This document discusses routing protocols in mobile ad hoc networks (MANETs). It begins by describing the unique characteristics of MANETs, such as mobile nodes and multi-hop routing without infrastructure. The main challenges for routing in MANETs are the need for dynamic routing due to frequent topological changes and minimizing routing overhead. The document then categorizes the main types of MANET routing protocols as topology-based, reactive, proactive, and hybrid approaches. It provides examples like DSR, AODV, and ZRP and describes the basic functioning of reactive on-demand and proactive routing protocols. Hybrid protocols combine aspects of both reactive and proactive routing.

1. ROUTING PROTOCOLS
IN MANETS
By Rohit Sharma

2. WHAT IS A MANET
Mobile nodes, wireless links
Infrastructure-less: by the nodes, …
Multi-hop routing: …, and for the nodes
Minimal administration: no hassles

3. WHAT’S UNIQUE ABOUT A
MANET ?
Moving nodes  ever changing topology
Wireless links
  various and volatile link quality
Pervasive (cheap) devices
  Power constraints
Security
 Confidentiality, other attacks

4. CHALLENGES IN MANET
ROUTING
Need dynamic routing
 Frequent topological changes possible.
 Very different from dynamic routing in the
Internet.
 Potential of network partitions.
Routing overhead must be kept minimal
 Wireless  low bandwidth
 Mobile  low power
 Minimize # of routing control messages
 Minimize routing state at each node

5. MANET PROTOCOL ZOO
Topology based routing
 Proactive approach, e.g., DSDV.
 Reactive approach, e.g., DSR, AODV, TORA.
 Hybrid approach, e.g., Cluster, ZRP.

6. ROUTING PROTOCOLS
Reactive (On-demand) protocols
 Discover routes when needed
 Source-initiated route discovery
Proactive protocols
 Traditional distributed shortest-path protocols
 Based on periodic updates. High routing
overhead
Hybrid protocols
 They introduces a hybrid model that combines
reactive and proactive routing protocols.

7. REACTIVE ROUTING
No routing structure created a priori. Let the structure
emerge in response to a need
Reactive routing is also known as on-demand routing
protocol since they do not maintain routing information or
routing activity at the network nodes if there is no
communication.
If a node want to send a packet to another node then this
protocol searches for the route in an on-demand manner
and establishes the connection in order to transmits and
receive the packet.
The route discovery occurs by flooding the route request
packets throughout the network.

8. REACTIVE (ON-DEMAND)
ROUTING:
Routing only when needed
0
5
1
2
4
3
query(0)
query(0)
query(0)
query(0)
query(0)
query(0)
query(0)
reply(0)
reply(0)
reply(0)
Advantages:
 eliminate periodic updates
 adaptive to network dynamics
Disadvantages:
 high flood-search overhead
with
mobility, distributed traffic
 high route acquisition latency

9. PROACTIVE ROUTING
In proactive routing, each node has to maintain one or
more tables to store routing information and any
changes in network topology need to be reflected by
propagating updates throughout the network in order to
maintain a consistent network view.

10. HYBRID ROUTING
They introduces a hybrid model that combines reactive
and proactive routing protocols.
The zone protocol (ZRP) is a hybrid routing protocol that
divide the network into zones.

11. ZONE ROUTING PROTOCOL
Zone 1
Zone 3
Zone 2