PIM-SMDM is an integrated protocol which handles both sparse groups and dense groups at the same time. In sparse-dense mode, if the group is in dense mode, the interface will be treated as dense mode. If the group is in sparse mode, the interface will be treated in sparse mode. The group is sparse if the router knows about an RP for that group.

The required steps to configure PIM-SMDM are the following:

All multicast group states are dynamically maintained as the result of IGMP Report/Leave and PIM Join/Prune messages.

This section provides the steps to configure the PIM-SMDM feature. Configuration steps and examples are used for two relevant scenarios. The following figure displays the network topology used in these examples:

Enable IP multicast routing on all of the PIM routers inside the PIM domain:

Enable PIM-SMDM on all participating interfaces within each of routers inside the PIM domain on which you want to run PIM. In the following sample configuration, both eth1 and eth2 are enabled for PIM-SMDM on the router.

Here is the sample configuration for Router_C:

The show ip pim interface command displays the interface details for Router_C.

The following examples differentiates the group operating in sparse mode versus dense mode:

Every PIM multicast group needs to be associated with the IP address of a Rendezvous Point (RP), which is a router that resides in a multicast network domain. The address of the RP is used as the root of a group-specific distribution tree. All nodes in the domain that want to receive traffic sent to the group are aware of the address of the RP. For all senders to reach all receivers within a group, all routers in the domain must be able to map to the RP address configured for the group. There can be several RPs configured in a network deploying PIM-SM, each serving a different group.

You can statically configure a RP by specifying the RP address in every router in the PIM domain. The use of statically configured RPs is ideal for small network environments or ones that do not require many RPs and/or require changing the assignment of the RPs often. Changing the assignment of an RP requires the re-configuration of the RP address in all of the routers in the PIM domain.

In static RP configurations, RP failover is not available.

When configuring the RP statically, do the following:

Using the topology depicted in Figure 9-11, Router_C is the RP, and all routers are statically configured with RP information. Host_1 and Host_2 join group 224.0.1.3 for all the sources. They send the IGMP membership report to Subnet 1. Two routers are attached to Subnet 1, Router_E and Router_F; both have default DR priority on eth1. Since Router_E has a higher IP address on interface eth1, it becomes the Designated Router, and is responsible for sending Join messages to the RP (Router_C).

Here is the sample configuration for Router_D:

At Router_D, the show ip pim rp mapping command shows that 10.10.1.5 is the RP for all multicast groups 224.0.0.0/4, and is statically configured. All other routers will have a similar output:

At Router_D, use the show ip pim rp-hash command to display the selected RP for a specified group (224.0.1.3):

The show ip pim interface command displays the interface details for Router_E, and shows that Router_E is the Designated Router on Subnet 1.

The show ip pim mroute command displays the IP multicast routing table. In this table, the following fields are defined:

At Router_E, eth2 is the incoming interface of the (*, G) entry, and eth1 is on the outgoing interface list of the
(*, G) entry. This means that there is a group member through eth1, and the RP is reachable through eth2.

The 0 position on this 32-bit index is for eth1 (as illustrated in the interface display above). The j on the 0 index indicates that the Join has come from eth1.

Since Router_C is the RP, and the root of this multicast tree, the show ip pim mroute command on Router_C shows RPF nbr as 0.0.0.0 and RPF idx as none.

For configuring Rendezvous point dynamically refer Configure Rendezvous Point Dynamically Using Bootstrap Router Method and Configuring Rendezvous Point Statically

In this network topology, the Source_1 address is 10.10.1.52 and the group address is set to 224.0.1.3.

In this network topology, the Source_1 address is 10.10.1.52 and the group address is set to 224.0.1.3

In this example all routers are running PIM-SMDM

Enter the commands listed in this section to confirm the previous configurations.

The show ip pim mroute command displays the IP multicast routing table.

The show ip pim dense-mode mroute command displays the IP PIM-DM multicast routing table