Cisco Technology, Inc.

Pedro Marques

William B May, Jr

Andrew J Valencia

Kenneth A Moberg

Claude Alan Cartee

Kirk Stewart Lougheed

Gregory D Stovall

David R Hampton

Timothy D Kolar

Steven P Lin

In an embodiment, a network router includes plural interfaces and a chain walker which, upon receipt of a first protocol packet in a first interface, processes the packet by walking the packet through a decapsulation chain associated with the interface and the first protocol and an encapsulation chain associated with an identified second interface and identified second protocol. The walker passes the packet to elements of the decapsulation chain to produce a decapsulated packet. The walker passes the decapsulated packet to elements of an encapsulation chain to produce an encapsulated packet. Each chain includes at least one packet-processing element. An element receives the packet from the walker as processed by a previous element, the packet being further processed as appropriate. The walker, upon receipt of the first protocol packet, passes the packet to elements of a demultiplexer chain associated with the first interface to produce a demultiplexed packet.

Packet processing using encapsulation and decapsulation chains

A method for processing packets in a router includes specifying operations on packets as chains of processing elements. Each chain is uniquely associated with one interface/protocol pair, and each processing element performs at least one function on a packet. An incoming packet is received, and processed, first by a demultiplexor element which determines the protocol of the next higher level used by the packet. Then, the packet is processed by the elements of a decapsulation chain associated with the interface on which the packet was received, and by the elements of an encapsulation chain associated with the interface on which the packet is to be transmitted. The demultiplexor element or operation passes the packet on to a decapsulation chain associated with the protocol and with the incoming interface, depending on protocol information contained in the incoming packet. Decapsulation and encapsulation chains can be built dynamically, by inserting new and removing old elements as necessary as new protocols are developed and new features added. A chain walker walks through the chains, passing the processed packet to each element in a chain, until either the end of the chain is reached and processing is complete, or until the packet is dropped because no function can process it, or because a packet is processed by an outside process or by hardware, which may optionally stop the chain walk. A chain walk may be temporarily halted, or may be terminated. If temporarily halted, the chain walk can be resumed at any element in the chain, depending on the packet's requirements. A chain walk can also begin at any element in a chain.

A method of distributing route information is described. The method includes maintaining a number of entries, indicating that at least one of the entries, requiring processing by a first process, has been processed by the first process, and causing the first process to process another of the entries requiring processing by the first process based on the indication. In doing so, the first process uses the indication to decide which of the entries requiring processing the process has already processed and which of those entries remain to be processed. Each one of the entries preferably corresponds to at least one characteristic of a network connection between a number of network elements, such as a route between network elements.

Scaleable route redistribution mechanism

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San Jose, CA, United States of America

Pedro Marques