Routing protocols in Routing protocols in Mobile Ad Hoc NetworkMobile Ad Hoc Network
UNIVERSITY COLLEGE OF ENGINEERING
BURLA, SAMBALPUR
Types of Wireless Networks
Infrastructure based(Cellular Network).
Infrastructureless Network(Mobile Ad hoc NETwork) (MANET).
Characteristics of an Ad-hoc networkCharacteristics of an Ad-hoc network
Collection of mobile nodes forming a temporary network
Network topology changes frequently and unpredictably
No centralized administration or standard support services
Host is also function as router
Why is Routing Different in Ad Hoc ???Why is Routing Different in Ad Hoc ???
Host mobility• Dynamic topology• link failure/repair due to mobility
Distributed Environment Bandwidth constrained Energy constrained
Categorization of Ad-Hoc Routing Protocols
Table Driven Routing ProtocolTable Driven Routing Protocol
Proactive. Each node maintains one or more tables
containing routing information to every other node in the network.
Tables need to be consistent and up-to-date view of the network.
Updates propagate through the network
Source Initiated On demand routing protocolSource Initiated On demand routing protocol
Reactive. on-demand style: create routes only when it is
desired by the source node When a node requires a route to a destination,
it initiates a route discovery process Route is maintained until destination becomes
unreachable, or source no longer is interested in destination.
Table Driven Routing ProtocolTable Driven Routing Protocol
Destination-Sequenced Distance Vector ProtocolDestination-Sequenced Distance Vector Protocol (DSDV) (DSDV)
Basic Routing Protocol Based on Bellman ford routing algorithm with some
improvement Each node maintains a list of all destinations and
number of hops to each destination. Each entry is marked with a sequence number. Periodically send table to all neighbors to maintain
topology
• Two ways to update neighbors:– Full dump– Incremental update
Example of DSDVExample of DSDV
Destination Next Hop Distance Sequence Number
A A 0 S205_A
B B 1 S334_B
C C 1 S198_C
D D 1 S567_D
E D 2 S767_E
F D 2 S45_F
Destination Next Hop Distance Sequence Number
A A 0 S304_A
B D 3 S424_B
C C 1 S297_C
D D 1 S687_D
E D 2 S868_E
F D 2 S164_F
A’s Routing Table Before Change
A’s Routing Table After Change
Clusterhead Gateway Switch RoutingClusterhead Gateway Switch Routing (CGSR) (CGSR)
Similar to DSDV Based on concept of clusters and cluster heads Routing is done via the cluster heads and
gateways A routing table among cluster heads are
maintained
Example of CGSRExample of CGSR
Data forwarding steps:•from cluster head to cluster head–in a hierarchical manner•then from cluster head to cluster members•between two cluster heads, gateways are used to forward the packets
Source Initiated On demand Source Initiated On demand routing protocolrouting protocol
Ad hoc On-demand Distance Vector RoutingAd hoc On-demand Distance Vector Routing(AODV)(AODV)
Pure on-demand protocol Node does not need to maintain knowledge of another
node unless it communicates with it AODV includes route discovery and route maintenance. AODV minimizes the number of broadcasts by creating
routes on-demand AODV uses only symmetric links because the route reply
packet follows the reverse path of route request packet AODV uses hello messages to know its neighbors and
to ensure symmetric links
Path discoveryPath discovery
In the path discovery (RREQ) phase, source broadcasts RREQ message.
Intermediate nodes record in their route tables the address of neighbor from which RREQ is received to establish a reverse path.
When RREQ reaches destination or an intermediate node responds by unicasting a route reply (RREP) back to neighbor.
Path maintenancePath maintenance
If source node moves, reestablish the path. If destination or intermediate node moves,
send link failure notification message to each of its active upstream.
Then reinitiate path discovery .
Dynamic Source Routing Protocol Dynamic Source Routing Protocol (DSR)(DSR)
on-demand A node maintains route cache containing the
routes it knows Two main phases
• Route discovery• Route maintenance
Basic Operation is similar to AODV. Main difference
• To use routing cache for link failure.• When route discovery phase, node send route
request message with its own address.
Example of DSRExample of DSR
Hybrid Routing Protocols
Zone Routing ProtocolZone Routing Protocol
Hybrid of table-driven and on-demand!! From each node, there is a concept of “zone”.
• Within each zone, the routing is performed in a table-driven manner (proactive).
• However, a node does not try to keep global routing information.
For inter-zone routing, on-demand routing is used.
Example of ZPRExample of ZPR
Three types of nodes:• Border Nodes• Peripherals Nodes• Interior Nodes
ComparisonComparison
Parameters On Demand Table Driven
Availability of routing
information
Available when
needed
Always available regardless of need
Routing philosophy Flat Mostly flat, except for
CGSR
Periodic route updates Not required Required
Coping with mobility Use localized route discovery
Inform other nodes to achieve a consistent routing
table
Signaling traffic generated Grows with
increasing mobility
Greater than that of on
demand routing
ReferencesReferences
Elizabeth M. Royer, Chai-Keong Toh, A Review of Current Routing Protocols for Ad Hoc Mobile Wireless Networks,Proc. IEEE,1999.
David B. Johnson, " Routing in Ad hoc Networks of Mobile Hosts", Proc
IEEE Workshop on Mobile Computing Systems and Applications. Nicklas Beijar “Zone Routing Protocol “. www.cse.wustl.edu/~jain/cis788-99/adhoc_routing/ http://www.comp.brad.ac.uk/~sburuha1/index.htm www.computingunplugged.com/
issues/issue200407/00001326001.html http://www.ietf.org/rfc/rfc3561.txt
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