Luminous Networks, Inc.

Adtran Gmbh

Jason C Fan

Vinay K Bannai

Prasad Prabhakar Jogalekar

Charles Barry

Robert F Kalman

Peter Geoffrey Jones

Neil Mammen

Paddy Vishnubhatt

Inwhan Choi

Hasnain Rashid

Phyllis Yip

Robert Stillman

Ajit Ninan

Sanjay Agrawal

Saravanan Coimbatore

Sohail Mallick

Richard Lindquist

Atul Shinde

Seshadri Srinivasan

Warren Watts

Steven Gemelos

Derek Mayweather

David Watson

Masood Ahmad

The disclosed network includes two rings, wherein a first ring transmits data in a clockwise direction, and the other ring transmits data in a counterclockwise direction. The traffic is removed from the ring by the destination node. During normal operations (i.e., all spans operational), data between nodes can flow on either ring. Thus, both rings are fully utilized during normal operations. The nodes periodically test the bit error rate of the links (or the error rate is constantly calculated) to detect a fault in one of the links. The detection of such a fault sends a broadcast signal to all nodes to reconfigure a routing table within the node so as to identify the optimum routing of source traffic to the destination node after the fault.

Utilizing bandwidth in ring network using path cost and protection techniques

Switch for dynamically rerouting traffic due to detection of faulty link

An automatic network topology identification technique is described herein. Each node in the network periodically or constantly transmits its unique address to its neighboring node. Once a node receives a different message from its neighbor, the node identifies a topology change in the network. In one embodiment, a current topology is associated with a session number. When a change in the topology is detected, the detecting node increments the session number and broadcasts the change in topology. The other nodes, detecting the changed session number, now know that there has been a change in the network. In response, the nodes in the network modify routing tables and other information stored at the node related to the topology. In one embodiment, the technique is used to reassign shortened addresses to each device on the network to support a dual-addressing mode of the network. The dual addressing mode substitutes reduced-length addresses (referred to as short addresses) for standard addresses (referred to as long addresses) for traffic whose source or destination is internal to a given virtual network topology. The required length of short addresses used for a given virtual topology is dependent on the number of devices reachable within the topology.

Automatic network topology identification by nodes in the network

Routing switch detecting change in session identifier before reconfiguring routing table

A method and system for selecting ring paths in service provisioning on optical networks including a plurality of interconnected rings. The method includes: receiving a request to provision a service between a first end point and a second end point in the optical network; identifying a plurality of possible ring paths between the first and second end points; validating a bandwidth of each ring path, including validating bandwidths of bandwidth bottlenecks in each ring path; selecting a path from the validated ring paths; and provisioning the service on the selected path. The system utilizes a path engine on a network management server that knows about the bandwidth allocation in the entire network and implements the method. The resources of the optical network used by the provisioned service is thus minimized.

Path engine for optical network

A method and structure for the distribution and utilization of synchronization within an asynchronous network is described herein. Synchronization is distributed through an asynchronous network via a synchronization symbol periodically inserted on the MAC layer. The priority of this symbol ensures that this symbol is inserted in the MAC layer data stream ahead of all other types of symbols. The insertion of the synchronization symbol in the middle of an ongoing data frame is supported. In addition, a method for synchronization symbol distribution throughout an asynchronous network is presented, along with a method for switching to a new synchronization path (in the event of loss of original synchronization path) based on minimum number of hops from the synchronization source. In addition, a method is described for utilization of the count and interval of received synchronization symbols and the count and interval of transmitted synchronization symbols to generate an error correction signal used in the process of frequency locking of a device's internal hardware to received synchronization symbols from another device. Using the prioritized insertion capability required for synchronization symbols, a variety of other MAC layer control symbols are defined to perform other functions, such as propagation time measurement between adjacent nodes.

Synchronization of asynchronous networks using media access control (MAC) layer synchronization symbols

A communications network is described having a class-based queuing architecture. Shared class queues receive packet flows from different customers. In one embodiment, there are eight classes and thus eight shared queues, one for each class. A scheduler schedules the output of packets by the various queues based on priority. Each customer (or other aggregate of packet flows) is allocated a certain space in a class queue based on the customers' Service Level Agreement (SLA) with the service provider. A queue input circuit detects bits in the packet header identifying the customer (or other criteria) and makes selections to drop or pass packets destined for a shared queue based on the customers' (or other aggregates') allocated space in the queue. In another embodiment, the relative positions of the nodes in the network are taken into account by each node when dropping packets forwarded by other nodes by detecting a node label (or other ID code) so that packets from the various nodes are dropped in a more fair way when there is congestion in the network, irrespective of the 'passing ' node's position relative to the other nodes.

Aggregate fair queuing technique in a communications system using a class based queuing architecture

A method and system for synchronizing data between a management system (MS) and network elements (NE) in an optical network utilizes a table counter and row counters for each row in a NE table, and a table counter and row counter for each row in a MS table. The NE table counter increments when a change in the NE table occurs. Each NE row counter increments when its row is changed. The MS table counter increments when a change in the MS table occurs. Each MS row counter is incremented when its row is changed. The MS polls the NE table counter and compares it with its MS table counter. If they are different, then the MS compares each NE row counter with the corresponding MS row counter. For any of the row counters that do not match, the rows between the MS table and the NE table are synchronized.

Smart poller for optical network management systems

Error codes output from a serializer/deserializer in a node of a communications network are detected by error decode logic that assumes that each new error occurrence reflects a one bit error in the word giving rise to the error code. Each error occurrence is then counted. When the error count reaches a predetermined limit (e.g., 250 errors), the total bit count required to accumulate the 250 errors is then determined. The total bits can be determined based on a clock count (time). The BER is then calculated based upon the fixed error limit and the total bit count. This BER is then reported and used to determine the health of the network.

Detecting bit errors in a communications system

The disclosed network includes two rings, wherein a first ring transmits data in a clockwise direction, and the other ring transmits data in a counterclockwise direction. The traffic is removed from the ring by the destination node. During normal operations (i.e., all spans operational), data between nodes flows on the ring that would provide the minimum number of hops to the destination node. Thus, both rings are fully utilized during normal operations. The nodes periodically test the bit error rate of the links (or the error rate is constantly calculated) to detect a fault in one of the links. The detection of such a fault sends a broadcast signal to all nodes to reconfigure a routing table within the node so as to identify the optimum routing of source traffic to the destination node after the fault. Since the available links will now see more data traffic due to the failed link, traffic designated as 'unprotected' traffic is given lower priority and may be dropped or delayed in favor of the 'protected' traffic. Specific techniques are described for identifying a failed link, communicating the failed link to the other nodes, differentiating between protected and unprotected classes of traffic, and updating the routing tables.

Dynamically allocated ring protection and restoration technique

A dual addressing mode is described in which reduced-length addresses (referred to as short addresses) are substituted for standard addresses (referred to as long addresses) for traffic whose source or destination is internal to a given virtual network topology. The required length of short addresses used for a given virtual topology is dependent on the number of devices reachable within the topology. For a virtual topology with less than 256 addressable devices, for example, 8-bit short addresses can be used. When a node within the virtual network sees a packet with a short destination address in the header, the node understands the address to be within the virtual network and routes the packet accordingly. If a source address is a short address, the virtual network can identify the source within the virtual network. For packets originating in the virtual network whose destination is also in the virtual network, both the source and destination addresses can be short addresses. Thus, devices within a virtual network topology are addressable in a dual manner on the data link layer and/or network layer by traffic flowing internal to, or private to, the virtual network. Also described is a technique for automatically assigning source addresses to devices within the virtual network.

Dual-mode virtual network addressing

The disclosed network includes two rings, wherein a first ring transmits data in a clockwise direction, and the other ring transmits data in a counterclockwise direction. The traffic is removed from the ring by the destination node. During normal operations (i.e., all spans operational), data between nodes flows on the ring that would provide the minimum number of hops to the destination node. Thus, both rings are fully utilized during normal operations. The nodes periodically test the bit error rate of the links (or the error rate is constantly calculated) to detect a fault in one of the links. The detection of such a fault sends a broadcast signal to all nodes to reconfigure a routing table within the node so as to identify the optimum routing of source traffic to the destination node after the fault. Since the available links will now see more data traffic due to the failed link, traffic designated as &ldquo;unprotected&rdquo; traffic is given lower priority and may be dropped or delayed in favor of the &ldquo;protected&rdquo; traffic. Specific techniques are described for identifying a failed link, communicating the failed link to the other nodes, differentiating between protected and unprotected classes of traffic, and updating the routing tables.

Selecting a routing direction in a communications network using a cost metric

An architecture for transport of multiple services in connectionless packet-based networks is described herein, along with the packet format used for data transport in this architecture. The architecture supports transport of both connectionless packetized data and framed data from synchronous leased lines. The architecture supports transparent packetization of incoming DS1 data. The architecture works for mesh architectures but is optimized for OSI Layer (crossconnect) and Layer (Virtual LAN, or VLAN) services and for ring topologies, since for these services in a ring no path setup is required using a label distribution protocol. In addition, it simultaneously supports OSI Layer , Layer , and Layer services.

Growing community of inventors

Mountain View, CA, United States of America

Jason C Fan