Patent ID: 7933201

Claim:
An entry compression and decompression method for use in a packet relay apparatus carrying out flow identification based on an entry of a flow table describing a bit pattern indicating a data included in a packet which is a subject of flow identification, the method comprising: judging whether a new bit pattern to be registered in the flow table is an incremental pattern, that is, a difference between the bit pattern described in the entry and the new bit pattern is one bit; changing a mask pattern described in the entry so as to indicate a position of a bit which is capable of taking an arbitrary logical value for the bit pattern if the new bit pattern is the incremental pattern; and additionally registering the new bit pattern in the flow table as an entry if the new bit pattern is not the incremental pattern, wherein when the number of entries registered in said flow table is equal to or more than a specified value, decompressing a compressed entry registered in said flow table, deleting an entry indicating a release bit pattern and an entry corresponding to the release bit pattern among the decompressed entries, sorting remaining entries, and instructing a re-registration of the sorted entries.