overview of ad hoc routing protocols. overview 1

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 cluster-

head-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 DiscoveryIf a mobile node has an unexpired route to the destination

This route request message contain destination address, source node’s address, a unique identification number

Use the route

Broadcasting a route request packet

YES

NO

Dynamic Source Routing (DSR)2/3

Each node receiving the packet checks whether it know of a route to the destination

Figure5.4a

Use the route

Add node’s own address to the route record of the packetand then forwards the packet along its outgoing links

YES

NO

Dynamic Source Routing (DSR)3/3

Route ReplyWhen 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 route-search 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