





Network Working Group                                S. Madanapalli, Ed.
Request for Comments: 4968                            Ordyn Technologies
Category: Informational                                      August 2007


      Analysis of IPv6 Link Models for IEEE 802.16 Based Networks

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document provides different IPv6 link models that are suitable
   for IEEE 802.16 based networks and provides analysis of various
   considerations for each link model and the applicability of each link
   model under different deployment scenarios.  This document is the
   result of a design team (DT) that was formed to analyze the IPv6 link
   models for IEEE 802.16 based networks.


























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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  IPv6 Link Models for IEEE 802.16 Based Networks  . . . . . . .  3
     3.1.  Shared IPv6 Prefix Link Model  . . . . . . . . . . . . . .  3
       3.1.1.  Prefix Assignment  . . . . . . . . . . . . . . . . . .  5
       3.1.2.  Address Autoconfiguration  . . . . . . . . . . . . . .  5
       3.1.3.  Duplicate Address Detection  . . . . . . . . . . . . .  5
       3.1.4.  Considerations . . . . . . . . . . . . . . . . . . . .  6
       3.1.5.  Applicability  . . . . . . . . . . . . . . . . . . . .  7
     3.2.  Point-to-Point Link Model  . . . . . . . . . . . . . . . .  7
       3.2.1.  Prefix Assignment  . . . . . . . . . . . . . . . . . .  8
       3.2.2.  Address Autoconfiguration  . . . . . . . . . . . . . .  8
       3.2.3.  Considerations . . . . . . . . . . . . . . . . . . . .  8
       3.2.4.  Applicability  . . . . . . . . . . . . . . . . . . . .  9
     3.3.  Ethernet-Like Link Model . . . . . . . . . . . . . . . . . 10
       3.3.1.  Prefix Assignment  . . . . . . . . . . . . . . . . . . 10
       3.3.2.  Address Autoconfiguration  . . . . . . . . . . . . . . 10
       3.3.3.  Duplicate Address Detection  . . . . . . . . . . . . . 10
       3.3.4.  Considerations . . . . . . . . . . . . . . . . . . . . 11
       3.3.5.  Applicability  . . . . . . . . . . . . . . . . . . . . 11
   4.  Renumbering  . . . . . . . . . . . . . . . . . . . . . . . . . 11
   5.  Effect on Dormant Mode . . . . . . . . . . . . . . . . . . . . 12
   6.  Effect on Routing  . . . . . . . . . . . . . . . . . . . . . . 12
   7.  Conclusions and Relevant Link Models . . . . . . . . . . . . . 13
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
   10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 14
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 14
     11.2. Informative References . . . . . . . . . . . . . . . . . . 14

1.  Introduction

   IEEE 802.16 [4] [5] is a point-to-multipoint, connection-oriented
   access technology for the last mile without bi-directional native
   multicast support.  IEEE 802.16 has defined only downlink multicast
   support.  This leads to two methods for running IP protocols that
   traditionally assume the availability of multicast at the link layer.
   One method is to use bridging, e.g., IEEE 802.1D [6], to support bi-
   directional multicast.  Another method is to treat the IEEE 802.16
   MAC (Message Authentication Code) transport connections between an MS
   (Mobile Station) and BS (Base Station) as point-to-point IP links so
   that the IP protocols (e.g., ARP (Address Resolution Protocol), IPv6
   Neighbor Discovery) can be run without any problems.





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   This is further complicated by the definition of commercial network
   models like WiMAX, which defines the WiMAX transport connection that
   extends the IEEE 802.16 MAC transport connection all the way to an
   access router by using a tunnel between the base station and the
   access router [14].  This leads to multiple ways of deploying IP over
   IEEE 802.16 based networks.

   This document looks at various considerations in selecting a link
   model for IEEE 802.16 based networks and provides an analysis of the
   various possible link models.  And finally, this document provides a
   recommendation for choosing one link model that is best suitable for
   the deployment.

2.  Terminology

   The terminology in this document is based on the definitions in [6],
   in addition to the ones specified in this section.

   Access Router (AR): An entity that performs an IP routing function to
   provide IP connectivity for Mobile Stations.  In WiMAX Networks, the
   AR is an Access Service Network Gateway.

   Access Service Network (ASN) - The ASN is defined as a complete set
   of network functions needed to provide radio access to a WiMAX
   subscriber.  The ASN is the access network to which the MS attaches.
   The IPv6 access router is an entity within the ASN.  The term ASN is
   specific to the WiMAX network architecture.

   Dormant Mode: A state in which a mobile station restricts its ability
   to receive normal IP traffic by reducing monitoring of radio
   channels.  This allows the mobile station to save power and reduces
   signaling load on the network.  In the dormant mode, the MS is only
   listening at scheduled intervals to the paging channel.  The network
   (e.g., the AR) maintains state about an MS that has transitioned to
   dormant mode and can page it when needed.

3.  IPv6 Link Models for IEEE 802.16 Based Networks

   This section discusses various IPv6 link models for IEEE 802.16 based
   networks and provides their operational considerations in practical
   deployment scenarios.

3.1.  Shared IPv6 Prefix Link Model

   In this model, all MSs attached to an AR share one or more prefixes
   for constructing their global IPv6 addresses, however this model does
   not provide any multicast capability.  The following figures
   illustrates a high-level view of this link model wherein one or more



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   prefixes advertised on the link would be used by all the MSs attached
   to the IPv6 link.

        +-----+
        | MS1 |-----+
        +-----+     |
                    |
                    |
        +-----+     |     +-----+          +--------+
        | MS2 |-----+-----| BS1 |----------|   AR   |-------Internet
        +-----+     |     +-----+          +--------+
           .        |           ____________
           .        |          ()__________()
        +-----+     |             L2 Tunnel
        | MSn |-----+
        +-----+

               Figure 1. Shared IPv6 Prefix Link Model

   The above figure shows the case where the BS and AR exist as separate
   entities.  In this case, a tunnel exists between the BS and AR per MS
   basis.

   In this link model, the link between the MS and the AR at the IPv6
   layer is viewed as a shared link, and the lower layer link between
   the MS and BS is a point-to-point link.  This point-to-point link
   between the MS and BS is extended all the way to the AR when the
   granularity of the tunnel between the BS and AR is on a per MS basis.
   This is illustrated in the following figure below.

          MS
        +----+                                     +----+
        |    |      IPv6 (Shared link)             |    |
        | L3 |=====================================|    |
        |    |                                     |    |
        |----|   PTP conn. +----+   L2 Tunnel      | AR |---Internet
        | L2 |-------------| BS |==================|    |
        |    |             |    |                  |    |
        +----+             +----+                  |    |
                                                   |    |
                           +----+   L2 Tunnel      |    |
                           | BS |==================|    |
                           |    |                  |    |
                           +----+                  +----+

         Figure 2. Shared IPv6 Prefix Link Model - Layered View





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   In this link model, an AR can serve one or more BSs.  All MSs
   connected to BSs that are served by an AR are on the same IPv6 link.
   This model is different from an Ethernet Like Link model wherein the
   later model provides an Ethernet link abstraction and multicast
   capability to the IPv6 layer, whereas the Shared IPv6 Prefix Link
   Model defined here does not provide native link-layer multicast and
   broadcast capabilities.

3.1.1.  Prefix Assignment

   One or more IPv6 prefixes are assigned to the link and hence shared
   by all the nodes that are attached to the link.  The prefixes are
   advertised with the autonomous flag (A-Flag) set and the On-link flag
   (L-flag) reset for address autoconfiguration so that the nodes may
   not make an on-link assumption for the addresses in those prefixes.

3.1.2.  Address Autoconfiguration

   The standard IPv6 address autoconfiguration mechanisms, which are
   specified in [2] [3], are used.

3.1.3.  Duplicate Address Detection

   The DAD procedure, as specified in [2], does not adapt well to the
   IEEE 802.16 air interface as there is no native multicast support.
   The DAD can be performed with MLD (Multicast Listener Discovery)
   snooping [7] and the AR relaying the DAD probe to the address owners
   in case the address is a duplicate, called Relay DAD.  In this
   method, the MS behavior is the same as specified in [2] and the
   optimization is achieved with the support of AR, which maintains the
   MLD table for a list of multicast addresses and the nodes that joined
   the multicast address.  The relay DAD works as below:

   1.  An MS constructs a Link Local Address as specified in [2].

   2.  The MS constructs a solicited node multicast address for the
       corresponding Link Local Address and sends an MLD Join request
       for the solicited node multicast address.

   3.  The MS starts verifying address uniqueness by sending a DAD NS on
       the initial MAC transport connection.

   4.  The AR consults the MLD table for who joined the multicast
       address.  If the AR does not find any entry in the MLD table, the
       AR silently discards the DAD NS.  If the AR finds a match, the AR
       relays the DAD NS to the address owner.





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   5.  The address owner defends the address by sending DAD NA, which is
       relayed to the DAD originating MS via the AR.

   6.  If the DAD originating MS does not receive any response (DAD NA)
       to its DAD NS, the MS assigns the address to its interface.  If
       the MS receives the DAD NA, the MS discards the tentative address
       and behaves as specified in [2].

3.1.4.  Considerations

3.1.4.1.  Reuse of Existing Specifications

   The shared IPv6 prefix model uses the existing specification and does
   not require any protocol changes or any new protocols.  However, this
   model requires implementation changes for DAD optimization on the AR.

3.1.4.2.  On-link Multicast Support

   No native on-link multicast is possible with this method.  However,
   the multicast can be supported with using a backend process in AR
   that maintains the multicast members list and forwards the multicast
   packets to the MSs belonging to a particular multicast group in a
   unicast manner.  MLD snooping [7] should be used for maintaining the
   multicast members list.

3.1.4.3.  Consistency in IP Link Definition

   The definition of an IPv6 link is consistent for all procedures and
   functionalities except for the support of native on-link multicast
   support.

3.1.4.4.  Packet Forwarding

   All the packets travel to the AR before being delivered to the final
   destination as the layer 2 transport connection exists between the MS
   and AR.  The AR normally handles the packets with external IPv6
   addresses.  However, the packets with link local destination
   addresses are relayed by the AR to the destination without
   decrementing the hop-limit.

3.1.4.5.  Changes to Host Implementation

   This link model does not require any implementation changes for the
   host implementation.







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3.1.4.6.  Changes to Router Implementation

   This link model requires MLD snooping in the AR for supporting Relay
   DAD.

3.1.5.  Applicability

   This model is good for providing shared on-link services in
   conjunction with the IP convergence sublayer with IPv6 classifiers.
   However, in public access networks like cellular networks, this model
   cannot be used for the end users to share any of their personal
   devices/services with the public.

   This link model was also under consideration of the WiMAX Forum
   Network Working Group for use with IPv6 CS (Convergence Sublayer)
   access.

3.2.  Point-to-Point Link Model

   In this model, a set of MAC transport connections between an MS and
   an AR are treated as a single link.  The point-to-point link model
   follows the recommendations of [8].  In this model, each link between
   an MS and an AR is allocated a separate, unique prefix or a set of
   unique prefixes by the AR.  No other node under the AR has the same
   prefixes on the link between it and the AR.  The following diagram
   illustrates this model.

                              +----+                   +----+
          +-----+             |    |      Tunnel       |    |
          | MS1 |-------------|....|===================|    |
          +-----+             |    |                   |    |
                              |    |                   |    |
          +-----+             |    |      Tunnel       |    |
          | MS2 |-------------|....|===================|    |---Internet
          +-----+             |    |                   | AR |
                              | BS |                   |    |
          +-----+             |    |      Tunnel       |    |
          | MS3 |-------------|....|===================|    |
          +-----+             |    |                   |    |
                              +----+                   +----+

                 Figure 3. Point-to-Point Link Model

   There are multiple possible ways that the point-to-point link between
   the AR and the MS can be implemented.






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   1.  One way to accomplish this is to run PPP on the link [8].
       Running PPP requires that the IEEE 802.16 link use the Ethernet
       CS and PPP over Ethernet [9].  Since the IPv6 CS does not support
       PPP, whether PPP can be run depends on the network architecture.

   2.  If the actual physical medium is shared, like Ethernet, but PPP
       is not run, the link can be made point to point between the MS
       and AR by having each MS on a separate VLAN [11].

   3.  If neither PPP nor VLAN is used, the set of IEEE 802.16
       connections can be viewed as a virtual point-to-point link.

3.2.1.  Prefix Assignment

   Prefixes are assigned to the link using the standard [1] Router
   Advertisement mechanism.  The AR assigns a unique prefix or a set of
   unique prefixes for each MS.  In the prefix information options, both
   the A-flag and L-flag are set to 1, as they can be used for address
   autoconfiguration and the prefixes are on the link.

3.2.2.  Address Autoconfiguration

   MSs perform link local as well as global address autoconfiguration
   exactly as specified in [2], including duplicate address detection.
   Because there is only one other node on the link, the AR, there is
   only a possibility of an address conflict with the AR, so collisions
   are statistically very unlikely, and easy to fix if they should
   occur.

   If DHCP is used for address configuration ('M=1' in the Router
   Advertisement), the DHCP server must provide addresses with a
   separate prefix per MS.  The prefix must of course match a prefix
   that the ASN Gateway has advertised to the MS (if any).

3.2.3.  Considerations

3.2.3.1.  Reuse of Existing Specifications

   This solution reuses RFC 2461, 2462, and, if PPP is used, RFC 2472
   and RFC 2516.  No changes in these protocols are required; the
   protocols must only be configured properly.

   If PPP is not used, any VLAN solution, such as IEEE 802.1Q [9] or any
   L2 tunnel, can be used.







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3.2.3.2.  On-link Multicast Support

   Since the link between the MS and the AR is point to point, any
   multicast can only be sent by one or the other node.  Link local
   multicast between other nodes and the AR will not be seen.

3.2.3.3.  Consistency in IP Link Definition

   The IP link is fully consistent with a standard IP point-to-point
   link, without exception.

3.2.3.4.  Packet Forwarding

   The MS always sends all packets to the AR because it is the only
   other node on the link.  Link local unicast and multicast packets are
   also forwarded only between the two.

3.2.3.5.  Changes to Host Implementation

   Host implementations follow standard IPv6 stack procedures.  No
   changes are needed.

3.2.3.6.  Changes to Router Implementation

   If PPP is used, no changes in router implementations are needed.  If
   PPP is not used, the AR must be capable of doing the following:

   1.  Each MS is assigned a separate VLAN when IEEE 802.1X [12] or each
       MS must have an L2 tunnel to the AR to aggregate all the
       connections to the MS and present these set of connections as an
       interface to the IPv6 layer.

   2.  The AR must be configured to include a unique prefix or a set of
       prefixes for each MS.  This unique prefix or set of prefixes must
       be included in Router Advertisements every time they are sent,
       and if DHCP is used, the addresses leased to the MS must include
       only the uniquely advertised prefixes.

   Note that, depending on the router implementation, these functions
   may or may not be possible with simple configuration.  No protocol
   changes are required, however.

3.2.4.  Applicability

   In enterprise networks, shared services including printers, fax
   machines, and other such online services are often available on the
   local link.  These services are typically discovered using some kind
   of link local service discovery protocol.  The unique prefix per MS



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   model is not appropriate for these kinds of deployments, since it is
   not possible to have shared link services in the ASN.

   The p2p link model is applicable to deployments where there are no
   shared services in the ASN.  Such deployments are typical of service
   provider networks like cellular networks, which provide public access
   to wireless networks.

3.3.  Ethernet-Like Link Model

   This model describes a scheme for configuration and provisioning of
   an IEEE 802.16 network so that it emulates a broadcast link in a
   manner similar to Ethernet.  Figure 4 illustrates an example of the
   Ethernet model.  This model essentially functions like an Ethernet
   link, which means the model works as described in [1], [2].

   One way to construct an Ethernet-like link is to implement bridging
   [13] between BSs and an AR, like a switched Ethernet.  In Figure 4,
   bridging performs link aggregation between BSs and an AR.  Bridging
   also supports multicast packet filtering.

              +-----+                 +---+       +----+
              | MS1 |---+             |   |   +---|AR1 |---Internet
              +-----+   |             |  S|   |   +----+
              +-----+   |   +-----+   |E w|   |
              | MS2 |---+---| BS1 |---|t i|   |
              +-----+       +-----+   |h t|---+
                                      |  c|   |   +----+
     +-----+  +-----+       +-----+   |  h|   +---|AR2 |---Internet
     |Hosts|--|MS/GW|-------| BS2 |---|   |       +----+
     +-----+  +-----+       +-----+   +---+
     A network
     may exist behind
     MS/GW

                  Figure 4: Ethernet Like Link Model

3.3.1.  Prefix Assignment

   Prefixes are assigned as specified in [1], [2].

3.3.2.  Address Autoconfiguration

   It is the same as described in [2].

3.3.3.  Duplicate Address Detection

   It is the same as described in [2].



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3.3.4.  Considerations

3.3.4.1.  Reuse of Existing Specifications

   All the IPv6 standards can be preserved or reused in this model.

3.3.4.2.  On-link Multicast Support

   On-link multicast can be emulated in a unicast manner by efficiently
   bridging between all BSs with IEEE 802.16 providing the links between
   the MSs and the bridge on top of the BS.  MLD snooping should be used
   for efficient forwarding of multicast packets as specified in [7].
   Nevertheless, in case of bridging, direct inter-MSs communication may
   not be not allowed due to restrictions from the service providers.

3.3.4.3.  Consistency in IP Link Definition

   This model is consistent with the IP link definition.

3.3.4.4.  Packet Forwarding

   When properly configured and assisted by simple bridging, IEEE 802.16
   can emulate a simple broadcast network like Ethernet.

3.3.4.5.  Changes to Host Implementation

   No special impact on host implementation.

3.3.4.6.  Changes to Router Implementation

   No special impact on router implementation under a separated AR-BS
   model, if the bridging is implemented in BS.  Some networks, e.g.,
   WiMAX networks, may require bridging to be implemented in the AR (ASN
   Gateway).

3.3.5.  Applicability

   This model works with the Ethernet CS and is chosen for fixed/nomadic
   WiMAX networks by the WiMAX Forum Network Working Group.

4.  Renumbering

   If the downstream prefixes managed by the AR are involved in
   renumbering, it may be necessary to renumber each link under the AR.
   [10] discusses recommended procedures for renumbering.

   If the prefixes are advertised in RAs, the AR must withdraw the
   existing prefixes and advertise the new ones.  Since each MS,



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   irrespective of the link model, is on a separate point-to-point link
   at the MAC level because of the IEEE 802.16 connection oriented
   architecture, the AR must send an RA withdrawing the old prefix and
   advertising the new one to each link.  In a point-to-point link
   model, the number of RAs sent is equal to the number of nodes the AR
   serves, whereas in the other two models, the AR sends a single RA to
   BS that is sent to all the MSs as separate RAs.

   If DHCP is used to assign addresses, either the DHCP address lease
   lifetime may be reduced prior to the renumbering event to encourage
   MSs to renew their addresses quickly, or a DHCP Reconfigure message
   may be sent to each of the MSs by the server to cause them to renew
   their addresses.

   In conclusion, the amount of traffic on the air-interface is the same
   for all link models.  However, the number of RAs sent by the AR to BS
   can be better compared to the other two models.

5.  Effect on Dormant Mode

   If the network needs to deliver packets to an MS, which is in dormant
   mode, the AR pages the MS.  The MS that is monitoring the paging
   channel receives the page and transitions out of the dormant mode to
   active mode.  It establishes connectivity with the network by
   requesting and obtaining the radio resources.  The network is then
   able to deliver the packets to the MS.  In many networks, packets
   destined to an MS in dormant mode are buffered at the AR in the
   network until connectivity is established.

   Support for dormant MSs is critical in mobile networks, hence it is a
   necessary feature.  Paging capability and optimizations possible for
   paging an MS are neither enhanced nor handicapped by the link model
   itself.  However, the multicast capability within a link may cause
   for an MS to wake up for an unwanted packet.  This can be avoided by
   filtering the multicast packets and delivering the packets to only
   for MSs that are listening for particular multicast packets.  As the
   Shared IPv6 Prefix model does not have the multicast capability and
   the point-to-point link model has only one node on the link, neither
   has any effect on the dormant mode.  The Ethernet-like link model may
   have the multicast capability, which requires filtering at the BS to
   support the dormant mode for the MSs.

6.  Effect on Routing

   The model used in an IEEE 802.16 network may have a significant
   impact on how routing protocols are run over such a network.  The
   deployment model presented in this document discusses the least
   impacting model on routing as connectivity on the provider edge is



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   intentionally limited to point-to-point connectivity from one BS to
   any one of multiple MSs.  Any other deployment model may cause a
   significant impact on routing protocols, however, they are outside
   the scope of this document.

7.  Conclusions and Relevant Link Models

   Ethernet-Like Link models would be used when the deployment requires
   the use of Ethernet CS, as this is the only model being proposed for
   the Ethernet CS and running IPv6 over Ethernet is well understood.

   For IP CS with IPv6 classifiers, a point-to-point link model appears
   to be the choice because of its simplicity for performing the DAD and
   because it does not break any existing applications nor requires
   defining any new protocol.  However, the IPv6 shared prefix model
   would be defined if there is any interest from the service provider
   community.

8.  Security Considerations

   This document provides the analysis of various IPv6 link models for
   IEEE 802.16 based networks, and as such does not introduce any new
   security threats.  No matter what the link model is, the networks
   employ the same link-layer security mechanisms defined in [5].
   However, the chosen link model affects the scope of link local
   communication, and this may have security implications for protocols
   that are designed to work within the link scope.  This is the concern
   for a shared link model compared with other models wherein private
   resources e.g., personal printer, cannot be put onto a public WiMAX
   network.  This may restrict the usage of a shared prefix model to
   enterprise environments.  The Neighbor Discovery related security
   issues are document in [1] [2] and these are applicable for all the
   models described in this document.  The model specific security
   considerations are documented in their respective protocol
   specifications.

9.  Acknowledgements

   This document is a result of discussions in the v6subnet design team
   for IPv6 Prefix Model Analysis.  The members of this design team are
   (in alphabetical order): Dave Thaler, David Johnston, Junghoon Jee,
   Max Riegel, Myungki Shin and Syam Madanapalli.  The discussion in the
   DT was benefited from the active participation of James Kempf, Behcet
   Sarikaya, Basavaraj Patil and JinHyeock Choi in the DT mailing list.
   The DT thanks the chairs (Gabriel Montenegro and Soohong Daniel Park)
   and Shepherding AD (Jari Arkko) for their active participation and
   motivation.




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10.  Contributors

   The members who provided the text based on the DT discussion are:

   Myung-Ki Shin
   ETRI
   EMail: myungki.shin@gmail.com

   James Kempf
   DoCoMo Communications Labs USA
   EMail: kempf@docomolabs-usa.com

   Soohong Daniel Park
   Samsung Electronics
   EMail: soohong.park@samsung.com

   Dave Thaler
   Microsoft
   EMail: dthaler@microsoft.com

   JinHyeock Choi
   Samsung Advanced Institute of Technology
   EMail: jinchoe@samsung.com

   Behcet Sarikaya
   Huawei USA
   EMail: sarikaya@ieee.org


11.  References

11.1.  Normative References

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

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

   [3]   Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M.
         Carney, "Dynamic Host Configuration Protocol for IPv6
         (DHCPv6)", RFC 3315, July 2003.

11.2.  Informative References

   [4]   "IEEE 802.16-2004, IEEE standard for Local and metropolitan
         area networks, Part 16:Air Interface for fixed broadband
         wireless access systems", October 2004.



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RFC 4968            IPv6 Link Models for IEEE 802.16         August 2007


   [5]   "IEEE 802.16e, IEEE standard for Local and metropolitan area
         networks, Part 16:Air Interface for fixed and Mobile broadband
         wireless access systems", October 2005.

   [6]   Jee, J., "IP over IEEE 802.16 Problem Statement and Goals",
         Work in Progress, October 2006.

   [7]   Christensen, M., Kimball, K., and F. Solensky, "Considerations
         for Internet Group Management Protocol (IGMP) and Multicast
         Listener Discovery (MLD) Snooping Switches", RFC 4541,
         May 2006.

   [8]   Wasserman, M., "Recommendations for IPv6 in Third Generation
         Partnership Project (3GPP) Standards", RFC 3314,
         September 2002.

   [9]   Mamakos, L., Lidl, K., Evarts, J., Carrel, D., Simone, D., and
         R. Wheeler, "A Method for Transmitting PPP Over Ethernet
         (PPPoE)", RFC 2516, February 1999.

   [10]  Baker, F., Lear, E., and R. Droms, "Procedures for Renumbering
         an IPv6 Network without a Flag Day", RFC 4192, September 2005.

   [11]  "IEEE, Virtual Bridged Local Area Networks, IEEE 802.1Q",
         May 2003.

   [12]  "IEEE, Port-based Network Access Control, IEEE 802.1X",
         December 2004.

   [13]  "IEEE Std 802.1D-2004, "IEEE Standard for Local and
         metropolitan area networks, Media Access Control (MAC)
         Bridges"", June 2004.

   [14]  "WiMAX End-to-End Network Systems Architecture", March 2007,
         <http://www.wimaxforum.org/technology/documents>.

Author's Address

   Syam Madanapalli (editor)
   Ordyn Technologies
   1st Floor, Creator Building, ITPL
   Bangalore - 560066
   India

   EMail: smadanapalli@gmail.com






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