This topic describes the functions of pipes in the Cisco TelePresence Video Communication Server (VCS).
A pipe defines the bandwidth limitations between two subzones or between a subzone and a zone.
A pipe applies bandwidth limits to links. By configuring subzones, links, and applying pipes to links, you can create a model of the physical network and its bandwidth limits on network connections such as WAN links. You can apply bandwidth restrictions per call and for the total bandwidth that goes over a link.
When calls are placed between endpoints in different subzones, you can control the bandwidth that is used on each link that is along the path between the two subzones.
First, you must create one or more pipes and configure them with the desired bandwidth limits. Then you must assign the pipes to the links to apply the desired limits. All calls that traverse one or more links that have a pipe applied must find enough available bandwidth on all links that are involved in the call. This implementation ofCAC is similar to Enhanced Location CAC in Cisco Unified Communications Manager.
Pipe Bandwidth Restrictions: Example
This section shows an example of bandwidth restrictions that are applied to links via pipes.
The figure shows an example of a call where pipe bandwidth restrictions apply.
Endpoint 1 calls endpoint 3 at 2 Mbps, but the bandwidth is downsized to 256 kbps because of the Per Call pipe limitation that is applied to the link between the subzones that are involved in the call. If there was no pipe applied to the link, 512 kbps of bandwidth would be used for the call because this bandwidth is the maximum bandwidth that is permitted, based on the bandwidth limits that are configured at the two subzones.
If another call was made between the default subzone and subzone SL, 256 kbps of bandwidth would be used for the second call. A third call between the two subzones would fail, but not because of the total bandwidth limit that is configured at the pipe (2048 kbps), but because of the In&Out bandwidth limit that is configured at the default subzone (512 kbps).