Ad-hoc routing protocols
- 2. Ad-hoc Routing Protocol: A standard, that controls how nodes decide which way to route packets between computing devices in a mobile ad hoc network . In ad-hoc networks, nodes are not familiar with the topology of their networks; instead, they have to discover it. The basic idea is that a new node may announce its presence and should listen for announcements broadcast by its neighbors. Each node learns about nodes nearby and how to reach them, and may announce that it, too, can reach them. The Routing Protocol deal with end-to-end communication. 2
- 3. i. Minimal control overhead: ► Control messaging consumes bandwidth, processing resources and battery power to both transmit and receive a message. ► Should not send more than the minimum no of control message they need for operation. While transmitting is roughly twice as power consuming as receiving. Thus need to reduce control messaging. ii. Minimal processing overhead: ► Algo that are computationally complex require more processing cycles, thus consume more resources. ► Protocol should be lightweight and use a minimum of processing resources from the mobile devices. Goal of Routing Protocol: 3
- 4. iii. Multihop routing capability : ► Transmission range of mobile node is limited. ► Routing protocol must be able to discover Multihop routes between source and destination so that communication between those node is possible who are not in direct transmission range of each other. iv. Dynamic topology maintenance: ► Once route is established , link may be break due to movement of nodes. ► A viable routing path must be maintained even while the intermediate nodes, or even the source or destination nodes are moving. ► If link breaks, it must be handled quickly with a minimum of associated overhead. 4
- 5. v. Loop prevention: ► When a routing loop exits , data and control packets may traverse the path multiple times until either the path or fixed and the loop is eliminated or until he time to live (TTL) of the packet reaches zero. ► As bandwidth is scarce and packet processing and forwarding is expensive, routing loops are extremely wasteful of resources. ► Loops should be avoided all the times. 5
- 6. 1. Table Driven / Proactive protocols : ♦ This type of protocols maintains fresh lists of destinations and their routes by periodically distributing routing tables throughout the network. ♦ Traditional distributed shortest-path protocols. ♦ Maintain routes between every host pair at all times. ♦ Based on periodic updates; High routing overhead. ♦ Example: DSDV (destination sequenced distance vector) The main disadvantages of such algorithms are: ■ Respective amount of data for maintenance. ■ Slow reaction on restructuring and failures. Routing Protocols: 6
- 7. 2. On-Demand Driven/ Reactive protocols: ♦ This type of protocol finds a route on demand by flooding the network with Route Request packets. ♦ Determine route if and only when needed. ♦ Source initiates route discovery. ♦ Example: DSR (dynamic source routing) The main disadvantages of such algorithms are: ■ High latency time in route finding. ■ Excessive flooding can lead to network clogging. 7
- 8. 3. Hybrid (both proactive and reactive) routing: This type of protocol combines the advantages of proactive and reactive routing. The routing is initially established with some proactively prospected routes and then serves the demand from additionally activated nodes through reactive flooding. The choice of one or the other method requires predetermination for typical cases. The main disadvantages of such algorithms are: ■ Advantage depends on number of other nodes activated. ■ Reaction to traffic demand depends on gradient of traffic volume. Examples of hybrid algorithms are: ■ZRP (Zone Routing Protocol) ZRP uses IARP as pro-active and IERP as reactive component. ■ ZHLS (Zone-based Hierarchical Link State Routing Protocol) 8
- 9. 4. Hierarchical routing protocols: With this type of protocol the choice of proactive and of reactive routing depends on the hierarchic level in which a node resides. The routing is initially established with some proactively prospected routes and then serves the demand from additionally activated nodes through reactive flooding on the lower levels. The choice for one or the other method requires proper attribution for respective levels. The main disadvantages of such algorithms are: ■ Advantage depends on depth of nesting and addressing scheme. ■ Reaction to traffic demand depends on meshing parameters. Examples of hierarchical routing algorithms are: ● CBRP (Cluster Based Routing Protocol. ● FSR (Fisheye State Routing protocol. ● ZHLS (Zone-based Hierarchical Link State Routing Protocol. 9
- 10. I. Jump up^ C. Perkins, E. Royer and S. Das: Ad hoc On-demand Distance Vector (AODV) Routing, RFC 3561 II. Jump up^ David Johnson, David Maltz, Yih-Chun Hu: The Dynamic Source Routing Protocol for Mobile Ad Hoc Networks for IPv4, RFC 4728 III. Jump up^ David B. Johnson, David A. Maltz: Dynamic Source Routing in Ad Hoc Wireless Networks, Mobile Computing, Thomasz Imielinski and Hank Korth (Editors), Vol. 353, Chapter 5, pp. 153–181, Kluwer Academic Publishers, 1996 IV. Jump up^ Yih-Chun Hu, David B. Johnson, David A. Maltz: Flow State in the Dynamic Source Routing Protocol Internet Draft, work in progress, June 2001. V. Jump up^ D. Djenouri, N. Badache. On Eliminating Packet Droppers in MANET: A Modular Solution, Ad hoc Networks Journal, Vol 7, Issue 6, pp 1243–1258, Elsevier Publisher, August 2009. VI. Jump up^ Zygmunt J. Haas, Marc R. Pearlman, Prince Samar: The Zone Routing Protocol (ZRP) for Ad Hoc Networks, Internet Draft, work in progress, July 2002. VII. ^ Jump up to:a b Mario Joa-Ng and I-Tai Lu. "A peer-to-peer two-level link state routing for mobile ad-hoc wireless network". The special issue on Wireless Ad Hoc Networks of IEEE JSAC, Vol. 17, No. 8, pp.1415-1425, Aug. 1999. VIII. Jump up^ M. Jiang, J. Li, Y. C. Tay: Cluster Based Routing Protocol (CBRP) Functional Specification, Internet Draft, work in progress, June 1999. Draft has expired. IX. Jump up^ Maria Gerla, Guangyu Pei, Xiaoyan Hong, Tsu-Wei Chen: Fisheye State Routing Protocol (FSR) for Ad Hoc Networks, Internet Draft, work in progress, June 2001. Draft has expired. 10