Dynamic Source Routing (DSR) protocol is an on-demand protocol based on the concept of source routing. Mobile nodes are required to maintain route caches that contain the source routes of which the mobile is aware. Entries in the route cache are continually updated as new routes are learned.

 The protocol consists of two major phases: route discovery and route maintenance. When a mobile node has a packet to send to some destination, it first consults its route cache to determine whether it already has a route to the destination. If it has an unexpired route, it will send the packet using this route. If the node does not have such a route, it will initiate the route discovery by broadcasting an RREQ. This RREQ contains the address of the destination, along with the source node's address and a unique identification number. Each node receiving the packet checks whether it knows a route to the destination. If it does not, it adds its own address to the outgoing packet. To limit the number of RREQs on the network, a mobile only forwards an RREQ if the mobile has not yet seen the request and if the mobile's address does not already appear in the route record.

 An RREP is generated when the route request reaches either the destination itself, or an intermediate node that contains in its route cache an unexpired route to the destination. By the time the packet reaches either the destination or such an intermediate node, it contains a route record yielding the sequence of hops taken. If the node generating the route reply is the destination, it places the route record contained in the route request into the route reply. If the responding node is an intermediate node, it will append its cached route to the route record and then generate the route reply.