  The main goal of routing protocol is to efficiency delivers data from source
to destination. All routing protocols are the same in this goal, but the way
they adopt to achieve it is different, so routing strategy has an egregious
role on the performance of an ad hoc network. Most of routing protocols
proposed for ad hoc networks have a flat structure. These protocols expand the
control overhead packets to discover or maintain a route. On the other hand a
number of hierarchical-based routing protocols have been developed, mostly are
based on layered design. These protocols improve network performances
especially when the network size grows up since details about remote portion of
network can be handled in an aggregate manner. Although, there is another
approach to design a protocol called cross-layer design. Using this approach
information can exchange between different layer of protocol stack, result in
optimizing network performances.
  In this paper, we intend to exert cross-layer design to optimize Cluster
Based Routing Protocol (Cross-CBRP). Using NS-2 network simulator we evaluate
rate of cluster head changes, throughput and packet delivery ratio. Comparisons
denote that Cross-CBRP has better performances with respect to the original
CBRP.
