Configuring Igmp Snooping; Information About Igmp Snooping - Cisco nexus 5000 series Cli Configuration Manual

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Configuring IGMP Snooping

Internet Group Management Protocol (IGMP) snooping streamlines multicast traffic handling for
VLANs. By examining (snooping) IGMP membership report messages from interested hosts, multicast
traffic is limited to the subset of VLAN interfaces on which the hosts reside.
This chapter includes the following sections:
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Information About IGMP Snooping

The IGMP snooping software examines IGMP protocol messages within a VLAN to discover which
interfaces are connected to hosts or other devices interested in receiving this traffic. Using the interface
information, IGMP snooping can reduce bandwidth consumption in a multi-access LAN environment to
avoid flooding the entire VLAN. The IGMP snooping feature tracks which ports are attached to
multicast-capable routers to help it manage the forwarding of IGMP membership reports. The IGMP
snooping software responds to topology change notifications.
IGMP snooping is supported on all Ethernet interfaces. The term snooping is used because Layer 3
Note
control plane packets are intercepted and influence Layer 2 forwarding decisions.
Cisco NX-OS supports IGMPv2 and IGMPv3. IGMPv2 supports IGMPv1, and IGMPv3 supports
IGMPv2. Although not all features of an earlier version of IGMP are supported, the features related to
membership query and membership report messages are supported for all IGMP versions.
Figure 1-1
IGMP snooping switch snoops the IGMP membership reports and leave messages and forwards them
only when necessary to the connected IGMP routers.
OL-16597-01
Information About IGMP Snooping, page 1-1
Configuring IGMP Snooping Parameters, page 1-4
Verifying IGMP Snooping Configuration, page 1-6
shows an IGMP snooping switch that is located between the host and the IGMP router. The
C H A P T E R
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
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