Internet Group Msnagment Protocol)

Internet Group Management Protocol)

No matter how many routing protocols are running on the multicast internet, IGMP must be run between the host and the router. IGMP must be run on all routers of multicast hosts that want to join multicast groups and subnets connected to all interfaces. This protocol is similar to ICMPInternetControlMessageProtocol ).

IGMP is responsible for managing high-level data exchanges. This is done by implementing IGMP rules and setting the TTL of the TP header to 1.

There are currently two versions of IGMP. IGMPv2 defined in IGMP v1 and RFC2236 in RFC1112 Cisco IOS software Release 11.1 supports IGMPv2 by default, but many hosts implement TCP/IP, IGMPv1 is still supported. For example, if the service is installed on Windows NT4.0 before SP4, you can use the command ip igmp version to change the default supported IGMP version.

IGMPv2 host Function

The host running IGMPv2 uses the following three types of messages:

• Membership Report Message

• Version 1 Membership Report (Version 1 member reports messages)

• Leava Group (Left Group) Message

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A member report message is used to send a message when a host is added to a multicast group for the first time. Sometimes it is also the response message of the Membership Query (member relationship Query) message sent by the local router.

When the host understands the multicast group and wants to join the reorganization, it does not wait for the query message sent by the local router. The router cannot know the specific multicast group that the host wants to join, therefore, no query message is sent for group members. If the host must wait for the query message, there is no chance to join the group. On the contrary, when a host is added to a multicast group for the first time, a member relationship report message is sent to the multicast group.

In a vro, the source, group, and address pairs are used to represent multicast sessions. The original address is the address of the session initiator and the Group address is the class D address. If the local multicast Router does not know the multicast session to be added to the RST lock, a request message is sent to the upstream Multicast Source. After receiving the data stream, the router starts to forward data traffic to the subnet where the host requesting the group member is located.

The destination address in the IP header of the report message is the group address. The message itself contains the Group address. To ensure that the local router is able to receive the member relationship report messages that are actively sent. The host needs to send one or two duplicate report messages within a short interval. The recommended RFC2236 interval is 10 seconds.

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This article is from the "industry diligence and waste in Taobao" blog, please be sure to keep this source http://sxsure.blog.51cto.com/2166161/1275918