Install guide

4 Software Reference
IP Multicast Routing
For multicasting to succeed, the switch needs to know which of its interfaces
are directly connected to members of each multicast group. To establish this,
the switch uses IGMP for multicast group management (see “Internet Group
Management Protocol (IGMP)” on page 17).
The switch must also know where to send multicast traffic. The switch
maintains a routing table for multicast traffic with the following:
■ PIM-Sparse Mode or PIM-Dense Mode
IGMP and one of the multicast routing protocols must be configured before the
switch can forward multicast packets.
The relationships between IP hosts, routers, and multicasting protocols are
shown in the following figure.
Figure 1: Multicast environment
IPMU1
IGMP
group
management
protocol
DVMRP, PIM-SM
or PIM-DM
multicast routing
protocol
IGMP
group
management
protocol
routers or
Layer 3
switches
senders and receivers - multicast group members (IP hosts)
senders and receivers - multicast group members (IP hosts)
IGMP
group
management
protocol