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Internet Group Management Protocol (IGMP)
Internet group management protocol (IGMP) is a Layer 3 multicast protocol that hosts use to join or leave a multicast group.
Multicast is premised on identifying many hosts by a single destination IP address; hosts represented by the same IP address are a
multicast group. Multicast routing protocols (such as protocol-independent multicast [PIM]) use the information in IGMP messages
to discover which groups are active and to populate the multicast routing table.
IGMP Implementation Information
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Dell Networking Operating System (OS) supports IGMP versions 1, 2, and 3 based on RFCs 1112, 2236, and 3376, respectively.
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Dell Networking OS does not support IGMP version 3 and versions 1 or 2 on the same subnet.
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IGMP on Dell Networking OS supports 95 interfaces on S4810 and S4820 and an unlimited number of groups on all other
platforms.
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Dell Networking systems cannot serve as an IGMP host or an IGMP version 1 IGMP Querier.
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Dell Networking OS automatically enables IGMP on interfaces on which you enable a multicast routing protocol.
IGMP Protocol Overview
IGMP has three versions. Version 3 obsoletes and is backwards-compatible with version 2; version 2 obsoletes version 1.
IGMP Version 2
IGMP version 2 improves on version 1 by specifying IGMP Leave messages, which allows hosts to notify routers that they no longer
care about traffic for a particular group.
Leave messages reduce the amount of time that the router takes to stop forwarding traffic for a group to a subnet (leave latency)
after the last host leaves the group. In version 1 hosts quietly leave groups, and the router waits for a query response timer several
times the value of the query interval to expire before it stops forwarding traffic.
To receive multicast traffic from a particular source, a host must join the multicast group to which the source is sending traffic. A
host that is a member of a group is called a receiver. A host may join many groups, and may join or leave any group at any time. A
host joins and leaves a multicast group by sending an IGMP message to its IGMP Querier. The querier is the router that surveys a
subnet for multicast receivers and processes survey responses to populate the multicast routing table.
IGMP messages are encapsulated in IP packets, as shown in the following illustration.
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Internet Group Management Protocol (IGMP)
Summary of Contents for S4048-ON
Page 1: ...Dell Configuration Guide for the S4048 ON System 9 9 0 0 ...
Page 146: ...Figure 14 BFD Three Way Handshake State Changes 146 Bidirectional Forwarding Detection BFD ...
Page 522: ...Figure 87 Configuring Interfaces for MSDP 522 Multicast Source Discovery Protocol MSDP ...
Page 523: ...Figure 88 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 523 ...
Page 528: ...Figure 91 MSDP Default Peer Scenario 1 528 Multicast Source Discovery Protocol MSDP ...
Page 529: ...Figure 92 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 529 ...
Page 530: ...Figure 93 MSDP Default Peer Scenario 3 530 Multicast Source Discovery Protocol MSDP ...
Page 633: ...Policy based Routing PBR 633 ...
Page 777: ...Figure 119 Single and Double Tag TPID Match Service Provider Bridging 777 ...
Page 778: ...Figure 120 Single and Double Tag First byte TPID Match 778 Service Provider Bridging ...