Wide area load balancing of web traffic

• US 6,981,056 B1
• Filed: 06/28/2000
• Issued: 12/27/2005
• Est. Priority Date: 06/28/2000
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Shaffer, Shmuel, Aviani, James A. Jr.
• Primary Examiner(s): Pwu, Jeffrey C.
• Application Number:
  US09/605,917
• Time in Patent Office: 2,008 Days
• Field of Search: 709/238, 709/239, 709/235, 709/219, 709/226, 709/227
• US Class Current: 709/239
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/60 Scheduling or organising the servicing of application requests, e.g. requests for application data transmissions using the analysis and optimisation of the required network resources admission control or resource allocation H04L47/70

Abstract

Methods and apparatus are described for intelligently for intelligently routing a request to a device (e.g., replica or server). A packet is received (e.g., by the client'"'"'s gateway router) from a client, and the packet has a destination identifier associated with a server. When the packet is a start packet, a tag is added to the start packet to indicate that the start packet should be forwarded to any replica that duplicates the data content of the server. The destination identifier of the start packet is stored for later use. After storing the destination identifier of the start packet and tagging the start packet, the start packet is sent to the server. When the start packet has a tag indicating that the start packet should be forwarded to any replica that duplicates the data content of the server, the start packet is encapsulated and sent to each replica associated with the server. A replica device then receives a start packet sent from the client to the server. The start packet is encapsulated. The encapsulated start packet is cracked to determine the client'"'"'s address. When the replica device is active and not busy, an immediate acknowledgement packet is sent to the client in response to the received start packet. When a first acknowledgement packet associated with the start packet is received (e.g., at the client gateway router), a source identifier of the first acknowledgement packet is stored and associated with the stored destination identifier of the start packet. After storing and associating the source identifier of the first acknowledgement packet, the first acknowledgement packet is sent to the client. Subsequent packets (e.g., after the start and acknowledgement packets) are then sent between the client and sender of the first acknowledgement packet.

Claims

1. A method of facilitating redirection of traffic between a server and a client to between the client and a selected one from a plurality of replicas, the method comprising:

receiving a packet from a client, the packet having a destination identifier associated with a server;

when the packet is a start packet, at the client side, adding a tag to the start packet to indicate that the start packet is to be forwarded by a device other than a client side device to a plurality of replicas that each duplicates the data content of the server, wherein the tag is an option byte having one of two states that indicate whether redirection is permissible or impermissible;

storing the destination identifier of the start packet;

after storing the destination identifier of the start packet and tagging the start packet, sending the start packet to the server;

for a first acknowledgement packet associated with the start packet that is received first, storing and associating a source identifier of the first acknowledgement packet with the stored destination identifier of the start packet;

after storing and associating the source identifier of the first acknowledgement packet, sending the first acknowledgement packet to the client;

prior to storing and associating the source identifier of the first acknowledgement packet, cracking the first acknowledgement packet to obtain the source identifier when the first acknowledgement packet has been encapsulated;

when cracked, encapsulating the cracked acknowledgement packet with the destination identifier stored for the associated start packet, wherein the encapsulated first acknowledgement packet is sent to the client; and

when a second acknowledgement packet associated with the start packet is received after the first acknowledgement packet, inhibiting sending of the second acknowledgement to the client.

2. A method as recited in claim 1, further comprising:

when a subsequent packet associated with the start packet is received that is not a start packet or an acknowledgement packet, replacing a destination identifier of the subsequent packet with the source identifier stored for the acknowledgement packet when the subsequent packet originates from the client; and

forwarding the altered subsequent packet to its destination.

3. A method as recited in claim 2, wherein the subsequent packet is only modified when the destination identifier of the subsequent packet equals the destination identifier stored for the associated start packet.

4. A method as recited in claim 1, wherein the start packet is only tagged when the start packet is associated with web data, and the method further comprising sending the start packet to the server without the tag when the start packet is not associated with web data.

5. A method as recited in claim 4, wherein the start packet is associated with web data when the start packet has a destination port utilized for accessing web data.

6. A computer system operable to facilitate redirection of traffic between a server and a client to between the client and a selected one from a plurality of replicas, the computer system comprising:

a memory; and

a processor coupled to the memory,

wherein at least one of the memory and the processor are adapted to provide;

receiving a packet from a client, the packet having a destination identifier associated with a server;

when the packet is a start packet, at the client side, adding a tag to the start packet to indicate that the start packet is to be forwarded by a device other than a client side device to a plurality of replicas that each duplicates the data content of the server, wherein the tag is an option byte having one of two states that indicate whether redirection is permissible or impermissible;

storing the destination identifier of the start packet;

after storing the destination identifier of the start packet and tagging the start packet, sending the start packet to the server;

for a first acknowledgement packet associated with the start packet that is received first, storing and associating a source identifier of the first acknowledgement packet with the stored destination identifier of the start packet;

after storing and associating the source identifier of the first acknowledgement packet, sending the first acknowledgement packet to the client;

prior to storing and associating the source identifier of the first acknowledgement packet, cracking the first acknowledgement packet to obtain the source identifier when the first acknowledgement packet has been encapsulated;

when cracked, encapsulating the cracked acknowledgement packet with the destination identifier stored for the associated start packet, wherein the encapsulated first acknowledgement packet is sent to the client; and

when a second acknowledgement packet associated with the start packet is received after the first acknowledgement packet, inhibiting sending of the second acknowledgement to the client.

7. A computer system as recited in claim 6, wherein at least one of the memory and the processor are further adapted to provide:

when a subsequent packet associated with the start packet is received that is not a start packet or an acknowledgement packet, replacing a destination identifier of the subsequent packet with the source identifier stored for the acknowledgement packet when the subsequent packet originates from the client; and

forwarding the altered subsequent packet to its destination.

8. A computer system as recited in claim 6, wherein the subsequent packet is only modified when the destination identifier of the subsequent packet equals the destination identifier stored for the associated start packet.

9. A computer system as recited in claim 6, wherein the start packet is only tagged when the start packet is associated with web data, and the method further comprising sending the start packet to the server without the tag when the start packet is not associated with web data.

10. A computer system as recited in claim 9, wherein the start packet is associated with web data when the start packet has a destination port utilized for accessing web data.

11. A computer program product for facilitating redirection of traffic between a server and a client to between the client and a selected one from a plurality of replicas, the computer program product comprising:

at least one computer readable medium;

computer program instructions stored within the at least one computer readable product configured for;

receiving a packet from a client, the packet having a destination identifier associated with a server;

when the packet is a start packet, at the client side, adding a tag to the start packet to indicate that the start packet is to be forwarded by a device other than a client side device to a plurality of replicas that each duplicates the data content of the server, wherein the tag is an option byte having one of two states that indicate whether redirection is permissible or impermissible;

storing the destination identifier of the start packet;

after storing the destination identifier of the start packet and tagging the start packet, sending the start packet to the server;

for a first acknowledgement packet associated with the start packet that is received first, storing and associating a source identifier of the first acknowledgement packet with the stored destination identifier of the start packet;

after storing and associating the source identifier of the first acknowledgement packet, sending the first acknowledgement packet to the client;

prior to storing and associating the source identifier of the first acknowledgement packet, cracking the first acknowledgement packet to obtain the source identifier when the first acknowledgement packet has been encapsulated;

when cracked, encapsulating the cracked acknowledgement packet with the destination identifier stored for the associated start packet, wherein the encapsulated first acknowledgement packet is sent to the client; and

when a second acknowledgement packet associated with the start packet is received after the first acknowledgement packet, inhibiting sending of the second acknowledgement to the client.

12. A computer program product as recited in claim 11, the at least one computer readable product further configured for:

when a subsequent packet associated with the start packet is received that is not a start packet or an acknowledgement packet, replacing a destination identifier of the subsequent packet with the source identifier stored for the acknowledgement packet when the subsequent packet originates from the client; and

forwarding the altered subsequent packet to its destination.

13. A computer program product as recited in claim 12, wherein the subsequent packet is only modified when the destination identifier of the packet equals the destination identifier of the start packet.

14. A computer program product as recited in claim 11, wherein the start packet is only tagged when the start packet is associated with web data, and the method further comprising sending the start packet to the server without the tag when the start packet is not associated with web data.

15. A computer program product as recited in claim 14, wherein the start packet is associated with web data when the start packet has a destination port utilized for accessing web data.

16. A method of facilitating redirection of traffic between a server and a client to between the client and a nearest replica selected from a plurality of replicas, the method comprising:

at the client side, receiving a packet that is traveling between a client and a server or between the client and a replica;

when the received packet is a start packet that is traveling from the client to the server, at the client side, adding a tag to the start packet to indicate that the start packet is to be forwarded by a device other than a client side device to a plurality of replicas that each duplicates the data content of the server, wherein the tag is an option byte having one of two states that indicate whether redirection is permissible or impermissible;

for the received packet that is an acknowledgement packet that is received first and spoofs the server, obtaining a source identifier of the replica from the acknowledgement when the acknowledgement originates from the replica and then sending the acknowledgement packet to the client;

for the received packet that is an acknowledgement packet that is not received first and spoofs the server, inhibiting sending of the second acknowledgement to the client; and

when the received packet is a subsequent packet received after the start packet and the acknowledgement packet, altering the subsequent packet so that it goes to the replica when the subsequent packet originates from the client, wherein the alteration is based on the obtained source identifier from the acknowledgement packet.

17. A method as recited in claim 16, wherein the source identifier of the replica is obtained from the acknowledgement packet by cracking the acknowledgement packet when it is encapsulated.

18. A method as recited in claim 17, further comprising re-encapsulating the cracked acknowledgement packet prior to sending it to the client.

19. A method as recited in claim 16, wherein the subsequent packet is altered by replacing the subsequent packet'"'"'s destination identifier with a destination identifier of the start packet.

20. A method as recited in claim 16, wherein the subsequent packet is altered by encapsulating the subsequent packet with a destination identifier of the start packet.

21. A computer system operable to facilitate redirection of traffic between a server and a client to between the client and a nearest replica selected from a plurality of replicas, the computer system comprising:

a memory; and

a processor coupled to the memory,

wherein at least one of the memory and the processor are adapted to provide;

at the client side, receiving a packet that is traveling between a client and a server or between the client and a replica;

when the received packet is a start packet that is traveling from the client to the server, at the client side, adding a tag to the start packet to indicate that the start packet is to be forwarded by a device other than a client side device to a plurality of replicas that each duplicates the data content of the server, wherein the tag is an option byte having one of two states that indicate whether redirection is permissible or impermissible;

for the received packet that is an acknowledgement packet that is received first and spoofs the server, obtaining a source identifier of the replica from the acknowledgement when the acknowledgement originates from the replica and then sending the acknowledgement packet to the client;

for the received packet that is an acknowledgement packet that is not received first and spoofs the server, inhibiting sending of the second acknowledgement to the client; and

when the received packet is a subsequent packet received after the start packet and the acknowledgement packet, altering the subsequent packet so that it goes to the replica when the subsequent packet originates from the client, wherein the alteration is based on the obtained source identifier from the acknowledgement packet.

22. A computer system as recited in claim 21, wherein the source identifier of the replica is obtained from the acknowledgement packet by cracking the acknowledgement packet when it is encapsulated.

23. A computer system as recited in claim 22, further comprising re-encapsulating the cracked acknowledgement packet prior to sending it to the client.

24. A computer system as recited in claim 21, wherein the subsequent packet is altered by replacing the subsequent packet'"'"'s destination identifier with a destination identifier of the start packet.

25. A computer system as recited in claim 21, wherein the subsequent packet is altered by encapsulating the subsequent packet with a destination identifier of the start packet.

26. A computer program product for facilitating redirection of traffic between a server and a client to between a server and a client to between the client and a nearest replica selected from a plurality of replicas, the computer program product comprising:

at least one computer readable medium;

computer program instructions stored within the at least one computer readable product configured for;

at the client side, receiving a packet that is traveling between a client and a server or between the client and a replica;

when the received packet is a start packet that is traveling from the client to the server, at the client side, adding a tag to the start packet to indicate that the start packet is to be forwarded by a device other than a client side device to a plurality of replicas that each duplicates the data content of the server, wherein the tag is an option byte having one of two states that indicate whether redirection is permissible or impermissible;

for the received packet that is an acknowledgement packet that is received first and spoofs the server, obtaining a source identifier of the replica from the acknowledgement when the acknowledgement originates from the replica and then sending the acknowledgement packet to the client;

for the received packet that is an acknowledgement packet that is not received first and spoofs the server, inhibiting sending of the second acknowledgement to the client; and

when the received packet is a subsequent packet received after the start packet and the acknowledgement packet, altering the subsequent packet so that it goes to the replica when the subsequent packet originates from the client, wherein the alteration is based on the obtained source identifier from the acknowledgement packet.

27. A computer program product as recited in claim 26, wherein the source identifier of the replica is obtained from the acknowledgement packet by cracking the acknowledgement packet when it is encapsulated.

28. A computer program product as recited in claim 27, the at least one computer readable product being further configured for re-encapsulating the cracked acknowledgement packet prior to sending it to the client.

29. A computer program product as recited in claim 26, wherein the subsequent packet is altered by replacing the subsequent packet'"'"'s destination identifier with a destination identifier of the start packet.

30. A computer program product as recited in claim 26, wherein the subsequent packet is altered by encapsulating the subsequent packet with a destination identifier of the start packet.

31. An apparatus product for facilitating redirection of traffic between a server and a client to between the client and a selected one from a plurality of replicas, the apparatus comprising:

means for receiving a packet from a client, the packet having a destination identifier associated with a server;

means for when the packet is a start packet, at the client side, adding a tag to the start packet to indicate that the start packet should is to be forwarded by a device other than a client side device to a plurality of replicas that each duplicates the data content of the server, wherein the tag is an option byte having one of two states that indicate whether redirection is permissible or impermissible;

means for storing the destination identifier of the start packet;

means for after storing the destination identifier of the start packet and tagging the start packet, sending the start packet to the server;

means for, for a first acknowledgement packet associated with the start packet that is received first, storing and associating a source identifier of the first acknowledgement packet with the stored destination identifier of the start packet;

means for after storing and associating the source identifier of the first acknowledgement packet, sending the first acknowledgement packet to the client;

means for prior to storing and associating the source identifier of the first acknowledgement packet, cracking the first acknowledgement packet to obtain the source identifier when the first acknowledgement packet has been encapsulated;

means for when cracked, encapsulating the cracked acknowledgement packet with a source address associated with the packet, wherein the encapsulated first acknowledgement packet is sent to the client; and

means for when a second acknowledgement packet associated with the start packet is received after the first acknowledgement packet, inhibiting sending of the second acknowledgement to the client.

32. An apparatus product for facilitating redirection of traffic between a server and a client to between the client and a nearest replica selected from a plurality of replicas, the apparatus comprising:

means for at the client side, receiving a packet that is traveling between a client and a server or between the client and a replica;

means for when the received packet is a start packet that is traveling from the client to the server, at the client side, adding a tag to the start packet to indicate that the start packet is to be forwarded by a device other than a client side device to a plurality of replicas that each duplicates the data content of the server, wherein the tag is an option byte having one of two states that indicate whether redirection is permissible or impermissible;

means for, for the received packet that is an acknowledgement packet that is received first and spoofs the server, obtaining a source identifier of the replica from the acknowledgement when the acknowledgement originates from the replica and then sending the acknowledgement packet to the client;

means for, for the received packet that is an acknowledgement packet that is not received first and spoofs the server, inhibiting sending of the second acknowledgement to the client; and

means for when the received packet is a subsequent packet received after the start packet and the acknowledgement packet, altering the subsequent packet so that it goes to the replica when the subsequent packet originates from the client, wherein the alteration is based on the obtained source identifier from the acknowledgement packet.