Gugrajah_Yuvaan_ Ramesh_2003.pdf
Gugrajah_Yuvaan_ Ramesh_2003.pdf
Gugrajah_Yuvaan_ Ramesh_2003.pdf
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Routing Protocols for Ad Hoc Networks Chapter 2<br />
cope with highly mobile networks. Another problem is that nodes forming part of the<br />
spine will need to utilize their resources (processing time and power) more than other<br />
nodes in the network.<br />
2.2.6. Multi-scope and Hybrid Routing Protocols<br />
The multi-scope routing protocols distinguish nodes by their relative positions. More<br />
resources are devoted to maintaining the topology information of nearby nodes rather<br />
than maintaining a global view of the network. Scalability is therefore the main<br />
advantage of the multi-scope routing protocols. The multi-scope routing protocols<br />
can be divided into flat and hierarchical routing protocols. The flat multi-scope<br />
routing protocols include DREAM (discussed in section 2.2.4.2), the Zone Routing<br />
Protocol (ZRP) [Haas99] and Fisheye State Routing (FSR) [Iwata99]. The<br />
hierarchical routing protocols include Cluster-Head Gateway Switch Routing<br />
(CGSR) [Chiang97], Hierarchical State Routing (HSR) [Iwata99] and Zone-based<br />
Hierarchical Link State (ZHLS) [Joa99] routing.<br />
2.2.6.1. ZRP<br />
The Zone Routing Protocol (ZRP) [Haas99] provides a hybrid routing framework<br />
\<br />
that is locally proactive and globally reactive. Each node proactively advertises its<br />
link state only to its routing zone, which includes all nodes within a certain number<br />
of hops away from the node. The zone radius is adjustable and provides an<br />
optimisation parameter. The local advertisements give each node an updated view of<br />
its own routing zone. The Intrazone Routing Protocol (IARP) is responsible for<br />
maintaining routes within each node's zone through periodic routing table updates.<br />
[Haas99] states that the type of proactive routing used in the IARP (distance vector<br />
or link state) has very little effect on the performance of ZRP. Figure 2-7 illustrates<br />
the concept of a zone in ZRP with zone radius of 2 hops.<br />
The neighbouring nodes that are exactly the number of hops away from the node as<br />
the zone radius dictates, are referred to as peripheral nodes. The peripheral nodes<br />
represent the boundary of the routing zone and play an important role in zone based<br />
route discovery. The Interzone Routing Protocol (IERP) uses on-demand routing to<br />
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