Routing in Mobile Ad hoc Networks
Fenglien Lee · InTech eBooks · 2011
Protocol Design 300 Routing protocols for MANETThe growth of laptops and 802.11/Wi-Fi wireless networking has made MANETs a popular research topic since the 1990s.Many academic papers evaluate protocols and abilities assuming varying degrees of mobility within a bounded space, usually with all nodes within a few hops of each other and usually with nodes sending data at a constant rate.Different protocols are then evaluated based on the packet drop rate, average routing load, average end-to-end-delay, and other measures.The proposed solutions for routing protocols could be grouped in three categories: proactive (or table-driven), reactive (or on-demand), and hybrid protocols.Even the reactive protocols have become the main stream for MANET routing.In this chapter, we introduce some popular routing protocols in each of the three categories and for IPv6 networks Applications for MANETAd hoc networks are suited for use in situations where infrastructure is either not available or not trusted, such as a communication network for military soldiers in a field, a mobile network of laptop computers in a conference or campus setting, temporary offices in a campaign headquarters, wireless sensor networks for biological research, mobile social networks such as Facebook, MySpace and Twitter, and mobile mesh networks for Wi-Fi devices [Lee2009]. Proactive routing protocolsEvery proactive routing protocol usually needs to maintain accurate information in their routing tables.It attempts to continuously evaluate all of the routes within a network.This means the protocol maintains fresh lists of destinations and their routes by periodically distributing routing tables throughout the network.So that when a packet needs to be forwarded, a route is already known and can be used immediately.Once the routing tables are setup, then data (packets) transmissions will be as fast and easy as in the tradition wired networks.Unfortunately, it is a big overhead to maintain routing tables in the mobile ad hoc network environment.Therefore, the proactive routing protocols have the following common disadvantages: 1. Respective amount of data for maintaining routing information.2. Slow reaction on restructuring network and failures of individual nodes.Proactive routing protocols became less popular after more and more reactive routing protocols were introduced.In this section, we introduce three popular proactive routing protocols -DSDV, WRP and OLSR.Besides the three popular protocols, there are many other proactive routing protocols for MNAET, such as CGSR, HSR, MMRP and so on [Wiki2010c][Sholander2002]. Destination-Sequenced Distance Vector (DSDV)Destination-Sequenced Distance-Vector Routing (DSDV) is a table-driven routing scheme for ad hoc mobile networks based on the Bellman-Ford algorithm.It was developed by C. Perkins and P. Bhagwat in 1994.The main contribution of the algorithm was to solve the routing loop problem.Each entry in the routing table contains a sequence number.If a link presents the sequence numbers are even generally, otherwise an odd number is used.