Dynamic source routing: A faster approach for wireless network

Introduction

Laymen explanation

While talking over phone, network latency matters. If you are talking, recipient should able to hear instantly. If recipient is in USA and you are in India, then each data packet needs to move as fast as possible. So, it should avoid any overhead. Routing of each packet is an overhead. DSR helps in this

Technical explanation

DSR is truly based on source routing whereby all the routing information is maintained (continually updated) at mobile nodes. The learned paths are used to route packets.

Protocol in brief

• It has only two major phases, which are Route Discovery and Route Maintenance.

• Determining source route requires accumulating the address of each device between the source and destination during route discovery.

  • Source node sends broadcast packet which is flooded by all nodes until it reaches to the distinction. Optimizations are in place to avoid duplicate packet forward (via sequence number)

  • A destination node, after receiving the first RouteRequest packet, replies to the source node through the reverse path the RouteRequest packet had traversed.

  • There is also approach to learn routes via adjacent nodes (but it needs promiscuous mode setup)

• The accumulated path information is cached by nodes processing the route discovery packets.

• To accomplish source routing, the routed packets contain the address of each device the packet will traverse.

Optimal routing

• • RFC allows node to decide the approach for deciding optimal route. It can be number of hops, latency etc.

Challenges

• • Connection setup delay

  • Route reconstruction can cause issues due to stale entries (programming challenge)

• This routing overhead is directly proportional to the path length.

Use cases

• • Mobile routing

  • Routing in Adhoc network

Reference

https://en.wikipedia.org/wiki/Dynamic_Source_Routing

https://tools.ietf.org/html/rfc4728

https://www.youtube.com/watch?v=7RSm19cLcko