Understanding Bandwidth Management for Multicast
Bandwidth management enables you to control the multicast flows that leave a multicast interface. This control enables you to better manage your multicast traffic and reduce or eliminate the chances of interface oversubscription or congestion.
Bandwidth management ensures that multicast traffic oversubscription does not occur on an interface. When managing multicast bandwidth, you define the maximum amount of multicast bandwidth that an individual interface can use as well as the bandwidth individual multicast flows use.
For example, the routing software cannot add a flow to an interface if doing so exceeds the allowed bandwidth for that interface. Under these circumstances, the interface is rejected. This rejection, however, does not prevent a multicast protocol (for example, PIM) from sending a join message upstream. Traffic continues to arrive on the router, even though the router is not sending the flow from the expected outgoing interfaces.
You can configure the flow bandwidth statically by specifying a bandwidth value for the flow in bits per second, or you can enable the flow bandwidth to be measured and adaptively changed. When using the adaptive bandwidth option, the routing software queries the statistics for the flows to be measured at 5-second intervals and calculates the bandwidth based on the queries. The routing software uses the maximum value measured within the last minute (that is, the last 12 measuring points) as the flow bandwidth.
For more information, see the following sections:
- Bandwidth Management and PIM Graceful Restart
- Bandwidth Management and Source Redundancy
- Logical Systems and Bandwidth Oversubscription
