[ppml] for your reading pleasure

Marshall Eubanks tme at multicasttech.com
Fri Mar 10 10:21:29 EST 2006

I must admit that I do not see much in the way of recommendations in  
this document, nor do
I see a strong need for it.

It says that

    This document revisits and updates the IAB/IESG recommendations on
    the assignment of IPv6 address space to end sites.

but it would be more appropriate to say that it voids them. It does  
imply that
smaller address blocks could be handed out - see this from the  

      1) It revisits the RFC 3177 recommendations and concludes that the
         default IPv6 assignment size could be changed from /48 to some
         other value (e.g., /56) with essentially no impact on existing
         IPv6 standards or implementations.

and this from Section 2

    The above concerns were met by the original /48 recommendation, but
    could also be realized through a more conservative approach. A key
    goal, however, is to avoid the need for a site to renumber into a
    smaller number of subnet bits when adding a new prefix.

but of course the same wording could be used to justify automatically  
handing out larger
blocks are well. Particularly, it provides no reason why /56's (or / 
32's, or /64's, or any other
size block) should be handed out in preference to any other size.

No doubt that there is no _technical_ reason why address blocks need  
to be any particular size (after all,
IPv4 CIDR works), but just stating that, while useful, is not  
actually a recommendation do to anything in particular.

I am surprised that the draft does not even promote aggregation in  
assignment policies.
Note this at the end of Section 2, where it says

    A key goal, however, is to avoid the need for a site to renumber  
into a
    smaller number of subnet bits when adding a new prefix.

As I read it, this implies that RIR's should (or, at least, could)  
hand out non-contiguous blocks
when end sites need more address space. It seems to approve of this,  
as long as the new block is the same size or larger than the existing  

I think that the minimum any IPv6 assignment policy should do is to  
promote the maximum amount of aggregation possible, and that any  
recommendation coming out of the IETF / IESG / IAB should clearly  
state that as a goal.


On Mar 10, 2006, at 4:41 AM, Michael.Dillon at btradianz.com wrote:

>> draft-narten-ipv6-3177bis-48boundary-01.txt
>> in you internetdrafts archive... posted today.
> For those who do not understand the IETF secret handshake,
> this document can be found at the following URL.
> http://www.ietf.org/internet-drafts/draft-narten- 
> ipv6-3177bis-48boundary-01.txt
> It is an update of RFC 3177 so you really should google
> for that RFC and read it before you read this draft.
> People working on new routing/multihoming  models should
> also take an interest in this RFC because of the statement:
>    RFC3177 suggested that some multihoming approaches (e.g., GSE)  
> might
>    benefit from having a fixed /48 boundary. This no longer appears to
>    be a significant issue. There is no such requirement coming out of
>    the IETF multi6 or shim6 efforts.
> The reference to GSE is to an early proposal that separated
> the IPv6 address into a routing identifier and an end-system
> designator.
> Cynical people might see this as an IETF attempt to block
> the efforts of people working on new routing/multihoming
> models.
> --Michael Dillon
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