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IGMP Snooping Commands
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IGMP Snooping Commands
Snooping of Internet Group Management Protocol (IGMP) messages is a
feature that allows PowerConnect switches to forward multicast traffic
intelligently on the switch. Multicast IP traffic is traffic that is destined to a
host group. Host groups are identified by class D IP addresses, which range
from 224.0.0.0 to 239.255.255.255. Based on the IGMP query and report
messages, the switch forwards traffic only to the ports that request the
multicast traffic. This prevents the switch from broadcasting the traffic to all
ports and possibly affecting network performance.
IGMP snooping switches build forwarding lists by monitoring for, and in
some cases intercepting, IGMP messages. Although the software processing
the IGMP messages could maintain state information based on the full IP
group addresses, the forwarding tables in PowerConnect are mapped to link
layer addresses.
The Multicast Forwarding Database (MFDB) manages the forwarding
address table for Layer 2 multicast protocols, such as IGMP Snooping.
The IGMP Snooping code in the CPU ages out IGMP entries in the MFDB.
If a report for a particular group on a particular interface is not received
within a certain time interval (query interval), the IGMP Snooping code
deletes that interface from the group. The value for query interval time is
configurable using management.
If an IGMP Leave Group message is received on an interface, the IGMP
Snooping code sends a query on that interface and waits a specified length of
time (maximum response time). If no response is received within that time,
that interface is removed from the group. The value for maximum response
time is configurable using management.
In addition to building and maintaining lists of multicast group
memberships, the snooping switch also maintains a list of multicast routers.
When forwarding multicast packets, they should be forwarded on ports that
have joined using IGMP and also on ports on which multicast routers are
attached. The reason for this is that in IGMP there is only one active query
mechanism. This means that all other routers on the network are suppressed
and thus not detectable by the switch. If a query is not received on an
2CSPC4.XCT-SWUM2XX1.book Page 479 Monday, October 3, 2011 11:05 AM
Summary of Contents for PowerConnect 7000 Series
Page 74: ...74 Contents 2CSPC4 XCT SWUM2XX1 book Page 74 Monday October 3 2011 11 05 AM ...
Page 164: ...164 Command Groups 2CSPC4 XCT SWUM2XX1 book Page 164 Monday October 3 2011 11 05 AM ...
Page 266: ...266 AAA Commands 2CSPC4 XCT SWUM2XX1 book Page 266 Monday October 3 2011 11 05 AM ...
Page 316: ...316 Auto VoIP Commands 2CSPC4 XCT SWUM2XX1 book Page 316 Monday October 3 2011 11 05 AM ...
Page 368: ...368 DHCP Snooping Commands 2CSPC4 XCT SWUM2XX1 book Page 368 Monday October 3 2011 11 05 AM ...
Page 454: ...454 Ethernet CFM Commands 2CSPC4 XCT SWUM2XX1 book Page 454 Monday October 3 2011 11 05 AM ...
Page 468: ...468 Green Ethernet Commands 2CSPC4 XCT SWUM2XX1 book Page 468 Monday October 3 2011 11 05 AM ...
Page 558: ...558 IP Source Guard Commands 2CSPC4 XCT SWUM2XX1 book Page 558 Monday October 3 2011 11 05 AM ...
Page 578: ...578 Link Dependency Commands 2CSPC4 XCT SWUM2XX1 book Page 578 Monday October 3 2011 11 05 AM ...
Page 606: ...606 LLDP Commands 2CSPC4 XCT SWUM2XX1 book Page 606 Monday October 3 2011 11 05 AM ...
Page 700: ...700 QoS Commands 2CSPC4 XCT SWUM2XX1 book Page 700 Monday October 3 2011 11 05 AM ...
Page 728: ...728 RADIUS Commands 2CSPC4 XCT SWUM2XX1 book Page 728 Monday October 3 2011 11 05 AM ...
Page 808: ...808 VLAN Commands 2CSPC4 XCT SWUM2XX1 book Page 808 Monday October 3 2011 11 05 AM ...
Page 814: ...814 Voice VLAN Commands 2CSPC4 XCT SWUM2XX1 book Page 814 Monday October 3 2011 11 05 AM ...
Page 848: ...848 802 1x Commands 2CSPC4 XCT SWUM2XX1 book Page 848 Monday October 3 2011 11 05 AM ...
Page 850: ...850 Layer 3 Commands 2CSPC4 XCT SWUM2XX1 book Page 850 Monday October 3 2011 11 05 AM ...
Page 912: ...912 DHCPv6 Commands 2CSPC4 XCT SWUM2XX1 book Page 912 Monday October 3 2011 11 05 AM ...
Page 920: ...920 DVMRP Commands 2CSPC4 XCT SWUM2XX1 book Page 920 Monday October 3 2011 11 05 AM ...
Page 946: ...946 IGMP Proxy Commands 2CSPC4 XCT SWUM2XX1 book Page 946 Monday October 3 2011 11 05 AM ...
Page 1062: ...1062 IPv6 Routing Commands 2CSPC4 XCT SWUM2XX1 book Page 1062 Monday October 3 2011 11 05 AM ...
Page 1174: ...1174 OSPF Commands 2CSPC4 XCT SWUM2XX1 book Page 1174 Monday October 3 2011 11 05 AM ...
Page 1234: ...1234 OSPFv3 Commands 2CSPC4 XCT SWUM2XX1 book Page 1234 Monday October 3 2011 11 05 AM ...
Page 1294: ...1294 Utility Commands 2CSPC4 XCT SWUM2XX1 book Page 1294 Monday October 3 2011 11 05 AM ...
Page 1304: ...1304 Auto Install Commands 2CSPC4 XCT SWUM2XX1 book Page 1304 Monday October 3 2011 11 05 AM ...
Page 1348: ...1348 CLI Macro Commands 2CSPC4 XCT SWUM2XX1 book Page 1348 Monday October 3 2011 11 05 AM ...
Page 1366: ...1366 Clock Commands 2CSPC4 XCT SWUM2XX1 book Page 1366 Monday October 3 2011 11 05 AM ...
Page 1478: ...1478 RMON Commands 2CSPC4 XCT SWUM2XX1 book Page 1478 Monday October 3 2011 11 05 AM ...
Page 1518: ...1518 Sflow Commands 2CSPC4 XCT SWUM2XX1 book Page 1518 Monday October 3 2011 11 05 AM ...
Page 1578: ...1578 Syslog Commands 2CSPC4 XCT SWUM2XX1 book Page 1578 Monday October 3 2011 11 05 AM ...
Page 1646: ...1646 Telnet Server Commands 2CSPC4 XCT SWUM2XX1 book Page 1646 Monday October 3 2011 11 05 AM ...
Page 1686: ...1686 Web Server Commands 2CSPC4 XCT SWUM2XX1 book Page 1686 Monday October 3 2011 11 05 AM ...
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