Multimedia Traffic Control with IP Multicast (IGMP)
How IGMP Operates
Automatic
IGMP Operation Presents a “Delayed Leave” Problem. Where multiple IGMP clients are connected to the same port on an IGMP device (switch or router), if only one IGMP client joins a given multicast group, then later sends a Leave Group message and ceases to belong to that group, the IGMP device retains that IGMP client in its IGMP table and continues forwarding IGMP traffic to the IGMP client until the Querier triggers confirmation that no other group members exist on the same port. This means that the switch continues to transmit unnecessary multicast traffic through the port until the Querier renews the multicast group status.
Switch Model or | Data- | IGMP Fast- | Default IGMP Behavior |
Series | Driven | Leave Setting |
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| IGMP |
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| Included? |
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|
Switch 8212zl | Yes | Always | Drops unjoined multicast traffic except for |
Switch 6400cl |
| Enabled | |
Switch 6200yl |
|
| Querier or multicast routers, and out of |
|
| ||
Switch 5400zl |
|
| |
|
| joined multicast traffic. | |
Switch 5300xl |
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| |
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| |
Switch 4200vl |
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Switch 3500yl |
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Switch 3400cl |
|
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Switch 2800 |
|
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Switch 2810 |
|
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Switch 2510G |
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Switch |
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Switch 2500 |
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Switch | No | Disabled in | IGMP |
Switch 2600 |
| the Default | configuration. Floods unjoined multicast |
Switch |
| Configuration | traffic to all ports. Selectively forwards |
Switch 4100gl |
|
| joined multicast traffic. |
Switch 6108 |
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On switches that do not support