Overture Networks, Inc.

Prayson Will Pate

Michael Joseph Poupard

Robert Leroy Lynch

Robert LeRoy Lynch

David Stephen Griswold

Glenn Russell Swope

Emily Jean Skinner

Scott Michael Harvey

David Lance O'Neal

Normal 802.3 Ethernet requires a tree topology. If a ring or a loop exists, then packets will be forwarded around the ring indefinitely. If the ring is broken, then there is no possibility of packets being propagated forever. This invention shows how to quickly impose a virtual break in the ring such that all nodes can communicate with each other, and how to remove the virtual break when a real failure occurs. This is accomplished by placing intelligent nodes on the ring that work together to virtually break and restore the ring. An embodiment is disclosed that handles a unidirectional break in a communication link where the unidirectional break is not sensed as an OPER DOWN state. This abstract is provided as an aid to those performing prior art searches and not a limitation on the scope of the claims.

Apparatus and method for rapid detection of unidirectional breaks in a network ring

Normal 802.3 Ethernet requires a tree topology. If a ring or a loop exists, then packets will be forwarded around the ring indefinitely. If the ring is broken, then there is no possibility of packets being propagated forever. This invention shows how to quickly impose a virtual break in the ring such that all nodes can communicate with each other, and how to remove the virtual break when a real failure occurs. This is accomplished by placing intelligent nodes on the ring that work together to virtually break and restore the ring. An embodiment is disclosed that allows a ring node to bridge user traffic in the case that no switch table entry is present for that traffic. This abstract is provided as an aid to those performing prior art searches and not a limitation on the scope of the claims.

Multipoint protected switching ring

A method of providing an ongoing indication of at least one piece of current status information about a network element through the use of status indicators in the command line prompt displayed on a command line interface display monitor. Optionally, the pop-up messages to the command line interface display monitor can be modified to provide an indicator of network element status. This abstract is provided as a tool for those searching for patents, and not as a limitation on the scope of the claims.

Command line interface with indication of network element status

Normal 802.3 Ethernet requires a tree topology. If a ring or a loop exists, then packets will be forwarded around the ring indefinitely. If the ring is broken, then there is no possibility of packets being propagated forever. This invention shows how to quickly impose a virtual break in the ring such that all nodes can communicate with each other, and how to remove the virtual break when a real failure occurs. This is accomplished by placing intelligent nodes on the ring that work together to virtually break and restore the ring. An embodiment is disclosed that handles a unidirectional break in a communication link. This abstract is provided as an aid to those performing prior art searches and not a limitation on the scope of the claims.

Protected switching ring

A system for optimally mapping circuits into packets based on round trip delay (RTD), and a system for measuring RTD for use in packet communications systems such as circuit emulation (CEM) systems is disclosed. The measured RTD value can be used in a system that adjusts packet size to reduce capture delay to partially offset an increase in RTD. As the use of smaller packets increases the overhead burden on the packet communication system, the packet size can be increased to reduce the overhead burden when the size of the current RTD becomes appropriately short. The disclosure also teaches the placement of data from two or more circuits destined for the same emulation endpoint into the same transmission packet in order to improve system performance. The abstract is a tool for finding relevant disclosures and not a limitation on the scope of the claims.

Flexible mapping of circuits into packets

The size of a Jitter Absorption Buffer (JAB) is automatically changed in response to changes in network conditions. The JAB size is changed based on the fullness of the JAB and the recent variations in JAB depth. Automatic adjustment allows for a balance of providing adequate correction for Packet Delay Variation (PDV) while avoiding unnecessary increases in Absolute Packet Delay (APD) from the prolonged use of an oversized JAB. This abstract is provided as a tool for those searching for patents, and not as a limitation on the scope of the claims.

Automatic adjustment of buffer depth for the correction of packet delay variation

A circular buffer is used to receive packets transmitted to an application. Normally, incoming packets are placed at the &ldquo;tail&rdquo; of the buffer, which is indicated by the write pointer. Packets to be used by the application are read from the &ldquo;head&rdquo; of the buffer, which is indicated by the read pointer. In contrast, the present invention uses the sequence number to direct the packets to specific places in the circular buffer. This inventive use of sequence number allows the packets to be written at the proper place in the buffer, regardless of the location of the write pointer. Within certain limits, a packet that arrives out of sequence is not bound by the position of the write pointer to be placed into the buffer out of sequence. This abstract is provided as a tool for those searching for patents, and not as a limitation on the scope of the claims.

Use of a circular buffer to assure in-order delivery of packets

Packet communication systems, or networks, are commonly used for the conveyance of information for data applications. The receive rate of incoming packets varies as congestion in the network causes variation in the amount of time for a packet to traverse the network before being placed into the JAB (Jitter Absorption Buffer). The disclosure contains methods for calculating a real time measurement of PDV (Packet Delay Variation). This real time measurement is useful as a metric on the quality of the service provided by the network or as a trigger for dynamic adjustment of the operation of equipment to optimize for current network conditions. More specifically, the disclosure includes a method that uses variations in the buffer depth of the JAB to measure PDV. This abstract is provided as a tool for those searching for patents, and not as a limitation on the scope of the claims.

Measurement of packet delay variation

A Phase-locked Loop (PLL) ( ) that is dynamically and automatically altered in response to changes in the jitter of the input is disclosed. The Analysis Block ( ) receives one or more inputs from the PLL operation. The output of the Analysis Block ( ) triggers a change in the Parametric Control Block ( ) which in turn imparts changes on the gains of one or more of the various components or the value of &ohgr; of the PLL Low Pass Filter ( ). The dynamic change to at least one parameter of the PLL adjusts the tradeoff between removing as much of the jitter as possible and having a responsive system that has a reduced risk of buffer underflow or overflow. This abstract is provided as a tool for those searching for relevant disclosures, and not as a limitation on the scope of the claims.

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Durham, NC, United States of America

Prayson Will Pate