Mechanisms for avoiding problems associated with network address protocol translation

• US 7,006,526 B1
• Filed: 07/31/2001
• Issued: 02/28/2006
• Est. Priority Date: 07/31/2001
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Biederman, Daniel C.
• Primary Examiner(s): Ngo, Ricky
• Assistant Examiner(s): Haile, Feben
• Application Number:
  US09/920,533
• Time in Patent Office: 1,673 Days
• Field of Search: 370/466, 370/392, 370/236, 370/252, 370/389, 455/432.2
• US Class Current: 370/466
• CPC Class Codes: H04L 47/193 at the transport layer, e.g. TCP related
• CPC Class Codes: H04L 47/29 using a combination of thresholds
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04L 47/36 by determining packet size, e.g. maximum transfer unit [MTU]
• CPC Class Codes: H04L 47/365 Dynamic adaptation of the packet size
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/251 between different IP versions
• CPC Class Codes: H04L 61/2564 for a higher-layer protocol, e.g. for session initiation protocol [SIP]
• 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 69/167 Adaptation for transition between two IP versions, e.g. between IPv4 and IPv6 translation of Internet protocol [IP] addresses H04L61/2503

Abstract

Disclosed are methods and apparatus for avoiding problems caused by converting between two different protocols, such as IPv4 and IPv6. These problems may include, but are not limited to, fragmentation of packets, dropping of packets, and retransmission of packets. Avoiding these problems will reduce the incidence of transmission delays, bandwidth degradation, and additional processing in the packet'"'"'s transmission path due to such problems. In general terms, the present invention provides mechanisms for modifying a protocol parameter, such as a TCP or UDP parameter, to avoid problems associated with protocol translation, such as fragmentation. In one implementation, the protocol parameter limits the size of a particular portion of the a packet transmitted by a sending computer node or device. For example, a packet size indicator is communicated to the sending computer node so that the sending computer node sends packets limited by the packet size indicator to thereby avoid associated with the size of such packets. In specific TCP embodiments, the size indicator specifies a window size and/or a maximum segment size. For example, if packets transmitted by a sending node to a receiving node are converted from IPv4 to IPv6 and the window size indicated to the sending node (e.g., by the receiving node) is 512 bytes, the window size is adjusted to 500 bytes before reaching the sending node. The adjustment amount may be based on an estimated size increase resulting from converting from IPv4 to IPv6. In this example, the window size is decreased by 12 bytes since a conversion from IPv4 to IPv6 where one 4 byte IPv4 address is changed to a 16 byte Ipv6 address has an associated size difference of 12 bytes. In a specific embodiment, actual changes in packet size may tracked and the adjusted size indicator may be dynamically based on such tracked changes. In other embodiments, the changes in packet size are predicted, and the adjusted size is preemptively changed as needed.

Claims

1. A method for avoiding problems associated with protocol translation comprising:

determining information related to converting data from a first protocol to a second protocol; and

modifying a protocol parameter of a first data based on the determined information to thereby avoid problems associated with a second data sent after the first data, wherein problems related to change in a size of the second data may result from converting the second data from the first to the second protocol,

wherein the protocol parameter is decreased based on the determined information and the determined information includes an estimated size increase of the second data resulting from converting the second data the first to the second protocol.

2. A method as recited in claim 1, wherein the avoided problems are selected from a group consisting of fragmentation of data, dropping of data, and retransmission of data.

3. A method as recited in claim 1, wherein the first protocol is IPv4 and the second protocol is IPv6.

4. A method as recited in claim 1, wherein the protocol parameter is related to a buffer size.

5. A method as recited in claim 4, wherein the protocol parameter is a window size.

6. A method as recited in claim 1, wherein the protocol parameter is related to a maximum data allowed in transmission.

7. A method as recited in claim 6, wherein the protocol parameter is a maximum segment size.

8. A method as recited in claim 7, wherein the maximum segment size is advertised by a sending device of the first data and the advertised maximum segment size is modified before it reaches its final destination.

9. A method as recited in claim 7, wherein modifying the maximum segment size is accomplished by performing a discovery algorithm to determine a network maximum transmission unit.

10. A method as recited in claim 1, wherein determining the information is accomplished by tracking size changes of data converted from the first to the second protocol.

11. A method as recited in claim 10, wherein determining the information is further accomplished by estimating a sizes change in data resulting from tunneling from the first to the second protocol.

12. A method as recited in claim 1, further comprising converting the first data from the first to the second protocol and the second data from the second to the first protocol.

13. A method as recited in claim 1, wherein converting data from a first protocol to a second protocol is accomplished by performing network address protocol translation (NAT-PT).

14. A method as recited in claim 1, wherein converting data from a first protocol to a second protocol is accomplished by tunneling.

15. A computer system operable to avoid one or more problems associated with protocol translation, the router comprising:

one or more processors;

one or more memory, wherein at least one of the processors and memory are adapted to;

determine information related to converting data from a first protocol to a second protocol; and

modify a protocol parameter of a first data based on the determined information to thereby avoid one or more problems associated with a second data sent after the first data, wherein the problem(s) are related to a change in a size of the second data that may result from converting the second data from the first to the second protocol,

wherein the protocol parameter is decreased based on the determined information and the determined information includes an estimated size increase of the second data resulting from converting the second data from the first to the second protocol.

16. A computer system as recited in claim 15, wherein the avoided problems are selected from a group consisting of fragmentation of data, dropping of data, and retransmission of data.

17. A computer system as recited in claim 15, wherein the first protocol is IPv4 and the second protocol is IPv6.

18. A computer system as recited in claim 15, wherein the protocol parameter is related to a buffer size.

19. A computer system as recited in claim 18, wherein the protocol parameter is a window size.

20. A computer system as recited in claim 15, wherein the protocol parameter is related to a maximum data allowed in transmission.

21. A computer system as recited in claim 20, wherein the protocol parameter is a maximum segment size.

22. A computer system as recited in claim 21, wherein the maximum segment size is advertised by a sending device of the first data and the advertised maxim segment size is modified before it reaches its final destination.

23. A computer system as recited in claim 15, wherein determining the information is accomplished by tracking size changes of data converted from the first to the second protocol.

24. A computer system as recited in claim 15, wherein converting data from a first protocol to a second protocol is accomplished by performing network address protocol translation (NAT-PT).

25. A computer system as recited in claim 15, wherein converting data from a first protocol to a second protocol is accomplished by tunneling.

26. A computer program product for avoiding one or more problems associated with protocol translation, the computer program product comprising:

at least one computer readable medium;

computer program instructions stored within the at least one computer readable product configured to cause a combining device to;

determine information related to converting data from a first protocol to a second protocol; and

modify a protocol parameter of a first data based on the determined information to thereby avoid one or more problems associated with a second data sent after the first data, wherein the problem(s) are related to a change in a size of the second data that may result from converting the second data from the first to the second protocol,

wherein the protocol parameter is decreased based on the determined information and the determined information includes an estimated size increase of the second data resulting from converting the second data from the first to the second protocol.

27. A computer program product as recited in claim 26, wherein the avoided problems are selected from a group consisting of fragmentation of data, dropping of data, and retransmission of data.

28. A computer program product as recited in claim 26, wherein the first protocol is IPv4 and the second protocol is IPv6.

29. A computer program product as recited in claim 26 wherein the protocol parameter is related to a buffer size.

30. A computer program product as recited in claim 29, wherein the protocol parameter is a window size.

31. A computer program product as recited in claim 26, wherein the protocol parameter is related to a maximum data allowed in transmission.

32. A computer system as recited in claim 31 wherein the protocol parameter is a maximum segment size.

33. A computer program product as recited in claim 32, wherein the maximum segment size is advertised by a sending device of the first data and the advertised maximum segment size is modified before it reaches its final destination.

34. A computer program product as recited in claim 26 wherein determining the information is accomplished by track size changes of data converted from the first to the second protocol.

35. A computer program product as recited in claim 26, wherein converting data from a first protocol to a second protocol is accomplished by performing network address protocol translation (NAT-PT).

36. An apparatus for avoiding one or more problems associated with protocol translation, the apparatus comprising:

means for determining information related to converting data from a first protocol to a second protocol; and

means for modifying a protocol parameter of a first data based on the determined information to thereby avoid one or more problems of a second data sent after the first data, wherein the problem(s) are related to a change in a size of the second data that may result from converting the second data from the first to the second protocol,

wherein the protocol parameter is decreased based on the determined information and the determined information includes an estimated size increase of the second data resulting from converting the second data from the first to the second protocol.

37. An apparatus as recited in claim 36, wherein the avoided problems are selected from a group consisting of fragmentation of data, dropping of data, and retransmission of data.

38. An apparatus as recited in claim 36, wherein the first protocol is IPv4 and the second protocol is IPv6.