protocols. Depending on the way the group members are connected, multicast ad-hoc routing
protocols can be categorized into tree-based and mesh-based routing protocols.
Table 2.2 Comparison between Multicast ad-hoc routing protocols
Routing Protocol |
MAODV |
AMRIS |
ODMRP |
CAMP |
Multicast structure |
Core based tree |
Tree |
Mesh |
Mesh |
Routing information exchange & |
Reactive |
Proactive |
Reactive |
Proactive |
Periodical messages required |
No |
Yes |
Yes |
Yes |
Dependency on unicast routing |
Yes |
No |
No |
Yes |
Routing hierarchy |
Flat |
Flat |
Flat |
Flat |
Scalability |
Fair |
Fair |
Fair |
Good |
MAODV and AMRIS discussed in more details earlier in this chapter are examples of tree-
based multicast ad-hoc routing protocols. MAODV is an extension for AODV, which is
considered as a reactive multicast routing protocol, it uses small size periodical (Grp-Hello)
messages to keep routes fresh. In AMRIS, there is no dependency on unicast routing
protocol, consequently, it can be considered as a proactive multicast routing protocol which
causes high overhead in comparison with MAODV. Both protocols give a fair solution to
scalability issue.
ODMRP and CAMP are considered as mesh-based multicast ad-hoc routing protocols. The
mesh-based provides redundant paths from source to destinations among the group. ODMRP
can be considered as reactive multicast routing protocol that uses periodical messages to keep
group members connected and information updated and improves the scalability feature by
using the Forwarding Group nodes (FG). CAMP can be considered as a proactive multicast
routing protocol, which requires running an underlying unicast routing protocol and is using
a periodical messages to keep routes up to date. This protocol distinguished by scalability
issue because it constructs a mesh for each group and each mesh can have more than one
core.
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