As you know, the first day of the upcoming interim meeting in Seattle
has been set aside for discussions with 3GPP on matters of IPv6. In
preparation for this, The IETF IPv6 directorate put together a number
of questions for 3GPP (appended below). Those questions were discussed
at a recent 3GPP meeting and I'm including a response from Stephen
Hayes, one of the 3GPP TSG chairs.
I'm looking forward to a productive meeting in Seattle.
Thomas
From: Thomas Narten <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
cc: Mikko Puuskari <[EMAIL PROTECTED]>,
"Stephen Hayes (EUS)" <[EMAIL PROTECTED]>
Date: Sun, 13 May 2001 15:29:32 -0400
Subject: IPv6 Questions on 3GPP [Joint IETF-IPv6 / 3GPP meeting]
The following set of questions was put together by the IPv6
Directorate after an initial study of some 3GPP documents. This note
is intended to start a dialog between the 3GPP & IETF communities on
IPv6.
Thomas Narten
3GPP is including IPv6 in its Release 5 specifications, an action that
excites the IETF IPv6 community greatly. The 3GPP work will be an
important driver for IPv6 deployment. Having said that, the IPv6
community has only a very limited understanding of how IPv6 will be
used by 3GPP, e.g., which RFCs will be used, in what parts of the
system they will be used, which parts are required and which are
optional, etc. We believe that it is in our mutual interest to
understand and educate each other on our perspectives on how IPv6 can
best be used to your advantage, which components (e.g., which RFCs)
are needed, whether there are any missing pieces, etc.
The IETF IPng WG will be holding an interim meeting in Seattle, WA
starting May 30. The first day of meeting has been reserved for a
joint meeting with members from 3GPP. It is our hope that such a
meeting will facilitate direct technical interactions between 3GPP and
IETF engineers on IPv6 issues.
The following describes some general areas where we have some specific
questions. These questions were put together after looking at some
3GPP documents that make reference to IPv6, including 23.060 and
23.221.
- What is the addressing model for the network and handsets? Will each
handset be given a single 128-bit address and no more? Or will each
handset be given its own /64 (e.g. an entire network) so that it can
connect additional devices, say through a bluetooth or 802.11
interface?
A related question is how many additional devices (e.g., a laptop)
will be able to connect to a handset (e.g., via bluetooth) and use
IP. Doing so would suggest each device would need an IPv6 address
and both the handset and the device being on the same subnet. One
way of providing such a capability would be to have each handset be
a router for a /64 subnet. Is such a configuration envisioned now,
or in the future?
- What parts of Neighbor Discovery (RFC 2461) will be implemented on
handsets? All of it? How will handsets using IPv6 communicate with
each other when on the same subnetwork (or link in IPv6
terminology)? Is ND needed to resolve addresses or does the handset
view its connection to the network as a point-to-point link with a
router on the other end (i.e., the GGSN)?
- What is the scope of problem for which IPv6 is viewed as a solution?
I.e., what features of IPv6 are needed immediately, and which are
assumed to be of interest at some later point in the future?
- How permanent are the IPv6 addresses that are assigned to handsets?
From our understanding, interface identifiers are assigned by the
GGSN, and handsets then form addresses by combining the interface
identifier with a prefix learned through Router Advertisements
(RAs). Is it envisioned that information specific to the mobile will
be used to form the interface identifier (e.g., IMSI)? Or will the
interface identifier assigned to a handset change over time (e.g.,
if it is power cycled or moves)? This question is important as it
will determine whether addresses are effectively permanent in the
sense that it will be stable for weeks or more.
In the case that addresses remain stable for weeks or longer, are
any of the concerns raised in RFC 3041 viewed as applicable?
- Will handsets be dual stack (i.e., support both IPv4 and IPv6) or
will they support only IPv6? Some of the documents suggest that in
the IM domain, IPv6 will be used "exclusively". Does that
specifically mean that IPv6 must be supported and the IPv4 doesn't
apply?
- Where will IPsec (RFC 2401) be used? Will IPsec be implemented on
the handset (to provide true end-to-end encryption) or will IPsec
terminate at the GGSN, with the remainder of the path (from the GGSN
to the handset) protected by link-layer encryption?
Note that it is our understanding that in the current specs MN to
SGSN communication is protected by GSM privacy but there is nothing
specified between the SGSN and the GGSN. Will the tunnel between the
SGSN and the GGSN will be carried over the Internet?
Finally, are there any plans to implement IKE? If not, how will
IPsec security associations be created?
- Are there any requirements in the area of QOS? Are diffserv and/or
RSVP being looked at as something that is important?
- What transition schemes will be used in communicating with IPv4
sites? Some of the 3GPP documents make mention of NAT-PT as well as
automatic and configured tunnels. However, automatic tunnels only
make sense if address numbering is done in a certain way. It is not
clear that the use of automatical tunnels makes sense in the 3GPP
environment. Has there been any study of schemes, in addition to
NAT-PT, that allow IPv6-only and IPv4-only nodes to communicate?
- Which IPv6 RFCs does 3GPP consider to be part of IPv6, in the sense
that they must be implemented as part of the 3GPP Release 5
specification? Are all of these RFCs to be implented in their
entirety, or are only subsets of (some of) them needed? Is there any
intention to take parts of the IETF protocols and modify or extend
them?
- Are there any plans or needs with regards to compression? For
example, the IETF has existing standards (e.g., RFC 2507) and
on-going efforts to compress IP traffic over link layers. Is it
anticipated that 3GPP will have needs here?
- What DNS components will be used? For example, IPv6 addresses can
reside in either AAAA or A6 records. Will resolvers in handsets be
implementing A6 records? Or both AAAA & A6?
Many of the above questions are somewhat open-ended and would probably
benefit from face-to-face discussion. It is our hope that this will
occur at the Seattle meeting and/or through e-mail followups. In
addition, we would welcome any questions you might have on IPv6
issues.
Overall, we would like to understand the overall 3GPP architecture and
how IPv6 fits into it. 3GPP documents are organized and structured
very differently from IETF documents, so for us it has been difficult
to understand where and how IPv6 is being used and whether its usage
will bring any unexpected surprises (e.g., are there any shortcomings
or missing components?). We believe a technical discussion between the
IETF and 3GPP communities on the topic of IPv6 would be mutually
beneficial to both communities.
From: "Stephen Hayes (EUS)" <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED],
[EMAIL PROTECTED], [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
Date: Mon, 21 May 2001 09:27:09 -0500
Subject: Additional info on May 30 IPnG/3GPP meeting
Dear Colleagues,
The 3GPP has been invited by the IETF IPng WG to a one day discussion
of how 3GPP will use IPv6. The meeting will be held on May 30, 2001
at Redmond, WA. Please see
(http://research.microsoft.com/ietf-ipv6-meeting) for info about the
meeting. At the 3GPP SA2 meeting held on May 14-18 there was a
discussion of what should be presented by the 3GPP at the IPng
meeting. Hopefully this quick synopsis of those discussions will help
in preparation of the meetings.
Based upon the discussions I would expect the following at the meeting
from the 3GPP side:
1. A presentation of the 3GPP architecture. This will include a
discussion of:
- the reference models
- 3GPP protocol stacks (involving IPv4/IPv6)
- 3GPP packet concepts (PDP context, APN, GTP)
- IP address allocation
2. A high level presentation on the 3GPP QoS architecture
3. Verbal answers to the questions posted previously( the list of
questions is attached at the end for convenience). The IETF may
find the answers unsatisfying as most of the answers are "it is an
implementation decision" (Questions 2,4,5,8,11) or "for further
study" (Questions 6,9,10). Some concrete answers are given below:
- Q 1 - There is currently no capability defined to allocate a subnetwork
- Q 3 - The main need is the address space
- Q 7 - Yes there are requirements - to be discussed in QoS presentation
Of course, these quick answers and the terms "implementation decision"
and "for further study" leave lots of degrees of freedom, so I would
not recommend waiting for the answers delivered by the 3GPP delegates
to get the full flavor of the answers.
4. Verbal guidelines for what 3GPP documents are relevant and how they
fit together.
There will be several 3GPP experts at the meeting, so I would expect a
lively discussion. The presentations will be being refined this week
on the 3GPP SA2 mailing list. The latest copies of the presentations
should be available on the mailing list.
Best regards, Stephen Hayes
3GPP CN Chair
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