Subject: RE: IPv6 Addr/Prefix clarification

From: "Michel Py" <[email-masked]>
Date: Fri, 1 Feb 2002 13:50:24 -0800

>> Pekka Savola wrote:
>> I'm broadening the topic to include all kinds of home users, e.g.
>> xDSL, Cable etc. in addition to dial-in.

> Tony Hain wrote:
> No problem as the actual implementation at the consumer end is
probably
> similar. There will be some device between the provider network and
the
> consumer network, be that dial or always-on. The device needs either a
> /48 so it can provide subnet based routing, or a /64 so it can provide
> a bridged subnet capability.

I concur with Tony.
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From: "Michel Py" <[email-masked]>
Date: Thu, 7 Feb 2002 15:28:30 -0800

About subnetting below /64, here is a quote from "ARIN Guidelines
for Requesting Initial IPv6 Address Space"
http://www.arin.net/regserv/ipv6/ipv6guidelines.html

"The host portion of an IPv6 address is represented by the
rightmost 64 bits of the address. A /64 SLA ID is the shortest
network prefix that can be assigned to a site. The boundary
between the network and host portions is "hard" and cannot be
further subdivided."

Michel.

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From: Steve Deering <[email-masked]>
Date: Thu, 7 Feb 2002 17:04:26 -0800

At 11:27 AM -0500 1/31/02, Keith Moore wrote:
>e.g. If an ISP gives its customers /64s they should still be able to subnet.
>subnetting a /64 is a lot beter than NAT.

Doing the multi-link subnet thing is a whole lot better than NAT as well.
I.e., even if you only get a /64, you don't HAVE to do NAT in order
to use multiple links.

Steve

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From: "Michel Py" <[email-masked]>
Date: Sun, 10 Feb 2002 20:12:34 -0800

> Jochen Kaiser wrote:
> the vlan is not the problem since you can have a default vlan
> which is member on all switch ports. it's pre configured.

Ah. Multiple subnets on a single VLAN. Maybe you can explain me
the purpose of the multiple subnets, then.

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From: "Michel Py" <[email-masked]>
Date: Wed, 23 Jan 2002 08:09:57 -0800

> Irina Dayal wrote:
> 1) Is it safe to assume that all IPv6 prefixes will be between 16 and 64
> bits long?  The current allocation of IPv6 prefixes seems to require
> Aggregatable Global Unicast Addresses, which restricts the prefixes to
> this range.

It's not safe (even if it might be true today). Slightly more than 1/8 of
the IPv6 address space has been allocated to a purpose so far. There are
drafts that are mentionning allocating 0001, which is a /4.

Even today, one might want to configure 2000::/3 as the default route
instead of 0::/0.

Michel.