Overview of Ad Hoc
Routing Protocols
Overview
 1.
Overview
Table-Driven Approaches
 Protocols require each node to maintain one or more table
to store routing information, and they respond to changes
in network topology by propagating route updates
throughout the network to maintain a consistent network
view.
Distance Vector Routing Algorithm 1/2
Distance Vector Routing Algorithm 2/2
 Count-to-infinite
Destination Sequenced Distance
Vector (DSDV) 1/2
 Introduction
 Table-Driven routing protocol
 Based on the classical distributed Bellman-Ford
Algorithm.
 Using the Sequence Numbering System to avoid the
routing loop in a mobile network of routers
 Two types of route update packets
-Full dump
-Incremental packets
Destination Sequenced Distance
Vector (DSDV) 2/2
 Routing
 New route broadcasts will contain the address of the
destination node, the number of hops to reach the
destination, the sequence number of the information
received regarding the destination
 In the event that two updates have the same sequence
number, the route with the smaller hop count is used.
Cluster Switch Gateway Routing
(CSGR) 1/3
 Introduction
 Mobile nodes are grouped into clusters and each cluster
has a cluster head.
 CSGR modifies DSDV by using a hierarchical clusterhead-to-gateway routing approach to route traffic from
source to destination.
Cluster Switch Gateway Routing
(CSGR) 2/3
 Routing
 Gateway nodes are nodes that are within communication
range of two or more cluster.
 Each node must keep a Cluster member table and Routing
table
 The cluster member tables are broadcast periodically by
each node using the DSDV protocol.
 To avoid invoking cluster head reselection every time the
cluster membership changes, a least cluster change (LCC)
algorithm is introduced.
Cluster Switch Gateway Routing
(CSGR) 3/3
Wireless Routing Protocol (WRP)
 Introduction
 WRP Belongs to the class of path-finding algorithm
 Avoid the count-to-infinity problem
 WRP must maintain four tables
(a) Distance table
(b) Routing table
(c) Link-cost table
(d) Message retransmission list table
 The update message contains a list of updates ( the
destination, the distance to destination, the predecessor of
the destination)
Source-Initiated On-Demand
Approaches
 This type of routing creates routes only when desired by
the source node.
 When a node requires a route to a destination, it initiates a
route discovery process within the network.
Ad Hoc On-Demand Distance Vector
Routing (AODV) 1/5
Introduction
 AODV is an improvement on DSDV
 Nodes that are not on a selected path do not maintain
routing information or participate in routing table
exchanges.
Ad Hoc On-Demand Distance Vector
Routing (AODV) 2/5
Routing Protocol
Ad Hoc On-Demand Distance Vector
Routing (AODV) 3/5
Ad Hoc On-Demand Distance Vector
Routing (AODV) 4/5
 Route Request (RREQ)
 Route Reply (RREP)
 AODV uses destination sequence numbers to
ensure that all routes are loop-free and contain the
most recent route information
Ad Hoc On-Demand Distance Vector
Routing (AODV) 5/5
 If a source node moves, it has to reinitiate the route
discovery protocol to find a new route to the destination
 If a node along the route moves, its upstream neighbor
notices the move and propagates a link failure
notification message to each of its active upstream
neighbors to inform them of the erasure of that part of the
route.
Dynamic Source Routing (DSR)
1/3
 Based on the concept of source routing
 Consist of two major phases
-Route Discovery
-Route Maintenance
 Route Discovery
If a mobile node has an unexpired route to the destination
YES
NO
Use the route
Broadcasting a route request packet
This route request message contain destination address,
source node’s address, a unique identification number
Dynamic Source Routing (DSR)
2/3
Each node receiving the packet
checks whether it know of a
route to the destination
YES
NO
 Figure5.4a
Use the route
Add node’s own address to the route record of the packet
and then forwards the packet along its outgoing links
Dynamic Source Routing (DSR)
3/3
 Route Reply
When either the route request
reaches the destination itself, or
when it reach an intermediate
node that contains in its route
cache an unexpired route to the
destination
Temporally Ordered Routing
Algorithm (TORA) 1/3
 Based on the concept of link reversal
 Key design concept of TORA is the localization of control
messages to a very small set of nodes near the occurrence
of a topological change
 The protocol performs three basic functions
-(a) Route creation
-(b) Route maintenance
-(c) Route erasure
Temporally Ordered Routing
Algorithm (TORA) 2/3
 Route creation
 Height
 Directed Acyclic Graph (DAG)
Temporally Ordered Routing
Algorithm (TORA) 3/3
 Route maintenance
 The DAG route is broken and route maintenance is necessary to re-
establish a DAG rooted at the same destination
Associativity Based Routing (ABR)
1/3
 A route is selected based on associativity states of nodes
 For every beacon received, a node increments its
associativity tick with respect to the node from which it
received
 The three phases of ABR are
-Route Discovery
-Route Reconstruction
-Route Deletion
Associativity Based Routing (ABR)
2/3
 Route Discovery
 The route discovery phase is a broadcast query and await-
reply (BQ-REPLY) cycle
 A node does not forward a BQ request more than once
 Each packet arriving at the destination will contain the
associativity ticks of the nodes along the route from source
to the destination
 Once a path has been chosen, the destination sends a
REPLY packet back to the source along this path.
Associativity Based Routing (ABR)
3/3
 Route Reconstruction
 Source node movement results in a new BQ-REPLY
process because the routing protocol is source-initiated
 When the destination moves, the destination’s immediate
upstream node erases its route
 A localized query (LQ [H]) process where H refers to the
hop count from the upstream node to the destination, is
initiated to determine if the node is still reachable
Signal Stability Routing (SSR) 1/5
 SSR is a descendent of Associativity-Based Routing
 SSR selects routes based on the signal strength between
nodes and on a node’s location stability
 SSR route selection criteria has the effect of choosing
routes that have “stronger” connectivities.
 SSR can be divided into two cooperative protocols
-(a) the Dynamic Routing Protocol (DRP)
-(b) the Static Routing Protocol (SRP)
Signal Stability Routing (SSR) 2/5
 Dynamic Routing Protocol (DRP)
 The DRP is responsible for the maintenance of the signal
strength of neighboring nodes
 The signal strength may be recorded as either a strong or
weak channel
 After updating all appropriate table entries, the DRP passes
a received packet to the SRP
Signal Stability Routing (SSR) 3/5
 Static Routing Protocol (SRP)
 The SRP passes the packet up the stack if it is the intended
receiver. If not, it looks up the destination in the RT and
forwards the packet.
 If no entry is found in the RT for the destination, a routesearch process is initiated to find a route
 Route requests are propagated throughout the network, but
are only forwarded to the next hop if they are received over
strong channels and have not been previously processed
Signal Stability Routing (SSR) 4/5
 The destination chooses the first arriving route-search
packet to send back because it is most probable that the
packet arriving over the shortest and/or least congested
path
 The DRP then reverses the selected route and sends a
route-reply message back to the initiator
 The DRP of the nodes along the path update their RTs
accordingly
Signal Stability Routing (SSR) 5/5
 The assumption made in SSR is that route search packets
arriving at the destination might have chosen the path of
strongest signal stability, as the packets are dropped at a
node if they have arrived over a weak channel
 If there is no route-reply message received at the source
within a special timeout period, the source changes the
PREF field in the header to indicate that weak channels are
as these may be the only links over which the packet can
be propagated
Power-Aware Routing (PAR) 1/2
 In Power-Aware Routing, battery life is taken as the
routing metric.
 PAR advocates for
-Minimizing the energy consumed per packet
-Maximizing the time before the network is partitioned
-Minimizing the variance in node power levels
-Minimizing the cost per packet
-Minimizing the maximium node cost
Power-Aware Routing (PAR) 2/2
Zone Routing Protocol (ZRP) 1/3
 The Zone Routing Protocol is a hybrid protocol
incorporating the merits of on-demand and proactive
routing protocols.
 With this zone, a table-driven-based routing protocol is
used
 If the destination node reside outside the source zone. An
on-demand search-query routing method is used.
 ZRP itself has three sub-protocols
- IARP
- IERP
- BRP
Zone Routing Protocol (ZRP) 2/3
Zone Routing Protocol (ZRP) 3/3
 The proactive (table-driven) Intrazone Routing




Protocol (IARP)
Its main role is to ensure that each node within the zone
has a consistent routing table that is up-to-date and reflects
information on how to reach all other nodes in the zone.
The reactive Interzone Routing Protocol (IERP)
IERP relies on border nodes to perform on-demand routing
to search for routing information to nodes reside its current
zone.
IERP uses the bordercast resolution protocol