Subject: Reporting of 224.0.0.[2,255] groups

From: [email-masked]
Date: Wed, 19 Jul 2000 12:03:03 -0700 (PDT)

Forwarded message:
> From: Bill Fenner <[email-masked]>
> To: [email-masked]
> Subject: Summary of IGMPv3 Last Call discussion so far
> Date: Wed, 19 Jul 2000 10:59:19 -0700
> 
> 
> Dear IDMR,
> 
>   With the IGMPv3 Last Call to Proposed Standard halfway over, I thought
> I'd summarize what I perceive as the state of the comments.
> 

<snip>

> - Are groups in 224.0.0.[2,255] reported?
> 
>   Yes.

Bill,

This is against the common practice of most router implementations.
This will break them right away. i.e. if one implementation reports these
groups and another doesn't, the switch will immidiately constraint
flow to one port and open to another, breaking the protocol that relies
on membership to 224.0.0.[2,255] group. Which means, OSPF, BGP can
break in addition to PIM, IGMPv3 etc.

I suggest that this requires a bit of discussion here, with my
humble vote being against it.

I understand that reporting these groups will allow switches to
constrain their ports. But IMHO, it's ok to let the switches flood
all their ports for these groups because there's only control traffic
on these groups anyway. Not, any high bandwidth data draffic.

$0.02.

- Paras.