Re: some questions about RFC4605 -- IGMP/MLD multicast proxy

On Feb 8, 2007, at 5:32 AM, Jayanth Chennamangalam wrote:

>
> (2) It is said in the RFC that the proxy device MUST NOT perform  
> the router portion of IGMP/MLD on its upstream interface. There's  
> no restriction on performing the host portion of IGMP/MLD on the  
> downstream interfaces. Does that mean it's okay to send out reports  
> which are received from one downstream interface to other  
> downstream interfaces? Wouldn't it cause problems if the hosts  
> attached to downstream interfaces support report suppression?
> >> The reason behind the lack of restriction on performing the host  
> portion of IGMP/MLD proxying on the dowstream is to support querier  
> election. The host functionality does not involve forwarding  
> received MLD Reports. Besides, if the proxy device sends Reports on  
> the downstream, it might lead to Report suppression.
>

Let me add: the downstream interfaces don't change the way they deal  
with IGMP or MLD.
Querier election is independent of caching forwarding information  
(installing an mroute)
Hosts do not install mroutes.

WRT your question of sending out received reports on other  
interfaces, that does not happen
in normal routing situations, why would you think it should happen here?

> (3) What should the proxy device do except for querier election if  
> it receives MLD query on downstream interfaces? Shuold it send out  
> MLD report on downstream interfaces? (This question is related to  
> (2) though.)
> >> If querier election is not implemented, the proxy device should  
> discard the MLD Query received on the downstream interface. Even if  
> querier election is implemented, MLD Reports should not be sent in  
> response to MLD Queries received on the downstream.
>
It proxy forwards upstream only.  Downstream hosts do not care what  
hosts on another interface might
be listening to.

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