Multimedia Traffic Control with IP Multicast (IGMP)

How IGMP Operates

Querier's processing of that Leave. For more on this topic, refer to “Forced Fast-Leave IGMP” on page 4-17.

ProCurve recommends that the following settings be used.

Use Delayed Group Flush on the Series 2610 switches whenever Fast Leave or Forced Fast Leave are set on a port (see page 4-17).

Forced fast leave can be used when there are multiple devices attached to a port.

Automatic Fast-Leave Operation. If a switch port is:

a.Connected to only one end node

b.The end node currently belongs to a multicast group; i.e. is an IGMP client

c.The end node subsequently leaves the multicast group

Then the switch does not need to wait for the Querier status update interval, but instead immediately removes the IGMP client from its IGMP table and ceases transmitting IGMP traffic to the client. (If the switch detects multiple end nodes on the port, automatic Fast-Leave does not activate—regardless of whether one or more of these end nodes are IGMP clients.)

In the next figure, automatic Fast-Leave operates on the switch ports for IGMP clients “3A” and “5A”, but not on the switch port for IGMP clients “7A” and 7B, Server “7C”, and printer “7D”.

Fast-Leave IGMP automatically operates on the ports connected to IGMP clients 3A and 5A, but does not operate on the port connected to Switch 7X

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Server

 

 

Fast-Leave IGMP

 

 

 

 

 

3A

 

 

 

 

 

5A

 

 

 

7A

 

 

 

 

 

 

 

 

7B

 

 

7C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

activates on these

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

two ports.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Switch 7X

 

 

 

 

Routing

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Printer

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Switch

 

A1

 

 

 

A3

 

A4 A6

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7D

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Acting as

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Querier

 

 

 

ProCurve Switch with

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Automatic Fast-Leave

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fast-Leave IGMP does

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

not activate on this port.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 4-3. Example of Automatic Fast-Leave IGMP Criteria

When client “3A” running IGMP is ready to leave the multicast group, it transmits a Leave Group message. Because the switch knows that there is only one end node on port A3, it removes the client from its IGMP table and halts multicast traffic (for that group) to port A3. If the switch is not the Querier, it

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