Routing protocols in Mobile Adhoc Network. Contents. Introduction. Types of wireless network. Adhoc network. Characteristics of Ad hoc network. Why is Routing Different in Ad hoc. Adhoc Routing Protocols. Comparison. Application. Conclusion. References.
Contents • Introduction • Types of wireless network • Adhoc network • Characteristics of Ad hoc network • Why is Routing Different in Ad hoc • Adhoc Routing Protocols • Comparison • Application • Conclusion • References
Types of Wireless Networks • Infrastructure based(Cellular Network). • Infrastructureless Network(Mobile Ad hoc Network) (MANET).
Characteristics 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 ??? • Host mobility • Dynamic topology • link failure/repair due to mobility • Distributed Environment • Bandwidth constrained • Energy constrained
Table 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 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.
Destination-Sequenced Distance Vector Protocol (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 DSDV A’s Routing Table Before Change A’s Routing Table After Change
Clusterhead Gateway Switch Routing (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 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.
Ad hoc On-demand Distance Vector Routing(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 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 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 (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.
Zone 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 ZPR • Three types of nodes: • Border Nodes • Peripherals Nodes • Interior Nodes
Applications • Virtual classroom • Deployment of sensors • Conferences • Exhibitions • Military
Conclusion • Several existing routing protocols for ad hoc wireless networks were described. • So, network context and goal must be kept in mind before choosing any routing protocol. • In terms of metrics: Throughput: The proactive protocols perform better than the reactive protocols. End to End delay:The proactive protocols perform better than reactive protocols. Routing Load: The reactive protocols perform better than the proactive protocols.
References • 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