Re: I-D Action:draft-ietf-v6ops-ipv6-cpe-router-03.txt

[Mark Smith <ipng@69706e6720323030352d30312d31340a.nosense.org>]

On Fri, 18 Dec 2009 09:09:21 -0800
Fred Baker <fred@cisco.com> wrote:

> I will open a WGLC on this after new years; My mind will be elsewhere  
> for the coming two weeks, I imagine yours will as well. However, if  
> you want to start reading/commenting now...
> 

Maybe I'm being a bit overly paranoid about people being precious with
IPv6 address space, however, the last sentence of -


"WPD-1:  The IPv6 CE router MUST support DHCP prefix delegation
           requesting router behavior as specified in [RFC3633] (IA_PD
           option).  The IPv6 CE router MUST ask for a prefix large
           enough to cover all of its LAN interfaces."

could be interpreted to mean that the ISP only needs to provide a
prefix to meet the requested size e.g. for two LAN interfaces a /63.
That would seem to me to be encouraging an "only enough" address space
model, rather than a "more than enough" address space model, which is
what I think IPv6 is aiming at.

There might be some value in stating that it is likely that an ISP will
delegate a prefix that not only meets this minimum requirement but also
allows for a number of additional subnets downstream of the CPE, with
the delegated prefix size likely significantly larger, possibly a /48
or /56. IOW, stating that the delegated prefix will likely be larger
than what is requested (not that it is probably likely, but I could see
a CPE vendor adding in a check to see if the delegated prefix size was
equal to that requested, and if it didn't, not using it).