C
HAPTER
15
| Multicast Filtering
Layer 2 IGMP (Snooping and Query)
– 399 –
Figure 233: Showing Current Interfaces Assigned to a Multicast Service
SETTING IGMP
SNOOPING STATUS
PER INTERFACE
Use the Multicast > IGMP Snooping > Interface (Configure) page to
configure IGMP snooping attributes for a VLAN interface. To configure
snooping globally, refer to "Configuring IGMP Snooping and Query
Parameters" on page 391.
CLI REFERENCES
â—† "IGMP Snooping" on page 904
COMMAND USAGE
Multicast Router Discovery
There have been many mechanisms used in the past to identify multicast
routers. This has lead to interoperability issues between multicast routers
and snooping switches from different vendors. In response to this problem,
the Multicast Router Discovery (MRD) protocol has been developed for use
by IGMP snooping and multicast routing devices. MRD is used to discover
which interfaces are attached to multicast routers, allowing IGMP-enabled
devices to determine where to send multicast source and group
membership messages. (MRD is specified in draft-ietf-magma-mrdisc-07.)
Multicast source data and group membership reports must be received by
all multicast routers on a segment. Using the group membership protocol
query messages to discover multicast routers is insufficient due to query
suppression. MRD therefore provides a standardized way to identify
multicast routers without relying on any particular multicast routing
protocol.
N
OTE
:
The default values recommended in the MRD draft are implemented
in the switch.
Multicast Router Discovery uses the following three message types to
discover multicast routers:
◆ Multicast Router Advertisement – Advertisements are sent by routers to
advertise that IP multicast forwarding is enabled. These messages are
sent unsolicited periodically on all router interfaces on which multicast
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