Cisco Systems 3130 User Manual
23-3
Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
OL-13270-01
Chapter 23 Configuring IGMP Snooping and MVR
Understanding IGMP Snooping
IGMP Versions
The switch supports IGMP Version 1, IGMP Version 2, and IGMP Version 3. These versions are
interoperable on the switch. For example, if IGMP snooping is enabled on an IGMPv2 switch and the
switch receives an IGMPv3 report from a host, the switch can forward the IGMPv3 report to the
multicast router.
interoperable on the switch. For example, if IGMP snooping is enabled on an IGMPv2 switch and the
switch receives an IGMPv3 report from a host, the switch can forward the IGMPv3 report to the
multicast router.
Note
The switch supports IGMPv3 snooping based only on the destination multicast MAC address. It does not
support snooping based on the source MAC address or on proxy reports.
support snooping based on the source MAC address or on proxy reports.
An IGMPv3 switch supports Basic IGMPv3 Snooping Support (BISS), which includes support for the
snooping features on IGMPv1 and IGMPv2 switches and for IGMPv3 membership report messages.
BISS constrains the flooding of multicast traffic when your network includes IGMPv3 hosts. It
constrains traffic to approximately the same set of ports as the IGMP snooping feature on IGMPv2 or
IGMPv1 hosts.
snooping features on IGMPv1 and IGMPv2 switches and for IGMPv3 membership report messages.
BISS constrains the flooding of multicast traffic when your network includes IGMPv3 hosts. It
constrains traffic to approximately the same set of ports as the IGMP snooping feature on IGMPv2 or
IGMPv1 hosts.
Note
IGMPv3 join and leave messages are not supported on switches running IGMP filtering or MVR.
An IGMPv3 switch can receive messages from and forward messages to a device running the Source
Specific Multicast (SSM) feature. For more information about source-specific multicast with IGMPv3
and IGMP, see this URL:
Specific Multicast (SSM) feature. For more information about source-specific multicast with IGMPv3
and IGMP, see this URL:
Joining a Multicast Group
When a blade server connected to the switch wants to join an IP multicast group and it is an IGMP
Version 2 client, it sends an unsolicited IGMP join message, specifying the IP multicast group to join.
Alternatively, when the switch receives a general query from the router, it forwards the query to all ports
in the VLAN. IGMP Version 1 or Version 2 blade servers wanting to join the multicast group respond
by sending a join message to the switch. The switch CPU creates a multicast forwarding-table entry for
the group if it is not already present. The CPU also adds the interface where the join message was
received to the forwarding-table entry. The blade server associated with that interface receives multicast
traffic for that multicast group. See
Version 2 client, it sends an unsolicited IGMP join message, specifying the IP multicast group to join.
Alternatively, when the switch receives a general query from the router, it forwards the query to all ports
in the VLAN. IGMP Version 1 or Version 2 blade servers wanting to join the multicast group respond
by sending a join message to the switch. The switch CPU creates a multicast forwarding-table entry for
the group if it is not already present. The CPU also adds the interface where the join message was
received to the forwarding-table entry. The blade server associated with that interface receives multicast
traffic for that multicast group. See
.