Gugrajah_Yuvaan_ Ramesh_2003.pdf

Routing Protocolsfor Ad Hoc Networks
2.2.6.2. FSR
o
IERP IARP
Dominate
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___ 0
Optimum
Zone Radius
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Dominate ;'
/
;'
;'
;'
/IARP
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./
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Zone Radius
Figure 2-8. The optimum region for the zone radius resides
between the IERP and IARP dominated regions [Haas99].
Chapter 2
The Fisheye State Routing (FSR) protocol [Iwata99] models the routing
methodology on the way in which the eye of a fish functions. The eye of a fish
captures with high detail the pixels near the focal point and the detail decreases as the
distance from the focal point increases. Figure 2-9 illustrates the concept of Fisheye
State Routing.
The aim of FSR is to reduce routing update overhead in large networks. Nodes
maintain a link state table based on the up-to-date information received from
neighbouring nodes and periodically exchange it with their local neighbours only,
which prevents flooding. Table entries with larger sequence numbers replace the
ones with smaller sequence numbers. The circles with different shades of grey in
Figure2-9 define the fisheye scopes with respect to the centre node. Three scopes are
shown for 1 hop, 2 hops and hops greater than 2, respectively. Different exchange
periods are used for different entries in the routing table. Entries corresponding to
nodes within the smallest scope are propagated to the neighbours most frequently.
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