Foundry Networks, Inc.

Chiaro Networks Ltd

Jeremy Benjamin As Receiver for Chiaro Networks Ltd.

Harry C Blackmon

Tony M Brewer

Harold Wallace Dozier

Thomas C McDermott, Iii

Dean E Walker

Gregory S Palmer

Keith W Shaw

Jim Kleiner

David Traylor

Steven Jeffrey Wallach

Chris Davies

Lou Yeh

William D O'Leary

Instead of alternatively utilizing only one fabric or the other fabric of a redundant pair, both fabrics simultaneously transmit duplicate information, such that each packet forwarding module (PFM) receives the output of both fabrics simultaneously. In real time, an internal optics module (IOM) analyzes each information chunk coming out of a working zero switch fabric; simultaneously examines a parallel output of a working one duplicate switch fabric; and compares on a chunk-by-chunk basis the validity of each and every chunk from both switch fabrics. The IOM does this by examining forward error correction (FEC) check symbols encapsulated into each chunk. FEC check symbols allow correcting a predetermined number of bit errors within a chunk. If the chunk cannot be corrected, then the IOM provides indication to all PFMs downstream that the chunk is defective. Under such conditions, the PFMs select a chunk from the non-defective switch fabric. Under error-free normal conditions, however, the PFMs select a chunk arbitrarily from a default switch fabric. In this way, each chunk in real time is selected from a non-defective source and is thus guaranteed to be error free. Accordingly, if a switch fabric fails, no information chunks are lost anywhere in the system.

Router switch fabric protection using forward error correction

A chunk format for a large-scale, high data throughput router includes a preamble that allows each individual chunk to have clock and data recovery performed before the chunk data is retrieved. The format includes a chunk header that contains information specific to the entire chunk. A chunk according to the present format can contain multiple packet segments, with each segment having its own packet header for packet-specific information. The format provides for a scrambler seed which allows scrambling the data to achieve a favorable zero and one balance as well as minimal run lengths. There can be a random choice of available scrambler seeds for any particular chunk to avoid malicious forcing of zero and one patterns or run lengths of bit zeroes and ones. There are a chunk cyclical redundancy check (CRC) as well as forward error correction (FEC) bytes to detect and/or correct any errors and also to insure a high degree of data and control integrity. Advantageously, a framing symbol inserted into the chunk format itself allows the receiving circuitry to identify or locate a particular chunk format. 'Break Bytes' and 'Make Bytes' fields located at the beginning of a chunk preamble precondition an optical receiver to a proper state before the actual chunk arrives at the receiver.

System and method for router data aggregation and delivery

A chunk format for a large-scale, high data throughput router includes a preamble that allows each individual chunk to have clock and data recovery performed before the chunk data is retrieved. The format includes a chunk header that contains information specific to the entire chunk. A chunk according to the present format can contain multiple packet segments, with each segment having its own packet header for packet-specific information. The format provides for a scrambler seed which allows scrambling the data to achieve a favorable zero and one balance as well as minimal run lengths. There are forward error correction (FEC) bytes as well as a chunk cyclical redundancy check (CRC) to detect and/or correct any errors and also to insure a high degree of data and control integrity. Advantageously, a framing symbol inserted into the chunk format itself allows the receiving circuitry to identify or locate a particular chunk format. 'Break Bytes' and 'Make Bytes' fields located at the beginning of a chunk preamble precondition an optical receiver to a proper state before the actual chunk arrives at the receiver.

A router line card is partitioned to separate the packet forwarding functions from physical port interfacing. For each packet forwarding card, at least one redundant port interface is provided. Identical input packets are transmitted via these redundant input port interfaces, one of which is eventually selected based on, for example, SONET standard criteria. If there is a failure, the router selects the interface path that is operating properly and rejects the path containing a failed element. Thus, the router decides locally how to correct the problem internally. Moreover, following an equipment failure the now offline failed interface path can be replaced, while the equipment remains in service using the duplicated interface path. The system can be restored to full duplex operation without affecting the existing traffic, providing for a hot replacement of a failed path. Because the interfaces are separate, a failed module can be renewed and replaced while the equipment is in service. If a failure occurs in an interface card between two peer routers, then packets flow between the two routers uninterrupted from exactly the same previous ports on one router to the same previous ports on the second router, using the same Internet protocol addresses as existed prior to the switching.

Router network protection using multiple facility interfaces

Router line cards are partitioned, separating packet forwarding from external or internal interfaces and enabling multiple line cards to access any set of external or internal data paths. Any failed working line card can be switchably replaced by another line card. In particular, a serial bus structure on the interface side interconnects any interface port within a protection group with a protect line card for that group. Incremental capacity allows the protect line card to perform packet forward functions. Logical mapping of line card addressing and identification provides locally managed protection switching of a line card that is transparent to other router line cards and to all peer routers. One-for-N protection ratios, where N is some integer greater than two, can be achieved economically, yet provide sufficient capacity with acceptable protection switch time under 100 milliseconds. Alternatively, protect line cards can routinely carry low priority traffic that is interruptible, allowing the protect line card to handle higher priority traffic previously carried by a failed working line card. This approach renders unnecessary engineering a network for less than full capacity to allow rerouting in the event of individual line card failure. Consequently, all data paths can be fully utilized. If a particular interface module on one data bus needs removal for maintenance, a duplicate data bus is available intact, allowing hot replacement of any working or protect interface module, even while a line card protection switch is in effect.

Router line card protection using one-for-N redundancy

Information and control are synchronized as they flow through a large distributed IP router system with independent clocks. The IP router includes multiple equipment racks and shelves, each containing multiple modules. The IP router is based on a passive switching device, which in some embodiments is an optical switch. Control and data come to the switching device from different sources, which have different clocks. Timing and synchronization control are provided, such that information and control both arrive at the switching device at the proper time. A single point in the system originates timing, which is then distributed through various ASICs of the system to deliver configuration control to the switch at the appropriate time. The launch of information to the switch is also controlled with a dynamic feedback loop from an optical switch controller. Control aspects of the optical switch are aligned by this same mechanism to deliver control and data to the optical switch simultaneously.

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Plano, TX, United States of America

Harry C Blackmon