AdHoc Routing: Proactive and Reactive

Mobile AdHoc Networks

Networks formed by wireless hosts that may be mobile and do not necessarily rely on pre-existing infrastructure.

Routing Protocols

Methods used to determine the best path for data transmission in a network.

Flooding

A data delivery method where a sender broadcasts a packet to all its neighbors, who then forward it to their neighbors.

Dynamic Source Routing (DSR)

A routing protocol where the source node initiates a route discovery process to find a path to the destination node.

Route Request (RREQ)

A message sent by a source node to discover a route to a destination node in DSR.

Route Reply (RREP)

A message sent by the destination node in response to a RREQ, providing the route back to the source.

Route Caching

The process of storing learned routes in a node's memory to speed up future route discoveries.

Route Error (RERR)

A message generated when a node cannot forward a packet due to a broken link, prompting a new route discovery.

Ad Hoc On-Demand Distance Vector Routing (AODV)

A routing protocol that maintains routing tables at nodes to avoid large packet headers and improve performance.

Broadcast Storm Problem

A situation where multiple nodes broadcast the same message simultaneously, leading to collisions and redundancy.

Sequence Numbers

Used in AODV to determine the freshness of routes and prevent the use of outdated or broken routes.

Link Failure Detection

Mechanisms such as hello messages or MAC-level acknowledgments used to identify broken links in a network.

Reverse Path Setup

The process in AODV where a reverse path is established when a Route Request is forwarded.

Timeout

A specified duration after which routing table entries are purged if not used, ensuring that stale routes are removed.

Proactive Protocols

Routing schemes that maintain up-to-date routing information regardless of the need for it, as opposed to reactive protocols that only update when necessary.

Link State Routing

A routing method where each node periodically floods the status of its links to all other nodes to maintain a complete view of the network.

Dijkstra’s Algorithm

A method used in link state routing to find the shortest path from a given node by calculating paths in order of increasing length.

Link State Packet (LSP)

A packet created by each node containing the node's ID, link costs to neighbors, a sequence number, and a time-to-live value.

Optimized Link State Routing (OLSR)

A routing protocol that reduces flooding overhead by using multipoint relays to forward link state information.

Distance-Vector Protocol

A routing protocol where each node maintains a table of available destinations, the next node to reach each destination, and the number of hops to each destination.

Destination-Sequenced Distance-Vector (DSDV)

A routing protocol that uses sequence numbers to prevent loops and maintain routing information in ad-hoc networks.

Multipoint Relays

Nodes in OLSR that are responsible for forwarding broadcast messages to reduce redundancy in link state information dissemination.

Sequence Number (SEQNO)

A number used in routing protocols to ensure the freshness of routing information and to prevent loops.

Cost Metric

A value representing the cost (or weight) associated with a path in routing protocols, used to determine the best route to a destination.

Full/Incremental Update

Methods of propagating routing information where full updates send all routing information, while incremental updates only send changed entries.

Count to Infinity

A problem in distance-vector protocols where routing loops can cause the metric to increase indefinitely, leading to network instability.

Loop Freedom

A property of routing protocols, such as DSDV, that ensures no routing loops occur, typically achieved through the use of sequence numbers.

Routing Information Protocol (RIP)

A specific distance-vector routing protocol that uses hop count as its metric for path selection.