
7-6 Industrial Communication Systems
in this category comprise core extraction distributed ad hoc routing (CEDAR) protocol [SSB99] and
zone-based
hierarchical link state (ZHLS) routing protocol.
7.2.2.2
Flat and Hierarchical
R
outing Protocols
Hierarchical routing protocols arrange nodes in the form of clusters or trees where every cluster has a clus-
ter head. Cluster heads may also aggregate data from cluster nodes to reduce the number of packet trans-
missions and hence conserve energy [CPF05] or may provide gateway to external networks. Advantages
of hierarchical routing protocols include scalability and ecient communication [AK04]. AODV