International Business Machines Corporation

Cisco Technology, Inc.

Gerard Brun

Claude R Galand

Olivier Maurel

Laurent Nicolas

Olivier Bertin

Jean-Francois Le Pennec

Patrick Michel

Alain Benayoun

Jean-Paul Chobert

Yves Ouvry

Jean Bidard

The present invention is directed to a high speed packet switching network and, in particular to a method and system for minimizing the time to establish a connection between an origin and a destination node. Due to high dynamicity of the traffic on transmission links, it is important to select a routing path according to a fully up-to-date information on all network resources. The simpler approach is to calculate a new path for each new connection request. This solution may be very time consuming because there are as many path selection operations as connection set up operations. On another hand, the calculation of paths based on an exhaustive exploration of the network topology, is a complex operation which may also take an inordinate amount of resources in large networks. Many of connections originated from a network node flow to the same destination network node. It is therefore possible to take a serious benefit in reusing the same already calculated paths for several connections towards the same node. The path calculated at the time the connection is requested is recorded in a Routing Database and updated each time a modification occurs in the network. Furthermore, alternate paths for supporting non-disruptive path switch on failure or preemption, and new paths towards potential destination nodes can be calculated and stored when the connection set up process is idle. These last operations are executed in background with a low processing priority and in absence of connection request.

Method and system for minimizing the connection set up time in high speed packet switching networks

The present invention is directed to a high speed packet switching network and, in particular to a method and system for minimizing the time to establish a connection between an origin and a destination node. A path calculated at the time the connection is requested is recorded in a Routing Database and updated each time a modification occurs in the network. Furthermore, alternate paths for supporting non-disruptive path switch on failure or preemption, and new paths towards potential destination nodes can be calculated and stored when the connection set up process is idle. These last operations are executed in background with a low processing priority and in absence of connection request.

This method enables optimizing the time required for reestablishing connections between end users attached to a data communication network, which connections were disrupted due to a network failure. The network includes access nodes and transit nodes interconnected with network links/trunks (with no specific distinction being herein required between both designations of a communication line). The end users are attached to the network through access nodes and each said access node permanently stores an image of the current network trunk including the number N.sub.i of connections currently supported by said network trunk. Upon detection of a trunk failure, each access node supporting connections affected by said failure, is made aware of the total number (N.sub.i) of connections in each priority group affected by the failure, together with a network dependent parameter (TP) representing the elementary processing time required to reroute a single network connection. Then each access node may independently, start a first reconnection set-up procedure at a time Ri randomly selected between zero and (N.sub.i -n.sub.i) *TP, where n.sub.i is the number of connections supported by the access node in each priority group, and then space the required subsequent reconnections set-ups by a time equal to (T.sub.i -R.sub.i)/n.sub.i, with T.sub.i =N.sub.i *TP.

Method and system for optimizing the connection set up time in high

The invention relates to a method and a system for routing messages or frames through network nodes connected to each other by network links and connected to a plurality of terminals by different input/output ports also called network attachment cards (NAC) in a multi-node communication network. In such a configuration, each terminal equipment stores a network table. The network table is updated in the terminal itself by a network manager which may by the way limit the access of the terminal to some terminals of the network. To route an incoming message or frame from a source terminal (T1) to the destination terminal (T7), a routing algorithm is implemented in each NAC. Each NAC has a different and unique integer address in the node, each node has a different and unique prime number address greater than the number of NACs in the node. Each terminal connected to a node sends frames with a routing identifier (RI). The different RIs are located in the network table. When an input NAC receives a frame, the routing algorithm computes the address of the output NAC given by the remainder of the division of the RI by the node address, then this output NAC sends the frames onto its network link. This process is performed in each node until the destination terminal is reached. The RI is kept unchanged during the frame transmission. A timer is also used to test if the frame is received because a network link may be down. In such case, an alternate RI is used to take an alternate route.

Method and system for routing massages in a multi-node data

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Nice, France

Gerard Brun