Examples on this kind of routing protocols are On-demand Multicast Routing
Protocol (ODMRP) [47] and Core Assisted Mesh Protocol (CAMP) [14].
These protocols follow the concepts of the traditional multicast protocols; the multicast
routing state maintenance and shared group membership management are stored in the
intermediate group members and updated periodically. If applied for use with large number
of small groups within the network these protocols may become more complex and less
efficient.
To solve this issue, recently there has been a shift toward the stateless multicast routing
protocols for small group networks and for MANETs. Some of these protocols were
developed to avoid or reduce any multicast routing state to be maintained by routers. This is
done by using explicit messages that encode receiver’s addresses or a set of group members
addresses in a header and the later is included in an ordinary unicast routing packet.
Examples of this type of multicast routing protocols are Differential Destination Multicast
(DDM) [20] Protocol, A Scalable Multicast protocol for MANETs (E2M) [38] and An
Explicit Multicast protocol for MANETs (EM2NET) [7].
A detailed discussion for the routing protocols previously mentioned above will be included
in the next two chapters of literature review and related work.
1.3 Motivation
Wireless ad-hoc networks have gained considerable importance in wireless communications.
Wireless communication is established by nodes acting as routers and transferring packets
from one to another in ad-hoc networks. Routing in these networks is highly complex due to
the moving nodes and the difficulty of keeping state information about the routers; hence in
the past few years a shift towards the stateless multicast routing protocols has happened.