[arin-discuss] IPv6 End User Assignments

[Lea Roberts]

Garry (et al) -

On Mon, 11 May 2009, Garry Dolley wrote:

> On Mon, May 11, 2009 at 02:00:31PM -0500, Chris Gotstein wrote:
> > Garry Dolley wrote:
> >
> >> Yeah, I understand what you're saying now.  I've been reading RFC
> >> 3177 and 5375, and indeed /48 is the standard assignment.  I won't
> >> plan to assign /64's to my customers b/c I can't be sure they are
> >> not going to want to subnet, therefore I should give them the room
> >> to do that with a /48.
> >> To those on the list that mentioned they are defaulting to /64's, I
> >> suggest you read RFC 3177 and 5375, and consider /48's.
> >
> > When you are referring to customers, does this apply to residential
> > end-users connected via, cable, dsl, etc?
>
> Yes.
>
> RFC 5375 ("IPv6 Unicast Address Assignment Considerations")
> specifically mentions residential sites / customers:
>
> "Consider assigning more than one /64 to a site - A small site may
> want to enable routing amongst interfaces connected to a gateway
> device.  For example, a residential gateway that receives a /48 and
> is situated in a home with multiple LANs of different media types
> (sensor network, wired, Wi-Fi, etc.), or has a need for traffic
> segmentation (home, work, kids, etc.), could benefit greatly from
> multiple subnets and routing in IPv6.  Ideally, residential networks
> would be given an address range of a /48 or /56 [RIPE_Nov07] such
> that multiple /64 subnets could be used within the residence." [1]
>
> 1. RFC 5375, Section 2.4 "Network-Level Design Considerations"

be advised that while RFC3177 is still "standard", there has been work in
IETF to update it with "operational experience", not the least of which is
that perhaps assinging a /48 to every user who wants to subnet may be a
bit excessive.  the /56 option for an individual residence should allow an
abundance of subnets for all but extreme cases.  and certainly the /64 and
/128 options seem overly restrictive in the IPv6 environment.

BTW, if you are delegating reverse DNS, then /60 is another small option,
since IPv6 reverse is on nibble boundaries.  some argue that by limiting
the number of subnets to 16, it should handle most small sites but not
discourage renumbering when the user's needs change...

my personal feeling is that any commercial enterprise should certainly get
a /48 by default and any residential user who asks for one should get it,
but the default for a normal single family site should be less than /48.
as others have mentioned, there are ample reasons to give all IPv6 users
the ability to have multiple subnets.  certainly any /64 assignments limit
the real advantages of moving to IPv6.  		/Lea