APPARATUS AND METHOD FOR ROUTING A COMMUNICATION IN A NETWORK

摘要

The invention concerns a method and apparatus for assigning the optimum route for a communication in an ATM digital broadband communication network. A route consists of one or more links, each link connecting one node in the network to one other node. Assignment of a route is made from a set of optimum routes. Each optimum route in the set is that route offering the best possible value of an additive attribute of the network, such as. signal delay, number of nodes or route cost, for a particular minimum acceptable value of a restrictive attribute of the network, such as bandwidth of the route. The calculation of the optimum route involves finding the best route with respect to the value of the additive attribute for a model or representation of the network containing only those links in the network having at least a particular value of the restrictive attribute. The network model is then further reduced to one having only links with a more limiting value of the restrictive attribute, and the optimum route for this network model is calculated. Thus a set of optimum routes is computed, each for a model of the network with successively fewer links which satisfy successively more stringent requirements on the restrictive attribute. A list of links, ranked in order of the severity of restriction placed on communications by their restrictive attribute, is used in this calculation. More than one list may be used, each list ranking the links in the network in order of a different restrictive attribute. The set of optimum routes is preferably calculated prior to receipt of a request for a route, but may be calculated on-demand, i.e. at the time of receipt of the route request.