A2- 1
APPENDIX (A 2 )
Routing approaches for WMNsA 2 .1 Optimized Link State Routing (OLSR)
The OLSR protocol is an optimized pure state link algorithm. It
is designed to reduce retransmission duplicates and with a proactive nature
the routes are always available when needed. It uses hop by hop mechanics
when forwarding packets [ 51 ]. In the OLSR approach, each node maintains
topology information about the network by periodically exchanging link-
state messages [52]. The usefulness of OLSR is that it minimizes the size
of each control message and the number of rebroadcasting nodes during
each route updates by employing Multi-Point Relaying (MPR) strategy,
and this set of nodes is called the MPRs of that node [52]. To select the
MPRs, each node periodically broadcasts a list of its one hop neighbors
using HELLO messages [53]. Each node selects some of the one hop
neighbors from the HELLO messages, which covers all of its two hop
neighbors. The optimal path to every known destination is determined by
each node by use of the topology information, and this information is
stored in a routing table, which is kept by each node [53]. Thus, routes to
every destination are readily available when data transmission starts. In
situate of increase nodes numbers, these routing tables create higher routing
overhead for OLSR compared to other reactive routing protocols [54].
A 2. 2 Ad Hoc On-demand Distance Vector Routing (AODV) protocol
The (AODV) protocol is a reactive unicast routing protocol for
mobile ad hoc networks [ 55 ]. When a source requires sending data to a
destination and if the route to that destination is not known then it initiates
route discovery [55]. AODV allows nodes to respond to link breakages and
changes in network topology in a timely manner. Routes which are not in