IGMP v3 - Purpose of Router alert option.

[shobha]

Hi All,

I recently started learning about IGMP.

In RFC3376, section 9 "Security considerations",
It says about the forged IGMP messages.

As far as i understood, the forged IGMP messages can affect the routing functionality, to filter such packets and not process them, the router alert option is used.
Please correct me if am wrong.

Does this mean, the routers will accept the packets only if the Router alert option is set?
Can anyone please explain bit more about the need of this Router alert option?

How to test this functionality, is it possible to simulate the forged IGMP messages?
If yes, can you please explain about that?
Do we have any conformance test suite for Router Alert?


Thanks,
Shobha