Load balancing using IPv6 mobility features

• US 8,078,755 B1
• Filed: 12/10/2009
• Issued: 12/13/2011
• Est. Priority Date: 10/29/2004
• Status: Active Grant

• Current Assignee: Akamai Technologies, Inc.
• Original Assignee: Akamai Technologies, Inc.
• Inventors: Liu, Zaide, Day, Richard David, Swildens, Eric Sven-Johan
• Primary Examiner(s): WON, MICHAEL YOUNG
• Application Number:
  US12/635,610
• Time in Patent Office: 733 Days
• Field of Search: 709/238, 709/239, 709/240, 709/241, 709/242, 709/243, 709/244
• US Class Current: 709/238
• CPC Class Codes: H04L 2463/101 applying security measures for digital rights management
• CPC Class Codes: H04L 63/102 Entity profiles
• CPC Class Codes: H04L 63/12 Applying verification of the received information cryptographic mechanisms or cryptographic arrangements for data integrity or data verification H04L9/32

Abstract

Techniques are provided that allow client and server nodes to communicate without the continuing intervention of a load-balancing node that selected the server node. A load-balancing node intercepts a TCP SYN packet addressed to a virtual IP address. The load-balancing node selects a server node from among multiple server nodes, and sends the packet toward the server node. The server node sends an IPv6 packet toward the client node. The packet contains a Binding Update option that specifies the virtual IP address as a Home Address. This information causes the client node to replace destination addresses in outgoing IP packets so that packets that the client node would have sent toward the virtual IP address are sent toward the selected server node'"'"'s IP address instead. Consequently, the IP packets are routed toward the selected server node instead of the load-balancing node.

Claims

1. A method for enabling communication between nodes, the method comprising:

receiving, at a server, a SYN packet forwarded from a load-balancing node, wherein the SYN packet (a) indicates a virtual address associated with a server cluster as a destination address of the SYN packet and (b) indicates a client address of a client from which the SYN packet originated as a source address of the SYN packet;

the server being one of a plurality of servers in the server cluster being load-balanced by the load-balancing node; and

sending, from the server to the client, a SYN/ACK packet that (a) indicates a physical non-virtual address of the server as a source address of the SYN/ACK packet, (b) indicates the client address as a destination address of the SYN/ACK packet, and (c) indicates a binding update destination option that specifies the virtual address as a home address;

receiving, with the server, an ACK packet sent from the client;

wherein the server and the load-balancing node each comprise one or more computing devices.

2. The method of claim 1, wherein the binding update destination option is contained in an IPv6 Mobility Header.

3. The method of claim 1, wherein the received SYN packet is encapsulated within a second packet sent from the load-balancing node, the second packet indicating the physical non-virtual address of the server as a destination address.

4. The method of claim 1, wherein sending the SYN/ACK packet further comprises:

sending, from the server to the client address, a packet header that instructs an Internet Protocol (IP) layer of the client to replace the source address specified in the SYN/ACK packet with the home address and thereby causes the SYN/ACK packet to appear to have originated from the home address rather than the source address.

5. The method of claim 1, wherein the SYN/ACK packet includes a header with information that will cause a Transmission Control Protocol (TCP) layer of the client to establish a connection with the server by sending the ACK packet addressed to the physical, non-virtual address of the server.

6. The method of claim 1, wherein the SYN/ACK packet includes a header with information that will cause a Transmission Control Protocol (TCP) layer of the client to send the ACK packet to the server via a route that excludes the load-balancing node.

7. A system, comprising:

a load-balancing node comprising a processor that executes stored instructions causing the load-balancing node to select, based on a requested service indicated by a SYN packet sent from a client, a server from a server cluster to respond to the client; and

the server selected from the server cluster comprising a processor and instructions that, when executed by the processor, cause the server to receive the SYN packet from the load-balancing node, wherein the SYN packet (a) indicates a virtual address associated with the server cluster as a destination address of the SYN packet and (b) indicates a client address of a client from which the SYN packet originated as a source address of the SYN packet;

the server further caused by the instructions to send a SYN/ACK packet that (a) indicates a physical non-virtual address of the server as a source address of the SYN/ACK packet, (b) indicates the client address as a destination address of the SYN/ACK packet, and (c) indicates a binding update destination option that specifies the virtual address as a home address;

the server further caused by the instructions to receive an ACK packet sent from the client.

8. The system of claim 7, wherein the binding update destination option is contained in a IPv6 Mobility Header.

9. The system of claim 7, wherein when executed the instructions cause the load-balancer to encapsulate the SYN packet within a second packet that indicates the physical non-virtual address of the particular server as a destination address and send the second packet to the server.

10. The system of claim 7, wherein when executed the instructions cause the server to send, to the client address, a packet header that instructs an Internet Protocol (IP) layer of the client to replace the source address specified in the SYN/ACK packet with the home address.

11. The system of claim 7, wherein the SYN/ACK packet includes a header with information that will cause a Transmission Control Protocol (TCP) layer of the client to establish a connection with the server by sending the ACK packet to the physical, non-virtual address of the server.

12. The system of claim 7, wherein the SYN/ACK packet includes a header with information that will cause a Transmission Control Protocol (TCP) layer of the client to send the ACK packet to the server via a route that excludes the load-balancing node.

13. A non-transitory machine-readable storage medium carrying one or more sequences of instructions, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform steps comprising:

receiving, at a server, a SYN packet forwarded from a load-balancing node, wherein the SYN packet (a) indicates a virtual address associated with a server cluster as a destination address of the SYN packet and (b) indicates a client address of a client from which the SYN packet originated as a source address of the SYN packet;

the server being one of a plurality of servers in the server cluster being load-balanced by the load-balancing node; and

sending, from the server to the client, a SYN/ACK packet that (a) indicates a physical non-virtual address of the server as a source address of the SYN/ACK packet, (b) indicates the client address as a destination address of the SYN/ACK packet, and (c) indicates a binding update destination option that specifies the virtual address as a home address;

receiving, with the server, an ACK packet sent from the client.

14. The non-transitory machine-readable medium of claim 13, wherein the binding update destination option is contained in a IPv6 Mobility Header.

15. The non-transitory machine-readable medium of claim 13, wherein the received SYN packet is encapsulated within a second packet sent from the load-balancing node, the second packet indicating the physical non-virtual address of the server as a destination.

16. The non-transitory machine-readable medium of claim 13, wherein sending the SYN/ACK packet further comprises:

sending, from the server to the client address, a packet header that instructs an Internet Protocol (IP) layer of the client to replace the source address specified in the SYN/ACK packet with the home address and thereby cause the packet to appear to have originated from the home address rather than the source address.

17. The non-transitory machine-readable medium of claim 13, wherein the SYN/ACK packet includes a header with information that will cause a Transmission Control Protocol (TCP) layer of the client to establish a connection with the server by sending the ACK packet addressed to the physical, non-virtual address of the server.

18. The non-transitory machine-readable medium of claim 13, wherein the SYN/ACK packet includes a header with information that will cause a Transmission Control Protocol (TCP) layer of the client to send the ACK packet to the server via a route that excludes load-balancing node.