44-13
Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
OL-13270-01
Chapter44 Configuring IP Multicast Routi ng Configuring IP Multicast Routing
In populating the multicast routing table, dense-mode int erfac e s are always adde d to t he t abl e.
Sparse-mode interfaces are added to the table on l y wh en pe riod ic jo in m es s ag es ar e rec eived fro m
downstream devices or when there is a directly connected member on the interface. When forwarding
from a LAN, sparse-mode operation occurs if there is an RP known fo r the group. If so, the packets are
encapsulated and sent toward the RP. When no RP is known, the packet is flooded in a dense-mode
fashion. If the multicast traffic from a specific source is sufficient, the receiver’s first-hop router might
send join messages toward the source to build a source-based distribution tree.
By default, multicast routing is disabled, and there is no default mode setting. This procedure is required.
Beginning in privileged EXEC mode, follow these steps to enable IP multicasting, to configure a PIM
version, and to configure a PIM mode. This procedure is req ui red.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 ip multicast-routing distributed Enable IP multicast distributed switching.
Step3 interface interface-id Specify the Layer 3 interface on which you want to enable multicast
routing, and enter interface configuration mode.
The specified interface must be one of the following:
A routed port: a physical port that has been configured as a Layer 3
port by entering the no switchport interface configuration
command.
An SVI: a VLAN interface created by using the interface vlan
vlan-id global configuration command.
These interfaces must have IP addresses assigned to them. For more
information, see the “Configuring Layer 3 Interfaces” section on
page 10-22.
Step4 ip pim version [1 | 2] Configure the PIM version on the interface.
By default, Version 2 is enabled and is the recommended setting.
An interface in PIMv2 mode automatically downgrades to PIMv1 mode
if that interface has a PIMv1 neighbor. The interface returns to Version 2
mode after all Version 1 neighbors are shut down or upgraded.
For more information, see the “PIMv1 and PIMv2 Interoperability”
section on page 44-11.