16ng BoF S. Jeong
Internet-Draft ETRI
Expires: August 29, 2006 H. Jang
SAIT
February 25, 2006
IPv6 Multicast Packet Delivery over IEEE 802.16 Networks
draft-jeong-16ng-multicast-delivery-00
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Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This memo describes transmission of IPv6 multicast packets over IEEE
802.16 networks, including the methods to deliver various scoped
multicast packets. It also presents the methods of forming multicast
CIDs on IEEE 802.16 networks.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Assumption and Scope . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology and Abbreviations . . . . . . . . . . . . . . 4
2. Brief Description of Subnet Models . . . . . . . . . . . . . . 5
3. Subnet Model A . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Link Local scope Multicast Packet . . . . . . . . . . . . 6
3.2. Non-link Local scope Multicast Packet . . . . . . . . . . 6
4. Subnet Model B . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Link Local scope Multicast Packet . . . . . . . . . . . . 8
4.2. Non-link Local scope Multicast Packet . . . . . . . . . . 8
5. Subnet Model C . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. Link Local scope Multicast Packet . . . . . . . . . . . . 10
5.2. Non-link Local scope Multicast Packet . . . . . . . . . . 10
6. Subnet Model D . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1. Link Local scope Multicast Packet . . . . . . . . . . . . 12
6.2. Non-link Local scope Multicast Packet . . . . . . . . . . 13
7. Considerations about MCID Format . . . . . . . . . . . . . . . 14
7.1. IPv6 scope-based MCID Format . . . . . . . . . . . . . . . 14
7.2. Distributed Link Local Multicast CID Format . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
9. Security Considerations . . . . . . . . . . . . . . . . . . . 16
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
Intellectual Property and Copyright Statements . . . . . . . . . . 19
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1. Introduction
IEEE 802.16 networks support mobile stations (MSs) to access
broadband wireless networks while moving at a vehicular speed
[IEEE802.16e]. However, 802.16 networks do not provide link layer
native multicast capability because of point-to-multipoint connection
characteristic [IEEE802.16]. This feature restricts the adoption of
protocols or applications that need IPv6 multicast capability. One
of the prominent ways to solve the multicast support problem is to
use the built-in LAN emulation feature of 802.16 which is based on
Convergence Sublayer [I-D.jee-16ng-problem-statement].
There are several previous work that focused on the transport of link
local scope multicast packets over 802.16 network [I-D.jeon-ipv6-ndp-
ieee802.16][I-D.jang-16ng-llm]. However, the IPv6 multicast service
requires not only the delivery of link local scope multicast packets,
but also the delivery of non-link local scope multicast packets such
as site local or global scope multicast packets. Since it is unclear
for 802.16 networks what constitutes a subnet, we need to consider
the transport of IPv6 multicast packets over various subnet models
[I-D.madanapalli-nd-over-802.16-problems].
This memo describes how the IPv6 multicast packets with various scope
can be delivered over four different types of subnet models.
1.1. Assumption and Scope
This document describes how to provide IP CS based IPv6 multicast
packets delivery over IEEE 802.16 networks. We will consider
Ethernet CS based IPv6 multicast packet transport in the later
version of this document.
We classify the IPv6 multicast packet into link local scope and non-
link local scope multicast packet. Node-local scope multicast packet
is not considered in this memo. When a BS is separated from an
access router (AR), we assume that the BS is connected to AR via
Ethernet. If Ethernet is not used between BS and AR, tunneling may
be used to apply our proposed approaches.
Our approaches are based on the use of multicast CID (MCID) to
distinguish between multicast and unicast packets, and to deliver the
multicast packets. This memo presents MCID based transport of IPv6
multicast packet not only link local scope, but also non-link local
scope. The initialization or distribution of MCID is not covered in
this document, but we may guess that the MCID will be initialized
during the establishment phase of host IP connectivity.
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1.2. Terminology and Abbreviations
In this memo, a link local multicast packet indicates a multicast
packet with link local scope such as NS, RA, and so on. A non-link
local multicast packet means that scope of the packet is neither node
local nor link local. The non-link local multicast packet also
includes a multicast data packet.
AR (access router)
BS (base station)
CID (connection id)
CS (convergence sublayer)
MCID (multicast CID) : CID for IP multicast service
MS (mobile station)
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2. Brief Description of Subnet Models
The relationship between BS and AR induces several IP subnet models
in 802.16 networks. We may deduce following four IP subnet models
from the IP prefix assignment method and the relationship of AR and
BS [I-D.shin-v6ops-802.16-deployment-scenarios]. This document
describes the transport of IPv6 multicast packets with IP CS over
each subnet models.
+--------+---------------------------+----------------------------+
| Subnet | Deployment architecture | Subnet components |
| model | | |
+--------+---------------------------+----------------------------+
| A | BS and AR are in same box | Single BS/AR, single MS |
+--------+---------------------------+----------------------------+
| B | BS and AR are in same box | Single BS/AR, multiple MSs |
+--------+---------------------------+----------------------------+
| C | BS is separated from AR | Single BS, single router, |
| | | multiple MSs |
+--------+---------------------------+----------------------------+
| D | BS is separated from AR | Multiple BSs, multiple MSs |
+--------+---------------------------+----------------------------+
Figure 1: IP subnet models in 802.16 networks
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3. Subnet Model A
When BS and AR are integrated in the same box, there exist two cases
of IPv6 prefix allocation method. The one is to assign an IPv6
prefix to each AR/BS box and the other is to allocate an IPv6 prefix
to each MS, similar to 3GPP scenario [RFC 3314].
In this section, we discuss the delivery of IPv6 multicast packets
over 'Subnet model A' depicted in Figure 2 where a BS is integrated
with a router, composing one box in view of implementation. In this
subnet model, each subnet consists of single BS/AR and only one MS.
Thus, each MS has a unique IPv6 prefix.
+-----+
| MS1 |<-------------+
+-----+ v
+-----+ +-------+ +--------+
| MS2 |<---------->|BS/AR1 |---------| Edge | ISP
+-----+ +-------+ | Router +==>Network
+--------+
+-----+ +-------+ |
| MS3 |<---------->|BS/AR2 |-----------+
+-----+ +-------+
<---> IP termination
Figure 2: Subnet model A
3.1. Link Local scope Multicast Packet
Since one MS exists in a subnet and the MS gets a unique IPv6 prefix,
it is not needed to transmit IPv6 multicast packet by using MCID. A
multicast packet sent from MS may be delivered to BS/AR by using
unicast CID. BS/AR may transmit a multicast packet to MS by using
unicast CID.
3.2. Non-link Local scope Multicast Packet
There are two types of non-link local scope multicast packets,
originated from MS and originated from other subnets or Internet. In
both types, BS/AR should support both MLDv2 [RFC 3810] and IPv6
multicast routing protocols.
3.2.1. Non-link Local Multicast Packet from MS
In the Figure 2, when BS/AR1 receives a non-link local scope
multicast packet from MS1, BS/AR1 looks up the multicast routing
table and forwards the packet to the edge router according to lookup
result. The packet forwarded by BS/AR1 is delivered to edge router
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or BS/AR2 by means of regular IPv6 multicast packet transport
procedure. If the packet is destined to BS/AR2's subnet, BS/AR2
transmits the packet to its downlinks with unicast CID.
3.2.2. Non-link Local Multicast Packet from Other Subnets or Internet
When BS/AR receives a multicast packet from edge router, it looks up
the multicast routing table and checks whether the packet is destined
to its own subnet. If there exists a receiver in the subnet, BS/AR
forwards the packet to its downlinks by using unicast CID.
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4. Subnet Model B
In this section, we discuss the delivery of IPv6 multicast packets
over 'Subnet model B' depicted in Figure 3 where a BS is integrated
with a router, composing one box, and a subnet consisting of only
single BS/AR and multiple MSs.
+-----+
| MS1 |<------+
+-----+ |
+-----+ | +-------+ +--------+
| MS2 |<------+--->|BS/AR1 |---------| Edge | ISP
+-----+ +-------+ | Router +==>Network
+--------+
+-----+ +-------+ |
| MS3 |<---------->|BS/AR2 |-----------+
+-----+ +-------+
<---> IP termination
Figure 3: Subnet model B
4.1. Link Local scope Multicast Packet
Link local scope multicast packets may be classified by packets
originated from MS and from BS/AR integrated box.
4.1.1. Link Local Multicast Packet from MS
In the Figure 3, when BS/AR1 receives a link local scope multicast
packet from MS1, BS/AR1 multicasts the packet onto its downlinks by
using MCID.
4.1.2. Link Local Multicast Packet from BS/AR
When BS/AR needs to send a multicast packet to MSs in the subnet,
BS/AR transmits the packet to its downlinks with MCID.
4.2. Non-link Local scope Multicast Packet
There are two types of non-link local scope multicast packets,
originated from MS and from other subnets or Internet. In both
types, BS/AR should support both MLDv2 and IPv6 multicast routing
protocols.
4.2.1. Non-link Local Multicast Packet from MS
In the Figure 3, when MS1 sends a non-link local scope multicast
packet, BS/AR1 receives the packet and transmits the packet to its
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downlinks by using MCID. After then, BS/AR1 looks up the multicast
routing table and forwards the packet to the edge router according to
the lookup result. The packet forwarded by BS/AR1 is delivered to
BS/AR2 or edge router by means of regular IPv6 multicast packet
transport procedure. If the packet is destined to BS/AR2's subnet,
BS/AR2 transmits the packet to its downlinks with MCID.
4.2.2. Non-link Local Multicast Packet from Other Subnets or Internet
When BS/AR receives a multicast packet from edge router, it looks up
the multicast routing table and checks whether the packet is destined
to its own subnet. If there exists a receiver in the subnet, BS/AR
sends the packet to its downlinks by using MCID.
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5. Subnet Model C
In this section, we discuss the transport of IPv6 multicast packets
over the 'Subnet model C' shown in Figure 4 where a BS is separated
from an AR and a subnet consists of multiple BSs and multiple MSs.
+-----+
| MS1 |<------+
+-----+ |
+-----+ | +-----+ +-----+ +--------+
| MSs |<------+----| BS1 |---->| AR |----| Edge | ISP
+-----+ +-----+ +-----+ | Router +==>Network
^ +--------+
+-----+ +-----+ |
| Mss |<-----------| BS2 |--------+
+-----+ +-----+
<---> IP termination
Figure 4: Subnet model C
5.1. Link Local scope Multicast Packet
Link local scope multicast packets may be classified by packets
originated from MS and from AR.
5.1.1. Link Local Multicast Packet from MS
In the Figure 4, when BS1 receives a link local scope multicast
packet originated from MS1, BS1 multicasts the packet onto its
downlinks by using MCID. After then, BS1 converts the IEEE 802.16
MAC frame format to IEEE 802.3 Ethernet frame and transmits the frame
into the link connected to AR.
5.1.2. Link Local Multicast Packet from AR
When BS receives an Ethernet frame sent from AR, it examines the IPv6
destination address. If the destination address is link local scope
multicast address, BS transmits the packet to its downlinks with
MCID.
5.2. Non-link Local scope Multicast Packet
Non-link local scope multicast packets can be classified into two
cases, packets sent from MS and sent from other subnets in the same
site or Internet. In both cases, AR should support both MLDv2 and
IPv6 multicast routing protocols.
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5.2.1. Non-link Local Multicast Packet from MS
In the Figure 4, when MS1 sends a non-link local scope multicast
packet, BS1 performs the same operation as link local scope case.
When AR receives the packet transmitted by BS1, it performs the
multicast routing table lookup and forwarding. The packet forwarded
by AR is delivered to BS2 or edge router according to regular IPv6
multicast packet transport procedure. If the packet is destined to
MSs in BS2's subnet, BS2 transmits the received packet to its
downlinks with predefined MCID.
5.2.2. Non-link Local Multicast Packet from Other Subnets or Internet
When AR receives a packet from edge router, it looks up the multicast
routing table and checks whether there exists a receiver of the
packet in AR's subnets. If there exists a receiver, AR sends the
packet to appropriate BSs in the downlinks. When BS receives the
multicast packet sent from AR, it checks the IPv6 destination
address. If the destination address is non-link local scope
multicast address, BS multicasts the packet to its downlinks with
MCID.
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6. Subnet Model D
In this section, we discuss the transport of IPv6 multicast packets
over the 'Subnet model D' shown in the Figure 5 where a BS is
separated from a router, and a subnet consists of multiple BS and
multiple MSs.
+-----+ +-----+ +-----+ ISP 1
| MS1 |<-----+ +->| AR1 |----| ER1 |===>Network
+-----+ | | +-----+ +-----+
+-----+ | +-----+ |
| MS2 |<-----+-----| BS1 |--|
+-----+ +-----+ | +-----+ +-----+ ISP 2
+->| AR2 |----| ER2 |===>Network
+-----+ +-----+ | +-----+ +-----+
| MS3 |<-----------| BS2 |--+
+-----+ +-----+
<---> IP termination
Figure 5: Subnet model D
6.1. Link Local scope Multicast Packet
Link local scope multicast packets may be classified by packets
originated from MS and from AR.
6.1.1. Link Local Multicast Packet from MS
In the Figure 5, when BS1 receives a link local scope multicast
packet originated from MS1, BS1 multicasts the packet onto its
downlinks by using MCID. After then, BS1 converts the IEEE 802.16
MAC frame format to IEEE 802.3 Ethernet frame and transmits the frame
into the link connected to AR according to the destination address.
BS2 which is on the same link as BS1, receives the Ethernet frame
sent from BS1 and examines the IPv6 destination address. If the
destination address is link local multicast address, BS2 multicasts
the packet to its downlinks with predefined MCID. If the destination
address is unicast, the received packet goes through IPv6 unicast
packet handling process.
6.1.2. Link Local Multicast Packet from AR
When BS receives an Ethernet frame sent from AR, it examines the IPv6
destination address. If the destination address is link local scope
multicast address, BS transmits the packet to its downlinks with
MCID.
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6.2. Non-link Local scope Multicast Packet
Non-link local scope multicast packets can be classified into two
cases, packets sent from MS and sent from other subnets in the same
site or Internet. In both cases, AR should support both MLDv2 and
IPv6 multicast routing protocols.
6.2.1. Non-link Local Multicast Packet from MS
In the Figure 5, when MS1 sends a non-link local scope multicast
packet, BS1 and BS2 perform same operation as link local scope case.
When AR1 receives the packet transmitted by BS1, it performs the
multicast routing table lookup and forwarding. The packet forwarded
by AR1 is delivered to AR2 or edge router according to regular IPv6
multicast packet transport procedure. If the packet is destined to
AR2's subnet, AR2 transmits the packet to its downlinks. BS which is
on the downlinks of AR2, receives the Ethernet frame sent from AR2
and examines the IPv6 destination address. If the destination
address is link local multicast address, BS multicasts the packet to
its downlinks with predefined MCID
6.2.2. Non-link Local Multicast Packet from Other Subnets or Internet
When AR receives the packet from edge router, it looks up the
multicast routing table and checks whether there exist receivers of
the packet in AR's subnet. If there exists a receiver, AR sends the
packet to BSs in the downlinks. Each BS in the subnet receives the
packet sent from AR and checks the IPv6 destination address. If the
destination address is non-link local scope multicast address, BS
multicasts the packet to its downlinks with MCID.
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7. Considerations about MCID Format
The allocation of MCID to IPv6 multicast packets needs to be
considered in IEEE. However, in this memo, we present a few
candidates.
7.1. IPv6 scope-based MCID Format
This section specifies a modification to the CID format as follows.
| 11 | 1 | 4 |
+------------------------------+---+----------+
| MCID prefix | M | scop |
+------------------------------+---+----------+
Figure 6: IPv6 Scope based MCID Format
MCID consists of MCID prefix, M, and scope field. MCID prefix is
used to indicate that a multicast packet is embedded in IEEE 802.16
frame. M field implies that IP CS is used to encapsulate the IPv6
packet. When M field is 1, scope field be set to the same value as
the scope field of encapsulated IPv6 destination address. When M
field is 0, scope field is reserved for future use and should be 0.
7.2. Distributed Link Local Multicast CID Format
This format is proposed in [I-D.jang-16ng-llm]. When IEEE 802.16
network interface is initialized, a MS generates a set of
corresponding link local multicast CIDs by affixing well-known prefix
n bit for IPv6 link local multicast, to the 16-n bit of the IPv6
multicast address. The well-known prefix will be allocated by IEEE
later and 'n' will be decided with much consideration in later
version.
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8. IANA Considerations
This document requests no action by IANA.
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9. Security Considerations
TBD
10. References
[IEEE802.16]
"IEEE 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 802.16e/D10 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", August 2005.
[I-D.jee-16ng-problem-statement]
Jee, J., "16ng Problem Statement",
draft-jee-16ng-problem-statement-02 (work in progress),
October 2005.
[I-D.jeon-ipv6-ndp-ieee802.16]
Jeon, H. and J. Jee, "IPv6 NDP for Common Prefix
Allocation in IEEE 802.16",
draft-jeon-ipv6-ndp-ieee802.16-00 (work in progress),
October 2005.
[I-D.jang-16ng-llm]
Jang, H., "Link-local Multicast Packet Transmission in
802.16 Networks", February 2006.
[I-D.madanapalli-nd-over-802.16-problems]
Madanapalli, S., "IPv6 Neighbor Discovery over 802.16:
Problems and Goals",
draft-madanapalli-nd-over-802.16-problems-00 (work in
progress), December 2005.
[I-D.shin-v6ops-802.16-deployment-scenarios]
Shin, M-K., "ISP IPv6 Deployment Scenarios in Wireless
Broadband Access Networks", February 2006.
[RFC3314] Wasserman, M., "Recommendations for IPv6 in Third
Generation Partnership Project (3GPP) Standards",
RFC 3314, September 2002.
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[RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery
Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.
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Authors' Addresses
Sangjin Jeong
ETRI
161 Gajeong-dong, Yusung-gu
Daejeon, 305-350
Korea
Phone: +82 42 860 1877
Email: sjjeong@gmail.com
Heejin Jang
SAIT
P.O. Box 111
Suwon 440-600
Korea
Email: heejin.jang@samsung.com
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