Internet DRAFT - draft-jee-16ng-problem-statement
draft-jee-16ng-problem-statement
Network Working Group J. Jee, Editor
Internet-Draft M-K. Shin, Editor
Expires: April 19, 2006 ETRI
E-K. Paik
KT
J. Cha
ETRI
G. Montenegro
Microsoft Corporation
October 16, 2005
16ng Problem Statement
draft-jee-16ng-problem-statement-02.txt
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Copyright (C) The Internet Society (2005).
Abstract
This document describes the IPv6 over IEEE 802.16(e) networks (16ng)
problem statement.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Problem Statement . . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . . . 8
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1. Introduction
Broadband Wireless Access networks address the inadequacies of low
bandwidth wireless communication for user requirements such as high
quality data/voice service, fast mobility, wide coverage, etc. The
IEEE 802.16 Working Group on Broadband Wireless Access Standards
develops standards and recommended practices to support the
development and deployment of broadband Wireless Metropolitan Area
Networks. Additionally, IEEE 802.16e is an amendment that adds
support for mobility over the base IEEE 802.16 specification.
Recently, the WiMAX Forum, and, in particular, its NWG (Network
Working Group) is defining the IEEE 802.16(e) network architecture
(e.g., IPv4, IPv6, Mobility, Interworking with different networks,
AAA, etc). The NWG is thus taking on work at layers above those
defined by the IEEE 802 standards (typically limited to the physical
and link layers only). Similarly, WiBro (Wireless Broadband), a
Korean effort which focuses on the 2.3 GHz spectrum band, is also
based on the IEEE 802.16e specification.
IEEE 802.16(e) is different from existing wireless access
technologies such as IEEE 802.11 or 3G. Accordingly, while 802.16
defines the encapsulation of an IP datagram in an IEEE 802.16 MAC
payload, complete description of IP operation is not present. Thus,
IP operation over IEEE 802.16(e) can benefit from IETF input and
specification. This document will describe the problems identified
in adopting IPv6 over IEEE 802.16(e) networks.
2. Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119] .
3. Terminology
The following terms come from IEEE 802.16 [IEEE802.16] and IEEE
802.16e [IEEE802.16e] specifications.
Base station (BS): A generalized equipment sets providing
connectivity, management, and control of the subscriber station (SS).
Subscriber station (SS): A generalized equipment set providing
connectivity between subscriber equipment and a base station (BS)
MOB_HO-IND: Handover indication message from SS to BS.
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REG-RSP: Registraion response message from BS to SS.
4. Problem Statement
The first problem identified in adopting IPv6 over IEEE 802.16(e)
networks is that IEEE 802.16(e) is different from existing wireless
access technologies such as IEEE 802.11 or 3G. For example:
immediately subsequent to network entry, an 802.16 SS (Subscriber
Station) has no capability whatsoever for data (as opposed to
management) connectivity. The criteria by which the BS (Base
Station) sets up the 802.16 MAC connections for data transport is not
part of the 802.16 standard and depends on the type of data services
being offered (ie. the set up of transport connections will be
different for IPv4 and IPv6 services). Additionally - as 802.16 is a
point-to-multipoint network - an 802.16 subscriber station is not
capable of broadcasting (e.g., for neighbor discovery) or direct
communication to the other nodes in the network. While the built-in
LAN emulation feature of 802.16 ("802.3 Convergence Sublayer")
rectifies this, it may involve additional packet overhead. This
lacking of facility for native multicasting for IPv6 packet transfer
results in inappropriateness to apply the standard Neighbor Discover
Protocol specially regarding, address resolution, router discovery,
duplicated address detection and stateless auto-configuration.
The second problem identified in adopting IPv6 over IEEE 802.16(e)
networks is applying the Fast Handovers for Mobile IPv6 [RFC4068]
owing to the difficulty in utilizing the layer 2 handover
information. From RFC 4068, mobile node is recommended to send FBU
(Fast Binding Update) message to the PAR (Previous Access Router)
based on the accurate target BS information on the connected link to
operate as predictive mode. In IEEE 802.16e [IEEE 802.16e], the
mobile subscriber station decides the ultimate target base station
and sends the MOB_HO-IND message to the serving BS to notify the
decided target BS information which results in disabling any IPv6
packet transfer on that link. This means that the layer 3's fast
handover processing needs to break into the layer 2 processing,
between the target decision and the MOB_HO-IND message transfer, to
operate as predictive mode. Normally, this kind of intervention is
not preferred, because this requires certain interruption of the
layer 2 processing, eventually resulting in the handover delay. For
reactive mode, utilizing the "Link up" trigger to immediately
initiate sending FNA (Fast Neighbor Advertisement) or performing DNA
(Detecting Network Attachment) procedures is highly desirable to
reduce delay and packet loss. In IEEE 802.16(e) networks, a SS
receives a REG-RSP message from the serving BS when the registration
is accepted. This registration authorizes a SS to forward IP traffic
to the network. Thus, receiving the REG-RSP can be mapped as "Link
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up" trigger in IEEE 802.16(e) networks. Accrodingly, special
considerations will be required when implementing Fast Mobile IPv6
(RFC 4068), something which may be pursued in the MIPSHOP WG.
The third problem identified in adopting IPv6 over IEEE 802.16(e)
networks is applying IP multicasting services. In IEEE 802.16
networks, two types of access to multicast and broadcast services
(MBS) may be supported : single-BS access and multi-BS access.
Single-BS access is implemented over multicast and broadcast
transport connections within one BS, while multi-BS access is
implemented by transmitting data from Service Flow(s) over multiple
BS. However, the MBS seems to be broadcast services, not
multicasting. MBS adheres to broadcast service, while traditional IP
multicast schemes define multicast routing using shared trees or a
source-specific tree to deliver packets efficiently. Therefore, two
types of MBS services need to be mapped into source-specific
multicast service, if necessary.
5. Security Considerations
None of considerations are required in this section.
6. Acknowledgment
We would like to express thanks to IETF Mobility Working Group
members of KWISF (Korea Wireless Internet Standardization Forum) for
their efforts on this work.
We would particularly like to thank to Jeff Mandin for his valuable
inputs for problem statement and characterization of the 802.16 MAC.
We also would like to express special thanks to Soohong Daniel Park,
Heeyoung Jung, Sung Il Kim, Se Jun Park, Sang Eon Kim, Han-Lim Kim
and Jung-Mo Moon for their valuable inputs.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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7.2. Informative References
[IEEE802.16]
IEEE Std 802.16-2004, "IEEE Standard for Local and
metropolitan area networks, Part 16: Air Interface for
Fixed Broadband Wireless Access Systems", October 2004.
[IEEE802.16e]
IEEE P802.16e/D10, "Draft IEEE Standard for Local and
metropolitan area networks, Amendment for Physical and
Medium Access Control Layers for Combined Fixed and
Mobile Operation in Licensed Bands", Auguest 2005.
[RFC1883] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 1883, December 1995.
[RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC 2461,
December 1998.
[RFC2462] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.
[RFC4068] Koodli, R., "Fast Handovers for Mobile IPv6", RFC 4068,
July 2005.
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Authors' Addresses
Junghoon Jee
ETRI
Email: jhjee@etri.re.kr
Myung-Ki Shin
ETRI
Email: mkshin@etri.re.kr
Eun-Kyoung Paik
KT
Email: euna@kt.co.kr
Jaesun Cha
ETRI
Email: jscha@etri.re.kr
Gabriel Montenegro
Microsoft Corporation
Email: gabriel_montenegro_2000@yahoo.com
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