  A mobile ad hoc network is a self organized cooperative network that works
without any permanent infrastructure. This infrastructure less design makes it
complex compared to other wireless networks. Lot of attacks and misbehavior
obstruct the growth and implementation. The majority of attacks and misbehavior
can be handled by existing protocols. But these protocols reduce the total
strength of nodes in a network because they isolate nodes from network
participation having lesser reputation value. To cope with this problem we have
presented the Possibility and Certainty model. This model uses reputation value
to determine the possibilities and certainties in network participation. The
proposed model classifies nodes into three classes such as certain or HIGH
grade possible or MED grade and not possible or LOW grade. Choosing HIGH grade
nodes in network activities improves the Packet Delivery Ratio which enhances
the throughput of the MANET. On the other hand when node strength is poor we
choose MED grade nodes for network activities. Thus the proposed model allows
communication in the worst scenario with the possibility of success. It
protects a network from misbehavior by isolating LOW grade nodes from routing
paths.
