System and method of reducing data corruption due to recycled IP indentification numbers

• US 20050025185A1
• Filed: 07/31/2003
• Published: 02/03/2005
• Est. Priority Date: 07/31/2003
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Jain, Vinit, Brown, Deanna Lynn Quigg, Fernandes, Lilian Sylvia
• Granted Patent: US 7,302,491 B2
• Time in Patent Office: Days
• US Class Current: 370/474
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/36 by determining packet size, e.g. maximum transfer unit [MTU]
• CPC Class Codes: H04L 47/43 Assembling or disassembling of packets, e.g. segmentation and reassembly [SAR]
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/161 Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields
• CPC Class Codes: H04L 69/165 Combined use of TCP and UDP protocols; selection criteria therefor
• CPC Class Codes: H04L 69/166 IP fragmentation; TCP segmentation
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A system and method of reducing data corruption due to recycled Internet Protocol (IP) identification numbers are provided. When IP packets are being fragmented and the IP identification number of the packets is cycling through a specific group of numbers, the size of the first fragment of a packet is decremented each time the IP identification cycles through the numbers. Initially, the size of the first fragment of a packet will be set to a maximum number. This size will be decremented at each pass of the IP identification through the numbers until the size of the first fragment of a packet reaches a pre-defined minimum size. When that occurs, the size of the first fragment of a packet will again be set to the maximum number. By decrementing the size of the first fragment, fragment offset of the other fragments that make up the packet will be changing. This then reduces the likelihood of having two fragments having the same IP identification number be mistaken as being from the same packet.

Claims

1. A method of reducing data corruption due to recycled Internet Protocol (IP) identification numbers comprising the steps of:

determining whether packets are to be divided into fragments;

determining, if packets are to be divided into fragments, whether IP identification numbers are being recycled; and

setting a size of a first fragment of a packet to a maximum transmission unit (MTU), if the IP identification numbers are recycling and decrementing the size of the first fragment of a packet each time the IP identification numbers recycle.

2. The method of claim 1 wherein the size of the first fragment of a packet is decremented until it is equal to a predefined minimum transmission unit.

3. The method of claim 2 wherein each time the size of the first fragment of a packet is to be decremented, it is decremented by one octet.

4. The method of claim 3 wherein after being equal to the minimum transmission unit, the size of the first fragment is set to MTU the next time the IP identification numbers recycle.

5. The method of claim 4 wherein when the first fragment of a packet is decremented, the fragment offset of all other fragments of the packet is modified.

6. The method of claim 5 wherein if the IP identification number of all fragments is the same and the fragment offset of a fragment is not consistent with each other, the packet is discarded.

7. The method of claim 6 wherein if the IP identification number of all fragments is the same and the fragment offset of a fragment is consistent with each other, the fragments are used to re-assemble the packet.

8. The method of claim 7 wherein the packet is discarded or re-assembled by a receiving host.

9. A computer program product on a computer readable medium for reducing data corruption due to recycled Internet Protocol (IP) identification numbers comprising:

code means for determining whether packets are to be divided into fragments;

code means for determining, if packets are to be divided into fragments, whether IP identification numbers are being recycled; and

code means for setting a size of a first fragment of a packet to a maximum transmission unit (MTU) if the IP identification numbers are recycling and decrementing the size of the first fragment of a packet each time the IP identification numbers recycle.

10. The computer program product of claim 9 wherein the size of the first fragment of a packet is decremented until it is equal to a predefined minimum transmission unit.

11. The computer program product of claim 10 wherein each time the size of the first fragment of a packet is to be decremented, it is decremented by one octet.

12. The computer program product of claim 11 wherein after being equal to the minimum transmission unit, the size of the first fragment is set to MTU the next time the IP identification numbers recycle.

13. The computer program product of claim 12 wherein when the first fragment of a packet is decremented, the fragment offset of all other fragments of the packet is modified.

14. The computer program product of claim 13 wherein if the IP identification number of all fragments is the same and the fragment offset of a fragment is not consistent with each other, the packet is discarded.

15. The computer program product of claim 14 wherein if the IP identification number of all fragments is the same and the fragment offset of a fragment is consistent with each other, the fragments are used to re-assemble the packet.

16. The computer program product of claim 15 wherein the packet is discarded or re-assembled by a receiving host.

17. A system for reducing data corruption due to recycled Internet Protocol (IP) identification numbers comprising:

at least one storage system for storing code data; and

at least one processor for processing the code data to determine whether packets are to be divided into fragments, to determine, if packets are to be divided into fragments, whether IP identification numbers are being recycled, and to set a size of a first fragment of a packet to a maximum transmission unit (MTU) if the IP identification numbers are recycling and decrementing the size of the first fragment of a packet each time the IP identification numbers recycle.

18. The system of claim 17 wherein the size of the first fragment of a packet is decremented until it is equal to a predefined minimum transmission unit.

19. The system of claim 18 wherein each time the size of the first fragment of a packet is to be decremented, it is decremented by one octet.

20. The system of claim 19 wherein after being equal to the minimum transmission unit, the size of the first fragment is set to MTU the next time the IP identification numbers recycle.