Foundry Networks, Inc.

Chiaro Networks Ltd

Jim Kleiner

Tony M Brewer

Gregory S Palmer

Keith W Shaw

Thomas C McDermott, Iii

Harold Wallace Dozier

Harry C Blackmon

David Traylor

Dean E Walker

Lance Arnold Visser

Qiang Li

Steve M Simmons

Bing Liu

Michael K Dugan

Paul F Vogel

Employing an asymmetric protocol, multiple sources reliably broadcast dynamically changing routing tables incrementally across multiple consumers from a single distributor. Each of multiple sources send current tables to the distributor using a snapshot mechanism. Message are buffered, segmented, paced by timers, and broadcast to the consumers repetitively at the distributor. Negative acknowledgments from the consumer request missing messages from the distributor after receipt of a keepalive message from the distributor. The distributor marks the missing messages and retransmits replacements from a history buffer only after firing of a resend timer. A unique Session ID included in all messages originating from each particular source facilitates reliable table distribution from multiple sources to multiple consumers via a single distributor.

System and method for router data distribution

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

In a multi-QOS level queuing structure, packet payload pointers are stored in multiple queues and packet payloads in a common memory pool. Algorithms control the drop probability of packets entering the queuing structure. Instantaneous drop probabilities are obtained by comparing measured instantaneous queue size with calculated minimum and maximum queue sizes. Non-utilized common memory space is allocated simultaneously to all queues. Time averaged drop probabilities follow a traditional Weighted Random Early Discard mechanism. Algorithms are adapted to a multi-level QOS structure, floating point format, and hardware implementation. Packet flow from a router egress queuing structure into a single egress port tributary is controlled by an arbitration algorithm using a rate metering mechanism. The queuing structure is replicated for each egress tributary in the router system.

System and method for router queue and congestion management

Employing an asymmetric protocol, multiple sources reliably broadcast dynamically changing routing tables incrementally across multiple consumers from a single distributor. Each of multiple sources sends current tables to the distributor using a snapshot mechanism. Messages are buffered, segmented, paced by timers, and broadcast to the consumers repetitively at the distributor. Negative acknowledgments from the consumer request missing messages from the distributor after receipt of a keepalive message from the distributor. The distributor marks the missing messages and retransmits replacements from a history buffer only after firing of a resend timer. A unique Session ID included in all messages originating from each particular source facilitates reliable table distribution from multiple sources to multiple consumers via a single distributor.

A multicast packet is transferred through a switching fabric from an input line card to a dedicated multicast card, which is substantially the same as an input and output line card, but without external facility interfaces. A dedicated output multicast card converts the multicast packet from an optical to an electrical packet and passes it to a dedicated input multicast card, where the packet is replicated electrically, converted back to an optical packet, and then transferred through the switching fabric to multiple destinations. In some embodiments, input and output dedicated multicast cards are actually a single card. Transfer of the multicast packet to multiple destinations occurs sequentially or simultaneously during a single switching cycle, if multiple parallel switching paths exist through the switching fabric. Some embodiments include multiple dedicated multicast cards, allowing rapid simultaneous expansion of the multicast tree.

System and method for router multicast control

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

Hardware interconnected around multiple packet forwarding engines prepends sequence numbers to packets going into multiple forwarding engines through parallel paths, After processing by the multiple forwarding engines, packets are reordered using queues and a packet ordering mechanism, such that the sequence numbers are put back into their original prepended order. Exception packets flowing through the forwarding engines do not follow a conventional fast path, but are processed off-line and emerge from the forwarding engines out of order relative to fast path packets. These exception packets are marked, such that after they exit the forwarding engines, they are ordered among themselves independent of conventional fast path packets. Viewed externally, all exception packets are ordered across all multiple forwarding engines independent of the fast path packets.

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Dallas, TX, United States of America

Jim Kleiner