Subject: FWD: Re: mboned: draft-pashby-ipv6-mc-scoped-addr-01 is now available

From: Thomas Narten <[email-masked]>
Date: Thu, 20 Apr 2006 08:42:53 -0400

FYI, discussion taking place in mboned.

------- Forwarded Message

From: John Zwiebel <[email-masked]>
To: "Pashby, Ronald W CTR NSWCDD-B35" <[email-masked]>
Cc: John Zwiebel <[email-masked]>, <[email-masked]>
Date: Mon, 17 Apr 2006 14:19:23 -0700
Subject: Re: mboned: draft-pashby-ipv6-mc-scoped-addr-01 is now available

On Apr 17, 2006, at 7:40 AM, Pashby, Ronald W CTR NSWCDD-B35 wrote:

> This draft was presented at the mboned wg in Dallas. It is available
> at
> http://www.ietf.org/internet-drafts/draft-pashby-ipv6-mc-scoped-addr-01.txt
> It discusses changing the range for Dynamically Assigned Multicast
> Identifiers so that they don't overlap with the Solicited
>
> Node Identifiers.  This is need to avoid the possibility of  
> flooding a host that has limited processing resources with multicast
>
> traffic that it has not requested.
>
> There were no objections to this in the wg, but there was little  
> time to discuss it. Please comment on it so we can determine how to  
> proceed.
>
>

2cents: it took me a (long) while to figure out that you were  
proposing a change to the multicast group-id
allocation so that there wouldn't be an L2 addressing overlap.  There  
is information included in the
draft that isn't directly relevant and caused me to doubt that I  
understood what you were proposing.
(ie, the probability tables didn't help)  The idea that you want to  
separate out the solicited node
group-ids at L2 from the other dynamically assigned group-ids should  
have been enough.

Abstract:  should be "multicast group id" [2373]
Para 1: should be 'multicast group id'
   Are 'multicast ids' the same thing as "multicast group ids"?

In para 3 these two statements need a reference to explain how these  
are allocated.
(ie, where are these methods defined?)  I don't see what these  
methods have to do
with your proposal

    Hosts may also join a multicast group based
      on an MD5 hash of its hostname.

   There is a method for creating dynamic multicast groups, which
      defines that, the multicast group id to be generated by a 32 bit
      random number and then setting the highest bit.

Why is this the easiest?  Why select this range?  Why not start the  
reserved group
at D?  The options in 4.3.2.1 (site-local, organization-local) don't  
seem to be broadly used.

   "The easiest way is to reduce the range from 0x80000000 -  
0xFFFFFFFF to the range
    of 0x80000000 - 0xBFFFFFFF. "

I don' t understand this.  These are bytes and it isn't clear how  
this references the
random number referred to earlier since there's no reference and it  
seems orthogonal to
what you are proposing.  (ie why mention it?)  The probability tables  
also confuse the issue.

    "This is accomplished by setting the highest 2 bits of the 32 bit  
random number to 0b10."

Para 4.0: explain that this is a proposal for changing the 3307  
definitions.  ie, repeat again.

para 4.1, why change it from the heading used in 3307?  Keep the  
headings consistent.
or provide a reason for changing the name.
	"Permanent IPv6 Multicast Addresses"

para 5.1: shouldn't this be LNCB?
    Add the definitions of the LCNB ranges as defined above.

FWIW: it isn't clear that you are referencing 2373 WRT multicast  
address assignments
	where only the last 32-bits are the group-ID
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