16ng Working Group S-E. Kim
Internet-Draft J-S. Jin
Expires: January 20, 2008 S-C. Lee
S-H. Lee
KT
July 19, 2007
Multicast Transport on IEEE 802.16 Networks
draft-sekim-802-16-multicast-01
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Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
This draft proposes two types of multicast transport over IEEE 802.16
networks. One is deirect mapping for IPv6 CS and the other is
indirect mapping for both IPv6 over Ethernet CS and IPv6 over VLAN
CS. An IPv6 multicast address transmits directly to a CID of IEEE
802.16 frame in direct mapping scheme. In indirect mapping, an IPv6
multicast address uses [RFC2464] and then transmits to a CID of IEEE
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802.16 frame.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Frame format for IEEE 802.16 Network . . . . . . . . . . . . . 4
4. CS Specific Multicast in IEEE 802.16 Network . . . . . . . . . 5
4.1. Multicast on IPv6 CS . . . . . . . . . . . . . . . . . . . 6
4.2. Multicast on Ethernet CS and IEEE 802.1Q VLAN CS . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
Intellectual Property and Copyright Statements . . . . . . . . . . 12
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1. Introduction
The [IEEE802.16] standards specify two modes for sharing wireless
media. One is point-to-multipoint(PMP) and the other is mesh. This
document focuses on PMP mode. In PMP mode, uplink supports only
unicast while downlink supports both unicast and multicast.
Therefore, [IEEE802.16] is not capable of multicasting in general
concept which should support both uplink and downlink as [IEEE802.3]
does.
[I-D.ietf-16ng-ipv6-over-ipv6cs] describes IPv6 related convergence
sublayer for unicast. The multicast transport capabilities are
important to both control and bearer aspects in Internet Protocol.
For examples, Ethernet Address Resolution Protocol [RFC0826] for IPv4
and Neighbor Discovery for IPv6 [RFC2461] require multicast mechanism
for control aspects.
The [IEEE802.16] standards specify service specific convergence
sublayer to process higher-layer protocol data unit based on
classification. The types of service specific convergence sublayer
are asynchronous transfer mode (ATM) and packets such as IPv6, IPv4,
IEEE 802.3/Ethernet, IEEE 802.1Q VLAN, IPv6 over IEEE 802.3/Ethernet,
IPv6 over IEEE 802.1Q VLAN, IPv4 over IEEE 802.3/Ethernet, IPv4 over
IEEE 802.1Q VLAN and so on. A multicast capability depends on the
convergence sublayer parameters of REGISTRATION message at IEEE
802.16 MAC messages. This document describes IPv6 multicast
[RFC4291] transport over IEEE 802.16 networks in accordance with
convergence sublayer.
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].
2. Terminology
o IEEE802.16 : IEEE802.16 standards including IEEE802.16e standards
o Base Station (BS):A generalized equipment sets providing
connectivity, management, and control between the subscriber
stations and the 802.16 networks.
o Connection Identifier(CID): A 16 bit value that identifies a
connection to equivalent peers in the MAC of the base station and
subscriber station. This is specified in IEEE802.16.
o Convergence Sublayer (CS): Sublayer in the IEEE 802.16 MAC layer
that classifies higher layer data and associates them to the
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proper MAC service flow identifier and connection identifier.
o IPv6 CS: A payload for an IEEE 802.16 frame is IPv6 packet.
o IPv6 over Ethernet CS: A payload for an IEEE 802.16 frame is
Ethernet frame based IPv6 packet. The Eternet frame is a service
data unit (SDU) of IEEE802.16 frame. The IPv6 packet is a SDU of
an Ethernet frame.
o IPv6 over IEEE 802.1Q VLAN CS: A payload for an IEEE 802.16 frame
is VLAN frame based IPv6 packet. The VLAN frame is a SDU of IEEE
802.16 frame. The IPv6 packet is a SDU of a VLAN frame.
o Mobile Station (MS): An user equipment that supports IP over IEEE
802.16e standard. It SHOULD support mobility capability.
3. Frame format for IEEE 802.16 Network
An 802.16 PDU consists of a MAC header, a data payload and CRC as
shown in Figure 1. The CRC field is an option.
| 48 bits | variable | 32 bits|
+-------------------+--------------------+--------+
| 802.16 MAC Header | Payload | CRC |
+-------------------+--------------------+--------+
Figure 1: IEEE 802.16 PDU format
Figure 2 shows an IEEE802.16 MAC header.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|H|E| TYPE |E|C|EKS|R| LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CID | HCS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: IEEE 802.16 MAC Header
o H: Header Type (1 bit).
o E: Encryption Control (1 bit). 0 = Payload is not encrypted; 1 =
Payload is encrypted.
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o TYPE (6 bits)
o E: Extended Subheader Field (1 bit)
o C: CRC Indicator. 1 = CRC is included, 0 = 1 No CRC is included
o EKS: Encryption Key Sequence (2 bits)
o R: Reserved (1 bit). Shall be set to zero.
o LENGTH: The Length in bytes of the MAC PDU including the MAC
header and the CRC if present (11 bits)
o CID: Connection Identifier (16 bits)
o HCS: Header Check Sequence (8 bits)
Table 1 shows well-known CID in [IEEE802.16e] standard.
[IEEE802.16e] describes that "For the downlink multicast service, the
same value is assigned to all MSs on the same channel that
participate in this connection."
+----------------------------+-------------+
| CID | hexadecimal |
+----------------------------+-------------+
| Initial Ranging | 0000 |
| Basic CID | 0001 ~ m |
| Primary management | m+1 ~ 2m |
| Transport CIDs | 2m+1 ~ FE9F |
| Multicast CID | FEA0 ~ FEFE |
| AAS initial ranging CID | FEFF |
| Multicast polling CID | FF00~FFF9 |
| Normal mode multicast CID | FFFA |
| Sleep mode multicast CID | FFFB |
| Idle mode multicast CID | FFFC |
| Fragmentable Broadcast CID | FFFD |
| Padding CID | FFFE |
| Broadcast CID | FFFF |
+----------------------------+-------------+
Table 1: Usage of CIDs for IEEE 802.16
4. CS Specific Multicast in IEEE 802.16 Network
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4.1. Multicast on IPv6 CS
IEEE 802.16 MAC header can be divided into two types: generic MAC
header and MAC header without payload. The IEEE 802.16 frame with
H=1, MAC header without payload, does not deliver a payload.
The Generic MAC header, H=0, begins each MAC PDU containing either
MAC management messages or CS data . The IPv6 CS, IPv6 over Ethernet
CS and IPv6 over IEEE 802.1Q VLAN CS can be a payload of generic MAC.
The 48 bits MAC address is used to identify a network device and used
IEEE 802.3 frame format. However, the IEEE 802.16 frame header does
not have the MAC address field. Instead, a CID field in the IEEE
802.16 frame header performs link layer identification between MS and
BS.
An IPv6 CS SHOULD set bit #2 for type 7 in REG-REQ and REG-RSP
message as specified by [IEEE802.16]. And this CS uses the value 2
for type 28 in DSx-REQ message. Figure 3 shows IPv6 CS over IEEE
802.16 frame.
| 48 bits |IPv6 Packet [RFC2460]| 32 bits|
+---------------+-----------+---------+--------+
| 802.16 Header |IPv6 Header| Payload | CRC |
+---------------+------+----+---------+--------+
^ |
+--direct mapping-+
Figure 3: IPv6 CS
IPv6 multicast address for IPv6 CS over IEEE 802.16 frame SHOULD be
used for multicasting with CID field at the 802.16 frame as shown in
Figure 4.
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| 8 | 4 | 4 | 108 bits | 4 |
+----+----+----+----------------+-+-+-+-+ IPv6 Multicast Address
| FF |flgs|scop| multicast group ID | [RFC4291]
+----+----+----+----------------+-+-+-+-+
|
+----------------------+
|
|
| 8 | 4 | 4 |
+----+----+----+
| FE |scop| ID | Multicast CID for IPv6 CS
+----+----+----+
Figure 4: Direct mapping for IPv6 CS
The multicast CID, 0XFFA0-0xFEFE, SHOULD use to multicast in IEEE
802.16 specification. The other CIDs are multicast polling CID,
normal mode multicast CID, sleep mode multicast CID, idle mode
multicast CID, fragmentable broadcast CID and broadcast CID. It is
for specific usage and difficult to identify layer 3 multicast
addresses.
The information for 802.16 multicast in CID SHOULD use scope field
and multicast group identifier that specified by [RFC4291]. The
scope and multicast group identifier are important to identify
multicast address [IPv6MA]. IPv6 multicast address prefix (0xFF)
translate to 802.16 CID multicast group (0xFE).
The flag information on IPv6 multicast address normally uses zero.
So, 802.16 CID SHOULD not use flag in [RFC4291] for multicast
mapping. The scope information on IPv6 multicast address is
important. Therefore, 802.16 CID SHOULD use scope information for
multicasting.
The last 4 bits in group identifier are important to IPv6 multicast
address [RFC4291]. The multicast group identifier uses last 4 bits
to 12 bits based on the purpose. So, last 4 bits of the IPv6
multicast group identifier SHOULD use because only 4 bits are
available at CID. The duplication of the last 4 bits for multicast
can resolve by use of scope information. The unique identification
to the whole IPv6 multicast address requires modification of such
specification as [IEEE802.16], [RFC2460], [RFC4291]. Therefore,
Figure 3 is RECOMMENDED for IPv6 multicast address mapping to 802.16
CID.
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4.2. Multicast on Ethernet CS and IEEE 802.1Q VLAN CS
IPv6 over Ethernet CS SHOULD set bit #6 for type 7 in REG-REQ and
REG-RSP message as specified by [IEEE802.16]. And this CS uses the
value 6 for type 28 in DSx-REQ message.
IPv6 over IEEE 802.1Q VLAN CS SHOULD set bit #8 for type 7 in REG-REQ
and REG-RSP message as specified by [IEEE802.16]. And this CS uses
the value 8 for type 28 in DSx-REQ message. Figure 5 shows IPv6 over
IEEE 802.3/VLAN CS over 802.16 frame.
| 48 bits | | IPv6 Packet |32bits|
+---------------+------------+-----------+---------+------+
| |802.3 Header| | | |
| 802.16 Header | or |IPv6 Header| Payload | CRC |
| | VLAN Header| | | |
+---------------+----+-------+--------+--+---------+------+
^ indirect | ^ |
+--mapping---+ +--RFC2464--+
Figure 5: IPv6 over Ethernet/VLAN CS
IPv6 multicast require at IPv6 over IEEE802.3 or [IEEE802.1Q] VLAN
CS. In this case, IPv6 multicast mapping to 802.16 CID SHOULD use
either direct mapping or indirect mapping. The direct mapping scheme
is described in section 4.1.
IPv6 multicast mapping to CID SHOULD use indirect mapping as
following. Firstly, [RFC2464] use for IPv6 multicast address mapping
to destination address at 802.3 frame. After that, multicast address
at 802.3 frame SHOULD translate to 602.16 CID as shown in Figure 6.
A BS transmit IPv6 multicast packet that destination address start
with 0X3333 at 802.3 frame for IPv6 over IEEE802.3 or VLAN
encapsulation
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| 16 | 24 bits | 8 |
+------+-----------------+-+-+-+-+-+-+-+-+ Ethernet Multicast Address
| 3333 | 802.3 multicast address | [RFC2464]
+------+-----------------+-+-+-+-+-+-+-+-+
|
+-------------------+
|
|
| 8 | 8 |
+----+--------------+
| FE | multicast ID | Multicast CID for IPv6 over Ethernet CS
+----+--------------+ Multicast CID for IPv6 over IEEE 802.1Q VLAN CS
Figure 6: Indirect mapping for Ethernet CS and VLAN CS
5. Security Considerations
This document does not introduce any new vulnerabilities to IPv6
specifications or operation. The security of the 802.16 air
interface is the subject to [IEEE802.16].
6. IANA Considerations
This document requests no action by IANA.
7. Acknowledgements
The authors would like to acknowledge the contributions of Dr. Tcha
for his review and comments.
8. References
8.1. Normative References
[IEEE802.16]
"IEEE Standard for Local and metropolitan area networks -
Specific requirements - Part 16: Air Interface for Fixed
Broadband Wireless Access Systems"", IEEE Standard 802.16,
June 2004.
[IEEE802.16e]
"IEEE Standard for Local and metropolitan area networks -
Specific requirements - Part 16: Air Interface for Fixed
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Broadband Wireless Access Systems, Amendment 2: Physical
and Medium Access Control layers for Combined Fixed and
Mobile Operation in Licensed bands and Corrigendum 1"",
IEEE Standard 802.16e, December 2005.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006.
8.2. Informative References
[I-D.ietf-16ng-ipv6-over-ipv6cs]
Patil, B., "IPv6 Over the IP Specific part of the Packet
Convergence sublayer in 802.16 Networks",
draft-ietf-16ng-ipv6-over-ipv6cs-09 (work in progress),
April 2007.
[IEEE802.1Q]
Institute of Electrical and Electronics Engineers, "IEEE
Standard for Local and Metropolitan Area Networks: Virtual
Bridged Local Area Networks", IEEE Standard 802.1Q,
May 2006.
[IEEE802.3]
"IEEE Standard for Information technology -
Telecommunications and information exchange between
systems - Local and metropolitan area networks - Specific
requirements - Part 3: Carrier sense multiple access with
collision detection (CSMA/CD) access method and physical
layer specifications"", IEEE Standard 802.3, March 2002.
[RFC0826] Plummer, D., "Ethernet Address Resolution Protocol: Or
converting network protocol addresses to 48.bit Ethernet
address for transmission on Ethernet hardware", STD 37,
RFC 826, November 1982.
[RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC 2461,
December 1998.
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Authors' Addresses
Sang-Eon Kim
Infra Lab., KT
17 Woomyeon-dong, Seocho-gu
Seoul, 137-792
Korea
Phone: +82 2 526 6117
Fax: +82 2 526 5200
Email: sekim@kt.co.kr
Jong Sam Jin
Infra Lab., KT
17 Woomyeon-dong, Seocho-gu
Seoul, 137-792
Korea
Phone: +82 2 526 6113
Fax: +82 2 526 5200
Email: jongsam@kt.co.kr
Seong-Choon Lee
Infra Lab., KT
17 Woomyeon-dong, Seocho-gu
Seoul, 137-792
Korea
Phone: +82 2 526 6153
Fax: +82 2 526 5200
Email: lsc@kt.co.kr
Sang-Hong Lee
Infra Lab., KT
17 Woomyeon-dong, Seocho-gu
Seoul, 137-792
Korea
Phone: +82 2 526 6500
Fax: +82 2 526 6502
Email: shleee@kt.co.kr
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