SMC Networks 8612XL3, Management Manual

Page: 373 / 846

M
ULTICAST
R
OUTING
3-319
neighbors.
Multicast Routing
This router can route multicast traffic to different subnetworks using
either Distance Vector Multicast Routing Protocol (DVMRP) or
Protocol-Independent Multicasting - Dense Mode (PIM-DM). These
protocols flood multicast traffic downstream, and calculate the
shortest-path, source-rooted delivery tree between each source and
destination host group. They also rely on messages sent from
IGMP-enabled Layer 2 switches and hosts to determine when hosts want
to join or leave multicast groups.
DVMRP builds a source-rooted multicast delivery tree that allows it to
prevent looping and determine the shortest path to the source of the
multicast traffic. PIM also builds a source-rooted multicast delivery tree for
each multicast source, but uses information from the router’s unicast
routing table instead of maintaining its own multicast routing table, making
it routing protocol independent. Also note that the Dense Mode version of
PIM is supported on this router because it is suitable for densely populated
multicast groups which occur primarily in the LAN environment.
If DVMRP and PIM-DM are not enabled on this router or another
multicast routing protocol is used on your network, you can manually
configure the switch ports attached to a multicast router (page 3-196).
Configuring Global Settings for Multicast Routing
To use multicast routing on this router, you must first globally enable
multicast routing as described in this section, globally enable DVRMP
Console#show ip ospf neighbor 3-182
ID Pri State Address
--------------- ------ ---------------- ---------------
10.2.44.5 1 FULL/DR 10.2.44.88
10.2.44.6 2 FULL/BDR 10.2.44.88
Console#