>>>>> On Sat, 17 Nov 2001 13:32:18 -0600,
>>>>> Jung Cyndi-ACJ099 <[EMAIL PROTECTED]> said:
> The link-local groups in IPv4 do not use IGMP, and the IGMP snooping
> switches take this into consideration, for the most part - those that don't
> consider it don't work. Those link-local addresses are things like OSPF
> Hellos and RIPv2 updates.
Hmm, then I misunderstood the current situation. I should also have
checked draft-ietf-magma-snoop-00.txt, which says:
To avoid this situation, IGMP snooping switches should be less con-
servative when forwarding packets to these addresses and flood them
to all ports.
(2.2. IGMPv2 snooping and 224.0.0.X)
> Are you suggesting that MLD become part of the minimum requirements
> because of as yet unavailable MLD snooping switches? Those switches
> could check the scope of the IPv6 destination and forward all link-local
> scope multicast to all ports of the subnet - it is at a fixed offset forever
> and always. Unless we really expect heavy traffic use of link-local scope
> multicast, using this as the reason for mandating MLD as a minimum
> requirement is more of an obstacle than an aid for IPv6, in my opinion.
I agree. The previous comment of mine was simply due to my
misunderstanding about the current IGMP snooping. I applied the wrong
analogy to the "as yet unavailable switches." Please just forget this.
However, I have still some concern about the "future" switches.
The magma draft only mentions addresses in the form of
FF0X:0:0:0:0:0:X:X. It does not directly talk about the link-local
multicast. Also, RFC 2710 explicitly says MLD messages are sent for
link-local groups:
MLD messages ARE sent for multicast addresses whose scope is 2
(link-local), including Solicited-Node multicast addresses [ADDR-
ARCH], except for the link-scope, all-nodes address (FF02::1).
So I'm still afraid the "future" switches might snoop and filter
link-local addresses. We should probably clarify this on the magma
draft.
JINMEI, Tatuya
Communication Platform Lab.
Corporate R&D Center, Toshiba Corp.
[EMAIL PROTECTED]
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