Patent ID: 7403999
Filing Date: 2008-07-22
Classification: H04L,Y10S

Abstract:
1. A method for supporting multifield classification of a packet fragmented into a plurality of fragments in a wire-speed forwarding platform, the method comprising: receiving a fragment of the fragmented packet at the forwarding platform and deriving a key from one or more fields of the received fragment; preprocessing the received fragment by querying a data structure that comprises one or more flags for determining whether the received fragment is to be classified in the forwarding platform, one queried flag indicating presence of any pre-defined transfer control protocol (TCP) rules to apply; performing multifield classification of the received fragment in the forwarding platform if said one queried flag indicates no TCP rules to apply; and, redirecting said received fragment to a further processor for processing said fragment or discarding the received fragment from the forwarding platform if it is determined that the received fragment is not to be classified at the forwarding platform; and performing multifield classification of the received fragment by matching the key to a rule out of a plurality of rules, the rule comprising a plurality of fields including at least a first field comprising a first fragmented flag (FRAG) for specifying if this rule should match fragmented frames, non-fragmented frames, or both; and a second field comprising a not subsequent fragment flag (NO SUBS) in the rule key specifying whether this rule should match only non-fragmented frames including a first fragment of a fragmented frame, or is to be matched only to subsequent fragments of a fragmented frame, whereby said first and second fields specify whether the received fragment's fragmentation characteristics are to be applied when performing the multifleld classification.