Method and apparatus for routing data to a load balanced server using MPLS packet labels

• US 20050149531A1
• Filed: 01/27/2005
• Published: 07/07/2005
• Est. Priority Date: 03/19/2002
• Status: Active Grant

• Current Assignee: Sunil K. Srivastava
• Original Assignee: Sunil K. Srivastava
• Inventors: Srivastava, Sunil K.
• Granted Patent: US 7,784,055 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 45/30 Routing of multiclass traffic
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 61/4511 using domain name system [DNS]
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/1021 based on client or server locations
• CPC Class Codes: H04L 67/1023 based on a hash applied to IP addresses or costs

Abstract

A method of routing data to a load-balanced server through a network having one or more load-balancing nodes is disclosed, comprising receiving a label value; storing the label value in a load balancing mapping at a load-balancing node in a network, wherein the load balancing mapping associates the label with a packet flow and with interface identifying information; and forwarding subsequent packets of the flow to a selected load-balancing server. The forwarding route is defined by the load-balancing mapping and without hop-by-hop routing decisions. The first server response packet is switched hop-by-hop and the label is stored at each node traversed by the response packets, with a flow identifier and interface identifiers. For other request and response packets, nodes fast-switch the packets based on the label mappings; thus, packet flows are rapidly routed from the client to the same server without time-consuming hop-by-hop routing or repeated load-balancing decisions.

Claims

1. A computer apparatus, comprising:

one or more processors;

one or more electronic digital memory devices that are communicatively coupled to the one or more processors;

one or more sequences of computer program instructions stored in the memory devices, which instructions, when executed by the one or more processors, cause the one or more processors to perform;

receiving a label value;

storing the label value in a load balancing mapping at a load-balancing node in a network, wherein the load balancing mapping associates the label with a packet flow and with interface identifying information; and

forwarding subsequent packets of the flow to a selected load-balancing server among a plurality of servers in a network, wherein the forwarding is on a route that is defined by the load-balancing mapping and without hop-by-hop routing decisions.

2. An apparatus as recited in claim 1, wherein the apparatus is communicatively coupled through the network to a client and to a selected load-balanced server among a plurality of servers in a network that comprises a plurality of load-balancing nodes.

3. An apparatus as recited in claim 2, further comprising instructions to perform:

receiving a first packet of a client request at one of the load-balancing nodes in the network;

storing information identifying a flow associated with the first packet, an identifier of an interface of that node on which the first packet arrived, and an outgoing interface identifier; and

receiving a first packet of a server reply at a last node associated with a selected server among the plurality of servers.

4. An apparatus as recited in claim 3, further comprising instructions to perform:

routing a first server response packet from the server to the client on a hop-by-hop basis;

storing the label value at each node traversed by the response packets in a second load-balancing mapping that associates the label value with a flow identifier and the incoming and outgoing interface identifiers; and

fast-switching all other packets in the request and response between the client and the server based on the second load-balancing mappings.

5. An apparatus as recited in claim 4, wherein fast-switching all other packets in the request and response comprises fast-switching all other packets in the request and response between the client and the server based on the second load-balancing mappings without performing hop-by-hop routing decisions and without performing repeated load-balancing decisions.

6. An apparatus as recited in claim 3, wherein the label value is selected to uniquely identify the flow associated with the first packet and a connection and route associated with the first packet.

7. An apparatus as recited in claim 1, wherein the label is generated and formatted according to multi-protocol label switching (MPLS) protocol.

8. An apparatus as recited in claim 3, further comprising instructions to perform selecting one of a plurality of servers to respond to the client request in response to receiving the first packet of a client request at one of the load-balancing nodes in the network.

9. An apparatus as recited in claim 3, further comprising instructions to perform:

receiving one or more subsequent packets of the server reply;

receiving an MPLS label value;

storing the MPLS label value in a load balancing mapping at the last node that associates the MPLS label value with the flow and interface identifying information; and

forwarding the subsequent packets of the server reply to the client on a route that is defined by the load-balancing mapping and without hop-by-hop routing decisions.

10. An apparatus as recited in claim 2, wherein the load-balancing nodes are load-balancing routers that participate in the network as Anycast nodes.

11. An apparatus as recited in claim 3, further comprising instructions to perform storing a client stickiness label in a cookie at the client in response to receiving the first packet of the client request at the last node, retrieving the client stickiness label from the cookie in response to receiving subsequent packets of the client request at the last node, and forwarding the subsequent packets of the client request to the selected server based on the client stickiness label.

12. An apparatus as recited in claim 3, further comprising instructions to perform distributing the label value from the last node to all other nodes using any of (a) Cisco tag switching protocol and (b) one or more MPLS messages.

13. A method, comprising:

receiving a label value;

storing the label value in a load balancing mapping at a load-balancing node in a computer network, wherein the load balancing mapping associates the label with a digital packet flow and with device interface identifying information; and

forwarding subsequent packets of the flow to a selected load-balancing server among a plurality of servers in a network, wherein the forwarding is on a route that is defined by the load-balancing mapping and without hop-by-hop routing decisions.

14. A method as recited in claim 13, performed in an apparatus that is communicatively coupled through the network to a client and to a selected load-balanced server among a plurality of servers in a network that comprises a plurality of load-balancing nodes.

15. A method as recited in claim 14, further comprising:

receiving a first packet of a client request at one of the load-balancing nodes in the network;

storing information identifying a flow associated with the first packet, an identifier of an interface of that node on which the first packet arrived, and an outgoing interface identifier; and

receiving a first packet of a server reply at a last node associated with a selected server among the plurality of servers.

16. A method as recited in claim 15, further comprising:

routing a first server response packet from the server to the client on a hop-by-hop basis;

storing the label value at each node traversed by the response packets in a second load-balancing mapping that associates the label value with a flow identifier and the incoming and outgoing interface identifiers; and

fast-switching all other packets in the request and response between the client and the server based on the second load-balancing mappings.

17. A computer-readable medium carrying one or more sequences of instructions for routing data from a client to a selected load-balanced server among a plurality of servers in a network that comprises a plurality of load-balancing nodes, which instructions, when executed by one or more processors, cause the one or more processors to carry out the steps of:

receiving a label value;

storing the label value in a load balancing mapping at a load-balancing node in a network, wherein the load balancing mapping associates the label with a packet flow and with interface identifying information; and

forwarding subsequent packets of the flow to a selected load-balancing server among a plurality of servers in a network, wherein the forwarding is on a route that is defined by the load-balancing mapping and without hop-by-hop routing decisions.

18. A computer-readable medium as recited in claim 17, wherein the computer-readable medium is communicatively coupled through the network to a client and to a selected load-balanced server among a plurality of servers in a network that comprises a plurality of load-balancing nodes.

19. A computer-readable medium as recited in claim 18, further comprising instructions to perform:

receiving a first packet of a client request at one of the load-balancing nodes in the network;

storing information identifying a flow associated with the first packet, an identifier of an interface of that node on which the first packet arrived, and an outgoing interface identifier; and

receiving a first packet of a server reply at a last node associated with a selected server among the plurality of servers.

20. A computer-readable medium as recited in claim 18, further comprising instructions to perform:

routing a first server response packet from the server to the client on a hop-by-hop basis;

storing the label value at each node traversed by the response packets in a second load-balancing mapping that associates the label value with a flow identifier and the incoming and outgoing interface identifiers; and

fast-switching all other packets in the request and response between the client and the server based on the second load-balancing mappings.