Hierarchical Routing with QoS Constraints in Optical Transport Networks

Optical Transport Networks (OTN) with automatical switching capabilities are named ASON. Hierarchical routing is required in the ASON recommendations to achieve scalability. Basically, hierarchical routing consists of three main components, an aggregation scheme, an update policy and a routing algorithm. This paper proposes a new network structure focusing on these three components. We propose a new aggregation scheme; an update policy based on a threshold value; and we also extend an already proposed routing mechanism to be applied to a hierarchical network. Main skill of this routing mechanism is to reduce the connection blocking increase because of selecting paths based on inaccurate routing information. This inaccuracy is introduced both by the aggregation process and by the update policy.