Re: Last Call: <draft-ietf-6man-rfc4291bis-07.txt> (IP Version 6 Address

Hi,

> In response to various comments to this message, I’d like to propose a 
> refinement:
>
> > IPv6 unicast routing is based on prefixes of any valid length up to 128 bits 
> > [BCP198]. However, in accordance with the reasoning explained in [RFC7421], 
> > the Interface ID part of host interface addresses is generally 64 bits, with 
> > exceptions only provided in special cases expressly recognized in IETF 
> > standards track documents.
Sounds good to me. It's clear on routing, it's clear on IIDs being 64 bits long 
except in special standards-track cases without trying to enumerate them and it 
provides an informational reference to explain why it should be 64 bits.

> For my personal part, I’d prefer to see a clear statement here using RFC 2119 
> requirements language keywords, but I recognize that consensus probably 
> requires compromise on that point. Hence, the proposed refinement above, 
> which does not use RFC 2119 keywords. (Here is how I would write this with 
> keywords: “IPv6 unicast routing is based on network prefixes that MAY have 
> any valid length up to 128 bits [BCP198]. However, in accordance with the 
> reasoning explained in [RFC7421], the Interface ID part of host interface 
> addresses SHOULD be 64 bits with exceptions only provided in special cases 
> expressly recognized in IETF standards track documents.”)
I'm a bit worried that the "MAY have any valid length up to 128 bits" 
definition is too loose when read by router vendors, but otherwise that version 
sounds good as well. I like to see explicit clear guidance in standards 
documents.

One question: don't the texts conflict with things like policy based routing? 
Do we need to take that into account here?

Cheers,
Sander

signature.asc
Description: Message signed with OpenPGP