Zone Routing Protocol

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  • Topic: Routing protocol, IS-IS, Routing
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  • Published : March 6, 2013
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Zone Routing Protocol in Computer Networking (ZRP)

Routing protocols for mobile ad-hoc networks have to
face the challenge of frequently changing topology, low
transmission power and asymmetric links. Both
proactive and reactive routing protocols prove to be
inefficient under these circumstances. The Zone Routing
Protocol (ZRP) combines the advantages of the proactive
and reactive approaches by maintaining an up-to-date
topological map of a zone centered on each node. Within
the zone, routes are immediately available. For
destinations outside the zone, ZRP employs a route
discovery procedure, which can benefit from the local
routing information of the zones.
This paper presents the Zone Routing Protocol. First, we
discuss the problem of routing in ad-hoc networks and
the motivation of ZRP. We describe the architecture of
ZRP, which consists of three sub-protocols. We describe
the routing process and illustrate it with an example.
Further, we describe the query control mechanisms,
which are used to reduce the traffic amount in the route
discovery procedure. ZRP does not define the actual
implementation of the protocol components. Therefore,
we present the guidelines for implementation, and
example implementations provided in the draft
specifications. We discuss the problem of routing in
networks with unidirectional links, and the proposal for a
solution to it. The overhead of the routing protocol is
important in the power and bandwidth limited ad-hoc
networks. We discuss the factors influencing on the
traffic amount based on measurements performed in a
number of papers. We describe the significant issue of
choosing an optimal zone radius, and two algorithms for
automatic selection of the radius. Finally, we draw some
conclusions about the performance of the protocol. The
paper is based on literature research.
Keywords: Zone Routing Protocol, ZRP, IARP, IERP,
BRP, Ad-hoc network, Routing, MANET
1 Introduction
Ad-hoc networks are mobile wireless networks that have
no fixed infrastructure. There are no fixed routers –
instead each node acts as a router and forwards traffic
from other nodes. Ad-hoc networks were first mainly
used for military applications. Since then, they have
become increasingly more popular within the computing
industry. Applications include emergency search-andrescue
operations, deployment of sensors, conferences,
exhibitions, virtual classrooms and operations in
environments where construction of infrastructure is
difficult or expensive. Ad-hoc networks can be rapidly
deployed because of the lack of infrastructure. [2] [16]
A MANET (Mobile Ad-hoc Network) is a type of adhoc
network with rapidly changing topology. These
networks typically have a large span and connect
hundreds to thousands of nodes [16]. Correspondingly,
the term Reconfigurable Wireless Networks (RWN)
refers to large ad-hoc networks that can be rapidly
deployed without infrastructure and where the nodes are
highly mobile [14]. In this paper, we concentrate on
routing in large ad-hoc networks with high mobility.
Since the nodes in a MANET are highly mobile, the
topology changes frequently and the nodes are
dynamically connected in an arbitrary manner. The rate
of change depends on the velocity of the nodes.
Moreover, the devices are small and the available
transmission power is limited. Consequently, the radio
coverage of a node is small. The low transmission power
limits the number of neighbor nodes, which further
increases the rate of change in the topology as the node
moves. Because of interference and fading due to high
operating frequency in an urban environment, the links
are unreliable. Ad-hoc networks are further characterized
by low bandwidth links. Because of differences in
transmission capacity, some of the links may be
unidirectional. As a result of link instability and node
mobility, the topology changes frequently and routing is
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