SNR S2989G-48TX-DC — настройка IGMP: Протоколы и Конфигурация Мультикастинга [255/553]

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S2989G-24TX Operation Manual

Chapter 5 Multicast Protocol Related Configuration

4-30

network segment. This query is called general group query. In IGMP version2, query of

specific group is added besides general group query. The destination IP address of this

kind of query message is the IP address of the multicast group, the group address field

part of the message is also the IP address of the multicast group. Thus it is prevented that

hosts which are other multicast group members transmit response message.

4. IGMP version2 added the biggest response time field

IGMP version2 added the biggest response time field to dynamically adjust the

response time of the host to group query message.

The main features of version3 is allowing the host to choose receiving from or

rejecting a certain source, which is the basis of SSM（Source-Specific Multicast）multicast.

For example, when a host is sending a report of INCLUDE{10.1.1.1, 10.1.1.2} to some

group G, that means the host needs the router to forward the flux from 10.1.1.1 and

10.1.1.2; when a host is sending a report of EXCLUDE{192.168.1.1} to some group G,

that means the host needs the flux from all sources of group G except 192.168.1.1. This

makes a great difference from the previous IGMP.

The main improvements of IGMP Version3 over IGMP Version1 and Version2 are:

1. The status to be maintained is group and source list, not only the groups in IGMPv2.

2. The interoperations with IGMPv1 and IGMPv2 are defined in IGMPv3 status.

3. IP service interface is modified to allow specific source list thereby.

4. The queried includes his/her Robustness Variable and Query Interval in query group

to allow the synchronization with these variables of non-queries.

5. Max Response Time in Query Message has an exponential range, with maximum

value from 25.5 secs of v2 to 53 mins, which can be used in links of great capacity.

6. In order to increase strength, the host retransmits State-Change message.

7. Additional data is defined to adapt future extension.

8. Report group is sent to 224.0.0.22 to help with IGMP Snooping of Layer 2 Switch.

9. Report group can include more than one group record, and it allows using small

group to report complete current status.

10. The host does not restrain operation any more, which simplifies the implement and

allows direct membership trace.

11. In querying messages, the new router side restraint process (S sign) modified the

existing strength of IGMPv2.

5.2.2

IGMP Configuration Task List

1. Enable IGMP (Required)

2. Configure IGMP sub-parameters (Optional)

（1） Configure IGMP group parameters