However,
the key concept of OLSR is an optimized broadcast mechanism for the
network-wide distribution of the necessary link-state information. Each
node selects the so-called multipoint relays (MPRs) among its neighbors
in such away that all 2-hop neighbors receive broadcastmessages even if
only the MPRs rebroadcast the messages. The forwarding of broadcast
messages by MPRs only can significantly reduce the number of
broadcast messages. Figure 4.3 shows an example where the number
of broadcast messages is reduced by half. This optimized forwarding
mechanismis used for all broadcasts in an OLSR network. Moreover, the
amount of link-state information to be distributed within the network
can be reduced with OLSR, because only the link state information to all
MPR selectors is necessary for the computation of shortest paths.