Subject: [v6ops] I-D Action: draft-ietf-v6ops-host-addr-availability-00.txt

From: [email-masked]
Date: Fri, 31 Jul 2015 13:37:16 -0700

A New Internet-Draft is available from the on-line Internet-Drafts directories.
 This draft is a work item of the IPv6 Operations Working Group of the IETF.

        Title           : Host address availability recommendations
        Authors         : Lorenzo Colitti
                          Vint Cerf
                          Stuart Cheshire
                          David Schinazi
	Filename        : draft-ietf-v6ops-host-addr-availability-00.txt
	Pages           : 12
	Date            : 2015-07-31

Abstract:
   This document recommends that networks provide general-purpose end
   hosts with multiple global addresses when they attach, and describes
   the benefits of and the options for doing so.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-ietf-v6ops-host-addr-availability/

There's also a htmlized version available at:
https://tools.ietf.org/html/draft-ietf-v6ops-host-addr-availability-00

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

---

From: Mark Smith <[email-masked]>
Date: Sat, 1 Aug 2015 11:10:18 +1000

Hi,

I'm still concerned that this intended BCP is recommending
Experimental status NDP and Informational status Sharing /64.

NDP was proposed and then rejected for Sharing a /64 because it
couldn't prevent possible loops forming.

Regarding Sharing a /64, it is a work around, because it violates a
number of IPv6 network routing/addressing models and expectations.
This is why DHCPv6-PD is stated as the right solution when 3GPP
supports it.

One example is that the 3GPP GGSN/PDN-GW (i.e., router) considers all
of the addresses in the "link's" /64 to be potentially present on the
3GPP User Equipment (i.e. host), so it universally forwards all
traffic to addresses within the /64 to the UE (so it is really a host
assigned /64, not a link assigned /64). I think this was done to avoid
having to perform Neighbor Discovery. This is the sort of IPv6
forwarding routers do towards other routers, not when routers are
forwarding across the final hop towards a host.

I think this is only possible when there is a literal point-to-point
link between a single router and a single host. I can't see how it
could be supported on a multi-access link, with potentially multiple
hosts, unless the multi-access link has a different /64 to those that
are used by the one or more individual host /64s. Cutting to the
chase, I'm now describing a scenario that is already satisfied by
DHCPv6-PD.

Regards,
Mark.