DELL S50V User Manual

Internet Group Management Protocol | 407

Figure 19-4. IGMP Membership Reports: Joining and Filtering

Leaving and Staying in Groups

Figure 19-5

shows how multicast routers track and refresh state changes in response to group-and-specific

and general queries.

1. Host 1 sends a message indicating it is leaving group 224.1.1.1 and that the include filter for 10.11.1.1

and 10.11.1.2 are no longer necessary.

2. The querier, before making any state changes, sends a group-and-source query to see if any other host

is interested in these two sources; queries for state-changes are retransmitted multiple times. If any are,
they respond with their current state information and the querier refreshes the relevant state
information.

3. Separately in

Figure 19-5

, the querier sends a general query to 224.0.0.1.

4. Host 2 responds to the periodic general query so the querier refreshes the state information for that

group.

1/1

Type: 0x22
Number of Group Records: 1
Record Type: 4
Number of Sources: 0
Multicast Address: 224.1.1.1

Interface Multicast Group Filter Source Source
Address Timer Mode Timer

1/1 224.1.1.1 GMI Exclude

None

1/1 224.1.1.1 Include

10.11.1.1 GMI

1/1 224.1.1.1 Include

10.11.1.1

GMI

10.11.1.2 GMI

IGMP Join message

Type: 0x22
Number of Group Records: 1
Record Type: 3
Number of Sources: 1
Multicast Address: 224.1.1.1
Source Address: 10.11.1.1

Change to Include

Type: 0x22
Number of Group Records: 1
Record Type: 5
Number of Sources: 1
Multicast Address: 224.1.1.1
Source Address: 10.11.1.2

Allow New

State-change reports retransmitted
Query Robustness Value-1 times at
Unsolicited Report Interval

Querier

Non-Querier

Membership Reports: Joining and Filtering

Type: 0x11
Group Address: 244.1.1.1
Number of Sources: 1
Source Address: 10.11.1.1

IGMP Group-and-Source
Specific Query

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