CSPF – Constrained Shortest Path First

CSPF is the term given to a shortest path routing algorithm which factors in a number of constraints to its routing calculation. Using CSPF means that a network administrator can ensure the SPF routing algorithm, for example, only considers routes able to support 100Mbps traffic throughput or routes with a particular end to end delay. Popular shortest path routing protocols such as OSPF (Open Shortest Path First) and IS-IS (Intermediate System to Intermediate System) have both been extended to support constraint based routing.