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Versions: (draft-shin-v6ops-802-16-deployment-scenarios) 00 01 02 03 04 05 06 07 RFC 5181

Network Working Group                                          M-K. Shin
Internet-Draft                                                      ETRI
Expires: November 25, 2006                                      Y-H. Han
                                                                     KUT
                                                            May 24, 2006


  ISP IPv6 Deployment Scenarios in Wireless Broadband Access Networks
            draft-ietf-v6ops-802-16-deployment-scenarios-00

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
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   This Internet-Draft will expire on November 25, 2006.

Copyright Notice

   Copyright (C) The Internet Society (2006).

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.



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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 . . . . . . . . . . . . . . . . . . . . . .  7
       2.2.2.  Scenario B . . . . . . . . . . . . . . . . . . . . . .  9
       2.2.3.  Scenario C . . . . . . . . . . . . . . . . . . . . . . 10
       2.2.4.  Scenario D . . . . . . . . . . . . . . . . . . . . . . 12
     2.3.  IPv6 Multicast . . . . . . . . . . . . . . . . . . . . . . 13
     2.4.  IPv6 Mobility  . . . . . . . . . . . . . . . . . . . . . . 14
     2.5.  IPv6 QoS . . . . . . . . . . . . . . . . . . . . . . . . . 14
     2.6.  IPv6 Security  . . . . . . . . . . . . . . . . . . . . . . 15
     2.7.  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



























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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] addresses
   fixed wireless applications only, the IEEE 802.16(e) standard
   [IEEE802.16e] aims to serve 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 services.
   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.












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2.  Wireless Broadband Access Network Technologies - IEEE 802.16

   This section describes the infrastructure that exists today in IEEE
   802.16 networks providing wireless broadband services to the
   customer.  It also describes IPv6 deployment options in these 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 the more people use it the more its
   limitations like short range or lack of mobility support were
   revealed.  Compared with such IEEE 802.11 network, IEEE 802.16
   supports enhanced features like wider range 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 IEEE 802.16 networks

   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).

   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 identified by a connection identifier (CID) and all
   traffic is carried on a 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 IEEE 802.16 networks.














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

       +-----+            +-----+     +------+   +--------+
       | MSs |--(802.16)--| BS  |-----+Access+---+ Edge   |    ISP
       +-----+            +-----+     |Router|   | Router +==>Network
                                      +--+---+   +--------+
       +-----+            +-----+        |            |  +------+
       | 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 two modes such as 2-way PMP (Point-to-
   Multipoint) and Mesh topology wireless networks.  In this document,
   we focus on 2-way PMP topology wireless networks.

   There are two different deployment options in current IEEE 802.16
   networks: Cellular-like and Hot-zone deployment scenarios.  IPv6 can
   be deployed in both of these deployment models.

   A. Cellular-like Deployment Model

   IEEE 802.16 BS can offer both fixed communications and mobile
   functions unlike IEEE 802.11.  In particular, IEEE 802.16e working
   group standardized such mobility features and the specification of
   IEEE 802.16e provides some competition to the existing cellular
   systems.  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
   will not survive and some of them might be compromised to efficiently
   serve IPv6 to this 'Cellular-like' use case.

   Under the use case, however, IEEE 802.16 standards are still IP-
   centric, providing packet-switched approach, while cellular standards
   like GSM have a more circuit-switched approach.

   B. Hot Zone Deployment Model

   The success of a Hotspot service with IEEE 802.11 has been prominent.
   The new IEEE 802.16 standards basically support such Hotspot services
   with large coverage area and high data rate.  An area served 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.




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   Many wireless Internet service providers (Wireless ISPs) have planned
   to use IEEE 802.16 for the purpose of high quality service.  A
   company can use 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 of this use case is that it can use
   unlicensed (2.4 & 5 GHz) band as well as licensed (2.6 & 3.5GHz)
   band.  By using the unlicensed band, a 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.




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   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 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.  The specification of IEEE 802.16
   defines several CSs for carrying IP packets, but does not 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.

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

2.2.1.  Scenario A

   Scenario A represents IEEE 802.16 access network deployment where a
   BS is separated from a router, and a subnet consists of only single
   router and multiple BSs and MSs.  Current celluar-like deployment
   models, WiMax and WiBro, fall within this scenario A.

       +-----+
       | MS1 |<------+
       +-----+       |
       +-----+       |    +-----+     +-----+    +--------+
       | MSs |<------+----| BS1 |---->| AR  |----| Edge   |    ISP
       +-----+            +-----+     +-----+    | Router +==>Network
                                         ^       +--------+
       +-----+            +-----+        |
       | Mss |<-----------| BS2 |--------+
       +-----+            +-----+
                                      <---> IP termination

   Figure 2: Scenario A

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), AR and Edge Router.  In
   this scenario the BS is Layer 3 unaware, so no changes are needed 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.






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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.

   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.  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.  All MSs attached
   to same AR can be on same IPv6 link.

2.2.1.3.  IPv6 Control and Data 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 on the same link.

   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 IPv6 basic protocols such as ND
   using multicast functions, or provide some schemes to facilitate the
   stateless auto-configuration.  Especially, IEEE 802.16 connection
   terminates at BS, not a router.  So, BS should look at the
   classifiers and decide where to send the packet.  In addition, one BS
   can send the packet to other BSs, since multiple BSs are on the same
   link.

   The operation and transmission methods are being intensively
   discussed in other documents [I-D.shin-16ng-ipv6-transmission].  Note
   that in this scenario Ethernet CS as well as IPv6 CS may be used to
   transport IPv6 packets.

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

   The service providers are deploying tunneling mechanisms to transport



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   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 scenario the BS is Layer 3 unaware, so no changes are needed 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.




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2.2.2.2.  Addressing

   In this scenario, multiple BSs and MSs form an IPv6 subnet and
   multiple prefixes are allocated to all the attached MS.  All MSs
   attached to different BSs under the same AR, can be on same IPv6
   link.

2.2.2.3.  IPv6 Control and Data Transport

   In a subnet, like scenario A, 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 on
   the same link.

   If stateless auto-configuration is used to get an IPv6 address,
   considerations on 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 in this scenario Ethernet CS 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, the service providers are deploying IPv6-in-IPv4
   tunneling mechanisms to transport IPv6 packets between an AR and an
   Edge router.

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 SP 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.

2.2.3.  Scenario C

   Scenario C represents IEEE 802.16 access network deployment where a
   BS is integrated with a router, composing one box in view of
   implementation, and a subnet consists of only single BS/router and
   multiple MSs.





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       +-----+
       | 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

   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 to all the attached
   MS.  All MSs attached to same BS 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
   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.

   The operation and transmission methods are being intensively
   discussed in other documents [I-D.shin-16ng-ipv6-transmission].  Note
   that in this scenario Ethernet CS as well as IPv6 CS may be used to
   transport IPv6 packets.

2.2.3.4.  Routing

   In general, BS/Router 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 SP 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.





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2.2.4.  Scenario D

   Scenario D 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 and single MS.  This scenario mimics the current 3GPP-like
   IPv6 deployment model.

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

   Figure 5: Scenario D

2.2.4.1.  IPv6 Related Infrastructure Changes

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

2.2.4.2.  Addressing

   In this case, if stateless auto-configuration is used, 3GPP-like IPv6
   addressing scheme [RFC 3314] can be used.  That is, a unique prefix
   can be allocated to each MS.  [RFC 3314] recommends that a given
   prefix should be assigned to only one primary PDP context so that
   3GPP terminals are allowed to generate multiple IPv6 address using
   the prefix without the concerns 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 BS is integrated with a router.  In addition,
   each MS can be on different IPv6 link.  So, many IPv6 protocols can
   be operated without much consideration about the underlying network
   implementation.

   Only IEEE 802.16 link will be taken into consideration for IPv6
   adoption.  For example, DAD operation is not needed 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-



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   16ng-ipv6-transmission].

   Note that in this scenario IPv6 CS type may be more suitable to
   transport IPv6 packets rather than Ethernet CS type since broadcast-
   like functions are not required.

2.2.4.4.  Routing

   In general, the access router 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 service provider 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.

2.3.  IPv6 Multicast

   In order to support multicast services in IEEE 802.16, Multicast
   Listener Discovery (MLD) [RFC2710] must be supported between the MS
   and BS/Router.  Also, the inter-working with IP multicast protocols
   and Multicast and Broadcast Service (MBS) should be considered.

   Within IEEE 802.16 networks, an MS connects to its BS/router via
   point-to-point links.  MLD allows an MS to send link-local multicast
   destination queries and reports.  The packets are transmitted as
   normal IEEE 802.16 MAC frames, as the same as regular unicast
   packets.  Especially, multicast CIDs can 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 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 is not
   link-local.

   MBS defines Multicast and Broadcast Services, 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 MBS may be supported:
   single-BS access and multi-BS access.  Therefore, these two types of
   services may be roughly mapped into Source-Specific Multicast.




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   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 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, if a BS is integrated
   with a AR.

   In addition, IEEE 802.16e has facilities in determining whether the
   change of MS's IP address is required during the handoff.  Therefore,
   Mobile IPv6 can get a hint from such low-layer facilities, 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 be occurred by the L2 trigger in case of inter-subnet handoff.

   Mobile IPv6 Fast Handover assumes the support from link-layer
   technology, but the particular link-layer information being
   available, as well as the timing of its availability (before, during
   or after a handover has occurred), differs according to the
   particular link-layer technology in use.  IEEE 802.16g which is
   under-developed defines L2 triggers for IEEE 802.16 link status such
   as link-up, link-down, handoff-start.  These L2 triggers may make
   Mobile IPv6 procedure more efficient and faster.

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

2.5.  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.




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2.6.  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
   an MS is once authenticated and associated successfully with BS, an
   IPv6 address will be acquired by the MS.  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.  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 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).















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3.  IANA Considerations

   This document requests no action by IANA.
















































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4.  Security Considerations

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















































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5.   Acknowledgements

   This work extends v6ops works on [I-D.ietf-v6ops-bb-deployment-
   scenarios].  We thank all the authors of the document.















































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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.

6.2.  Informative References

   [RFC3316]  Arkko, J., Kuijpers, G., Soliman, H., Loughney, J., and J.
              Wiljakka, "Internet Protocol Version 6 (IPv6) for Some
              Second and Third Generation Cellular Hosts", RFC 3316,
              April 2003.

   [I-D.ietf-mipshop-fast-mipv6]
              Koodli, R., "Fast Handovers for Mobile IPv6",
              draft-ietf-mipshop-fast-mipv6-03 (work in progress),
              October 2004.

   [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.mandin-ip-over-80216-ethcs]
              Mandin, J., "Transport of IP over 802.16",
              draft-mandin-ip-over-80216-ethcs-00 (work in progress),
              October 2005.

   [I-D.ietf-v6ops-security-overview]



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              Davies, E., "IPv6 Transition/Co-existence Security
              Considerations", draft-ietf-v6ops-security-overview-04
              (work in progress), March 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 (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 (work
              in progress), February 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.

























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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
































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