Adaptive routing, also called dynamic routing, is a process for determining the optimal path a data packet should follow through a network to arrive at a specific destination. Adaptive routing can be compared to a commuter taking a different route to work after learning that traffic on his usual route is backed up.
Adaptive routing uses algorithms and routing protocols that read and respond to changes in network topology. In addition to Open Shortest Path First (OSPF), other routing protocols that facilitate adaptive routing include Intermediate System to Intermediate System (IS-IS) protocol for large networks such as the internet and routing information protocol (RIP) for short-distance transport.
Similar to GPS, which uses information about road conditions to redirect drivers, adaptive routing uses information about network congestion and node availability to direct packets. When a packet arrives at a node, the node uses information shared among network routers to calculate which path is most suitable. If the default path is congested, the packet is sent along a different path and the information is shared among network routers.
Advantages and challenges of adaptive routing
The purpose of adaptive routing is to help prevent packet delivery failure, improve network performance and relieve network congestion. Adaptive routing can cause nodes to become overloaded, however, due to the complex processing decisions they make. Because routers share information about the network topology, adaptive routing can be less secure than non-adaptive routing processes and require more bandwidth.
Adaptive routing vs. non-adaptive routing
Adaptive routing is an alternative to non-adaptive, static routing, which requires network engineers to manually configure fixed routes for packets. When a node is unavailable in a static routing environment, the packet must either wait for the node to become available again or the packet will fail to be delivered. Static routing is often used for simple, closed network topologies, while adaptive routing is often used for open, complex network topologies.