint 4 at 1 Mbps, but the bandwidth is downsized to 256 kbps because of the bandwidth restriction within the zone. The Within bandwidth is set to 256 kbps on Subzone SL, and because both endpoints are registered to this subzone, the Within limit is considered for the call.

Zone Bandwidth Restrictions: In&Out

This section shows an example of the bandwidth restriction for a call that goes beyond a subzone.

The figure shows an example of a call where the In&Out bandwidth restriction parameter applies.

Endpoint 4 calls endpoint 5 at 2 Mbps, but the bandwidth is downsized to 512 kbps because of the bandwidth restrictions that apply to calls that go beyond a single subzone. The In&Out bandwidth is set to 768 kbps on subzone SL and to 512 kbps on subzone SJ. Both limits are applied because the two endpoints that are involved in the call are located in these two zones. The lower limit is enforced and therefore the call results in a bandwidth of 512 kbps.

Zone Bandwidth Restrictions: Total

This section shows an example of the bandwidth restriction for two calls that involve the same subzone.

The figure shows an example of two calls where the Total bandwidth restriction parameter applies.

Endpoint 2 calls Endpoint 3 at 2 Mbps, but the bandwidth is downsized to 512 kbps because of the bandwidth restrictions that apply to calls that go beyond subzone NY. While the call between endpoint 2 and endpoint 3 is active, endpoint 4 calls endpoint 5 at 2 Mbps. The bandwidth of the call between endpoint 4 and endpoint 5 is downsized to 256 kbps because the total limit of subzone SL would be exceeded if more bandwidth was used. The first call consumed 512 kbps and the remaining total bandwidth that is left in subzone SL is only 256 kbps.