Importance

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Abstract

The invention routes SVC ATM call setups by utilizing one of a plurality of designated transit lists (DTLs) stored at an originating node. The DTLs describe all routes in the network from the originating node to endpoint destinations. When a call setup message is received at the originating node, it inserts a desired DTL as an information element (IE) of the setup message. Each DTL is formatted as a concatenation of elements with each element including the node ID and output ports of each successive node in the route. Preferably, each element of the DTL includes flags such as a 'process' flag which indicates whether an element of the DTL has been processed by a node, a 'link up' flag which indicates that an alternative route is available between two nodes should the preferred route be down, a 'bandwidth' flag which allows the alternate link to be used if the preferred link is busy, and a 'last node' flag which is used in the last element of the concatenated DTL. If the 'last node' flag is not set, the destination node internally generates a route ID as the last element based on the destination address specified in an IE for the call. As the DTL IE is passed from node to node along the connection path, the receiving node inserts the input port at which it received the call setup message as well as a VPI/VCI into its element of the DTL. At its destination, the DTL is attached to a CONNECT request message which is returned to the source node.

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First Claim