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Figure 40. IGMP Messages in IP Packets
Join a Multicast Group
There are two ways that a host may join a multicast group: it may respond to a general query from its
querier or it may send an unsolicited report to its querier.
Responding to an IGMP Query
The following describes how a host can join a multicast group.
1.
One router on a subnet is elected as the querier. The querier periodically multicasts (to all-multicast-
systems address 224.0.0.1) a general query to all hosts on the subnet.
2.
A host that wants to join a multicast group responds with an IGMP Membership Report that contains
the multicast address of the group it wants to join (the packet is addressed to the same group). If
multiple hosts want to join the same multicast group, only the report from the first host to respond
reaches the querier and the remaining hosts suppress their responses (For how the delay timer
mechanism works, refer to
Adjusting Query and Response Timers
).
3.
The querier receives the report for a group and adds the group to the list of multicast groups
associated with its outgoing port to the subnet. Multicast traffic for the group is then forwarded to
that subnet.
Sending an Unsolicited IGMP Report
A host does not have to wait for a general query to join a group. It may send an unsolicited IGMP
Membership Report, also called an IGMP Join message, to the querier.
Leaving a Multicast Group
The following describes how a host can leave a multicast group.
1.
A host sends a membership report of type 0x17 (IGMP Leave message) to the all routers multicast
address 224.0.0.2 when it no longer cares about multicast traffic for a particular group.
2.
The querier sends a Group-Specific Query to determine whether there are any remaining hosts in
the group. There must be at least one receiver in a group on a subnet for a router to forward
multicast traffic for that group to the subnet.
3.
Any remaining hosts respond to the query according to the delay timer mechanism (refer to
Adjusting Query and Response Timers
). If no hosts respond (because there are none remaining in
the group), the querier waits a specified period and sends another query. If it still receives no
Internet Group Management Protocol (IGMP)
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Содержание S6000-ON
Страница 1: ...Dell Configuration Guide for the S6000 ON System 9 9 0 0 ...
Страница 505: ...Figure 60 Inspecting Configuration of LAG 10 on ALPHA Link Aggregation Control Protocol LACP 505 ...
Страница 508: ...Figure 62 Inspecting a LAG Port on BRAVO Using the show interface Command 508 Link Aggregation Control Protocol LACP ...
Страница 509: ...Figure 63 Inspecting LAG 10 Using the show interfaces port channel Command Link Aggregation Control Protocol LACP 509 ...
Страница 552: ...mac address table static multicast mac address vlan vlan id output range interface 552 Microsoft Network Load Balancing ...
Страница 557: ...Figure 80 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 557 ...
Страница 558: ...Figure 81 Configuring PIM in Multiple Routing Domains 558 Multicast Source Discovery Protocol MSDP ...
Страница 562: ...Figure 83 MSDP Default Peer Scenario 1 562 Multicast Source Discovery Protocol MSDP ...
Страница 563: ...Figure 84 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 563 ...
Страница 564: ...Figure 85 MSDP Default Peer Scenario 3 564 Multicast Source Discovery Protocol MSDP ...
Страница 665: ...Policy based Routing PBR 665 ...
Страница 672: ...ip pim bsr border Remove candidate RP advertisements clear ip pim rp mapping 672 PIM Sparse Mode PIM SM ...
Страница 818: ...Figure 110 Single and Double Tag TPID Match 818 Service Provider Bridging ...
Страница 819: ...Figure 111 Single and Double Tag First byte TPID Match Service Provider Bridging 819 ...
Страница 995: ...Figure 140 Setup OSPF and Static Routes Virtual Routing and Forwarding VRF 995 ...