PIM Route Table

Multicast routing information is gathered and stored by PIM in the PIM Route Table. The PIM Route Table contains one row for each port in PIM mode. Each routing entry contains information about the source and multicast group, and incoming and outgoing interfaces.

The PIM Route Table displays the following Fields:

• Group — Specifies the multicast group IP address. The range is 244.0.0.0-239.255.255.255.

• Source — Specifies the source IP address from where the multicast packets are being sent.

• Source Mask — Mask all or part of the source IP address.

• Upstream Assert Timer — Indicates the time before the router reverts from its upstream router to its Reverse Path Forwarding (RPF) neighbor. When a multicast packet is received, the router sends an assert packet on a subnet indicating what metrics were used to reach the packet source address. The router with the best metrics becomes the forwarding router. All other upstream routes are pruned. The downstream routers also compare if the RPF with the forwarding router. This ensures that the downstream routers send their prunes and grafts to the correct neighbor. The forwarding router sends an assert message to notify the other routers that it is the forwarding router. Downstream routers select the upstream router with the smallest metrics as their RPF neighbor. If two routers have the same metrics, the router with the highest IP address is chosen. When the assert timer expires, the downstream may switch from the forwarding router to a RPF neighbor. A value of 0 indicates that the assert has not changed the upstream neighbor to a RPF neighbor.

• Assert Metric — Specifies the metrics advertised by the forwarding router. A value of 0 indicates that no assert is received.

• Assert MetricPref — Indicates the preference advertised by the forwarding router on the upstream interface. Asset MetricPref is used when upstream routers are running different Unicast protocols. A value of 0 indicates that no assert is in effect.

• Assert RPT Bit — Indicates the value of the RPT bit advertised by the forwarding router.

• Flags — Specifies the PIM-specific flags pertaining to the multicast state entry.

To view the PIM Route Table:

1. On the Menu Bar, click IPM.

2. On the IPM menu, point to PIM and click Route Table. The PIM Route Table is displayed.