Netgear XCM8810 - 8800 SERIES 10-SLOT CHASSIS SWITCH ユーザーズマニュアル
Chapter 27. Multicast Routing and Switching
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NETGEAR 8800 User Manual
IGMP Overview
IGMP is a protocol used by an IP host to register its IP multicast group membership with a
router. A host that intends to receive multicast packets destined for a particular multicast
address registers as a member of that multicast address group. Periodically, the router
queries the multicast group to see if the group is still in use. If the group is still active, a single
IP host responds to the query, and group registration is maintained.
router. A host that intends to receive multicast packets destined for a particular multicast
address registers as a member of that multicast address group. Periodically, the router
queries the multicast group to see if the group is still in use. If the group is still active, a single
IP host responds to the query, and group registration is maintained.
IGMPv2 is enabled by default on the switch, and the XCM8800 software supports IGMPv3.
However, the switch can be configured to disable the generation of periodic IGMP query
packets. IGMP should be enabled when the switch is configured to perform IP multicast
routing.
However, the switch can be configured to disable the generation of periodic IGMP query
packets. IGMP should be enabled when the switch is configured to perform IP multicast
routing.
IGMPv3, specified in RFC 3376, adds support for source filtering. Source filtering is the
ability for a system to report interest in receiving packets only from specific source addresses
(filter mode include) or from all sources except for specific addresses (filter mode exclude).
IGMPv3 is designed to be interoperable with IGMPv1 and IGMPv2.
ability for a system to report interest in receiving packets only from specific source addresses
(filter mode include) or from all sources except for specific addresses (filter mode exclude).
IGMPv3 is designed to be interoperable with IGMPv1 and IGMPv2.
Note:
The XCM8800 software supports IGMPv3 source include mode
filtering, but it does not support IGMPv3 specific source exclude
mode filtering.
mode filtering.
The following sections provide information on IGMP features:
IGMP Snooping
IGMP snooping is a Layer 2 function of the switch; it does not require multicast routing to be
enabled. In IGMP snooping, the Layer 2 switch keeps track of IGMP reports and only
forwards multicast traffic to that part of the local network that requires it. IGMP snooping
optimizes the use of network bandwidth and prevents multicast traffic from being flooded to
parts of the local network that do not need it. The switch does not reduce any IP multicast
traffic in the local multicast domain (224.0.0.x).
enabled. In IGMP snooping, the Layer 2 switch keeps track of IGMP reports and only
forwards multicast traffic to that part of the local network that requires it. IGMP snooping
optimizes the use of network bandwidth and prevents multicast traffic from being flooded to
parts of the local network that do not need it. The switch does not reduce any IP multicast
traffic in the local multicast domain (224.0.0.x).
IGMP snooping is enabled by default on all VLANs in the switch. If IGMP snooping is
disabled on a VLAN, all IGMP and IP multicast traffic floods within the VLAN. IGMP snooping
expects at least one device on every VLAN to periodically generate IGMP query messages.
disabled on a VLAN, all IGMP and IP multicast traffic floods within the VLAN. IGMP snooping
expects at least one device on every VLAN to periodically generate IGMP query messages.
To enable or disable IGMP snooping, use the following commands: