METHOD OF REPRESENTING A GENERIC FORMAT HEADER USING CONTINUOUS BYTES AND AN APPARATUS THEREOF

摘要

Embodiments of the apparatus for modifying packet headers relate to a rewrite engine that represents each protocol header of packets in a generic format specific to that protocol to enable programmable modifications of packets, resulting in hardware and software flexibility in modifying packet headers. Software programs generic formats in a hardware table for various protocols. The rewrite engine is able to detect missing fields from a protocol header and is able to expand the protocol header to a maximum size such that the protocol header contains all possible fields of that protocol. Each of the fields has the same offset irrespective of which variation of the protocol the protocol header corresponds to. The expanded protocol header is represented by a data structure that is independent of a size of the protocol header.

主权项

1. A method of a rewrite engine, the method comprising:
detecting missing fields from a protocol header of an incoming packet; based on the detection, expanding the protocol header to a generic format for a corresponding protocol, wherein the generic format includes all possible fields that the corresponding protocol can have; and maintaining a data structure for the expanded protocol header, wherein the data structure includes a first field and a second field, wherein the first field indicates a number of contiguous valid bytes from a start of the expanded protocol header, and the second field is a bit vector indicating which validity of each byte after the contiguous valid bytes in the expanded protocol header.