Mci Communications Corporation

Mci, Inc.

Nortel Networks Corporation

Mci Worldcom, Inc.

Mci World Com, Inc.

Sridhar S Nathan

John Arthur Fee

Lev B Sofman

Jasvantrai C Shah

Jonathan Weston-Dawkes

Anis Khalil

Jennifer S Huang

Jay C Box

Qinglin Wang

Jennifer Shu-Chen Huang

A network architecture for use in a data traffic network that includes a plurality of nodes and a plurality of data links coupling the nodes. The network architecture includes a working data link( ) that forms a signal pathway between a first router ( ) and a second router ( ) within the network. A protection data link( ) is likewise provided and forms a second signal pathway. The routers ( ) include both working data ports ( ) and protection data ports ( ) with each port including associated transmit and receive terminals. A combination of line splitting devices ( ), line selection devices ( ) and switch arrays ( ) are used to switch the flow of traffic data from the working data link ( ) to the protection data link ( ) or a protection channel ( ) as is appropriate.

Network architecture and method of providing link protection in a bidirectional data traffic network

A method of and system for managing a SONET ring computes an optimally balanced demand loading for the SONET ring and generates an updated time slot assignment map for each node of the SONET ring based upon the optimally balanced demand loading. The method causes each node of the SONET ring to switch substantially simultaneously to its updated time slot assignment map, thereby reconfiguring the SONET ring.

Method of and system for managing a SONET ring

A system and method for sharing a spare channel among two or more optical ring networks that have a common span. A first optical cross-connect switch (OCCS) and a first OCCS controller are placed at one end of the span and a second OCCS and OCCS controller are placed at the other end of the span. The first OCCS and the first OCCS controller are coupled to a first ADM from each optical ring, and the second OCCS and the second OCCS controller are coupled to a second ADM from each optical ring. The first OCCS controller receives alarm indications from each ADM that it is coupled to that senses a ring failure. The second OCCS controller receives alarm indications from each ADM that it is coupled to that senses a ring failure. Upon receiving an alarm indication, the first OCCS controller directs the first OCCS to optically couple the ADM that originated the alarm indication to the spare channel, and the second OCCS controller directs the second OCCS to optically couple the ADM that originated the alarm indication to the spare channel.

System and method for sharing a spare channel among two or more optical ring networks

A method of assigning capacity and routing flow in a bi-directional line switched SONET ring based upon ring topology and demand data defines for each pair of links of the ring a two-edge cut. Each two-edge cut divides the ring into two sets of nodes. For each two-edge cut, the capacity assignment method calculates a demand equal to the sum of all demands between nodes on opposite sides of the two-edge cut. The capacity assignment method then determines the maximum demand and sets the capacity of each link equal to one-half the maximum demand plus one-half of one demand unit. The flow routing method of the present invention calculates a cut difference for each two-edge cut. A critical cut is a two-edge cut having a cut difference equal to or less than one. If there is a critical cut with demands greater than zero on the same side of the critical cut, the method performs a first processing routine. If there is no critical cut with demands greater than zero on the same side of the critical cut, the method performs a second processing routine. The flow routing method performs the first or second processing routine until the occurrence of a terminating condition.

Method of optimal routing in a bi-directional line switched sonet ring

A method of optimizing a network includes a plurality of nodes interconnected by high multiplex level links, in which at least some of the links carry a number of low multiplex level remaining demands that is less than the capacity of the links, by rerouting lower multiplex level remaining demands through the network to reduce the total number of higher multiplex level links in the network. The method eliminates from consideration any bridges and spurs in the network, thereby forming one or more connected components of the network. After the spurs and bridges have been eliminated from consideration, the method reroutes remaining low multiplex level demands through each of the remaining connected components of the network to reduce the total number of high multiplex level links in each remaining portion. Computationally, the rerouting step of the present invention includes the step of solving an integer multicommodity flow problem by minimizing the cost of links of each of the connected components, subject to a symmetry constraint, an initial solution constraint, a conservation constraint, and a modularity constraint.

Method of routing and bundling demands with low utilization in a

A system and method for increasing the robustness of an optical ring network having a plurality of ring nodes. Optical data traffic is transmitted between a plurality of ring nodes via optical links. A first optical cross connect switch and a second optical cross connect switch are coupled to an alternate network. The first optical cross connect switch is coupled to a first ring node. The second optical cross connect switch is coupled to a second ring node. When a failure is detected in the first optical link, then the first optical cross connect switch couples the first ring node to an alternate path of the alternate network, and the second optical cross connect switch couples the second ring node to the alternate path, such that optical data traffic is transmitted between the first ring node and the second ring node via the alternate path.

System and method for increasing the robustness of an optical ring

A plurality of optical cross-connect switches are freely interconnected to form a mesh type network. At least three of the optical cross-connect switches are switched to form a line-switched ring network, thereby forming a ring/mesh network. Simply by changing the switching logic of the optical cross-connect switches within the ring/mesh network, new rings can be created and existing rings can be modified, thereby providing a great deal of flexibility to make changes to the network as traffic patterns change without incurring hardware costs or significant network downtime. Another advantage of the ring/mesh design approach is that spare capacity within the line-switched ring can be utilized by the mesh network, and spare capacity within the mesh network can be utilized by the line-switched ring, thereby significantly increasing the spare efficiency.

Ring/mesh optical network

A method of optimizing a telecommunications network in terms of transmission and equipment cost by multiplexing lower bandwidth level telecommunications demand-routes to form higher bandwidth level bundles, by determining, for each demand-route, whether the demand-route includes a patching subroute. For each patching subroute, the method finds a best bundle of demand-routes that includes the patching subroute. The best bundle is the one that has the highest cost gradient between the sum of the costs associated with the demand-routes included in the best bundle and the total cost associated with the best bundle. The method then multiplexes the demand-routes according to the best bundles.

Method of telecommunications demand-route multiplexing (DEROM)

A method of routing lower multiplex level demands in a telecommunications network including a plurality of interconnected nodes to form higher multiplex level demand-routes. The method defines an initial lower multiplex level demand-route for each pair of nodes of the network. The initial lower multiplex level demand-route carries all lower multiplex level demands originating or terminating at a node of the pair. The method then splits the demand of each initial lower multiplex level demand-route between an express demand and an overflow demand and routes express demands in higher multiplex level express routes. The method patches the overflow demands into higher multiplex level routes according to a predetermined patching policy.

Method of routing and multiplexing demands in a telecommunications

A self-healing optical network carrying traffic between first and second optical linear terminals. The self-healing optical network including first, second, and third optical switching units, first, second, and third spare optical channels, and a working optical channel. The first, second, and third optical switching units are coupled in a ring configuration using said first, second, and third spare optical channels. The first and second optical switching units are coupled by the first spare optical channel and by the working optical channel. The first and second optical switching units each direct the traffic between the first and second optical linear terminals along the working optical channel or along the second and third spare optical channels in the event the working optical channel is not available.

Self-healing optical network

An apparatus and method is described that is used to design a minimal spares network for a given communications network. Three data files are used as input which describe the communications network. The information comprising such data files include the number and configuration of the nodes and spans, the current demand in terms of the required capacity between the source and destination nodes, current spare capacity (if any), and optionally current paths used to carry the demand traffic (including the presence or absence of glass-throughs). A three pass method is used to design an efficient and economical spares network from the given input data. A simulated cut is performed on each span in the communications network. From each simulated span cut, the affected demand traffic is identified and rerouted via spare capacity that is `purchased` on an incremental cost basis. Pre-purchased spares are used before new spares are purchased.

Spare capacity allocation tool

In a telecommunications network having a plurality of intelligent nodes interconnected by multiple communication channels, alternate paths and spare channels are set up for restoring traffic disrupted by failure to one or more of the communications channels. The alternate paths may be set up irrespective of the number of custodial node pairs, also referred to as leader/follower or sender/chooser pairs, that could simultaneously be involved in the restoration operation. The interconnected nodes have bi-directional working and/or spare channels. There is stored at each node in the network participating in the recovery operation a spare channel manifest for each of the leader/follower combinations. The first end node, or leader node, of every identified failed channel initiates a request message for each disrupted working channel to set up an alternate path. Spare channels are assigned to the alternate path so that, with the help of intermediate helper nodes, the request message, guided by the spare channel manifests, is sent to the second end node, or follower node, of the failed channel. An acknowledgement is sent by the follower node back to the leader node on the same path that the request message travelled on. The spare channel manifests are suitably configured to realize desired levels of restoration under various scenarios of failures in the network and are modified as warranted to account for changes in the network.

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Plano, TX, United States of America

Sridhar S Nathan