11-34
Ethernet Card Software Feature and Configuration Guide, R7.2
January 2009
Chapter 11 Configuring Networking Protocols
Configuring IP Multicast Routing
PIM dense mode assumes that the downstream networks want to receive the datagrams forwarded to
them. The ML-Series card forwards all packets on all outg oing interfaces until pruning and truncating
occur. Interfaces that have PIM dense mode enabled receive the multicast data stream until it times out.
PIM dense mode is most useful under these conditions:
• When senders and receivers are in close proximity to each other
• When the internetwork has fewer senders than receivers
• When the stream of multicast traffic is constant
PIM sparse mode assumes that the downstream networks do not want to forward multicast packets f or a
group unless there is an explicit request for the traffic. PIM sparse mode defines a rendezvous point,
which is used as a registration point to facilitate the proper routing of packets.
When a sender wants to send data, it first sends the data to the rendezvous point. When a ML-Series card
is ready to receive data, it registers with the rendezvous point. After the data stream begins to flow from
the sender to the rendezvous point and then to the receiver, ML-Series cards in the data path optimize
the path by automatically removing any unnecessary hops, including the rendezvous point.
PIM sparse mode is optimized for environments in which there are many multipoint data streams and
each multicast stream goes to a relatively small number of LANs in the internetwork. PIM sparse mode
is most useful under these conditions:
• When there are few receivers in the group
• When senders and receivers are separated by WAN links
• When the stream of multicast traffic is intermittent
Note The ML-Series card support Reverse Path Forwarding (RPF) multicast, but not RPF unicast.
Configuring IP Multicast Routing
To configure IP multicast routing, perform the following procedure, beginning in global configuration
mode:
Command Purpose
Step 1 Router(config)# ip multicast-routing Enables IP multicasting on the ML-Series card.
Step 2 Router(config)# interface
type number
Enters interface configuration mode to configure
any interface.
Step 3 Router(config-if)# ip pim {dense-mode |
sparse mode | sparse-dense-mode}Runs IP multicast routing on each interface on
which you enter this command. You must indicate
dense mode, sparse mode, or sparse-dense mode.
Step 4 Router(config)# ip pim rp-address
rendezvous-point ip-address
Configures a rendezvous point for the multicast
group.
Step 5 Router(config-if)# end Returns to privileged EXEC mode.
Step 6 Router# copy running-config startup-config (Optional) Saves your configuration changes to
NVRAM.