Subject: [Capwap] Question on CAPWAP's use of multicast for IPv6

From: "Pat Calhoun (pacalhou)" <[email-masked]>
Date: Sun, 7 Dec 2008 17:17:10 -0800

All,

During the IETF Last Call and IESG Review, we added support for IPv6
multicast. I created issue 202 for this, and posted the proposed text to
the list. However, IANA has asked that we confirm the request is valid.
Specifically, IANA's question is:

<iana's question>
Before we assign this document's IPv6 multicast address, can you confirm
that the address should come from the Variable Scope block? We generally
expect to see requests for IPv4 Local Network Control Block addresses
accompanied by requests for the corresponding IPv6 Link-Local Scope
address (e.g., the LL-MANET-Routers addresses 224.0.0.109 and
FF02:0:0:0:0:0:0:6D registered by [RFC-ietf-manet-iana-07.txt]). In
addition, earlier versions of this document appear to have requested a
Link-Local Scope address. 

</iana's question>

The current IANA considerations text reads:

<current spec text>
   This document requires a new organization local multicast address
   called the "All ACs multicast address" from the Variable Scope IPv6
   multicast address registry [to be removed upon publication
   http://www.iana.org/assignments/ipv6-multicast-addresses]. The new
   multicast address is to be inserted in <xref target="AC Discovery"/>.
</current spec text>

Could someone please confirm?

PatC
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From: Margaret Wasserman <[email-masked]>
Date: Wed, 10 Dec 2008 17:04:44 -0500

Hi Pat,

I sent this answer publicly, but thought I should send it on the list,  
too...

> Link-Local Scope address.

This is a good catch by IANA, as the IPv4 Local Network Control block  
does
correspond more closely to the IPv6 Link-Local Scope addresses.

I think the fix is backwards, though.  IMO, we want an IPv6 multicast  
address
from the Variable Scope block, as specified, but we want an IPv6  
address from
the Internetwork Control Block.  This would allow multicast routers to  
forward
our CAPWAP-AC multicast packets throughout a site.  If we get an IPv4  
multicast
address from the Local Network Control Block, it will not be routed  
beyond the
attached link.

>   multicast address is to be inserted in <xref target="AC Discovery"/ 
> >.
> </current spec text>
>

IMO, this section is right, but the IPv4 multicast address should be  
changed
to an allocation from the Internetwork Control Block, as described  
above.

Sorry for not noticing this earlier.

Margaret