Network device incorporating selective compression of stored data packets

• US 6,763,031 B1
• Filed: 11/17/1999
• Issued: 07/13/2004
• Est. Priority Date: 10/05/1999
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Allwright, Gareth E, Choi, Kam, Hay, Christopher, Gibson, Patrick
• Primary Examiner(s): Olms, Douglas
• Assistant Examiner(s): Phunkulh, Bob A.
• Application Number:
  US09/442,238
• Time in Patent Office: 1,700 Days
• Field of Search: 370/389, 370/400, 370/401, 370/412, 370/413, 370/428, 370/429, 370/477, 370/521, 370/474, 711/101, 711/147, 711/170, 711/171, 711/172, 382/232, 382/233, 709/246, 709/247
• US Class Current: 370/428
• CPC Class Codes: H04L 47/38 by adapting coding or compression rate
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/9042 Separate storage for different parts of the packet, e.g. header and payload
• CPC Class Codes: H04L 69/04 Protocols for data compression, e.g. ROHC
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A network device incorporating selective compression of stored data packets is disclosed. The network device receives, stores and forwards data packets and includes a system for applying a compression algorithm to packets after their header portions and storing the partially compressed packets, which are decompressed after readout from storage and before they are forwarded. Lengths of a packet as received and as subject to the compression algorithm are compared to prevent storage when the algorithm fails to produce a shorter packet.

Claims

1. A network device for use in packet-bases data communication system, comprising:

means for receiving data packets;

a memory for storing received data packets;

means for partially compressing at least some received data packets before they are stored in said memory;

means for providing in response to a received packet a version which has not been subject to any compression algorithm and a version which has been subjected to a compression algorithm; and

means for selecting between said versions according to predetermined criterion.

2. A network device according to claim 1 wherein said packets each have a header portion and a subsequent portion and said means for partially compressing includes means for providing for storage packets of which the said subsequent portion has been subjected to a compression algorithm.

3. A network device according to claim 1 wherein said criterion is such that the version which has not been subjected to the compression algorithm is selected if the received packet is less than a predetermined size.

4. A network device according to claim 1 wherein said criterion is the size of said versions, the smaller thereof being selected.

5. A network device according to claim 1, further comprising first-in and first-out buffers for each of said versions, said means for selecting being coupled to said buffers and operative to select the smaller version for storage in said memory.

6. A network device according to claim 1 further comprising means for decompressing the partially compressed packets after they are read out from said memory.

7. A network device for use in a packet-based data communication system, comprising:

means for receiving data packets each having a header portion and a subsequent portion;

a memory for storing received data packets;

means for subjecting said subsequent portion of each of a plurality of received packets to a compression algorithm before said packets are stored in said memory;

means for reading out packets from the memory;

means for subjecting to a decompression algorithm the said subsequent portions of packets read out from said memory;

means for providing in response to a received packet a version which has not been subject to any compression algorithm and a version which has been subjected to a compression algorithm; and

means for selecting for storage in said memory between said versions according to a predetermined criterion.

8. A network device for use in a packet-based data communication system, comprising means for receiving data packets each comprising a header portion and a message portion,

means for applying a compression algorithm to said message portion of a data packet to produce a first version of said packet,

means for providing a second uncompressed version of said data packet;

means for selecting, between said first and second versions of the data packet according to a predetermined criterion, and a store for storing whichever version of the data packet is selected by the means for selecting.

9. A network device as in claim 8 wherein the said criterion is a predetermined size of said data packet whereby said second uncompressed version is selected of a packet which is less than said predetermined size.

10. A network device as in claim 8 wherein said criterion is whichever of the first and second versions is shorter.

11. A network device as in claim 8 and further comprising first-in first-out stores for storing said first and second versions of said data packet.

12. A method for operating a packet-based data communication system, comprising:

receiving data packets;

storing received data packets;

partially compressing at least some received data packets before they are stored;

providing in response to a received packet a version which has not been subject to any compression algorithm and a version which has been subjected to a compression algorithm; and

selecting between said versions according to a predetermined criterion.