ipv6workshop2003-aodv-jaehoon

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					Ad Hoc 라우팅 표준(RFC3561)과
                         IPv6 적용기법
      정재훈 (Jaehoon Paul Jeong)
    한국전자통신연구원 표준연구센터
                   paul@etri.re.kr
      http://www.adhoc.6ants.net/
                                   2003. 10. 23

         제1회 IPv6 표준화워크샵 및 표준설명회                  1
    Contents
   Introduction
   Ad Hoc Unicast Routing Protocols
       Demand-driven Routing Protocols
   AODV (RFC 3561)
       AODV Message Formats
   IPv6 AODV
   Autoconfiguration Technologies for IPv6 MANET
   Summary
   References

                        제1회 IPv6 표준화워크샵 및 표준설명회     2
Introduction (1/2)
   Categories of Wireless Networks
       Infrastructured Network
            Cellular Network, Wireless LAN (WLAN)
       Infrastructureless Network
            Ad Hoc Network

   Ad Hoc Network
       Temporary network composed of mobile nodes without
        preexisting communication infrastructure, such as Access
        Point (AP) and Base Station (BS).
       Each node plays the role of router for multi-hop routing.
       Application
            War-field communication, Emergency recovery, Home-
             networking, Video-conferencing etc.
                          제1회 IPv6 표준화워크샵 및 표준설명회                 3
Mobile Ad Hoc Networks
                        Internet

      WLAN

                          Cellular




 Mobile Ad Hoc Networks
               제1회 IPv6 표준화워크샵 및 표준설명회   4
    Introduction (2/2)
   Issues in MANET
       Ad Hoc Unicast Routing
       Ad Hoc Multicast/Broadcast Routing
       Power Saving
       Global Connectivity for MANET
       Addressing & DNS
       Automatic Support of Networking Facility in
        MANET
            Autoconfiguration Technology


                           제1회 IPv6 표준화워크샵 및 표준설명회    5
   Ad Hoc Unicast Routing Protocols
                  Ad Hoc routing protocols


   Table-driven         Demand-driven
                                                   Hybrid
   (Proactive)            (Reactive)




DSDV OLSR TBRPF AODV     DSR        LMR      ABR    ZRP


CGSR                                TORA     SSR




                       제1회 IPv6 표준화워크샵 및 표준설명회              6
    Demand-driven Routing Protocols
   Characteristics
        Creation of routes only when desired by the source node
              By Route Discovery Process
        Route Discovery Process is completed
              Once a route is found
              When all possible route permutations have been examined
        Maintenance of a Route
              Until the destination becomes inaccessible along every path
               from the source
              Until the route is no longer desired

   Criterion of Classification of Routing Protocols
        Method by which route finding is performed
   Examples
        AODV, DSR, LMR, TORA, ABR, SSR
                           제1회 IPv6 표준화워크샵 및 표준설명회                       7
        AODV (RFC 3561)
Ad hoc On-Demand Distance Vector

      C. Perkins, E. Belding-Royer and S. Das,
                                    July 2003.




            제1회 IPv6 표준화워크샵 및 표준설명회              8
    Contents
   Overview of AODV
   Route Discovery
   Route Maintenance
   Optimizations
   AODV Message Formats




                제1회 IPv6 표준화워크샵 및 표준설명회   9
    Overview of AODV (1/2)
   AODV is improved DSDV algorithm
       Reactive or On-demand
       Provides unicast and multicast communication
        (MAODV)
       AODV doesn’t maintain a complete list of routes
        as in DSDV algorithm.
            Nodes that are not on a selected path don’t maintain
             routing information or participate in routing table
             exchanges.
       Loop-free
            AODV utilizes destination sequence numbers to ensure
             all routes are loop-free.

                           제1회 IPv6 표준화워크샵 및 표준설명회                  10
    Overview of AODV (2/2)
   Route Discovery process
       When does it happen?
            When source node doesn’t already have
             a valid route to a destination

       Route Discovery
            It broadcasts a route request (RREQ) packet to its
             neighbors.
            Neighbors forward the request to their neighbors, and so
             on until either the destination or
             an intermediate node with a “fresh enough” route
             to the destination is located.

                           제1회 IPv6 표준화워크샵 및 표준설명회                 11
 Route Discovery (1/10)
                    B


  S        A


                    C            D



1. Node S needs a route to D in order to send data
   packets to D




                   제1회 IPv6 표준화워크샵 및 표준설명회           12
 Route Discovery (2/10)
                       B


  S          A


                       C            D



1. Node S needs a route to D in order to send data
   packet to D
2. Creates a Route Request (RREQ)
  Enters D’s IP addr, seq#,
  S’s IP addr, seq#
  hopcount (=0)

                      제1회 IPv6 표준화워크샵 및 표준설명회        13
 Route Discovery (3/10)
                       B
      RREQ
  S          A


                       C            D



2. Creates a Route Request (RREQ)
  Enters D’s IP addr, seq#,
  S’s IP addr, seq#
  hopcount (=0)
3. Node S broadcasts RREQ to neighbors

                      제1회 IPv6 표준화워크샵 및 표준설명회   14
 Route Discovery (4/10)
                        B
       RREQ
  S           A


                        C           D



4. Node A receives RREQ
     Makes reverse route entry for S
      dest = S, nexthop = S, hopcnt = 1




                      제1회 IPv6 표준화워크샵 및 표준설명회   15
 Route Discovery (5/10)
                         B
            RREQ
  S           A


                         C           D



4. Node A receives RREQ
     Makes reverse route entry for S
      dest = S, nexthop = S, hopcnt = 1
     It has no route to D, so it rebroadcasts RREQ



                       제1회 IPv6 표준화워크샵 및 표준설명회        16
 Route Discovery (6/10)
                        B
           RREQ
  S           A


                        C           D



5. Node C receives RREQ
     Makes reverse route entry for S
      dest = S, nexthop = A, hopcnt = 2
     It has a route to D, and
      the seq# for route for D is >=D’s seq# in RREQ


                      제1회 IPv6 표준화워크샵 및 표준설명회          17
 Route Discovery (7/10)
                        B


  S           A     RREP

                        C            D



6. Node C sends RREP
     C creates a Route Reply (RREP)
      Enters D’s IP addr, seq #
      S’s IP addr, hopcount to D (=1)
      Lifetime
     Unicasts RREP towards A

                       제1회 IPv6 표준화워크샵 및 표준설명회   18
 Route Discovery (8/10)
                        B
       RREP
  S           A     RREP

                        C           D



7. Node A receives RREP
     Makes forward route entry to D
      dest = D, nexthop = C, hopcount = 2, Lifetime
     Unicasts RREP to S



                      제1회 IPv6 표준화워크샵 및 표준설명회         19
 Route Discovery (9/10)
                        B
       RREP
  S           A


                        C           D



8. Node S receives RREP
     Makes forward route entry to D
      dest = D, nexthop = C, hopcount = 3, Lifetime




                      제1회 IPv6 표준화워크샵 및 표준설명회         20
 Route Discovery (10/10)
                    B


  S        A


                    C           D



9. Node S sends data packets on route to D




                  제1회 IPv6 표준화워크샵 및 표준설명회    21
Route Maintenance (1/5)
                       B


  S          A     RERR

                       C            D


1. Link between C and D breaks down
     C can perform local repair for the route to D




                     제1회 IPv6 표준화워크샵 및 표준설명회          22
 Route Maintenance (2/5)
                         B


  S           A      RERR

                         C           D


1. Link between C and D breaks down
      C can perform local repair for the route to D
2. Node C invalidates route to D in route table




                       제1회 IPv6 표준화워크샵 및 표준설명회         23
Route Maintenance (3/5)
                          B


  S           A      RERR

                          C             D


3. Node C creates Route Error (RERR) message
     C creates a Route Error (RERR)
      Enters DestCount (=1), D’s IP addr, seq #
     Lists all destinations which are now unreachable
          “DestCount” field indicates the number of unreachable
           destinations included in the RERR message.
     Sends to upstream neighbors in precursor list
                        제1회 IPv6 표준화워크샵 및 표준설명회                    24
Route Maintenance (4/5)
                            B
      RERR
  S             A       RERR

                            C             D


4. Node A receives RERR
     Checks whether C is its next hop on route to D
     Deletes route to D
      or invalidates the route to D according to N flag
      (No delete flag)
         When N flag is set, A does not send RERR to S and may reinitiate
          route discovery for D.
     Forwards RERR to S
                          제1회 IPv6 표준화워크샵 및 표준설명회                      25
Route Maintenance (5/5)
                        B
      RERR
  S           A


                        C           D


5. Node S receives RERR
     Checks whether A is its next hop on route to D
     Deletes route to D
     Rediscovers route if still needed




                      제1회 IPv6 표준화워크샵 및 표준설명회          26
    Optimizations (1/2)
   Expanding Ring Search
       It prevents flooding of network during route
        discovery
       Control Time To Live (TTL) of RREQ to search
        incrementally larger areas of network
       Advantage
           Less overhead when successful
       Disadvantage
           Longer delay if route not found immediately


                           제1회 IPv6 표준화워크샵 및 표준설명회        27
    Optimizations (2/2)
   Local Repair
       It repairs breaks in active routes locally instead of
        notifying source.
           If the first repair attempt is unsuccessful, it sends RERR to
            source.
       Advantage
           Link repair with less overhead, delay and packet loss.
       Disadvantage
           Longer delay and greater packet loss when unsuccessful



                              제1회 IPv6 표준화워크샵 및 표준설명회                       28
AODV Message Formats




      제1회 IPv6 표준화워크샵 및 표준설명회   29
Route Request (RREQ)
Message Format
    0                   1                          2                      3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Type      |J|R|G|D|U|         Reserved           |   Hop Count       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                    RREQ ID                                  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                Destination IP Address                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                           Destination Sequence Number                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                Originator IP Address                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                           Originator Sequence Number                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                            제1회 IPv6 표준화워크샵 및 표준설명회                               30
Route Reply (RREP)
Message Format
    0                      1                          2                        3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Type      |R|A|         Reserved          | Prefix Sz |   Hop Count       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                 Destination IP address                           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                              Destination Sequence Number                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                 Originator IP Address                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                       Lifetime                                   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




                               제1회 IPv6 표준화워크샵 및 표준설명회                                 31
Route Error (RERR)
Message Format
    0                         1                         2                      3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Type           |N|              Reserved                  |   DestCount   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         Unreachable Destination IP Address (1)                   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Unreachable Destination Sequence Number (1)                  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
|               Additional Unreachable Destination IP Addresses (if needed)        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|         Additional Unreachable Destination Sequence Numbers (if needed)          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




                                  제1회 IPv6 표준화워크샵 및 표준설명회                              32
Route Reply Acknowledgement
(RREP-ACK) Message Format
            0                   1
            0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |        Type      |    Reserved      |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



   RREP-ACK message MUST be sent in response to
    a RREP message with the ‘A’ bit set.
       This is typically done when there is danger of unidirectional
        links preventing the completion of
        a Route Discovery cycle.



                               제1회 IPv6 표준화워크샵 및 표준설명회              33
                    IPv6 AODV
C. Perkins, E. Belding-Royer and S. Das,
         draft-perkins-manet-aodv6-01,
                        November 2001.




      제1회 IPv6 표준화워크샵 및 표준설명회              34
    AODV for IPv6 Operation
   Message Handling
       The handling of IPv6 AODV for IPv6 AODV messages is
        analogous to IPv4 AODV.
           AODV messages have the formats appropriate for use with 128-
            bit IPv6 addresses.


   ICMP Processing
       Whenever IPv4 AODV specifies use of ICMP, the
        operation for IPv6 uses ICMPv6.

   Configuration Parameters
       IPv4 and IPv6 AODVs use the same parameters.

                            제1회 IPv6 표준화워크샵 및 표준설명회                    35
Autoconfiguration Technologies
               for IPv6 MANET
                                     Reference Paper:

           http://www.adhoc.6ants.net/publications/
     international-conference/icoin2004-jaehoon.pdf




               제1회 IPv6 표준화워크샵 및 표준설명회                  36
    Autoconfiguration?
   What is Autoconfiguration?
       The technology that allows IP-enabled devices be able to
        communicate one another in infrastructureless environment.

   Issues of IETF Zeroconf Working Group
       Unicast Address Autoconfiguration
       Multicast Address Allocation
       Name Resolution (DNS)
       Service Discovery

   Why is Autoconfiguration needed in MANET?
       To provide the quick and easy configuration related to the
        networking in MANET with dynamic topology.

                           제1회 IPv6 표준화워크샵 및 표준설명회                   37
Autoconfiguration Technology for
IPv6 MANET
   Unicast Address Autoconfiguration
        Automatic configuration of a unique IPv6 address within
         MANET

   Multicast Address Allocation
        Allocation of a unique multicast address for the application
         which needs a new multicast address
                                                                       Unicast Address Autoconfiguration


   Multicast DNS




                                                  Service Discovery
         Translation between name and




                                                                                                      Multicast DNS
     
                                                                         Autoconfiguration
         IPv6 address                                                       Technology
                                                                          for IPv6 MANET

   Service Discovery
        Discovery of the necessary service                           Multicast Address Allocation


                            제1회 IPv6 표준화워크샵 및 표준설명회                                                  38
    Summary
   AODV
       It is a Reactive/On-demand Ad Hoc routing protocol.
         Route Discovery cycle
       Sequence numbers are used for route freshness and loop
        prevention.
       It maintains only active routes.
       Optimizations can be used to reduce overhead and
        increase scalability.

   IPv6 AODV

   Autoconfiguration Technologies for IPv6 MANET
                        제1회 IPv6 표준화워크샵 및 표준설명회              39
 References
[1] C. Perkins, E. Belding-Royer and S. Das,
    “Ad hoc On-Demand Distance Vector (AODV) Routing”,
     RFC 3561, July 2003.
[2] C. Perkins, E. Belding-Royer and S. Das,
    “Ad Hoc On Demand Distance Vector (AODV) Routing for IP
     version 6”, draft-perkins-manet-aodv6-01, November 2001.
[3] Auto-Networking Technologies for IPv6 MANET,
    http://www.adhoc.6ants.net/publications/international-
    conference/icoin2004-jaehoon.pdf

[4] ETRI Ad Hoc Project,
    http://www.adhoc.6ants.net/

                      제1회 IPv6 표준화워크샵 및 표준설명회                40

				
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