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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 38 Configuring IP Multicast
Configuring IP Multicast Routing
Switch# show ip pim rp mapping
Switch# show ip igmp groups
Switch# show ip mroute cbone-audio
Configuring a Single Static RP
If you are configuring PIM sparse mode, you must configure a PIM RP for a multicast group. An RP can
either be configured statically in each device, or learned through a dynamic mechanism. This task
explains how to statically configure an RP, as opposed to the router learning the RP through a dynamic
mechanism such as Auto-RP.
PIM designated routers (DRs) forward data from directly connected multicast sources to the RP for
distribution down the shared tree. Data is forwarded to the RP in one of two ways. It is encapsulated in
register packets and unicast directly to the RP, or, if the RP has itself joined the source tree, it is multicast
forwarded per the RPF forwarding algorithm. Last hop routers directly connected to receivers may, at
their discretion, join themselves to the source tree and prune themselves from the shared tree.
A single RP can be configured for multiple groups that are defined by an access list. If no RP is
configured for a group, the router treats the group as dense using the PIM dense mode techniques. (You
can prevent this occurrence by configuring the no ip pim dm-fallback command.)
If a conflict exists between the RP configured with the ip pim rp-address command and one learned by
Auto-RP, the Auto-RP information is used, unless the override keyword is configured.
To configure a single static RP, perform this task:
Command or Action Purpose
Step 1
Switch> enable
Enables privileged EXEC mode.
Step 2
Switch# configure terminal
Enters global configuration mode.
Step 3
Switch(config)# ip multicast-routing
Enables IP multicast routing.
Step 4
Switch(config)# interface type number
Selects an interface that is connected to hosts on which PIM
can be enabled.
Step 5
Switch(config-if)# ip pim [sparse-mode |
sparse-dense-mode]
Enables PIM on an interface. You must use sparse mode.
Step 6
Repeat Steps 4 and 5 on every interface that uses IP
multicast.
—
Step 7
Switch(config-if)# exit
Returns to global configuration mode.
Step 8
Switch(config)# ip pim rp-address rp-address
[access-list] [override]
Configures the address of a PIM RP for a particular group.
• Perform this step on any router.
• The access-list argument specifies the number or name
of an access list that defines for which multicast groups
the RP should be used.
• The override keyword specifies that if there is a
conflict between the RP configured with this command
and one learned by Auto-RP, the RP configured with
this command prevails.
Step 9
Switch(config)# end
Ends the current configuration session and returns to EXEC
mode.
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