wdiff draft-ietf-v6ops-802-16-deployment-scenarios-00.txt draft-ietf-v6ops-802-16-deployment-scenarios-01.txt

Network Working Group M-K. Shin
Internet-Draft ETRI
Expires: November 25, 2006
Intended status: Informational Y-H. Han
Expires: April 4, 2007 KUT
May 24,
S-E. Kim
KT
D. Premec
Siemens Mobile
October 1, 2006

ISP

IPv6 Deployment Scenarios in Wireless Broadband Access 802.16(e) Networks
draft-ietf-v6ops-802-16-deployment-scenarios-00
draft-ietf-v6ops-802-16-deployment-scenarios-01

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Abstract

This document provides detailed description of IPv6 deployment and
integration methods and scenarios in wireless broadband access
networks in coexistence with deployed IPv4 services. In this
document we will discuss main components of IPv6 IEEE 802.16 access
network and its differences from IPv4 IEEE 802.16 networks and how
IPv6 is deployed and integrated in each of the IEEE 802.16
technologies using tunneling mechanisms and native IPv6.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Wireless Broadband Access Network Technologies - IEEE
802.16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Elements of IEEE 802.16 Networks . . . . . . . . . . . . . 4
2.2. Deploying IPv6 in IEEE 802.16 Networks . . . . . . . . . . 5
2.2.1. Scenario A . . . . . . . . . . . . Mobile Access Deployment Scenarios . . . . . . . . . . 7 6
2.2.2. Scenario B . . . . . . . . . . . . . . . . . . . . . . 9
2.2.3. Scenario C . . . . . . . . . . . . Fixed/Nomadic Deployment Scenarios . . . . . . . . . . 10
2.2.4. Scenario D . . . . . . . . . . . . . . . . . . . . . . 12
2.3. IPv6 Multicast . . . . . . . . . . . . . . . . . . . . . . 13
2.4. IPv6 Mobility . . . . . . . . . . . . . . . . . . . . . . 14
2.5. IPv6 QoS . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.6.
2.5. IPv6 Security . . . . . . . . . . . . . . . . . . . . . . 15
2.7. 14
2.6. IPv6 Network Management . . . . . . . . . . . . . . . . . 15
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
4. Security Considerations . . . . . . . . . . . . . . . . . . . 17
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.1. Normative References . . . . . . . . . . . . . . . . . . . 19
6.2. Informative References . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21
Intellectual Property and Copyright Statements . . . . . . . . . . 22

1. Introduction

Recently, broadband wireless access network is emerging for wireless
communication for user requirements such as high quality data/voice
service, fast mobility, wide coverage, etc. The IEEE 802.16 Working
Group develops standards and recommended practices to support the
development and deployment of broadband wireless metropolitan area
networks.

Whereas the existing IEEE 802.16 standard [IEEE802.16] standard addresses fixed wireless
applications only, the IEEE 802.16(e) standard [IEEE802.16e] aims to serve standard serves the needs of
fixed, nomadic, and fully mobile networks. It adds mobility support
to the original standard so that mobile subscriber stations can move while receiving
during services. The standardization of IEEE 802.16e is completed,
which plans to support mobility up to speeds of 70~80 mile/h that
will enable the subscribers to carry mobile devices such as PDAs,
phones, or laptops. IEEE 802.16e is one of the most promising access
technologies which would be applied to the IP-based broadband mobile
communication.

WiMAX Forum is an industrial corporation formed to promote and
certify compatibility and interoperability of broadband wireless
products mainly based on IEEE 802.16. The Network Working Group
(NWG) of WiMAX Forum is defining the IEEE 802.16 network architecture
(e.g., IPv4, IPv6, Mobility, interworking with different networks,
AAA, etc). Similarly, WiBro (Wireless Broadband), Korea effort which
focuses on the 2.3 GHz spectrum band, is also based on the IEEE
802.16 and IEEE 802.16e specifications.

As the deployment of wireless broadband access network progresses,
users will be connected to IPv6 networks. While the IEEE 802.16
defines the encapsulation of an IPv4/IPv6 datagram in an IEEE 802.16
MAC payload, a complete description of IPv4/IPv6 operation and
deployment is not present. In this document, we will discuss main
components of IPv6 IEEE 802.16 access network and its differences
from IPv4 IEEE 802.16 networks and how IPv6 is deployed and
integrated in each of the IEEE 802.16 technologies using tunneling
mechanisms and native IPv6.

This document extends works of [I-D.ietf-v6ops-bb-deployment-
scenarios] and follows the structure and common terminology of the
document.

2. Wireless Broadband Access Network Technologies - IEEE 802.16

This section describes the infrastructure that exists today in is based on IEEE
802.16 networks providing wireless broadband services to the
customer. It also describes a way to deploy IPv6 deployment options in these over IEEE 802.16
networks.

2.1. Elements of IEEE 802.16 Networks

The IEEE 802.11 access network (WLAN) has driven the revolution of
wireless communication but communication. However, the more people use it the more its
limitations like such as short range or and lack of mobility support were
revealed. arose.
Compared with such IEEE 802.11 network, IEEE 802.16 supports enhanced
features like such as wider range coverage and mobility. So it is expected that
IEEE 802.16 network could be the next step of IEEE 802.11 network.

The mechanism of transporting IP traffic over IEEE 802.16 networks is
outlined in [IEEE802.16], but the details of IPv6 operations over
IEEE 802.16 are being discussed now.

Here are some of the key elements of an IEEE 802.16 networks network:

o MS: Mobile Station. A station in the mobile service intended to
be used while in motion or during halts at unspecified points. A
mobile station (MS) is always a subscriber station (SS). (SS) which must
provide mobility function.

o BS: Base Station. A generalized equipment set providing
connectivity,
management and control of MS connections. There is a
unidirectional mapping between BS and MS medium access control
(MAC) peers for the purpose of transporting a service flow's
traffic.
Connections are A connection is identified by a connection identifier (CID) and all
(CID). All traffic is carried on a the connection. Sometimes there
can be alternative IEEE 802.16 network deployment where a BS is
integrated with an access router, composing one box in view of
implementation.

Figure 1 illustrates the key elements of

o AR: Access Router. A generalized equipment set providing IP
connectivity between BS and IP based network. An AR performs
first hop routing function to all MS.

Figure 1 illustrates the key elements of IEEE 802.16 802.16(e) networks.

Customer | Access Provider | Service Provider
Premise | | (Backend Network)

+-----+ +-----+ +------+ +----+ +----+ +--------+
| MSs |--(802.16)--| BS |-----+Access+---+ |-----| | | Edge | ISP
+-----+ +-----+ |Router| +----+ | AR |---| Router +==>Network
+--+---+ |==>Network
+--| | | (ER) |
| +----+ +--------+
+-----+ +-----+ +----+ | | +------+
| Mss MSs |--(802.16)--| BS |--------+ |--+ +--|AAA |
+-----+ +-----+ +----+ |Server|
+------+

Figure 1: Key Elements of IEEE 802.16(e) Networks

2.2. Deploying IPv6 in IEEE 802.16 Networks

IEEE 802.16 supports

[IEEE802.16] specifies two modes such as 2-way PMP (Point-to-
Multipoint) and Mesh topology for sharing the wireless networks. In this document,
we focus medium:
point-to-multipoint (PMP) and mesh (optional). This document only
focuses on 2-way PMP topology wireless networks.

There are two different deployment options in current IEEE 802.16
networks: Cellular-like and Hot-zone mode.

Some of the factors that hinder deployment scenarios. of native IPv6 can
be deployed in both core
protocols are introduced by [I-D.jee-16ng-problem-statement]. The
summary of these deployment models.

A. Cellular-like Deployment Model them is as follows:

1. Lacking of Facility for IPv6 Native Multicasting

IEEE 802.16 BS can offer both fixed communications and mobile PMP mode is a connection oriented technology without bi-
directional native multicast support. IPv6 neighbor discovery
[RFC2461] supports various functions unlike IEEE 802.11. In particular, IEEE 802.16e working
group standardized for the interaction between
nodes attached on the same subnet, such mobility features as on-link determination and
address resolution. It is designed with no dependence on a specific
link layer technology, but requires that the specification link layer technology
support native multicast. This lacking of
IEEE 802.16e provides some competition facility for IPv6 native
multicast results in inappropriateness to apply the standard neighbor
discover protocol specially regarding, address resolution, router
discovery, stateless auto-configuration and duplicated address
detection.

2. Impact on IPv6 Subnet Model

IEEE 802.16 is different from existing cellular
systems. This use case will be implemented only with the licensed
spectrum. wireless access technologies
such as IEEE 802.11 or 3G, and, while IEEE 802.16 BS might be deployed with a proprietary
backend managed by defines the
encapsulation of an operator. All original IP datagram in an IEEE 802.16 MAC payload, a
complete description of IPv6 functionalities
will operation is not survive present. IEEE 802.16
can rather benefit from IETF input and some of them might be compromised specification to efficiently
serve support IPv6
operation. Especially, BS should look at the classifiers and decide
where to this 'Cellular-like' use case.

Under send the use case, however, packet, since IEEE 802.16 standards are still IP-
centric, providing packet-switched approach, connection always ends at
BS, while cellular standards
like GSM have IPv6 connection terminates at a more circuit-switched approach.

B. Hot Zone Deployment Model

The success default router. This
operation and limitation may be dependent on the given subnet model
[I-D.madanapalli-16ng-subnet-model-analysis].

3. Multiple Convergence Sublayers (CS)

There are operational complexity problems of a Hotspot service with IEEE 802.11 has been prominent.
The new IEEE IP over 802.16 standards basically support such Hotspot services
with large coverage area and high data rate. An area served caused by one
base station is usually termed 'Hot Zone' because it is considerably
larger than an IEEE 802.11 access point service area called Hotspot.

Many wireless Internet service providers (Wireless ISPs) have planned
to use IEEE 802.16 for
the purpose existence of high quality service. A
company multiple convergence sublayers [I-D.iab-link-
encaps]. We should consider which type of Convergence Sublayer (CS)
can use be efficiently used on each subnet models and scenarios. IEEE
802.16 to build up mobile office. Wireless
Internet spreading through a campus or a cafe can be also implemented
with it. The distinct point CS delivers and classifies various kinds of this use case is that it can use
unlicensed (2.4 & 5 GHz) band as well higher layer PDUs
such as licensed (2.6 & 3.5GHz)
band. By using the unlicensed band, a ATM, IPv4 packet and IPv6 packets over radio channel. For
this purpose, IEEE 802.16 BS might be used
just as a wireless hub which a user purchases to build a private
wireless network in his/her home or laboratory.

Under 'Hot Zone' use case, a IEEE 802.16 BS will be deployed using an
Ethernet (IP) backbone rather than a proprietary backend like
cellular systems. Thus, many IPv6 functionalities will be preserved
when adopting IPv6 to IEEE 802.16 networks, which brings out many
research issues [I-D.jee-16ng-problem-statement] [I-D.madanapalli-nd-
over-802.16-problems].

Some of the factors that hinder deployment of native IPv6 core
protocols include:

1. Lacking of Facility for IPv6 Native Multicasting

IEEE 802.16 is a PMP connection oriented technology without bi-
directional native multicast support. IPv6 neighbor discovery
[RFC2461] supports various functions for the interaction between
nodes attached on the same subnet, such as on-link determination and
address resolution. It is designed with no dependence on a specific
link layer technology, but requires that the link layer technology
support native multicast. The specification of IEEE 802.16 provides
multicast and broadcast services. However, the aim of such services
is to transmit IEEE 802.16 MAC management messages, not IP messages.
This lacking of facility for IPv6 native multicast results in
inappropriateness to apply the standard neighbor discover protocol
specially regarding, address resolution, router discovery, stateless
auto-configuration and duplicated address detection.

2. Impact of BS on Subnet Model

IEEE 802.16 is different from existing wireless access technologies
such as IEEE 802.11 or 3G, and, while IEEE 802.16 defines the
encapsulation of an IP datagram in an IEEE 802.16 MAC payload, a
complete description of IPv6 operation is not present. IEEE 802.16
can rather benefit from IETF input and specification to support IPv6
operation. Especially, BS should look at the classifiers and decide
where to send the packet, since IEEE 802.16 connection always ends at
BS, while IPv6 connection terminates at a default router. This
operation and limitation may be dependent on the given subnet model.

Also, we should consider which type of Convergence Sublayer (CS) can
be efficiently used on each subnet models. IEEE 802.16 CS provides
the tunneling of IP(v6) packets over IEEE 802.16 air-link. The
tunnels are identified by introduces the Connection Identifier (CID).
Generally, CS performs the following functions in terms of IP packet
transmission: 1) Receipt of protocol data units (PDUs) from the
higher layer, 2) Performing classification and CID mapping of the
PDUs, 3) Delivering the PDUs to the appropriate MAC SAP, 4) Receipt
of PDUs from the peer MAC SAP. SAP, and 5) Forwarding the PDUs to the
corresponding AR. The specification of IEEE 802.16 defines several
CSs for carrying IP packets, but does not provide a provide a detailed
description of how to carry them. The several CSs are generally
classified into two types of CS: IPv6 CS and Ethernet CS.

In addition, due to the problems caused by the existence of multiple
convergence sublayers [I-D.iab-link-encaps], the mobile access
scenarios need solutions about how roaming will work when forced to
move from one CS to another. Note that, at this phase this issue is
the out of scope of this draft. It should be also discussed in 16ng
WG.

There are two different deployment scenarios: fixed and mobile
access. A fixed access scenario substitudes for existing wired-based
access technologies such as digital subscriber line (xDSL) and cable
network. This fixed access scenario can provide nomadic access
within the radio coverages, which is called Hot-zone model. A mobile
access scenario is for new paradigm for voice, data and video over
mobile network. This scenario can provide high speed data rate
equalivent to wire-based Internet as well as mobility function
equivalent to cellular system. The mobile access scenario can be
classified into two different IPv6 sunbet models: shared IPv6 prefix
link model and point-to-point link model.

2.2.1. Mobile Access Deployment Scenarios

Unlike IEEE 802.11, IEEE 802.16 BS can offer mobility function as
well as fixed communication. [IEEE802.16e] has been standardized to
provide mobility features on IEEE 802.16 environments. This use case
will be implemented only with the licensed spectrum. IEEE 802.16 BS
might be deployed with a proprietary backend managed by an operator.
All original IPv6 functionalities [RFC2461], [RFC2462] will not
survive. Some architectural characteristics of IEEE 802.16 networks
may affect the detailed description operations of how to carry them. The several CSs NDP [RFC2461].

There are
generally classified into two types of CS: possible IPv6 CS subnet models for mobile access
deployment scenarios: shared IPv6 prefix link model and Ethernet CS.

While deploying point-to-
point link model [I-D.madanapalli-16ng-subnet-model-analysis]. The
mobile access deployment models, WiMax and WiBro, fall within this
deployment model.

1. Shared IPv6 in the above mentioned approach, there are four
possible typical scenarios as discussed below.

2.2.1. Scenario A

Scenario A Prefix Link Model

This link model represents IEEE 802.16 mobile access network
deployment where a
BS is separated from a router, and a subnet consists of only single
router interface of AR and
multiple BSs and MSs. Current celluar-like deployment
models, WiMax Therefore, all MSs and WiBro, fall within this scenario A. corresponding interface of AR
share the same IPv6 prefix as shown in Figure 2. IPv6 prefix will be
different from the interface of AR.

+-----+
| MS1 |<------+ |<-(16)-+
+-----+ |
+-----+ | +-----+ +-----+ +--------+
| MSs |<------+----| MS2 |<-(16)-+----| BS1 |---->| |--+->| AR |----| Edge | ISP
+-----+ +-----+ | +-----+ | Router +==>Network
^
| +--------+
+-----+ +-----+ |
| Mss |<-----------| MS3 |<-(16)-+----| BS2 |--------+ |--+
+-----+ | +-----+
+-----+ |
| MS4 |<-(16)-+
+-----+
<---> IP termination

Figure 2: Scenario A Shared IPv6 Prefix Link Model

2. Point-to-Point Link Model

This link model represents IEEE 802.16 mobile access network
deployment where a subnet consists of only single AR, BS and MS.
That is, each connection to a mobile node is treated as a single
link. Each link between the MS and the AR is allocated a separate,
unique prefix or unique set of prefixes by the AR. The point-to-
point link model follows the recommendations of [RFC3314].

+-----+
| MS1 |<-(16)---------+
+-----+ |
+-----+ +-----+ +-----+ +--------+
| MS2 |<-(16)------| BS1 |--+->| AR |----| Edge | ISP
+-----+ +-----+ | +-----+ | Router +==>Network
| +--------+
+-----+ +-----+ |
| MS3 |<-(16)------| BS2 |--+
+-----+ +-----+
+-----+ |
| MS4 |<-(16)---------+
+-----+

Figure 3: Point-to-Point Link Model

2.2.1.1. IPv6 Related Infrastructure Changes

IPv6 will be deployed in this scenario by upgrading the following
devices to dual-stack: MS, BS (if possible), BS, AR and Edge Router. In
this scenario the ER. In this scenario, IEEE
802.16 BSs have only MAC and PHY layers without router function and
operates as a bridge. The BS is Layer 3 unaware, so no changes are needed does not need to support IPv6.
However, if IPv4 stack is loaded to them for management and
configuration purpose, it is expected that BS should be upgraded by
implementing IPv6 stack, too.

2.2.1.2. Addressing

IPv6 MS has two possible options to get an IPv6 address. These
options will be equally applied to the other three scenarios below. scenario below (Section
2.2.2).

1. IPv6 MS can get the IPv6 address from an access router using
stateless auto-configuration. In this case, router discovery and DAD
operation using multicast should be properly operated over IEEE 802.16 link.

2. IPv6 MS can use DHCPv6 to get an IPv6 address from the DHCPv6
server. In this case, the DHCPv6 server would be located in the
service provider core network and Edge Router would simply act as a
DHCP Relay Agent. the AR should provide DHCPv6 relay
agent. This option is similar to what we do today in case of DHCPv4.

In this scenario, a router and multiple BSs form an IPv6 subnet and a
single prefix is allocated to all the attached MS. MSs. All MSs attached
to same AR can be on same IPv6 link.

2.2.1.3.

As for the prefix assignment, in case of shared IPv6 Control prefix link
model, one or more IPv6 prefixes are assigned to the link and Data hence
shared by all the nodes that are attached to the link. In point-to-
point link model, the AR assigns a unique prefix or set of unique
prefixes for each MS.

2.2.1.3. IPv6 Transport

In a subnet, there are always two underlying links: one is the IEEE
802.16 wireless link between MS and BS, and the other is a wired link
between BS and AR. Also, there are multiple BSs The IPv6 packet should be classified by IPv6
source/destination addresses, etc. BS generates the flow based on
the same link. classification. It also decides where to send the packet or just
forward the packet to the ACR, since IEEE 802.16 connection always
ends at BS while IPv6 connection terminates at the AR. This
operation may be dependent on IPv6 subnet models.

If stateless auto-configuration is used to get an IPv6 address,
router discovery and DAD operation should be properly operated over
IEEE 802.16 link. So, BS may support In case of shared IPv6 basic protocols such as ND
using multicast functions, or provide some schemes to facilitate prefix link model, the
stateless auto-configuration. Especially, IEEE 802.16 connection
terminates at BS, DAD
[RFC2461] does not a router. So, BS should look at the
classifiers and decide where adapt well to send the packet. In addition, one BS
can send the packet to other BSs, since multiple BSs are 802.16 air interface as there is
no native multicast support and when supported consumes air bandwidth
as well as it would have adverse effect on MSs that were in the same
link.

The operation and transmission methods are being intensively
discussed
dormant mode. An optimization, called Relay DAD, may be required to
perform DAD. However, in other documents [I-D.shin-16ng-ipv6-transmission]. case of point-to-point link model, DAD is
easy since each connection to a MN is treated as a unique IPv6 link.

Note that in this scenario Ethernet CS as well as IPv6 CS may be used more appropriate than
Ethernet CS to transport IPv6 packets. packets, since there are some overhead
of Ethernet CS (e.g., Ethernet header) under mobile access
environments .

Simple or complex network equipments may constitute the underlying
wired network between BS the AR and AR. the ER. If the IP aware equipments
between the AR and the ER do not support IPv6, the service providers are deploying
can deploy IPv6-in-IPv4 tunneling mechanisms to transport IPv6
packets between an the AR and an
Edge router. the ER.

The service providers are deploying tunneling mechanisms to transport
IPv6 over their existing IPv4 networks as well as deploying native
IPv6 where possible. Native IPv6 should be preferred over tunneling
mechanisms as native IPv6 deployment option might be more scalable
and provide required service performance. Tunneling mechanisms
should only be used when native IPv6 deployment is not an option.
This can be equally applied to other three scenarios below.

2.2.1.4. Routing

In general, the AR is configured with a default route that points to
the Edge router. No routing protocols are needed on these devices
which generally have limited resources.

The Edge Router runs the IGP used in the ISP network such as OSPFv3
or IS-IS for IPv6. The connected prefixes have to be redistributed.
Prefix summarization should be done at the Edge Router.

2.2.2. Scenario B

Scenario B represents IEEE 802.16 network deployment where a BS is
separated from a router, there are multiple access routers, and a
subnet consists of multiple BS and MSs. If 802.16 access networks
are widely deployed like WLAN, this scenario should be also
considered. Hot-zone deployment model falls within this scenario B.

+-----+ +-----+ +-----+ ISP 1
| MS1 |<-----+ +->| AR1 |----| ER1 |===>Network
+-----+ | | +-----+ +-----+
+-----+ | +-----+ |
| MS2 |<-----+-----| BS1 |--|
+-----+ +-----+ | +-----+ +-----+ ISP 2
+->| AR2 |----| ER2 |===>Network
+-----+ +-----+ | +-----+ +-----+
| Ms3 |<-----------| BS2 |--+
+-----+ +-----+
<---> IP termination

Figure 3: Scenario B

2.2.2.1. IPv6 Related Infrastructure Changes

IPv6 will be deployed in this scenario by upgrading the following
devices to dual-stack: MS, BS (if possible), AR and Edge Router. In
this
This can be equally applied to other scenario below (Section 2.2.2).

2.2.1.4. Routing

In general, the BS MS is Layer 3 unaware, so configured with a default route that points to
the the AR. Therefore, no changes routing protocols are needed on the MS.
The MS just sends to
support IPv6. However, if IPv4 stack is loaded the AR by default route.

The AR can configure multiple link to them ER for
management and configuration purpose, it is expected that BS network reliability.
The AR should
be upgraded by implementing support IPv6 stack, too.

2.2.2.2. Addressing

In this scenario, multiple BSs and MSs form an routing protocol such as OSPFv3 [RFC2740]
or IS-IS for IPv6 subnet and
multiple prefixes are allocated when connected to all the attached MS. All MSs
attached to different BSs under ER with multiple links.

The ER runs the same AR, IGP such as OSPFv3 or IS-IS for IPv6 in the service
provider network. The routing information of the ER can be on same IPv6
link.

2.2.2.3.
redistributed to the AR. Prefix summarization should be done at the
ER.

2.2.1.5. Mobility

As for mobility management, the movement between BSs is handled by
Mobile IPv6 Control and Data Transport

In [RFC3775], if it requires a subnet, like scenario A, there are always two underlying links:
one subnet change. Also, in
certain cases (e.g., fast handover [I-D.ietf-mipshop-fmipv6-
rfc4068bis]) the link mobility information must be available for
facilitating layer 3 handoff procedure.

Mobile IPv6 defines that movement detection uses Neighbor
Unreachability Detection to detect when the default router is no
longer bi-directionally reachable, in which case the mobile node must
discover a new default router. Periodic Router Advertisements for
reachability and movement detection may be unnecessary because IEEE
802.16 MAC provides the reachability by its Ranging procedure and the
movement detection by the Handoff procedure.

IEEE 802.16 wireless link between MS and BS, and the other defines L2 triggers whether refresh of an IP address is a wired link between BS and AR. Also, there are multiple BSs on
required during the same link.

If stateless auto-configuration is used to get handoff. Though a handoff has occurred, an IPv6 address,
considerations on
additional router discovery and DAD operation are the same as
scenario A.

The operation and transmission methods are being intensively
discussed in other documents [I-D.shin-16ng-ipv6-transmission]. Note
that procedure is not required in this scenario Ethernet CS case of
intra-subnet handoff. Also, faster handoff may be more suitable to transport
IPv6 packets, rather than IPv6 CS, since this scenario requires
broadcast-like functions (e.g., multi-homing).

Simple or complex network equipments may constitute the underlying
wired network between BS and AR. If the IP aware equipments do not
support IPv6, occurred by the service providers are deploying IPv6-in-IPv4
tunneling mechanisms to transport L2
trigger in case of inter-subnet handoff.

Also, IEEE 802.16g which is under-developed defines L2 triggers for
link status such as link-up, link-down, handoff-start. These L2
triggers may make Mobile IPv6 packets between an AR procedure more efficient and an
Edge router.

2.2.2.4. Routing faster.
In this scenario, addition, Mobile IPv6 multi-homing considerations exist. For
example, if there exist two routers to support MSs, default router
must be selected.

The Edge Router runs Fast Handover assumes the IGP used in support from link-
layer technology, but the SP network such particular link-layer information being
available, as OSPFv3 well as the timing of its availability (before, during
or
IS-IS for IPv6. The connected prefixes have after a handover has occurred), differs according to be redistributed.
Prefix summarization should be done at the Edge Router.

2.2.3. Scenario C

Scenario C represents
particular link-layer technology in use. This issue is also being
discussed in [I-D.ietf-mipshop-fh80216e].

2.2.2. Fixed/Nomadic Deployment Scenarios

The IEEE 802.16 access network networks can provide plain Ethernet
connectivity end-to-end. Wireless DSL deployment where a
BS model is integrated with a router, composing one box in view an example
of
implementation, and a subnet consists of only single BS/router and
multiple MSs.

+-----+
| MS1 |<------+
+-----+ |
+-----+ | +-------+ +--------+
| MS2 |<------+--->|BS/AR1 |---------| Edge | ISP
+-----+ +-------+ | Router +==>Network
+--------+
+-----+ +-------+ |
| Ms3 |<---------->|BS/AR2 |-----------+
+-----+ +-------+
<---> IP termination

Figure 4: Scenario C

2.2.3.1. IPv6 Related Infrastructure Changes fixed/nomadic IPv6 will be deployed in this scenario by upgrading the following
devices to dual-stack: MS, BS/AR and Edge Router.

2.2.3.2. Addressing

In this scenario, a single prefix is allocated deployment of IEEE 802.16. Many wireless
Internet service providers (Wireless ISPs) have planned to all use IEEE
802.16 for the attached
MS. All MSs attached to same BS purpose of high quality broadband wireless service. A
company can be on same IPv6 link.

2.2.3.3. IPv6 Control and Data Transport

If stateless auto-configuration is used to get an IPv6 address,
router discovery and DAD operations should be properly operated over use IEEE 802.16 link. So, BS/AR should support IPv6 basic protocols such
as ND using multicast functions, or provide some schemes to
facilitate the stateless auto-configuration. build up mobile office. Wireless
Internet spreading through a campus or a cafe can be also implemented
with it. The operation and transmission methods are being intensively
discussed in other documents [I-D.shin-16ng-ipv6-transmission]. Note
that in distinct point of this scenario Ethernet CS use case is that it can use
unlicensed (2.4 & 5 GHz) band as well as IPv6 CS may licensed (2.6 & 3.5GHz)
band. By using the unlicensed band, an IEEE 802.16 BS might be used to
transport IPv6 packets.

2.2.3.4. Routing

In general, BS/Router is configured with
just as a default route that points
to the Edge router. No routing protocols are needed on these devices wireless switch/hub which generally have limited resources.

The Edge Router runs the IGP used a user purchases to build a
private wireless network in his/her home or laboratory.

Under fixed access model, the SP network IEEE 802.16 BS will be deployed using
an IP backbone rather than a proprietary backend like cellular
systems. Thus, many IPv6 functionalities such as OSPFv3 or
IS-IS for IPv6. The connected prefixes have to be redistributed.
Prefix summarization should [RFC2461],
[RFC2462] will be done at the Edge Router.

2.2.4. Scenario D

Scenario D preserved when adopting IPv6 to IEEE 802.16
devices.

This scenario also represents IEEE 802.16 access network deployment where a
BS is integrated with a router, composing one box in view of
implementation. In this scenario, a
subnet consists of only single
BS/router multiple MSs and single MS. multiple interface of the
multiple BSs. Multiple access routers can exist. There exist
multiple hosts behind an SS (networks behind an MS may exist). When
802.16 access networks are widely deployed like WLAN, this case
should be also considered. Hot-zone deployment model falls within
this case.

+-----+ +-----+ +-----+ ISP 1
| SS1 |<-(16)+ +->| AR1 |----| ER1 |===>Network
+-----+ | | +-----+ +-----+
+-----+ | +-----+ |
| SS2 |<-(16)+-----| BS1 |--|
+-----+ +-----+ | +-----+ +-----+ ISP 2
+->| AR2 |----| ER2 |===>Network
+-----+ +-----+ +-----+ | +-----+ +-----+
|Hosts|<-->|SS/GW|<-(16)------| BS2 |--+
+-----+ +-----+ +-----+
This scenario mimics network
behind MS may exist

Figure 4: Fixed/Nomadic Deployment Scenario

While Figure 3 illustrates a generic deployment scenario, the
following Figure 4 shows in more detail how an existing DSL ISP would
integrate the current 3GPP-like
IPv6 deployment model. 802.16 access network into its existing infrastructure.

+-----+ +---+ +-----+ +-----+ ISP 1
| MS1 |<-------------+ SS1 |<-(16)+ | | +-->|BRAS |----| ER1 |===>Network
+-----+ | | b| | +-----+ +-----+ v
+-----+ +-------+ +--------+ | MS2 |<---------->|BS/AR1 |---------| Edge +-----+ |E r| |
| SS2 |<-(16)+-----| BS1 |-----|t i| |
+-----+ +-----+ |h d|--+
| g| | +-----+ +-----+ ISP 2
+-----+ +-----+ +-------+ | Router +==>Network
+--------+ e| +-->|BRAS |----| ER2 |===>Network
| SS3 |<-(16)------| BS2 |-----| | | +-----+ +-----+
+-----+ +-------+ +-----+ +---+ |
| Ms3 |<---------->|BS/AR2 |-----------+
+-----+ +-------+
<---> IP termination +-----+ |
| TE |<-(DSL)-----|DSLAM|------------+
+-----+ +-----+

Figure 5: Scenario D

2.2.4.1. Integration of 802.16 access into DSL infrastructure

In this approach the 802.16 BS is acting as a DSLAM (Digital
Subscriber Line Access Multiplexer). On the network side, the BS is
connected to an Ethernet bridge which can be separate equipment or
integrated into BRAS (Broadband Remote Access Server).

2.2.2.1. IPv6 Related Infrastructure Changes

IPv6 will be deployed in this scenario by upgrading the following
devices to dual-stack: MS, BS/AR BS, AR and Edge Router.

2.2.4.2. Addressing ER. In this case, scenario, IEEE
802.16 BSs have only MAC and PHY layers without router function and
operates as a bridge. The BS does not need to support IPv6.
However, if stateless auto-configuration IPv4 stack is used, 3GPP-like IPv6
addressing scheme [RFC 3314] can be used. That is, a unique prefix
can be allocated loaded to each MS. [RFC 3314] recommends them for management and
configuration purpose, it is expected that a given
prefix BS should be assigned to only one primary PDP context so that
3GPP terminals are allowed to generate multiple upgraded by
implementing IPv6 address using
the prefix without stack, too.

The BRAS in Figure 4 is providing the concerns functionality of address confliction (DAD).

2.2.4.3. IPv6 Control and Data Transport

In this scenario, IEEE 802.16 connection and IPv6 termination point
are the same, since a AR. The
Ethernet bridge is necessary for protecting the BRAS from 802.16 link
layer peculiarities. The Ethernet bridge relays all traffic received
through BS to its network side port(s) connected to BRAS. Any
traffic received from BRAS is integrated with a router. In addition,
each relayed to appropriate BS. Since
802.16 MAC layer has no native support for multicast (and broadcast)
in the uplink direction, the Ethernet bridge will emulate Ethernet
level multicast (and broadcast) by relaying the multicast frame
received from the MS can be on different to all of its ports. Ethernet bridge may also
provide some IPv6 link. So, many specific functions to increase link efficiency of
the 802.16 radio link (see Section 2.2.2.3).

2.2.2.2. Addressing

One or more IPv6 protocols prefixes can be operated without much consideration about shared to all the underlying network
implementation.

Only IEEE 802.16 link will attached MSs.
Prefix delegation can be taken into consideration for IPv6
adoption. For example, DAD operation is not needed required since each MS has
only a well-known neighbor, a router. The operation and transmission
methods are being intensively discussed in other documents [I-D.shin-
16ng-ipv6-transmission]. networks can exist behind SS.

2.2.2.3. IPv6 Transport

Note that in this scenario IPv6 Ethernet CS type may be more suitable appropriate than
IPv6 CS to transport IPv6 packets rather than packets, since the scenario need to support
plain Ethernet connectivity end-to-end. However, the IPv6 CS can
also be supported. Every MS and the BS has the Ethernet type since broadcast-
like functions are not required.

2.2.4.4. Routing MAC
address. If the MS is using IP CS, then the BS needs to take care of
the Ethernet header. In general, the access router upstream direction, the BS will need to
generate an appropriate Ethernet header and prepend it to the IP
datagram. In the downstream direction, the BS will use the
destination address from the Ethernet header to identify the MS and
then it will strip the Ethernet header before relaying the IP
datagram over the 802.16 MAC connection. Ethernet bridge may provide
implementation of authoritative address cache and Relay DAD.
Authoritative address cache is configured with a default route mapping between the IPv6 address and
the MAC addresses of all attached MSs.

The bridge builds its authoritative address cache by parsing the IPv6
Neighbor Discovery messages used during address configuration (DAD).
Relay DAD means that
points the Neighbor Solicitation message used in DAD
process will be relayed only to the Edge Router. No routing protocols are needed on these
devices MS which generally have limited resources. already has configured
the solicited address as its own address (if such MS exist at all).

2.2.2.4. Routing

In this scenario, IPv6 multi-homing considerations exist. For
example, if there exist two routers to support MSs, default router
must be selected.

The Edge Router runs the IGP used in the service provider SP network such as OSPFv3
[RFC2740] or IS-IS for IPv6. The connected prefixes have to be
redistributed. Prefix summarization should be done at the Edge
Router.

2.3. IPv6 Multicast

In order to

2.2.2.5. Mobility

No mobility functions are supported in fixed access scenario.
However, mobility can support multicast services in IEEE 802.16, Multicast
Listener Discovery (MLD) [RFC2710] must be supported between the MS
and BS/Router. Also, radio coverage without any
mobility protocol like WLAN technology. Therefore, a user can access
Internet nomadically in the inter-working with IP multicast protocols
and coverage.

2.3. IPv6 Multicast and Broadcast Service (MBS) should be considered.

Within

In IEEE 802.16 networks, an MS connects to its BS/router via
point-to-point links. MLD allows an MS to send link-local air link, downlink connections can be shared among
multiple MSs, enabling multicast
destination queries and reports. The packets are transmitted as
normal IEEE 802.16 MAC frames, as channels with multiple MSs receiving
the same as regular unicast
packets. Especially, multicast CIDs can information from the BS. MBS may be used to transmit efficiently query packets on the downlink.

There are exactly two IP devices connected to the point-to-point
link, and no attempt
implement multicast. However, it is made (at the link-layer) to suppress the
forwarding of multicast traffic. Consequently, sending MLD reports
for link-local addresses in IEEE 802.16 network may not always be
necessary. MLD is needed for multicast group knowledge that clear how to do this, as
currently CID is not
link-local.

MBS defines Multicast and Broadcast Services, assigned by BS, but actually, MBS seems
to be a broadcast service, not multicasting. MBS adheres to
broadcast services, while traditional IP multicast schemes define
multicast routing using a shared tree or source-specific tree to
deliver packets efficiently.

In IEEE 802.16 networks, two types of access to in MBS may it should be supported:
single-BS access done at an
AR and multi-BS access. Therefore, these two types of
services may be roughly mapped into Source-Specific Multicast. it's network scope. For MBS how this mapping will happen is
not clear, so MBS discussions have been postponed in WiMax for now.
Note that it should be intensively researched later, since MBS will
be one of the killer services in IEEE 802.16 networks.

2.4. IPv6 Mobility

As for mobility management, the movement between BSs is handled by
Mobile IPv6 [RFC3775], if it requires a subnet change. Also, in
certain cases (e.g., fast handover [I-D.ietf-mipshop-fast-mipv6]) the
link mobility information must be available for facilitating layer 3
handoff procedure.

Mobile IPv6 defines that movement detection uses Neighbor
Unreachability Detection

In order to detect when the default router is no
longer bi-directionally reachable, support multicast services in which case the mobile node IEEE 802.16, Multicast
Listener Discovery (MLD) [RFC2710] must
discover a new default router. Periodic Router Advertisements for
reachability and movement detection may be unnecessary because IEEE
802.16 MAC provides supported between the reachability by its Ranging procedure MS
and the
movement detection by the Handoff procedure, if a BS is integrated
with a AR.

In addition, IEEE 802.16e has facilities in determining whether Also, the
change of MS's inter-working with IP address is required during the handoff. Therefore,
Mobile IPv6 can get a hint from such low-layer facilities, multicast protocols and
conduct its Layer 3 mobility protocol only when it is needed. Though
a handoff has occurred, an additional router discovery procedure is
not required in case of intra-subnet handoff. Also, faster handoff
may
Multicast and Broadcast Service (MBS) should be occurred by the L2 trigger in case of inter-subnet handoff.

Mobile IPv6 Fast Handover assumes the support from link-layer
technology, considered.

MBS defines Multicast and Broadcast Services, but the particular link-layer information being
available, as well as the timing of its availability (before, during
or after actually, MBS seems
to be a broadcast service, not multicasting. MBS adheres to
broadcast services, while traditional IP multicast schemes define
multicast routing using a handover has occurred), differs according shared tree or source-specific tree to the
particular link-layer technology in use. IEEE 802.16g which is
under-developed defines L2 triggers for
deliver packets efficiently.

In IEEE 802.16 link status such
as link-up, link-down, handoff-start. These L2 triggers networks, two types of access to MBS may make
Mobile IPv6 procedure more efficient be supported:
single-BS access and faster.

This issue is also being discussed in [I-D.ietf-mipshop-fh80216e].

2.5. multi-BS access. Therefore, these two types of
services may be roughly mapped into Source-Specific Multicast.

2.4. IPv6 QoS

In IEEE 802.16 networks, a connection is unidirectional and has a QoS
specification. The QoS has different semantics with IP QoS (e.g.,
diffserv). Mapping CID to Service Flow IDentifier (SFID) defines QoS
parameters of the service flow associated with that connection. In
order to interwork with IP QoS, IP QoS (e.g., diffserv, or flow label
for IPv6) mapping to IEEE 802.16 link specifics should be provided.

2.6.

2.5. IPv6 Security

When initiating the connection, an MS is authenticated by the AAA
server located at its service provider network. All the parameters
related to authentication (username, password and etc.) are forwarded
by the BS to the AAA server. The AAA server authenticates MSs. If the MSs
and once authenticated. When an MS is once authenticated and
associated successfully with BS, an IPv6 address will be acquired by the MS.
MS with stateless autoconfiguration or DHCPv6. Note the initiation
and authentication process is the same as used in IPv4.

IPsec is a fundamental part of IPv6. Unlike IPv4, IPsec for IPv6 may
be used within the global end-to-end architecture. But, we don't
have PKIs across organizations and IPsec isn't integrated with IEEE
802.16 network mobility management.

IEEE 802.16 network threats may be different from IPv6 and IPv6
transition threat models [I-D.ietf-v6ops-security-overview]. It
should be also discussed.

2.7.

2.6. IPv6 Network Management

For IPv6 network management, the necessary instrumentation (such as
MIBs, NetFlow Records, etc) should be available.

Upon entering the network, an MS is assigned three management
connections in each direction. These three connections reflect the
three different QoS requirements used by different management levels.
The first of these is the basic connection, which is used for the
transfer of short, time-critical MAC management message messages and radio
link control (RLC) messages. The primary management connection is
used to transfer longer, more delay-tolerant messages such as those
used for authentication and connection setup. The secondary
management connection is used for the transfer of standards-based
management messages such as Dynamic Host Configuration Protocol
(DHCP), Trivial File Transfer Protocol (TFTP), and Simple Network
Management Protocol (SNMP).

IPv6 based IEEE 802.16 network can be managed by IPv4 or IPv6 when
network elements are implemented dual stak. For example, network
management system (NMS) can send SNMP message by IPv4 with IPv6
related object identifier. Also, an NMS can use IPv6 for SNMP
request and response including IPv4 related OID.

3. IANA Considerations

This document requests no action by IANA.

4. Security Considerations

Please refer to sec 2.6 Section 2.5 "IPv6 Security" technology sections for
details.

5. Acknowledgements

This work extends v6ops works on [I-D.ietf-v6ops-bb-deployment-
scenarios]. We thank all the authors of the document. Special
thanks are due to Maximilian Riegel, Jonne Soininen, Brian E
Carpenter, Jim Bound, and Jung-Mo Moon for extensive review of this
document.

6. References

6.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.

[RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC 2461,
December 1998.

[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.

[RFC2462] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.

[RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast
Listener Discovery (MLD) for IPv6", RFC 2710,
October 1999.

[RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
RFC 2740, December 1999.

6.2. Informative References

[RFC3316] Arkko, J., Kuijpers, G., Soliman, H., Loughney, J., and J.
Wiljakka, "Internet Protocol Version 6 (IPv6)

[RFC3314] Wasserman, M., "Recommendations for Some
Second and IPv6 in Third
Generation Cellular Hosts", Partnership Project (3GPP) Standards",
RFC 3316,
April 2003.

[I-D.ietf-mipshop-fast-mipv6]
Koodli, R., "Fast Handovers for Mobile 3314, September 2002.

[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6",
draft-ietf-mipshop-fast-mipv6-03 RFC 3775, June 2004.

[I-D.jee-16ng-problem-statement]
Jee, J., "16ng Problem Statement",
draft-jee-16ng-problem-statement-02 (work in progress),
October 2004.

[I-D.madanapalli-nd-over-802.16-problems] 2005.

[I-D.madanapalli-16ng-subnet-model-analysis]
Madanapalli, S., "IPv6 Neighbor Discovery over 802.16:
Problems and Goals",
draft-madanapalli-nd-over-802.16-problems-00 "Analysis of IPv6 Link Models for 802.16
based Networks",
draft-madanapalli-16ng-subnet-model-analysis-01 (work in
progress), September 2006.

[I-D.ietf-mipshop-fmipv6-rfc4068bis]
Koodli, R., "Fast Handovers for Mobile IPv6",
draft-ietf-mipshop-fmipv6-rfc4068bis-00 (work in
progress), December 2005.

[I-D.mandin-ip-over-80216-ethcs]
Mandin, J., "Transport of IP May 2006.

[I-D.ietf-mipshop-fh80216e]
Jang, H., "Mobile IPv6 Fast Handovers over 802.16",
draft-mandin-ip-over-80216-ethcs-00 IEEE 802.16e
Networks", draft-ietf-mipshop-fh80216e-00 (work in
progress),
October 2005. April 2006.

[I-D.ietf-v6ops-security-overview]
Davies, E., "IPv6 Transition/Co-existence Security
Considerations", draft-ietf-v6ops-security-overview-04 draft-ietf-v6ops-security-overview-05
(work in progress), March September 2006.

[I-D.ietf-v6ops-bb-deployment-scenarios]
Asadullah, S., "ISP IPv6 Deployment Scenarios in Broadband
Access Networks",
draft-ietf-v6ops-bb-deployment-scenarios-04
draft-ietf-v6ops-bb-deployment-scenarios-05 (work in
progress), October 2005.

[I-D.shin-16ng-ipv6-transmission]
Shin, M. and H. Jang, "Transmission of IPv6 Packets over
IEEE 802.16", draft-shin-16ng-ipv6-transmission-00 June 2006.

[I-D.iab-link-encaps]
Aboba, B., "Multiple Encapsulation Methods Considered
Harmful", draft-iab-link-encaps-02 (work in progress), February
August 2006.

[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 Std. for Local and metropolitan area networks Part
16: Air Interface for Fixed and Mobile Broadband Wireless
Access Systems Amendment 2: Physical and Medium Access
Control Layers for Combined Fixed and Mobile Operation in
Licensed Bands and Corrigendum 1", February 2006.

Authors' Addresses

Myung-Ki Shin
ETRI
161 Gajeong-dong Yuseng-gu
Daejeon, 305-350
Korea

Phone: +82 42 860 4847
Email: myungki.shin@gmail.com

Youn-Hee Han
KUT
Gajeon-Ri 307 Byeongcheon-Myeon
Cheonan-Si Chungnam Province, 330-708
Korea

Email: yhhan@kut.ac.kr

Sang-Eon Kim
KT
17 Woomyeon-dong, Seocho-gu
Seoul, 137-791
Korea

Email: sekim@kt.co.kr

Domagoj Premec
Siemens Mobile
Heinzelova 70a
10010 Zagreb
Croatia

Email: domagoj.premec@siemens.com

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