One document matched: draft-lee-ndp-ieee802.16-01.txt

Differences from draft-lee-ndp-ieee802.16-00.txt





Network Working Group                                           J-C. Lee
Internet-Draft                                                      ETRI
Expires: August 5, 2006                                   S. Madanapalli
                                                             Samsung ISO
                                                               H-J. Jang
                                                             Samsung AIT
                                                           February 2006


                     NDP over IEEE 802.16 Networks
                      draft-lee-ndp-ieee802.16-01

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
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   http://www.ietf.org/ietf/1id-abstracts.txt.

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   This Internet-Draft will expire on August 5, 2006.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   IEEE 802.16 issued the new standards for PHY and MAC providing
   broadband wireless access network.  Currently, it is being developed
   under the assumption that IPv4 is used over it and the use of IPv6
   over IEEE 802.16 networks has not been considered yet.  Hence, this
   draft describes several problems in running NDP over IEEE 802.16



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   networks and presents some proposed solutions for those problems.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
     1.2.  Specification of Requirements  . . . . . . . . . . . . . .  4
   2.  Problem Statements . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Issues Regarding IEEE 802.16 Architecture  . . . . . . . .  5
       2.1.1.  IEEE 802.16 Network Aspect Issues  . . . . . . . . . .  5
       2.1.2.  IEEE 802.16 Node Aspect Issues . . . . . . . . . . . .  7
     2.2.  Issues Regarding NDP . . . . . . . . . . . . . . . . . . .  8
       2.2.1.  Address Autoconfiguration  . . . . . . . . . . . . . .  8
       2.2.2.  Address Resolution . . . . . . . . . . . . . . . . . .  9
       2.2.3.  Conceptual Sending Algorithm . . . . . . . . . . . . .  9
   3.  Solutions  . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     3.1.  Multicast Support  . . . . . . . . . . . . . . . . . . . . 11
     3.2.  Solution CASE 1  . . . . . . . . . . . . . . . . . . . . . 12
     3.3.  Solution CASE 2  . . . . . . . . . . . . . . . . . . . . . 13
     3.4.  Solution CASE 3  . . . . . . . . . . . . . . . . . . . . . 14
     3.5.  Solution CASE 4  . . . . . . . . . . . . . . . . . . . . . 15
   4.  Secuirty Considerations  . . . . . . . . . . . . . . . . . . . 17
   5.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     5.1.  Normative References . . . . . . . . . . . . . . . . . . . 18
     5.2.  Informative References . . . . . . . . . . . . . . . . . . 18
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
   Intellectual Property and Copyright Statements . . . . . . . . . . 21























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1.  Introduction

   The IEEE 802.16 specifies a new PHY and MAC for providing broadband
   wireless access networks.  This protocol is a connection-oriented
   technology without bi-directional native multicast support that
   Ethernet can provide.  Since IPv6 operation is based on multicast
   such as router advertisement, this characteristic can be a major
   reason to prevent IPv6 from being deployed over IEEE 802.16 networks
   immediately.  To deploy IPv6 over IEEE 802.16 networks, we also have
   to consider different kinds of convergence sublayers and subnet
   models

   To deploy IPv6 over IEEE 802.16 networks, we also have to consider
   convergence sublayers and several subnet models.  These factors make
   problems more complicated.  We will describe these problems in more
   detail later.

   There are several feasible deployment scenarios [I-D.shin-ipv6-
   ieee802.16] that we have to consider when we introduce IEEE 802.16
   networks.  These deployment scenarios may have close relation with
   problems, thus we will describe proposed solution for these problems
   according to the each scenario.

   This problems and solution described in this document may also be an
   input to other standard organization like WiMax.

1.1.  Terminology

   SS:

      Subscriber Station.  A general equipment set providing
      connectivity between subscriber equipment and a BS.

   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) unless
      specifically excepted otherwise in this document.

   BS:

      Base Station.  A generalized equipment set providing connectivity,
      management and control of MS connection.  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).  All traffic is
      carried on a connection.



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   CID:

      Connection IDentifier.  A 16-bit value that identifies a
      connection to equivalent peers in the MAC of the BS and the MS.
      It maps to a service flow identifier (SFID), which also defines
      QoS parameters of the service flow associated with that
      connection.

   CS:

      Convergence Sublayer.  CS provides any transformation or mapping
      of external network data, received through the CS service access
      point (SAP), into MAC SDUs received by the MAC Common Part
      Sublayer (CPS) through the MAC SAP.

   PDU:

      Protocol Data Unit.  The data unit exchanged between peer entities
      of the same protocol layer.  On the downward direction, it is the
      data unit generated for the next lower layer.  On the upward
      direction, it is the data unit received from the previous lower
      layer.

   MBS:

      Multicast and Broadcast Service.  Some globally defined service
      flows which may carry broadcast or multicast information that
      should be delivered to a plurality of SS or MS.

   and all other terminologies defined in [RFC2461]

1.2.  Specification of Requirements

   In this document, several words are used to signify the requirements
   of the specification.  These words are often capitalized.  The key
   words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
   "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document
   are to be interpreted as described in [RFC2119].













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2.  Problem Statements

   The problems can be classified into two categories like "issues
   regarding IEEE 802.16 architecture" and "issues regarding NDP".

2.1.  Issues Regarding IEEE 802.16 Architecture

   MS, BS, AR comprise IEEE 802.16 networks.  When we establish IPv6
   networks over IEEE 802.16 technology, we can assume several
   architectural variations.  NDP considerations for IEEE 802.16
   networks may be affected by these variations.

2.1.1.  IEEE 802.16 Network Aspect Issues

   IEEE 802.16 connection always ends at BS, which is connected to AR.
   In this situation, we can make BS integrated with AR or separated
   from AR, and make the sebnet comprised of one BS & MSs or several BSs
   & MSs.

2.1.1.1.  Subnet Models

   1.  A Prefix per each MS: [RFC3314] 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.  This
       recommendation can be also applied to IEEE 802.16 network system
       if it is reasonable to the given usage scenario.  In such case,
       many IPv6 functionalities can be implemented without difficulty.

   2.  A Prefix for all MSs attached to BS(s) : Different usage scenario
       such as 'Hot zone' [I-D.shin-v6ops-deployment-scenarios] would
       not allow [RFC3314] recommendation because of the compatibility
       with the existing IPv6 devices.  In this case, there will be more
       issues for adopting IPv6 to IEEE 802.16.

2.1.1.2.  BS Architecture

   1.  BS and AR are in one box: This case represents an alternative
       IEEE 802.16 network deployment where a BS is integrated with a
       AR.  A subnet may consist of a router and a BS.  In this case,
       both of <subnet model>.1 and <subnet model>.2 are possible.










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                   /------------------\
                  |  Backbend Network  |
                   \------------------/
                       /          \
                      /            \
                     /              \
                ---------        ---------
               | Router1 |      | Router2 |
               | BS1     |      | BS2     |
                ---------        ---------

       Figure 3.  BS and AR are in one box

   2.  BS is separated from AR: In this case, IEEE 802.16 BSs have only
       MAC and PHY layers without router function.  A router and several
       BSs form an IPv6 subnet.  BSs may not have IPv6 stack, but for
       management and configuration purpose IPv6 stack will be loaded to
       them.  With this BS architecture, <subnet model>.1 can't be
       applied to IPv6 over IEEE 802.16 networks and if ethernet CS is
       used a L2 tunnel should be used between BS and AR.

           /-------------------------------------\
          |           Backbend Network            |
           \-------------------------------------/
                 |                         |
           /-----------\             /-----------\
          |   Router1   |           |   Router2   |
           \-----------/             \-----------/
           /  /  |  \  \             /  /  |  \  \
          /  /   |   \  \           /  /   |   \  \
         /   |   |   |   \         /   |   |   |   \
       BS1 BS2  BS3  BS4 BS5     BS6 BS7  BS8  BS9 BS10

       Figure 4.  BS is separated from AR

2.1.1.3.  Multicast Support

   IEEE 802.16 is a point-to-multipoint connection oriented technology
   without bi-directional native multicast support.  This prevents IPv6
   nodes from multicasting like [RFC2464] without any explicit support
   on network side.  Most of NDP functions depend on the multicast
   support from the lower layer.  So for NDP to function normally on
   IEEE 802.16 networks, there must be some explicit support for
   multicasting from network side.  More detailed solution for multicast
   support will be dealt in Section 3.1.

   The consequence of the lack of optimal multicast supports in IEEE
   802.16 networks is that any IP layer protocol like NDP, DHCPv6, IPv4



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   ARP depending on the lower layer multicast support may not function
   normally.

2.1.2.  IEEE 802.16 Node Aspect Issues

   IEEE 802.16 MAC includes service-specific Convergence Sublayers (CS)
   that interface to higer layers.  Some NDP operations may have
   dependency on the CS that IEEE 802.16 node adopts.

2.1.2.1.  Convergence Sublayer

   Currently, IEEE 802.16 provides two CS: the asynchronous transfer
   mode (ATM) CS and the packet CS.  The ATM CS is used for ATM
   services, the packet CS is used for transport for all packet-based
   protocols such as IP, PPP, and ethernet.  The primary job of CS is to
   perform classification of higher-layer PDUs [IEEE802.16].

   In this document, only the packet CS would be considered.  The packet
   CS includes ethernet CS and IP CS.

   IPv6 CS

      In case of IPv6 CS, its classification parameters are IPv6 header
      and transport header.  If MS adopts IPv6 CS, some kind of tunnel
      between BS and AR may be needed to transfer IPv6 packets from MS
      to AR in case that BS is separated from AR.  Address resolution
      process is trivial in case of IPv6 CS, because there is no need to
      make ethernet header.

   Ethernet CS

      When ethernet CS is used, the following parameters are used for
      classification: destination MAC address, source MAC address,
      ethertype.  For IP over IEEE 802.3/ethernet, IP headers may be
      included in classification.

      In case of ethernet CS, IP packet from MS can be delivered to AR
      without any help of tunnel even though BS is separated from AR.
      IEEE 802.16 MAC header doesn't include 48bits MAC address, but
      address resolution process may be needed if MS adopts ethernet CS.
      The more details about this would be described in solution
      section.

      For clarification, the support of ethernet CS doesn't mean IEEE
      802.3/ethernet emulation. multicast/broadcast frame can not be
      processed at the IEEE 802.16 MAC layer.





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2.1.2.2.  Transport Connection for NDP Message Transmission

   At MS initialization, two pairs of management connections (uplink/
   downlink) shall be established between the MS and the BS and the
   third pair of management connections may be optionally generated.

   The basic connection is used to exchange short, time-urgent MAC
   management messages.  The primary management connection is used to
   exchange longer, more delay-tolerant MAC management messages.
   Finally, the secondary management connection is used to transfer
   delay tolerant, standards-based messages like DHCP, TFTP, SNMP etc.

   But it is unclear that the secondary management connection can be
   used to transfer NDP messages.  Thus, MS and BS are required to set
   up transport connections for transfering NDP messages.

2.2.  Issues Regarding NDP

   Basically, the lack of native multicast support in IEEE 802.16
   networks makes it harder for NDP to function normally and some
   architectural characteristics of IEEE 802.16 networks may affect the
   detailed operations of NDP.

2.2.1.  Address Autoconfiguration

   Global/site-local address

      The explicit multicast support is required to forward unsolicited
      router advertisement message (RA) to all MSs which belong to a
      same subnet.  This solution would be described in Section 3.1 in
      detail.

   Prefix Assignment

      Prefix assignment has dependency on BS architecture and subnet
      model.  If BS is separated from AR, <subnet model>.1 is impossible
      because AR have no capability to assign different prefix per each
      MS (i.e.  AR is normal router). <subnet model>.1 and <subnet
      model>.2 are possible if BS and AR are in one box.

      If a prefix is shared among MSs then the subnet may consist of one
      or more BS(s) and multiple MSs (<subnet model>.2).  In this model,
      a MS assumes that every other MS which shares same prefix are on-
      link, thus it would try to resolve the L2 address for the on-link
      prefixes.  But direct communication using L2 address between two
      MSs may not be possible because of IEEE 802.16 network's
      structural reason.  One way to prevent this situation is to
      advertise a prefix with 'L' bit reset.



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   DAD procedure

      Duplicate Address Detection must take place on all unicast
      addresses, regardless of whether they are obtained through
      stateful, stateless or manual configuration [RFC2462].

      DAD procedure has some dependency on subnet model described in
      Section 2.1.1.1.  If a prefix is assigned to each MS (<subnet
      model>.1) then the subnet consists of only a MS and a BS.  Thus,
      there is no chance to collide with other address and hence DAD
      procedure seems to be trivial.  If MSs share a prefix (<subnet
      model>.2) then DAD procedure should not be ignored, but DAD in
      IEEE 802.16 requires explicit multicast support.  This problem can
      be solved through the solution described in Section 3.1 or proxy
      DAD.  In proxy DAD, each BS/AR maintains the list of all addresses
      that are currently used and then BS/AR does proxy DAD on behalf of
      each address owner.

2.2.2.  Address Resolution

   Address resolution has dependency on CS and subnet model.

   In case of ethernet CS, if a prefix is assigned to each MS (<subnet
   model>.1) address resolution is trivial (the next-hop of each MS's
   always BS/AR).  If a prefix with 'L' bit set is shared among MSs
   (<subnet model>.2), address resolution is required.

   In case of IPv6 CS, address resolution is trivial.  The next-hop of
   each MS is always BS/AR (<BS architecture>.1) or AR(<BS
   architecture>.2).

2.2.3.  Conceptual Sending Algorithm

   To send an IPv6 packet to a destination, the IPv6 node determines its
   next-hop firstly (Next hop Determination) and looks up the L2 address
   of next-hop in neighbor cache (Address Resolution) and finally send
   the IPv6 packet to the next-hop.  Once a neighbor cache entry is
   made, whenever it is referred its reachability is checked (Neighbor
   Unreachability Detection).

   Next Hop Determination

      It depends on subnet model.  In case of <subnet model>.1, the
      next-hop of the MS is always BS/AR.  In case of <subnet model>.2,
      if MSs share a prefix with 'L' bit set the next-hop determination
      would be performed as usual.  If MSs share a prefix with 'L' bit
      off, the next-hop of the MS is always BS/AR or AR.




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   Neighbor Cache

      The maintenance of neighbor cache depends on CS and subnet model.
      In case of IPv6 CS, address resolution is not strongly required
      because there is no ethernet header and hence the next-hop of MS
      is always BS/AR or AR.  If the MS adopts ethernet CS and it shares
      a prefix with 'L' bit set with other MSs (<subnet model>.2), the
      address resolution is required and neighbor cache would be
      maintained.

   Neighbor Unreachability Detection

      If MSs share a prefix with 'L' bit set, NUD would be performed as
      usual and if 'L' bit off or a prefix is assigned to each MS, the
      NUD would be required only for BS/AR or AR.




































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3.  Solutions

   In this section, we introduce a proposed multicast support mechanism
   and describe solution per feasible deployment scenario [I-D.shin-
   v6ops-deployment-scenarios]

3.1.  Multicast Support

   As mentioned before, some NDP functions need explicit multicast
   support to function normally over IEEE 802.16 networks.  Hence we
   introduce the solution for multicast support in IEEE 802.16 networks.

   Mutiple Unicast

      Multiple unicast is the approach that is very simple but uses more
      network resources.  The BS maintains the list of members which
      join a specific multicast address and if the BS receives a packet
      destined for the specific multicast address, it sends a copy of
      the packet as many times as the number of members.

   Multicast CID

      IEEE 802.16 provides support for downlink multicast from BS to MSs
      (MBS).  Multicast CID approach uses this feature of IEEE 802.16.

      Multicast CID is a CID shared among the member nodes of a
      multicast group.  To transmit multicast packets over the link with
      multicast CID, each CID should be shared by each multicast group
      member prior to packet transmission.  For NDP, three multicast
      CIDs are needed (all-nodes multicast address, all-routers
      multicast address, solicited-node multicast address).

      The simple operation procedure of this approach is as follows.
      For more detailed procedure, refer to [I-D.jang-16ng-llm]:

      1.  Each MS joins following CIDs at initialization stage.

          +  all-nodes multicast CID: all MSs join the all-nodes
             multicast group by generating the predefined CID for this
             group.

          +  solicited-node multicast CID: all MSs make its solicit-node
             multicast by generating the corresponding CID for its
             group.

          +  all-routers multicast CID: all MSs join the all-routers
             multicast group by generating the predefined CID for this
             group if it acts as a router



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      2.  MS may send packets destined for all-node multicast, all-
          router multicast, solicited-node multicast to BS or AR may
          send packets destined for all-node multicast, solicited-node
          multicast to BS.

      3.  BS delivers packets to MSs through multicast CID.

3.2.  Solution CASE 1


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

   Figure 5.  Scenario A

   o  Subnet model: 1.A prefix per each MS.

   o  BS architecture: 1.BS/AR are in one box.

   o  Convergence Sublayer: Both are ok.

   o  Address autoconfiguration:

      *  Unsolicited RA from BS/AR: Use Multicast CID approach.

      *  DAD: DAD procedure is trivial

   o  Address resolution: In case of ethernet CS and IPv6 CS, the next-
      hop of all MSs is BS/AR.  Therefore, address resolution is
      trivial.

   o  Conceptual sending algorithm

      *  Neighbor cache: In case of ethernet CS, needs only for BS/AR.

      *  NUD: Checks only the reachability of BS/AR.

      *  Next-hop determination: The next-hop of each MS is always
         BS/AR.




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3.3.  Solution CASE 2


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

   Figure 6.  Scenario B

   o  Subnet model: 2.A prefix for all MSs attached to a BS/AR.

   o  BS architecture: 1.BS/AR are in one box.

   o  Convergence Sublayer: Both are ok.

   o  Address autoconfiguration:

      *  Unsolicited RA from BS/AR: Use Multicast CID approach.

      *  DAD: Use multicast CID approach for NS/NA message.  DAD
         procedure should be performed as usual.

   o  Address resolution: In case of ethernet CS, address resolution
      should be performed as usual if MSs share a prefix with 'L' bit
      set.  Use multicast CID approach for NS message.  In case of IPv6
      CS, the next-hop of MS is always BS/AR.  Therefore, address
      resolution is trivial.

   o  Conceptual sending algorithm

      *  Neighbor cache: In case of ethernet CS, maintain other MS'
         cache if MSs share a prefix with 'L' bit set.  In case of IPv6
         CS, needs only for BS/AR.

      *  NUD: If ethernet CS and 'L' bit set checks every entry as
         usual.  Otherwise, checks only the reachability of BS/AR.

      *  Next-hop determination: If ethernet CS and 'L' bit set next-hop
         d etermination should be performed as usual.  Otherwise, the
         next-hop of each MS is always BS/AR.




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3.4.  Solution CASE 3


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

   Figure 7.  Scenario C

   o  Subnet model: 2.A prefix for all MSs attached to BSs.

   o  BS architecture: 2.BSs are separated from AR.

   o  Convergence Sublayer: In case of IPv6 CS, L2 tunnel should be used
      between BS and AR.

   o  Address autoconfiguration:

      *  Unsolicited RA from AR: Use Multicast CID approach.  RA should
         delivered to all BSs.

      *  DAD: Use multicast CID approach for NS/NA message.  DAD
         procedure should be performed as usual.

   o  Address resolution: In case of ethernet CS, address resolution
      should be performed as usual if MSs share a prefix with 'L' bit
      set.  Use multicast CID approach for NS message.  In case of IPv6
      CS, the next-hop of MS is always AR.  Therefore, address
      resolution is trivial.

   o  Conceptual sending algorithm

      *  Neighbor cache: In case of ethernet CS, maintain other MS'
         cache if MSs share a prefix with 'L' bit set.  In case of IPv6
         CS, needs only for AR.

      *  NUD: If ethernet CS and 'L' bit set checks every entry as
         usual.  Otherwise, checks only the reachability of AR.

      *  Next-hop determination: If ethernet CS and 'L' bit set next-hop
         determination should be performed as usual.  Otherwise, the



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         next-hop of each MS is always AR.

3.5.  Solution CASE 4


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

   Figure 8.  Scenario D

   o  Subnet model: 2.A prefix for all MSs attached to BSs.

   o  BS architecture: 2.BSs are separated from ARs.

   o  Convergence Sublayer: In case of IPv6 CS, L2 tunnel should be used
      between BS and AR.

   o  Address autoconfiguration:

      *  Unsolicited RA from AR: Use Multicast CID approach.  RA should
         delivered to all BSs.

      *  DAD: Use multicast CID approach for NS/NA message.  DAD
         procedure should be performed as usual.

   o  Address resolution: In case of ethernet CS, address resolution
      should be performed as usual if MSs share a prefix with 'L' bit
      set.  Use multicast CID approach for NS message.  In case of IPv6
      CS, the next-hop of MS is always one of ARs.  Therefore, address
      resolution is trivial.

   o  Conceptual sending algorithm

      *  Neighbor cache: In case of ethernet CS, maintain other MS'
         cache if MSs share a prefix with 'L' bit set.  In case of IPv6
         CS, needs only for AR.

      *  NUD: If ethernet CS and 'L' bit set checks every entry as
         usual.  Otherwise, checks only the reachability of AR.




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      *  Next-hop determination: If ethernet CS and 'L' bit set next-hop
         determination should be performed as usual.  Otherwise, the
         next-hop of each MS is always AR.
















































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4.  Secuirty Considerations

   Until now there is no special security consideration found for these
   issues and most of the security considerations might follow
   [RFC2461].














































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5.  References

5.1.  Normative References

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

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

   [RFC2472]  Haskin, D. and E. Allen, "IP Version 6 over PPP",
              RFC 2472, December 1998.

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

   [RFC3314]  Wasserman, M., "Recommendations for IPv6 in Third
              Generation Partnership Project (3GPP) Standards",
              RFC 3314, September 2002.

   [RFC2464]  Crawford, M., "Transmission of IPv6 Packets over Ethernet
              Networks", RFC 2464, December 1998.

   [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.

5.2.  Informative References

   [I-D.shin-ipv6-ieee802.16]
              Shin, M., "Scenarios and Considerations of IPv6 in IEEE
              802.16 Networks", draft-shin-ipv6-ieee802.16-02 (work in
              progress), February 2006.

   [I-D.madanapalli-nd-over-802.16-problems]
              Madanapalli, S., "IPv6 Neighbor Discovery over 802.16:
              Problems and Goals",
              draft-madanapalli-nd-over-802.16-problems-00 (work in
              progress), December 2005.

   [I-D.jang-16ng-llm]
              "Link-local Multicast packet Transmission in 802.16
              Networks", January 2006.

   [I-D.shin-v6ops-deployment-scenarios]
              "ISP IPv6 Deployment Scenarios in Wireless Broadband



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              Access Networks", February 2006.


















































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Authors' Addresses

   Joo-Chul Lee
   ETRI
   161 Gajeong-dong Yuseong-gu
   Daejeon, 305-350
   Korea

   Fax:   +82 42 861 5404
   Email: rune@etri.re.kr


   Syam Madanapalli
   Samsung ISO
   3/1 Millers Road
   Bangalore-560 052
   India

   Fax:   +91 80 51197777
   Email: syam@samsung.com


   Hee-Jin Jang
   Samsung AIT
   P.O. Box 111
   Suwon
   Korea

   Fax:   +82 31 280 9569
   Email: heejin.jang@samsung.com





















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