The routing controller is defined in ITU-TG.8080 to:

• respond to requests from connection controllers for path (route) information needed to set up connections. This information can vary from end-to-end (e.g., source routing) to next hop .
• respond to requests for topology (SNPs and their abstractions) information for network management purposes.

Information contained in the routing controller enables it to provide routes within the domain of its responsibility. This information includes both topology (SNPPs, SNP Link Connections) and SNP addresses (network addresses) that correspond to the end system addresses all at a given layer.

Addressing information about other subnetworks at the same layer (peer subnets) is also maintained. It may also maintain knowledge of SNP state to enable constraint based routing. Using this view, a possible route can be determined between two or more (sets of ) SNPs taking into account some routing constraints. There are varying levels of routing detail that span the following:

MARBEN™ GMPLS Routing Controller provides path computation capabilities as listed:

• A simple Djiikstra shortest-path-first algorithm,
• A cost-optimized node-diverse path computation algorithm,
• A number-of-hops-optimized node-diverse path computation algorithm,
• A cost-optimized link-diverse path computation algorithm,
• A number-of-hops-optimized link-diverse path computation algorithm.

All these algorithms are constrained by various Traffic Engineering parameters such as the requested setup priority, resource affinities and switching capabilities, excluded or mandated resources, etc... : before invoking one of the path computation algorithm, the MARBEN™ GMPLS Routing Controller is in charge of extracting routing information from the Traffic Engineering development kit database, pruning nodes or links according to exclude routes, crankback information, requested bandwidth, priorities and resource affinities, etc... , and formatting the resulting routing information.