C
ONFIGURING
THE
S
WITCH
3-192
Note that IGMP neither alters nor routes IP multicast packets. A multicast
routing protocol must be used to deliver IP multicast packets across
different subnetworks. Therefore, when DVMRP or PIM routing is
enabled for a subnet on this switch, you also need to enable IGMP.
Layer 2 IGMP (Snooping and Query)
IGMP Snooping and Query – If multicast routing is not supported on
other switches in your network, you can use IGMP Snooping and IGMP
Query (page 3-193) to monitor IGMP service requests passing between
multicast clients and servers, and dynamically configure the switch ports
which need to forward multicast traffic.
Static IGMP Router Interface – If IGMP snooping cannot locate the
IGMP querier, you can manually designate a known IGMP querier (i.e., a
multicast router/switch) connected over the network to an interface on
your switch (page3 -196). This interface will then join all the current
multicast groups supported by the attached router/switch to ens ure that
multicast traffic is passed to all appropriate interfaces within the switch.
Static IGMP Host Interface – For multicast applications that you need to
control more carefully, you can manually assign a multicast service to
specific interfaces on the switch (page 3-199).
L3- network core
(multicastrouting)
L2- edge switches
(snoopingand query)
L2switch to end nodes
(snoopingon IGMP clients)