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INTERNET-DRAFT                       Zygmunt J. Haas,  Cornell University
                                     Marc R. Pearlman, Cornell University
                                     Prince Samar,     Cornell University

Expires in six months on January 2003                           July 2002

           The Zone Routing Protocol (ZRP) for Ad Hoc Networks

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC 2026, except the right to produce
   derivative works is not granted.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that other
   groups may also distribute working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time. It is inappropriate to use Internet-Drafts as reference material
   or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at

   The list of Internet-Draft Shadow Directories can be accessed at

   Distribution of this memo is unlimited.


   This document describes the Zone Routing Protocol (ZRP) framework, a
   hybrid routing framework suitable for a wide variety of mobile ad-hoc
   networks, especially those with large network spans and diverse
   mobility patterns.  Each node proactively maintains routes within a
   local region (referred to as the routing zone).  Knowledge of the
   routing zone topology is leveraged by the ZRP to improve the
   efficiency of a globally reactive route query/reply mechanism. The
   proactive maintenance of routing zones also helps improve the quality
   of discovered routes, by making them more robust to changes in network
   topology. The ZRP can be configured for a particular network by proper
   selection of a single parameter, the routing zone radius.

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   Status of this Memo . . . . . . . . . . . . . . . . . . . . . .  i
   Abstract  . . . . . . . . . . . . . . . . . . . . . . . . . . .  i

   Applicability Statement . . . . . . . . . . . . . . . . . . .  iii
       A. Networking Context   . . . . . . . . . . . . . . . . .  iii
       B. Protocol Characteristics and Mechanisms  . . . . . . .  iii

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . .  1

   2.  Overview of the Zone Routing Framework . . . . . . . . . . . 2
       2.1  Routing Zones and the Intrazone Routing Protocol  . . . 2

       2.2  Bordercast-Based Global Reactive (Interzone) Routing  . 4

   3.  The ZRP Architecture . . . . . . . . . . . . . . . . . . . . 5

   4.  Other Considerations . . . . . . . . . . . . . . . . . . . . 6
       4.1  Sizing the Routing Zone . . . . . . . . . . . . . . . . 6
       4.2  Hierarchical Routing and the ZRP  . . . . . . . . . . . 6

   5. Patent Rights Statement . . . . . . . . . . . . . . . . . . . 8

   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . 9

   Authors' Information  . . . . . . . . . . . . . . . . . . . . . 11
   MANET Contact Information . . . . . . . . . . . . . . . . . . . 11

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Applicability Statement

A.  Networking Context

    The hybrid Zone Routing Protocol (ZRP) framework can adapt to a wide
    variety of network scenarios by adjusting the range of the nodes'
    proactively maintained routing zones.  Large routing zones are
    preferred when demand for routes is high and/or the network consists
    of many slowly moving nodes.  In the extreme case of a network with
    fixed topology, the ideal routing zone radius would be infinitely
    large.  (Consider the purely proactive routing protocols used on the
    fixed Internet).  On the other hand, smaller routing zones are
    appropriate in situations where route demand is low and/or the
    network consists of a small number of nodes that move fast relative
    to one another.  In the "worst case", a routing zone radius of one
    hop is best, and the ZRP defaults to a traditional reactive flooding

    When the ZRP is properly configured for a particular network scenario,
    it can perform at least as well as (and often better than) its purely
    proactive and reactive constituent protocols.  In situations where
    the network behavior varies across different regions, the ZRP
    performance can be fine-tuned by individual adjustment of each node's
    routing zone.

    The global reactive component of the ZRP uses the multicast based
    "bordercast" mechanism to propagate route queries throughout the
    network efficiently, rather than relying on neighbor-broadcast
    flooding found in traditional reactive protocols.  Consequently, the
    ZRP provides the most benefit in networks where reliable neighbor
    broadcasting is either inefficient or altogether impossible.  In
    particular, the ZRP is well suited for multi-channel, multi-
    technology routing fabrics and networks operating under high load.

B.  Protocol Characteristics and Mechanisms

   * Does the protocol provide support for unidirectional links?
     (if so, how?)
        Yes.  The ZRP provides "local" support for unidirectional links.
        A unidirectional link can be used as long as the link source and
        link destination lie within each other's routing zone.

   * Does the protocol require the use of tunneling? (if so, how?)

   * Does the protocol require using some form of source routing?
     (if so, how?)

        No.  The ZRP's framework supports global route discovery based
        on source routing, distributed distance vectors, or various
        combinations of both.

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   * Does the protocol require the use of periodic messaging?
     (if so, how?)

        Yes.  The ZRP framework proactively maintains local routing
        information (routing zones) based on periodic exchanges of
        neighbor discovery messages.

   * Does the protocol require the use of reliable or sequenced packet
     delivery? (if so, how?)

        The ZRP only assumes that link-layer (neighbor) unicasts are
        delivered reliably and in-sequence.  Reliable and sequenced
        delivery of neighbor broadcasts and IP unicasts is not

   * Does the protocol provide support for routing through a multi-
     technology routing fabric? (if so, how?)

        Yes.  It is assumed that each node's network interface is
        assigned a unique IP address.

   * Does the protocol provide support for multiple hosts per router?
     (if so, how?)

        Yes.  Multiple hosts may be associated with a router.  These
        hosts can be identified by the neighbor discovery/maintenance

        By default, it is assumed that a host's association with a router
        is not permanent.  As a result, the ZRP exchanges routing
        information for individual hosts in the same manner as routing
        information for routers.

        In cases where a router is permanently associated with a network
        (subnetwork), the ZRP supports the exchange of network
        (subnetwork) prefixes in place of all aggregated host IP

   * Does the protocol support the IP addressing architecture?
     (if so, how?)

        Yes.  Each node is assumed to have a unique IP address (or
        set of unique IP addresses in the case of multiple interfaces).
        The ZRP references all nodes/interfaces by their IP address.

        This version of the ZRP also supports IP network addressing
        (network prefixes) for routers that provide access to a
        network of non-router hosts.

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   * Does the protocol require link or neighbor status sensing
     (if so, how?)

        Yes.  The ZRP proactively maintains local routing information
        (routing zones) based on detected changes in neighbor status.

   * Does the protocol have dependence on a central entity?
     (if so, how?)

        No.  The ZRP is a fully distributed protocol.

   * Does the protocol function reactively? (if so, how?)

        Yes.  The ZRP's GLOBAL route discovery mechanism is reactive.
        A route query is initiated, on demand, when a node requires
        routing information that is not immediately available in its
        routing table.

        The route query propagates through the network, using a special
        packet delivery service called "bordercasting".  Bordercasting
        leverages knowledge of local network topology to direct route
        queries away from the source, thereby reducing redundancy.

   * Does the protocol function proactively? (if so, how?)

        Yes.  The ZRP proactively maintains LOCAL routing information
        (routing zones) for each node.  The routing zone information is
        leveraged, through the bordercasting mechanism, to support
        efficient global propagation of route queries.

   * Does the protocol provide loop-free routing? (if so, how?)

        Yes.  If the reactive Interzone Routing is based on source
        routing, loop-freedom in the route discovery process is ensured
        by inspection of accumulated source routes. For distributed
        distance vector approaches, loop-freedom can be ensured by
        labeling queries (replies) with the source (destination) address
        and locally unique sequence number.  Nodes that relay these
        messages can temporarily cache these identifiers in order to
        identify and terminate loops.

        The proactive Intrazone Routing based on link states is
        inherently loop-free, although temporary loops may form while new
        link state updates propagate through the routing zone.

   * Does the protocol provide for sleep period operation? (if so, how?)

        No. Sleep period operation is not addressed in this draft.
        However, sleep period support can be included as needed.

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   * Does the protocol provide some form of security? (if so, how?)

        No.  It is assumed that security issues are adequately addressed
        by the underlying protocols (IPsec, for example).

   * Does the protocol provide support for utilizing multi-channel,
     link-layer technologies? (if so, how?)

        Yes.  It is assumed that each node's network interface is
        assigned a unique IP address.

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1. Introduction

   One of the major challenges in designing a routing protocol for the
   ad hoc networks stems from the fact that, on one hand, to determine
   a packet route, a node needs to know at least the reachability
   information to its neighbors.  On the other hand, in an ad hoc
   network, the network topology can change quite often.  Furthermore,
   as the number of network nodes can be large, the potential number of
   destinations is also large, requiring large and frequent exchange of
   data (e.g., routes, routes updates, or routing tables) among the
   network nodes. Thus, the amount of update traffic can be quite high.
   This is in contradiction with the fact that all updates in a
   wirelessly interconnected ad hoc network travel over the air and,
   thus, are costly in resources.

   In general, the existing routing protocols can be classified either
   as proactive or as reactive. Proactive protocols attempt to
   continuously evaluate the routes within the network, so that when
   a packet needs to be forwarded, the route is already known and can
   be immediately used.  The family of Distance-Vector protocols is an
   example of a proactive scheme.  Examples of proactive routing
   protocols include the Wireless Routing Protocol (WRP) [11] and
   Destination-Sequenced Distance-Vector (DSDV) routing [16]. Reactive
   protocols, on the other hand, invoke a route determination procedure
   on demand only. Thus, when a route is needed, some sort of global
   search procedure is employed. The family of classical flooding
   algorithms belong to the reactive group. Some other examples of
   reactive (also called on-demand) ad hoc network routing protocols are
   Dynamic Source Routing (DSR) [9], Ad-hoc On demand Distance Vector
   Routing (AODV) [17] and the Temporally Ordered Routing Algorithm
   (TORA) [13].

   The advantage of the proactive schemes is that, once a route is
   needed, there is little delay until the route is determined. In
   reactive protocols, because route information may not be available
   at the time a datagram is received, the delay to determine a route
   can be quite significant. Furthermore, the global flood-search
   procedure  of the reactive protocols requires significant control
   traffic.  Because of this long delay and excessive control traffic,
   pure reactive routing protocols may not be applicable to real-time
   communication.  However, pure proactive schemes are likewise not
   appropriate for the ad hoc networking environment, as they
   continuously use a large portion of the network capacity to keep the
   routing information current. Since nodes in an ad hoc network move
   quite fast, and as the changes may be more frequent than the route
   requests, most of this routing information is never even used! This
   results in a further waste of the wireless network capacity. What is
   needed is a protocol that, on one hand, initiates the route
   determination procedure on-demand, but at limited search cost. The
   protocol described in this draft, termed the "Zone Routing Protocol
   (ZRP)" ([1],[2],[14]), is an example of a such a hybrid proactive/
   reactive scheme.

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   The ZRP, on one hand, limits the scope of the proactive procedure
   only to the node's local neighborhood. On the other hand, the search
   throughout the network, although global in nature, is done by
   efficiently querying selected nodes in the network, as opposed to
   querying all the network nodes.

   A related issue is that of updates in the network topology. For a
   routing protocol to be efficient, changes in the network topology
   should have only a local effect. In other words, creation of a new
   link at one end of the network is an important local event but, most
   probably, not a significant piece of information at the other end of
   the network.  Globally proactive protocols tend to distribute such
   topological changes widely in the network, incurring large costs. The
   ZRP limits propagation of such information to the neighborhood of the
   change only, thus limiting the cost of topological updates.

2. Overview of the Zone Routing Framework

   In the Zone Routing framework, a proactive routing protocol provides a
   detailed and fresh view of each node's surrounding local topology
   (routing zone) at the local level.  The knowledge of local topology is
   used to support services such as proactive route maintenance,
   unidirectional link discovery and guided message distribution. One
   particular message distribution service, called bordercasting [5],
   directs queries throughout the network across overlapping routing
   zones. Bordercasting is used in place of traditional broadcasting to
   improve the efficiency of a global reactive routing protocol.

   The benefits provided by routing zones, compared with the overhead of
   proactively tracking routing zone topology, determine the optimal
   framework configuration.  As network conditions change, the framework
   can be dynamically reconfigured through adjustment of each node's
   routing zone

2.1 Routing Zones and the Intrazone Routing Protocol (IARP)

  In Zone Routing, the Intrazone Routing Protocol (IARP) proactively
  maintains routes to destinations within a local neighborhood, which we
  refer to as a routing zone.  More precisely, a node's routing zone is
  defined as a collection of nodes whose minimum distance in hops from
  the node in question is no greater than a parameter referred to as the
  zone radius.  Note that each node maintains its own routing zone. An
  important consequence is that the routing zones of neighboring nodes

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  An  example of a routing zone (for node A) of radius 2 is shown below.

          |                       +---+             |
          |            +---+   ---| F |-------|     |
   +---+  |  +---+   --| C |--/   +---+     +---+   |
   | G |-----| D |--/  +---+                | E |   |  Routing Zone of
   +---+  |  +---+       |        +---+     +---+   |      node A
          |            +---+   ---| B |-------|     |  (radius = 2 hops)
          |            | A |--/   +---+             |
          |            +---+                        |

   Note that in this example nodes B through F are within the routing
   zone of A. Node G is outside A's routing zone. Also note that E can be
   reached by two paths from A, one with length 2 hops and one with
   length 3 hops.  Since the minimum is less or equal than 2, E is within
   A's routing zone.

   Peripheral nodes are nodes whose minimum distance to the node in
   question is equal exactly to the zone radius. Thus, in the above
   figure, nodes D, F, and E are A's peripheral nodes.

   The construction of a routing zone requires a node to first know who
   its neighbors are.  A neighbor is defined as a node with whom direct
   (point-to-point) communication can be established and is, thus, one
   hop away.  Identification of a node's neighbors may be provided
   directly by the media access control (MAC) protocols, as in the case
   of polling-based protocols.  In other cases, neighbor discovery may
   be implemented through a separate Neighbor Discovery Protocol (NDP).
   Such a protocol typically operates through the periodic broadcasting
   of "hello" beacons.  The reception (or quality of reception) of a
   "hello" beacon can be used to indicate the status of a connection to
   the beaconing neighbor.

   Neighbor discovery information is used as a basis for the IARP.
   IARP can be derived from globally proactive link state routing
   protocols that provide a complete view of network connectivity.
   [3] describes the Intrazone Routing Protocol (IARP) in detail and
   lists the conversion guidelines for adapting a proactive link-state
   based routing protocol to serve as an IARP.

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2.2 Bordercast-Based Global Reactive (Interzone) Routing

   Route discovery in the Zone Routing framework is distinguished from
   standard broadcast-based route discovery through a message
   distribution service known as the Bordercast Resolution Protocol (BRP)
   [5]. Rather than blindly broadcasting a route query from neighbor to
   neighbor, bordercasting allows the query to be directed outward,
   toward regions of the network (specifically, toward peripheral nodes)
   that have not yet been "covered" by the query.  (A covered node is one
   that belongs to the routing zone of a node that has received a route
   query). The query control mechanisms reduce route query traffic by
   directing query messages outward from the query source and away from
   covered routing zones.

   A node can determine local query coverage by noting the addresses of
   neighboring nodes that have forwarded the query.  In the case of
   multiple channel networks, a node can only detect query packets that
   have been directly forwarded to it.  For single channel networks, a
   node may be able to detect any query packet forwarded within the
   node's radio range. When a node identifies a query forwarding
   neighbor, all known members of that neighbor's routing zone (i.e.,
   those members which belong to both the node's and neighbor's routing
   zones) are marked as covered.

   When a node is called upon to relay a bordercast message, it again
   uses its routing zone topology to construct a bordercast tree, that is
   rooted at itself and spans its uncovered peripheral nodes.  The
   message is then forwarded to those neighbors in the bordercast tree.
   By virtue of the fact that this node has forwarded the query, all of
   its routing zone members are marked as covered.  Therefore, a
   bordercasting node will not forward a query more than once.
   The details of the Bordercast Resolution Protocol are described in [5].

   Given the availability of an underlying bordercast service, the
   operation of Zone Routing's global reactive Interzone Routing Protocol
   (IERP) is quite similar to standard route discovery protocols. An IERP
   route discovery is initiated when no route is locally available to the
   destination of an outgoing data packet.  The source generates a route
   query packet, which is uniquely identified by a combination of the
   source node's address and request number. The query is then relayed to
   a subset of neighbors as determined by the bordercast algorithm. Upon
   receipt of a route query packet, a node checks if the destination lies
   in its zone or if a valid route to it is available in its route cache.
   If the answer is affirmative, a route reply is sent back to the
   source. If not, the node bordercasts the query again. The operation of
   the IERP is sufficiently general, so that many existing reactive
   protocols can be used as an IERP with minimal modification. The
   details of IERP's operation can be found in [4].

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3.0 The ZRP Architecture

             :                 Z R P                 :
             :                                       :
+---------+  :      +---------+         +---------+  :      +---------+
|   NDP   |========>|  IARP   |========>|  IERP   |<========|  ICMP   |
+---------+  :      +---------+         |---+-----+  :      +---------+
    /|\      :          /|\             |BRP|  /|\   :          /|\
     |       :           |              +---+   |    :           |
     |       :           |               /|\    |    :           |
     |       :...........|................|.....|....:           |
     |                   |                |     |                |
    \|/                 \|/              \|/   \|/              \|/
|                                 IP                                  |


        A <---> B      exchange of packets between protocols A & B
        A  ===> B      information passed from protocol A to protocol B

        Existing Protocols
                IP              Internet Protocol
                ICMP            Internet Control Message Protocol

        ZRP Entities
                IARP            IntrAzone Routing Protocol
                IERP            IntErzone Routing Protocol
                BRP             Bordercast Resolution Protocol

      Additional Protocols
                NDP             Neighbor Discovery Protocol

   The architecture of the hybrid Zone Routing framework is modular, so
   that a link state routing protocol can be used as an IARP [3] and an
   on-demand routing protocol can be used as an IERP [4]. As an example,
   consider TBRPF [12] or OLSR [7] as an IARP and AODV [15] or DSR [8] as
   an IERP.

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4. Other Considerations

4.1 Sizing the Zone Radius

   The performance of the Zone Routing Protocol is determined by the
   routing zone radius.  In general, dense networks consisting of a few
   fast moving nodes favor smaller routing zones.  On the other hand, a
   sparse network of many slowly moving nodes operates more efficiently
   with a larger zone radius.

   The simplest approach to configuring the routing zone radius is to
   make the assignment once, prior to deploying the network.  This can
   be performed by the network administration, if one exists, or by
   the manufacturer, as a default value.  This may provide acceptable
   performance, especially in situations where network characteristics
   do not vary greatly over space and time.  Alternatively, the ZRP can
   adapt to changes in network behavior, through dynamic configuration
   of the zone radius [6].  In [14], it was shown that a node can
   accurately estimate its optimal zone radius, on-line, based on local
   measurements of ZRP traffic.  The re-sizing of the routing zone can be
   carried out by a protocol that conveys the change in zone radius to
   the members of the routing zone.

   In Zone Routing with independently sized routing zones capability,
   each of the nodes in the network can adaptively configure its own
   optimal zone radius in a distributed fashion. The performance of Zone
   Routing is further improved by the ability to provide fine-tuned
   adaptation to local and temporal variations in network characteristics
   [19]. The details of the Independent Zone Routing (IZR) framework will
   be included in a future version of this draft.

4.2 Hierarchical Routing and the ZRP

   In a hierarchical network architecture, network nodes are organized
   into a smaller number of (often disjoint) clusters.  This routing
   hierarchy is maintained by two component routing protocols.  An intra-
   cluster protocol provides routes between nodes of the same cluster,
   while an inter-cluster protocol operates globally to provide routes
   between clusters.

   The ZRP, with its routing zones and intrazone / interzone routing
   protocol (IARP/IERP) architecture may give the appearance of being a
   hierarchical routing protocol.  In actuality, the ZRP is a flat
   routing protocol.  Each node maintains its own routing zone, which
   heavily overlaps with the routing zones of neighboring nodes. Because
   there is a one-to-one correspondence between nodes and routing zones,
   the routing zones, unlike hierarchical clusters, do not serve to hide
   the details of local network topology.  As a result, the network-wide
   interzone routing protocol (IERP) actually determines routes between
   individual nodes, rather than just between higher level network

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   For small to moderately sized networks, flat routing protocols, like
   the ZRP, are preferable to hierarchical routing protocols.  In order
   for a node to be located, its address needs to reflect the node's
   location within the network hierarchy (i.e.  {cluster id,node id}).
   Because of node mobility, a node's cluster membership (and thus
   address) is subject to change.  This complicates mobility management,
   for the benefit of more efficient routing.  In many hierarchical
   routing protocols, each cluster designates a single clusterhead node
   to relay inter-cluster traffic.  These clusterhead nodes become
   traffic "hot-spots", potentially resulting in network congestion and
   single point of failure. Furthermore, restricting cluster access
   through clusterhead nodes can lead to sub-optimal routes, as potential
   neighbors in different clusters are prohibited from communicating
   directly.   Some hierarchical routing protocols, such as the
   Zone-Based Hierarchical Link-State (ZHLS) [8], avoid these problems by
   distributing routing information to all cluster nodes, rather than
   maintaining a single clusterhead.

   In spite of these disadvantages, hierarchical routing protocols are
   often better suited for very large networks than flat routing
   protocols. Because hierarchical routing protocols provide global
   routes to network clusters, rather than individual nodes, routing
   table storage is more scalable.  Similarly, the amount of route update
   messages is also more scalable.  To some extent, the reduction in
   routing traffic is offset by extra mobility management overhead (i.e.
   identifying which cluster a node belongs to).  However, it is quite
   common that the environment or existing organizational structure
   causes nodes to naturally cluster together.  In these cases, there may
   be a high degree of intra-cluster mobility, with inter-cluster
   mobility is less common.

   A hierarchical routing protocol can be viewed as a set of flat routing
   protocols, each operating at different levels of granularity.  In a
   two-tier routing protocol, the inter-cluster components is essentially
   a flat routing protocol that computes routes between clusters.
   Likewise, the intra-cluster component is a flat routing protocol, that
   computes routes between nodes in each cluster.  For example, the Near
   Term Digital Radio (NTDR) System [18] and ZHLS both employ proactive
   link state protocols to determine inter and intracluster connectivity.

   In place of traditional proactive or reactive protocols, we recommend
   that the intra-cluster and inter-cluster routing protocol components
   be implemented based on the hybrid proactive/reactive ZRP.  As
   described throughout this draft, the ZRP is designed to provide an
   optimal balance between purely proactive and reactive routing. This
   applies equally well to routing between nodes at the intra-cluster
   level and between clusters at the inter-cluster level. Additionally,
   the hybrid ZRP methodology can be applied to the related mobility
   management protocols, which determine complete node addresses based on
   a node's location in the network hierarchy.

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5.  Patent Rights Statement

   Cornell University has filed one or more patents protecting the
   inventions described in this submission (the "Patents").  If Cornell
   University's submission, or material portions thereof, is accepted and
   becomes part of the IETF standard (the "Standard"), then Cornell will
   grant any entity wishing to practice the Standard a non-exclusive,
   royalty-free license under the Patents to the extent, but only to the
   extent, that such license is required to implement (a) mandatory
   elements of the Standard; or (b) elements of Cornell's submission that
   are explicitly specified (and not merely incorporated by reference) in
   the Standard.

   Use of any elements of Cornell's submission that are neither required
   in order to implement the Standard nor explicitly specified in the
   Standard will require an additional license from Cornell University
   under terms to be negotiated between the parties.

   While the protocol disclosed in Cornell's submission is being
   evaluated by the IETF, whether on the standards track or otherwise,
   Cornell University will and hereby does grant any party a license to
   utilize, test and evaluate such protocol solely for non-commercial,
   research purposes.

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6. References

   [1]   Haas, Z.J., "A New Routing Protocol for the Reconfigurable
              Wireless Networks," ICUPC'97, San Diego, CA, Oct. 12,1997.

   [2]   Haas, Z.J. and Pearlman, M.R., "The Performance of Query
              Control Schemes for the Zone Routing Protocol,"
              SIGCOMM'98, Vancouver, BC, Sept. 2-4, 1998.

   [3]   Haas, Z.J., Pearlman, M.R. and Samar, P., "Intrazone Routing
              Protocol (IARP)," IETF Internet Draft,
              draft-ietf-manet-iarp-02.txt, July 2002.

   [4]   Haas, Z.J., Pearlman, M.R. and Samar, P., "Interzone Routing
              Protocol (IERP)," IETF Internet Draft,
              draft-ietf-manet-ierp-02.txt, July 2002.

   [5]   Haas, Z.J., Pearlman, M.R. and Samar, P., "Bordercasting
              Resolution Protocol (BRP)," IETF Internet Draft,
              draft-ietf-manet-brp-02.txt, July 2002.

   [6]   Haas, Z.J. and Tabrizi, S., "On Some Challenges and Design
              Choices in Ad-Hoc Communications," MILCOM'98, Boston, MA,
              October 18-21, 1998.

   [7]   Jacquet, P., Muhlethaler, P., Qayyum A., Laouiti A., Viennot L.,
              and Clausen T., "Optimized Link State Routing Protocol,"
              IETF Internet Draft, draft-ietf-manet-olsr-03.txt,
              November 2000.

   [8]   Joa-Ng, M. and Lu, I.T., "A Peer-to-Peer Zone-based Two-Level
              Link State Routing for Mobile Ad-Hoc Networks," to appear
              in IEEE JSAC issue on Ad-Hoc Networks, June, 1999.

   [9]   Johnson, D.B., and Maltz, D.A., "Dynamic Source Routing
              in Ad-Hoc Wireless Networks," in Mobile Computing,
              edited by T. Imielinski and H. Korth, chapter 5,
              pp. 153-181, Kluwer, 1996.

   [10]   Moy, J., "OSPF Version 2," INTERNET DRAFT STANDARD,
              RFC 2178, July 1997.

   [11]   Murthy, S., and Garcia-Luna-Aceves, J.J., "An Efficient
              Routing Protocol for Wireless Networks," MONET, vol. 1,
              no. 2, pp. 183-197, October 1996.

   [12]   Ogier, R. "Efficient Routing Protocols for Packet-Radio
              Networks Based on Tree Sharing," MoMUC '99, November 1999.

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INTERNET DRAFT              The Zone Routing Protocol           July 2002

   [13]   Park, V.D., and Corson, M.S., "A Highly Adaptive Distributed
              Routing Algorithm for Mobile Wireless Networks,"
              IEEE INFOCOM'97, Kobe, Japan, 1997.

   [14]   Pearlman, M.R. and Haas, Z.J., "Determining the Optimal
              Configuration for the Zone Routing Protocol," IEEE JSAC,
              August, 1999.

   [15]  Pearlman, M.R. and Haas, Z.J., "Improving the Performance of
              of Query-Based Routing Protocols Through 'Diversity
              Injection'", IEEE WCNC'99, New Orleans, LA, Sept. 1999.

   [16]  Perkins, C.E., and Bhagwat, P., "Highly Dynamic
              Destination-Sequenced Distance-Vector Routing (DSDV) for
              Mobile Computers," ACM SIGCOMM, vol.24, no.4, October 1994.

   [17]  Perkins, C.E. and Royer, E.M., "Ad-Hoc On-Demand Distance
              Vector Routing," IEEE WMCSA'99, New Orleans, LA, Feb. 1999

   [18]  Ruppe, R., Griswald, S., Walsh, P. and Martin, R., "Near Term
              Digital Radio (NTDR) System," IEEE MILCOM'97, Monterey, CA,
              Nov. 1997.

   [19]  Samar, P., Pearlman, M.R. and Haas, Z.J., "Hybrid Routing: The
              Pursuit of an Adaptable and Scalable Routing Framework for
              Ad Hoc Networks," in Handbook of Ad Hoc Wireless Networks,
              M. Ilyas, ed., CRC Press 2002.

   [20]  Waitzman, D., Partridge, C., Deering, S.E., "Distance
              Vector Multicast Routing Protocol," RFC 1075, Nov. 1, 1988.

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INTERNET DRAFT              The Zone Routing Protocol           July 2002

Authors' Information

   Zygmunt J. Haas
   Wireless Networks Laboratory
   323 Frank Rhodes Hall
   School of Electrical & Computer Engineering
   Cornell University
   Ithaca, NY 14853
   United States of America
   tel: (607) 255-3454, fax: (607) 255-9072
   Email: haas@ece.cornell.edu

   Marc R. Pearlman
   389 Frank Rhodes Hall
   School of Electrical & Computer Engineering
   Cornell University
   Ithaca, NY 14853
   United States of America
   tel: (607) 255-0236, fax: (607) 255-9072
   Email: pearlman@ece.cornell.edu

   Prince Samar
   374 Frank Rhodes Hall
   School of Electrical & Computer Engineering
   Cornell University
   Ithaca, NY 14853
   United States of America
   tel: (607) 255-9068, fax: (607) 255-9072
   Email: samar@ece.cornell.edu

 The MANET Working Group contacted through its chairs:

   M. Scott Corson
   Institute for Systems Research
   University of Maryland
   College Park, MD 20742
   (301) 405-6630

   Joseph Macker
   Information Technology Division
   Naval Research Laboratory
   Washington, DC 20375
   (202) 767-2001

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