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.
Figure 44. 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.
370
Internet Group Management Protocol (IGMP)
Содержание S4048T-ON
Страница 1: ...Dell Configuration Guide for the S4048 ON System 9 11 2 1 ...
Страница 148: ...Figure 10 BFD Three Way Handshake State Changes 148 Bidirectional Forwarding Detection BFD ...
Страница 251: ...Dell Control Plane Policing CoPP 251 ...
Страница 363: ... RPM Synchronization GARP VLAN Registration Protocol GVRP 363 ...
Страница 511: ...Figure 64 Inspecting the LAG Configuration Link Aggregation Control Protocol LACP 511 ...
Страница 512: ...Figure 65 Inspecting Configuration of LAG 10 on ALPHA 512 Link Aggregation Control Protocol LACP ...
Страница 515: ...Figure 67 Inspecting a LAG Port on BRAVO Using the show interface Command Link Aggregation Control Protocol LACP 515 ...
Страница 516: ...Figure 68 Inspecting LAG 10 Using the show interfaces port channel Command 516 Link Aggregation Control Protocol LACP ...
Страница 558: ...Figure 84 Configuring Interfaces for MSDP 558 Multicast Source Discovery Protocol MSDP ...
Страница 559: ...Figure 85 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 559 ...
Страница 560: ...Figure 86 Configuring PIM in Multiple Routing Domains 560 Multicast Source Discovery Protocol MSDP ...
Страница 564: ...Figure 88 MSDP Default Peer Scenario 2 564 Multicast Source Discovery Protocol MSDP ...
Страница 565: ...Figure 89 MSDP Default Peer Scenario 3 Multicast Source Discovery Protocol MSDP 565 ...
Страница 729: ...protocol spanning tree pvst no disable vlan 300 bridge priority 4096 Per VLAN Spanning Tree Plus PVST 729 ...
Страница 841: ...Figure 115 Single and Double Tag TPID Match Service Provider Bridging 841 ...
Страница 842: ...Figure 116 Single and Double Tag First byte TPID Match 842 Service Provider Bridging ...