US 5,629,930 A · Call routing in an ATM switching network

Abstract

A routing scheme for an ATM switching network includes a plurality of switching nodes, each of which includes individual storage for storing routing messages for each outgoing link. A call at a source node is routed through one possible routing path which requires only one or two links to complete a connection to a destination node. In such case, one of the routing paths is selected based on link state information concerning only the possible routing paths. If the call requires a route path which includes three or more links to the destination node, the source node performs a predefined sequential routing to its neighboring node before the neighboring node negotiates with selected intermediate nodes for a connection involving two links. The routing messages stored at each node are processed independently and simultaneously by each node. The main requirement is that routing decisions must be based on true link-state information. A protocol is devised for fast and efficient bulk processing while avoiding protential deadlocks.

Claims15

Dependent claims

A method of routing a call between an originating node and a destination node in an ATM network having a plurality of nodes wherein each node stores routing information, comprising steps of:

selecting candidate route paths from the originating node to the destination node;
selecting direct route paths among the candidate route paths which require only one link to complete a connection for the call between the originating and destination nodes;
granting the call a connection using one of the selected direct route paths whose routing information meets predetermined criteria;
if no direct route paths are found,
selecting two-link route paths which require two links to complete a connection for the call between the originating and destination nodes;
the originating node sending connection messages to candidate middle nodes located in the selected two-link route paths;
each of the middle nodes storing the connection message in a respective message queue and responding to the originating node with state information when the connection message in the queue of the middle node reaches the head of the queue;
comparing the routing information given to the originating node by each candidate middle node;
and
granting the call a connection using one of the selected two-link route paths whose routing information meets predetermined criteria.

7 more elements

A method of routing a call between an originating node and a destination node in an ATM network having a plurality of nodes wherein each node having one message queue for each of its outgoing links and a candidate table containing a list of candidate route paths to complete connections for calls requested thereat, comprising each node performing independently from each other following steps of:

sending connection messages for calls requested thereat to appropriate nodes;
storing and processing the connection messages in its respective message queues;
selecting a route path to each destination node according to the order of preference among direct route paths, two-link route paths and multiple-link route paths, respectively requiring one, two or three or more links to complete a connection from the node to the destination node of each call;
and
granting the call a connection using a route path whose routing parameters meet predetermined criteria.

2 more elements

Dependencies are inferred from the claim text.

Call routing in an ATM switching network

Life of this patent

Call routing in an ATM switching network

Life of this patent

Abstract

Claims15