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DA5. Proactive vs Reactive Routing Protocols

Statement

Compare and contrast proactive and reactive wireless routing protocols. In your opinion, what are the best circumstances to deploy either proactive or reactive wireless routing protocols?

Answer

MANET (Mobile Ad-hoc Network) is a network designed in a wireless environment by various mobile nodes to establish communication during mobility, that is, the nodes on the network are not fixed either in location or in their presence; in other words, every node in the network is can go off or change its position in any minute (Jatwani, 2018). Any node in the network can be a host and a router at the same time, which means they can receive/send packets, or deliver packets to other nodes as a middlemen.

These characteristics of MANET are important, as some nodes may participate in a hop-by-hop route for the packets of other nodes, and going off the network may leave a hole or packet loss in the network. Changing the location of a node may also change the network’s topology, leaving any previously planned routes outdated. There are multiple examples and use cases of MANET, such as e Healthcare, Navy, and Industrial IoT (Network Simulation Tools, 2021).

The dynamic nature of MANET requires an approach to handle the networking process as nodes change, this is the function of the routing protocols, which may rely on different routing algorithms to control the network; these algorithms can be classified into reactive, proactive, hybrid, location-aware, multipath, hierarchical, and power-aware routing algorithms (Jatwani, 2018). The focus of this text is on the proactive and reactive routing protocols.

Reactive protocols are source-initiated, that is, the route is created only when the source requests a route to a destination. The process involves discovering a proper route and then marinating that route while the packets are transferred. Request, error, and acknowledgment packets are used in this process. Examples of Reactive protocols include Dynamic Source Routing (DSR), Ad-hoc On-Demand Distance Vector (AODV), etc (Jatwani, 2018).

Proactive protocols, on the other hand, are table-driven, that is, they always maintain the updated information of possible routes at every node, and each node propagates its information to other nodes to keep the network state up to date. This process of marinating routing tables at all nodes and constantly updating them may increase the overhead of the network and the cost of transferring packets. Examples of Proactive protocols include Destination Sequenced Distance Vector (DSDV), Optimized Link State Routing (OLSR), etc (Jatwani, 2018).

Proactive protocols (table-driven) have extensive research on wired networks as opposed to Reactive protocols (source-initiated, dynamic), but they are not suitable for dynamic routing as maintaining the routing tables is a big challenge. On the other hand, Reactive protocols are more suitable for dynamic routing as they only create routes when needed, but they have high overhead due to the route discovery and maintenance process (Jatwani, 2018).

To conclude, the best choice between reactive or proactive protocols depends on the circumstances; for example, proactive protocols may work for a small home network with a few number of nodes as the routing tables will be small; but as the network expands geographically and in the number of nodes, the reactive protocols become more suitable as they only create routes when needed, and there are rare occasions that every node needs to talk to every other node. Other approaches like hybrid that combine the benefits of both proactive and reactive protocols or hierarchical that aim to reduce routing table sizes may also be considered.

References

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