Coalescing acknowledgement responses to improve network communications

• US 7,826,487 B1
• Filed: 06/09/2005
• Issued: 11/02/2010
• Est. Priority Date: 05/09/2005
• Status: Active Grant

• Current Assignee: F5 Networks, Inc. (F5 Incorporated)
• Original Assignee: F5 Networks, Inc. (F5 Incorporated)
• Inventors: Mukerji, Arindum, Rothstein, Jesse Abraham
• Primary Examiner(s): Ferris; Derrick W
• Assistant Examiner(s): BROCKMAN, ANGEL T
• Application Number:
  US11/150,361
• Time in Patent Office: 1,972 Days
• Field of Search: 370/273, 370/503, 370/389, 370/477, 370/394
• US Class Current: 370/477
• CPC Class Codes: H04L 43/026 using flow identification
• CPC Class Codes: H04L 43/18 Protocol analysers
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/5651 Reducing the amount or size of exchanged application data
• CPC Class Codes: H04L 69/04 Protocols for data compression, e.g. ROHC

Abstract

A system, apparatus, and method are directed to managing network communications by, in part, reducing a number of packets between a client and a server communicating through another device, such as a traffic management device (TMD). The invention reduces the number of packets communicated, in part, by coalescing acknowledgements (ACKs) and/or finish (FIN) flags into another packet. In one embodiment, if the client provides a substantially complete request for the server, an ACK to the request may be coalesced into a corresponding response from the server. When another request is to be provided to the server, within about half of the minimum retransmission timeout, an ACK to the prior response may be coalesced into a subsequent request to the server. Packet reduction may also be achieved by stretching a packet to insert additional data when the insertion maintains a packet size that is within a negotiated maximum segment size (MSS).

Claims

1. A network device for managing a communication over a network, comprising:

a transceiver for receiving and sending packets to a client and a server; and

a management component that is within the network device, the network device being interposed between the client and the server, and wherein the management component is programmed to perform actions comprising;

receiving, from the server, a response to a first request from the client;

receiving, a second request, wherein the second request is received absent an acknowledgement (ACK) to the response; and

selectively coalescing, by the network device, the acknowledgement (ACK) to the response within the second request, wherein the second request is a Hypertext protocol Transfer protocol (HTTP) request; and

forwarding the second request with the ACK to the server.

2. The network device of claim 1, wherein the actions further comprise:

determining whether the second request is received within a timeout period, and wherein selectively coalescing the acknowledgement is based on whether the second request is received within the timeout period.

3. The network device of claim 2, wherein the timeout period is based on a minimum retransmission timeout period.

4. The network device of claim 2, further comprising

if the second request is received after the timeout period, sending an ACK to the response to the server separate from forwarding the second request to the server.

5. The network device of claim 1, wherein the management component being programmed to perform actions, further comprising:

receiving at the network device a separate ACK to the response from the client; and

employing the separate ACK as the ACK that is selectively coalesced with the second request that is forwarded to the server.

6. The network device of claim 1, wherein the actions further comprise:

coalescing a finish (FIN) flag into a last portion of a final response from the server, and sending the coalesced last portion of the final response to the client, wherein the final response is received at the network device separate from the FIN flag.

7. The network device of claim 1, wherein the first request comprises a first application layer request using a first protocol and the second request comprises a second application layer request using a second protocol different from the first protocol.

8. The network device of claim 1, wherein the actions further comprise:

if the ACK is coalesced within the second request, selectively stretching at least one packet of the second request to an increased length, based on whether the increased length is within a maximum segment size (MSS).

9. The network device of claim 1, wherein coalescing the ACK further comprises adjusting at least one of an acknowledgement number and an offset associated with the request.

10. The network device of claim 1, wherein the actions further comprise:

if the ACK is coalesced within the second request and additional information is to be sent to the client, determining if a combination of the additional information and the response from the server are within a maximum segment size (MSS), and if it is, stretching the response from the client by inserting the additional information into the response, and sending the stretched response to the server.

11. The network device of claim 1, wherein the second request is received from another client.

12. The network device of claim 1, wherein the network device is configured to operate as at least one of a router, proxy, firewall, load balancer, cache device, gateway, a network address translator, port translator, a sequence translator, or a traffic management device.

13. The network device of claim 1, wherein the actions further comprise:

performing a three-way handshake with the client prior to receiving the first request from the client.

14. The network device of claim 13, wherein performing the three-way handshake further comprises employing at least one of a SYN cookie or a SYN cache mechanism.

15. A network device for managing a communication over a network, comprising:

a transceiver for receiving and sending packets to a client and a server; and

a management component that is within the network device, the network device being interposed between the client and the server, and wherein the management component is programmed to perform actions comprising;

receiving, from the server, a response to a first request from the client;

receiving, a second request, wherein the second request is received absent an acknowledgement (ACK) to the response; and

selectively coalescing, by the network device, the acknowledgement (ACK) to the response within the second request;

forwarding the second request with the ACK to the server, wherein the first request comprises an HyperText Transfer Protocol (HTTP) request;

parsing the HTTP request;

selectively coalescing a request ACK with the response, based on the parsing of the HTTP request; and

forwarding the response to the client.

16. A method of managing a communication between a client and a server over a network, comprising:

performing a three-way handshake with the client to establish a session;

receiving a request from the client by a network device interposed between the client and the server;

forwarding the request to the server;

receiving a separate acknowledgement (ACK) to the request from the server;

receiving a response to the request from the server;

selectively coalescing an acknowledgement (ACK) to the request into the response, wherein the request is a HyperText Transfer Protocol (HTTP) request; and

forwarding the response to the client.

17. The method of claim 16, wherein performing the three-way handshake further comprises employing at least one of a SYN cookie or a SYN cache mechanism across a wide area network.

18. The method of claim 16, further comprising:

if another request that is to be sent to the server is received within a specified time period, coalescing another ACK into the other request, and sending the other request to the server.

19. The method of claim 18, wherein the other request is received from another client.

20. The method of claim 18, further comprising

if the other request destined to be sent to the server is received after the specified time period, sending the other ACK to the response to the server separate from sending the other request to the server.

21. The method of claim 18, wherein at least one of a address translation, a port translation, or a sequence translation is performed on at least one of the request, the response, or the other response.

22. The method of claim 18, wherein the specified time period is based on a minimum retransmission timeout.

23. The method of claim 16, further comprising

coalescing a finish (FIN) flag into at least a portion of a final response from the server, and sending the coalesced FIN and at least the portion of the final response to the client.

24. The method of claim 16, further comprising:

if additional information is to be sent to the server

determining if a combination of the additional information and the request from the client are within a maximum segment size (MSS), and if it is, stretching the request from the client by inserting the additional information into the request, adjusting at least one of an acknowledgement number and an internal offset, and sending the stretched request to the server.

25. The method of claim 16, further comprising parsing the content of the request and determining whether the request is complete, and wherein selectively coalescing the acknowledgement is based on whether the request is complete.

26. The method of claim 16, further comprising parsing the HTTP request and determining whether the HTTP request is complete, and wherein selectively coalescing the acknowledgement is based on whether the HTTP request is complete.

27. The method of claim 16, further comprising determining whether the response is received within a timeout period, and wherein selectively coalescing the acknowledgement is based on whether the response is received within the timeout period.

28. The method of claim 16, wherein selectively coalescing the acknowledgement into the response further comprises:

parsing application layer content within the request and determining whether the request is complete; and

if the request is complete, determining whether the reply is received within a timeout period and selectively coalescing the acknowledgement based on whether the reply is received within the timeout period.

29. A method of managing a communication between a client and a server over a network, comprising:

performing a three-way handshake with the client to establish a session;

receiving a request from the client by a network device interposed between the client and the server;

forwarding the request to the server;

receiving a separate acknowledgement (ACK) to the request from the server;

receiving a response to the request from the server;

selectively coalescing an acknowledgement (ACK) to the request into the response;

forwarding the response to the client; and

if another request that is to be sent to the server is received within a specified time period, coalescing another ACK into the other request, and sending the other request to the server, wherein at least one of the request and the other request comprises a HyperText Transfer Protocol (HTTP) request.

30. A computer-readable non-transitory storage medium having computer-executable instructions, the computer-executable instructions when installed onto a traffic management device (TMD) that is interposed between a client and a server enable the TMD to perform actions, comprising:

receiving a request at the TMD from the client;

sending the request from the TMD to the server;

receiving an acknowledgement (ACK) from the server to the request;

receiving, separate from the ACK, a response to the request, at the TMD, from the server;

coalescing at the TMD the ACK to the request into the response;

sending by the TMD the coalesced response to the client; and

if another request is received within a specified time period, coalescing at the TMD another ACK to the response into the other request, and sending by the TMD the coalesced other request to the server, wherein the other request was received by the TMD absent the other ACK;

wherein at least one of the request and the other request comprises an HTTP request.

31. The computer-readable storage medium of claim 30, further comprising:

if additional information is to be sent towards the server;

determining at the TMD if a combination of the additional information and the request from the client are within a maximum segment size (MSS), and if it is, stretching at the TMD the request from the client by inserting the additional information into the request, and sending by the TMD the stretched request to the server.

32. A traffic management device for managing a HTTP communication between a client and a server connection, comprising:

a transceiver to exchange HTTP data between the client and the server; and

a processor programmed to perform actions including;

receiving a request from the client;

sending the request to the server;

receiving a response to the request from the server, wherein the response is received absent an acknowledgement (ACK) to the request;

coalescing an ACK to the request into the response;

sending the coalesced response and ACK to the client; and

if another request is received within a specified time period and wherein the other request is received absent an ACK, coalescing another ACK to the response into the other request, and sending the coalesced other request and ACK to the server, wherein at least one of the request and the other request comprises an HTTP request.

33. The traffic management device of claim 32, wherein the actions further comprise:

if additional information is to be sent to the server;

determining if a combination of the additional information and the request from the client are within a maximum segment size (MSS), and if it is, stretching the request from the client by inserting the additional information into the request, adjusting at least one of an acknowledgement number, an offset, and a checksum associated with the request, and sending the stretched request to the server.

34. A network device that forwards packets between a first device and a second device, comprising a component that is programmed to perform actions comprising:

performing a three-way handshake with the first device to establish a session with the first device;

receiving a first packet from the first device;

determining whether a second packet that is to be sent to the first device is received within a timeout period, based on a temporal relation between receiving the first packet and receiving the second packet, wherein the second packet has an unset acknowledgment for the first packet;

if the determining is affirmative, modifying the second packet to be an acknowledgement of the first packet and forwarding the second packet to the first device; and

if the determining is negative, sending an acknowledgement of the first packet in a third packet to the first device.

35. The network device of claim 34, wherein the first device is a client device and the second device is a server.

36. The network device of claim 34, wherein the first device is a server and the second device is a client device.

37. The network device of claim 34, wherein the actions further comprise:

determining the timeout period based on a minimum retransmission timeout of a network session.

38. The network device of claim 34, wherein the actions further comprise forwarding the first packet to the second device, and receiving the second packet from a third device.

39. The network device of claim 34, wherein the first device is a server, the second device is a client device, and the second packet is received from a third device.

40. The network device of claim 34, wherein the first device is a client device and the second device is a server, and wherein the actions further comprise:

determining whether a third packet that is to be sent to the second device is received within a second timeout period;

if the determining of the third packet is affirmative, setting an ACK bit in the third packet and forwarding the third packet to the second device; and

if the determining of the third packet is negative, sending an acknowledgement in a fourth packet to the second device.

41. The network device of claim 34, wherein the actions further comprise:

if the determining is positive, increasing the length of the second packet.

42. The network device of claim 34, wherein performing the three-way handshake further comprises employing at least one of a SYN cookie or a SYN cache.

43. A network device that forwards packets between a client and a server, comprising a component that is programmed to perform actions comprising:

receiving a request packet containing at least a portion of an HTTP request from the client;

parsing the request packet to determine whether it includes a complete HTTP request;

forwarding the HTTP request to the server;

receiving a response from the server, wherein the response has an unset acknowledgment for the HTTP request; and

determining when to send an acknowledgement to the client based on whether the request packet includes a complete HTTP request.

44. The network device of claim 43, wherein the actions further comprise:

if the request packet includes the complete HTTP request, receiving the response from the server prior to sending the acknowledgement to the client.

45. The network device of claim 43, wherein the actions further comprise:

selectively coalescing an ACK with the response from the server based on whether the request packet includes the complete HTTP request.

46. The network device of claim 43, wherein the actions further comprise:

selectively coalescing an ACK with the response from the server based on whether the request packet includes the complete HTTP request and whether the response is received within a timeout period.

47. A network device that forwards packets between a client and a server, comprising a component that is programmed to perform actions comprising:

receiving a request packet containing at least a portion of an HTTP request from the client;

parsing the request packet to determine whether it includes a complete HTTP request;

forwarding the HTTP request to the server;

receiving a response from the server, wherein the response is received absent an acknowledgement to the HTTP request; and

determining when to send an acknowledgement to the client based on whether the request packet includes a complete HTTP request; and

if the request packet includes the complete HTTP request, forwarding the HTTP request to the server prior to sending the acknowledgement to the client.

48. A method of managing a communication over a network comprising:

receiving, from a server, a first message for a first client;

forwarding the first message to the first client;

receiving, from either the first client or a second client, a second message wherein the second message includes an unset ACK bit; and

selectively setting an ACK bit within the second message and forwarding the modified second message to the server, based on a temporal relation between receiving the first message and receiving the second message and wherein the set ACK bit is associated with the first message.

49. A traffic management device for managing a communication between at least one client and at least one server, comprising:

a transceiver that receives packets from the at least one client and the at least one server and sends packets to the at least one client and the at least one server;

a module that forwards packets from the at least one client to the at least one server, and forwards packets from the at least one server to the at least one client;

means for sending an acknowledgement to a server of the at least one server, based on a temporal relation between a first packet received from the server and a second packet received from the at least one client wherein the second packet received from the at least one client is received with an unset acknowledgement bit set.

50. The traffic management device of claim 49, wherein the means for sending an acknowledgement selectively coalesces an ACK into the second packet based on whether the second packet is received within a specified timeout period of receiving the first packet.

51. The traffic management device of claim 49, further comprising:

means for sending an acknowledgment to the client, based on a temporal relation between the second packet and a third packet received from the server.

52. The traffic management device of claim 49, further comprising:

a parsing module that parses the second packet to determine whether a request within the second packet is complete; and

means for sending an acknowledgment to the client, based on the results of parsing the second packet and based on a temporal relation between the second packet and a third packet received from the server.

53. A traffic management device for managing a communication between at least one client and at least one server, comprising:

a transceiver that receives packets from the at least one client and the at least one server and sends packets to the at least one client and the at least one server;

a module that forwards packets from the at least one client to the at least one server, and forwards packets from the at least one server to the at least one client;

means for sending an acknowledgement to a client of the at least one client, based on a temporal relation between a first packet received from the client and a second packet received from a server of the at least one server wherein the second packet received from the server is received absent an acknowledgement within being set for the first packet.

54. The traffic management device of claim 53, further comprising:

a parsing module that parses the first packet to determine whether a request within the first packet is complete; and

wherein the means for sending an acknowledgment to the client is further based on the results of parsing the first packet.

55. The traffic management device of claim 53, wherein the means for sending an acknowledgement selectively coalesces an ACK into the second packet based on whether the second packet is received within a specified timeout period of receiving the first packet.

56. The traffic management device of claim 53, further comprising:

a parsing module that parses the first packet to determine whether a request within the first packet is complete; and

means for selectively coalescing a TCP FIN with the second packet and forwarding the resultant packet to the client, wherein the means for sending an acknowledgment to the client is further based on the results of parsing the first packet.