Internet DRAFT - draft-kim-v6ops-ipv6overwibro-issues
draft-kim-v6ops-ipv6overwibro-issues
V6ops S. Kim
Internet-Draft S. Park
Expires: December 3, 2005 S. Kim
H. Kim
KT
June 2005
Problem Statement in IPv6 over WiBro
draft-kim-v6ops-ipv6overwibro-issues-00.txt
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document proposes two issues both in WiBro and in IEEE 802.16
environment. Firstly, it describes needs to define payload header
suppression (PHS) rules for IPv6 packets. Secondly, it accounts for
the need to discuss IPv6 address auto-configuration.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terms and Abbreviations . . . . . . . . . . . . . . . . . . . 3
3. PHS rules for IPv6 packets . . . . . . . . . . . . . . . . . . 4
3.1 PHS in the IEEE 802.16 . . . . . . . . . . . . . . . . . . 4
3.2 Header considerations . . . . . . . . . . . . . . . . . . 4
3.3 v6ops considerations . . . . . . . . . . . . . . . . . . . 5
4. IPv6 address Auto-Configuration over IEEE 802.16 . . . . . . . 6
4.1 Modes affecting IPv6 multicast . . . . . . . . . . . . . . 6
4.2 v6op Considerations . . . . . . . . . . . . . . . . . . . 6
5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 8
Intellectual Property and Copyright Statements . . . . . . . . 10
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1. Introduction
WiBro is deeply related with IEEE 802.16 specification. Some parts
of WiBro technology are developed by Korea. The other parts comply
with IEEE 802.16 specification.
This document deals with two issues. One is about payload header
suppression (PHS). In WiBro, downlink and uplink bandwidth is
approximately 18Mbps and 6Mbps respectively. Limited bandwidth is
one of the problems for quality in the IEEE 802.16 wireless network
both fixed and mobile environment. In most cases, bandwidth for a
user could be not enough because many subscriber stations (SS) share
the bandwidth. Therefore using wireless bandwidth efficiently is
important.
One of the ways to increase radio bandwidth is reducing size of media
access control (MAC) frames. The PHS is one of the methods that can
achieve such goal effectively. The PHS is defined in the IEEE 802.16
specification. This document focuses on PHS rules for IPv6. For
now, IPv6 PHS rules have not been specified. This draft would like
to describe the needs for setting PHS rules to clarify the reason why
v6ops should do it.
The other issue is how to transmit IP multicast when a SS performs
IPv6 address auto-configuration in 802.16 wireless environments. RFC
3041 about auto-configuration is made for fixed IPv6 networks.
However, it is not applied in 802.16 wireless environments. Unlike
fixed network such as IEEE 802.3 and 802.16, wireless networks have
downsides such as limited bandwidth, expose to hacking and packet
loss.
This document proposes that v6ops working group needs to consider
ways to transmit IP multicast from SS to base station (BS).
2. Terms and Abbreviations
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)
Convergence Sublayer(CS): The packet CS resides on top of the IEEE
Std 802.16 MAC CPS.
Common Part Sublayer(CPS): The MAC CPS provides the core MAC
functionality of system access, bandwidth allocation, connection
establishment, and connection maintenance. It receives data from the
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various CSs, through the MAC SAP, classified to particular MAC
connections.
Classifier: a set of matching criteria applied to each packet
entering the IEEE Std 802.16 network. It consists of some protocol-
specific packet matching criteria (destination IP address, for
example), a classifier priority, and a reference to a CID. If a
packet matches the specified packet matching criteria, it is then
delivered to the SAP for delivery on the connection defined by the
CID.
Payload header suppression index (PHSI): An 8-bit mask that indicates
which bytes in the Payload Header Suppression Field (PHSF) to
suppress and which bytes not to be suppressed
3. PHS rules for IPv6 packets
3.1 PHS in the IEEE 802.16
While PHS rules can be applied in various cases such as IPv4, IPv6,
etc., this draft focuses on setting PHS rules for IPv6 packets. The
IEEE 802.16 physical and MAC layer can transmit IPv6 packets from/to
BS to/from SS. Convergence Sublayer (CS), positioned in 802.16e MAC
layer, assembles or dissembles incoming/outgoing IPv6 packets.
Then, the classifier in CS extracts information for transmission from
IPv6 packet header and transforms incoming IPv6 packets into MAC
protocol data unit (PDU) that can be processed in the IEEE 802.16 MAC
CPS. The classifier in CS performs PHS for IPv6 during the
transformation. The PHS for IPv6 is the process of suppressing the
repetitive portion of IPv6 packet headers at the sender and restoring
the headers at the receiver.
IPv6 PHS is defined as optional in IEEE 802.16. PHS has a Payload
Header Suppression Valid (PHSV) option to verify or not verify the
payload header before suppressing it. PHS has also a Payload Header
Suppression Mask (PHSM) option to allow select bytes not to be
suppressed. More information is available in the 5.2.3 of IEEE Std
802.16-2004 specification.
3.2 Header considerations
To setting IPv6 PHS efficiently, v6ops working group should consider
each header described as below.
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3.4.1 IPv6 header
- Traffic class
- Flow label
- Payload length
- Next header
- Hop Limit
- Source address and Destination address. etc
3.4.2 IPv6 Option header
- Destination Option Header
- Routing header
- Fragment header
- Authentication Header
- Encapsulating Security Payload header
- Destination Option header. etc
3.3 v6ops considerations
Considering limited bandwidth and instability in 802.16 wireless
environments, the probability to transmit IPv6 packet to PSS is lower
than fixed networks. Reducing the length of IPv6 packets by setting
PHS rules is a way to overcome wireless networks limitations. If
IPv6 PHS is applied to Ipv6 option headers, more IPv6 packets can be
transmitted.
IPv6 PHS is effective when a lot of IPv6 packets are transmitted,
which have many repetitive parts in IPv6 header. Setting the detail
of IPv6 PHS is more related with IP layer than MAC layer because IPv6
header is used in IP layer. Only IP layer can decide which parts of
IPv6 header can be suppressed when applying PHS rules. Therefore,
V6ops working group should pay attention to setting PHS rules for
IPv6.
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4. IPv6 address Auto-Configuration over IEEE 802.16
4.1 Modes affecting IPv6 multicast
IEEE 802.16 defines two transmission modes with which a BS and a SS
(or a SS and a SS) communicate. One is the PMP (point-to-multipoint)
mode, the other is the mesh mode. In WiBro specification, only PMP
mode is considered.
4.1.1 PMP mode
A BS broadcasts IEEE 802.16 MAC frames periodically to its area
when transmitting data from the BS to SSs. Therefore, each frame
can be shared by SSs. On the contrary, SSs share the uplink to
the BS on a demand basis. In other words, SSs cannot communicate
each other without BS. The MAC scheduler located in the BS,
controls uplink/downlink in IEEE 802.16 environments.
4.1.2 Mesh mode
In the Mesh mode, IEEE 802.16 MAC frames can be transmitted using
other SSs. In some cases, direct communication between SSs is
possible. Therefore, SSs can send SS-initiated IPv6 multicast
messages to BS and other SSs. More information is available in
6.2 of IEEE Std 802.16-2004 specification.
4.2 v6op Considerations
Both in PMP and mesh mode, IEEE 802.16 specification can be changed
in order to send SS-initiated Ipv6 multicast for IPv6 address Auto-
configuration. For example, a certain SS in a BS and other SS in
other BS can have same IP address because groups of BSs can have
different IP allocation policies and IP management policies which has
not specified in the IEEE 802.16 specification. Therefore, v6ops
needs to consider both MAC layer and IP layer in order that a SS-
initiated multicast to all SSs can be transmitted.
5. Acknowledgments
Thanks to Eun-Kyoung Paik for her cooperation and excellent review
comments.
6. Security Considerations
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6.1.1 PHS for IPv6
When PHS rule is applied to IPv6 packets, BS and SS should be
authorized and authenticated in WiBro.
6.1.2 IPv6 multicast transmission in IEEE 802.16
When IPv6 multicast transmission in IEEE 802.16 is applied to IPv6
packets, BS and SS should be authorized and authenticated in
WiBro.
7. Normative References
[IEEE P802.16e/D9, June 2005]
"Draft IEEE Standard for Local and metropolitan area
networks Part 16: Air Interface for Fixed and Mobile
Broadband Wireless Access Systems Amendment for Physical
and Medium Access Control Layers for Combined Fixed and
Mobile Operation in Licensed Bands".
[IEEE Std 802.16-2004(Revision of IEEE Std 802.16-2001)]
"IEEE Standard for Local and metropolitan area networks
Part 16: Air Interface for Fixed Broadband Wireless Access
Systems".
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
December 1998.
[RFC3513] Hinden, R. and S. Deering, "Internet Protocol Version 6
(IPv6) Addressing Architecture", RFC 3513, April 2003.
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Authors' Addresses
Sung Il Kim
KT
Convergence Laboratory
17 Woomyeon-dong, Seocho-gu
Seoul 137-792
Korea
Phone: +82-2-526-6118
Fax: +82-2-526-5200
Email: semperor@kt.co.kr
Se Jun Park
KT
Convergence Laboratory
17 Woomyeon-dong, Seocho-gu
Seoul 137-792
Korea
Phone: +82-2-526-6116
Fax: +82-2-526-5200
Email: semperor@kt.co.kr
Sang Eon Kim
KT
Convergence Laboratory
17 Woomyeon-dong, Seocho-gu
Seoul 137-792
Korea
Phone: +82-2-526-6117
Fax: +82-2-526-5200
Email: sekim@kt.co.kr
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Han-Lim Kim
KT
Convergence Laboratory
17 Woomyeon-dong, Seocho-gu
Seoul 137-792
Korea
Phone: +82-2-526-6189
Fax: +82-2-526-5200
Email: nangel@kt.co.kr
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