Server load balancing using IP option field approach to identify route to selected server

• US 20060233155A1
• Filed: 06/16/2006
• Published: 10/19/2006
• 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 7,830,896 B2
• Time in Patent Office: Days
• US Class Current: 370/351
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/36 Backward learning
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• 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 67/101 based on network conditions
• CPC Class Codes: H04L 67/1014 based on the content of a request
• CPC Class Codes: H04L 67/1027 Persistence of sessions during load balancing
• CPC Class Codes: H04L 67/1029 using data related to the state of servers by a load balancer
• CPC Class Codes: H04L 67/1031 Controlling of the operation of servers by a load balancer, e.g. adding or removing servers that serve requests

Abstract

A router for routing data from a client through load-balancing nodes to a selected load-balanced server among a plurality of servers in a network involves: receiving, at a last load balancing node associated with a selected server among the plurality of servers, a first packet of a server reply to a request from the client; storing identifiers of ingress interfaces on which the packet arrives, in a send path list for server load balancing, as the first packet of the server reply is routed from the last load balancing node to the client using hop-by-hop decisions; receiving subsequent packets of the client request; and forwarding the subsequent packets to the selected server only on a route that is defined by the send path list and without hop-by-hop routing decisions. Packet flows are routed from the same client to the same server without hop-by-hop routing decisions or repeated load-balancing decisions.

Claims

1. A router, comprising:

a network interface that is coupled to a data network for receiving one or more packet flows therefrom;

a processor;

one or more stored sequences of instructions which, when executed by the processor, cause the processor to perform;

receiving, at a last node associated with a selected server among a plurality of servers, a first packet of a server reply to a client request from a client;

storing one or more identifiers of ingress interfaces on which the first packet arrives, in a send path list, as the first packet of the server reply is routed from the selected server to the client using hop-by-hop decisions;

receiving one or more subsequent packets of the client request;

forwarding the one or more subsequent packets to the selected server on a route that is defined by the send path list and without hop-by-hop routing decisions.

2. A router as recited in claim 1, further comprising sequences of instructions which, when executed by the processor, cause the processor to perform:

setting a first flag value in the first packet of the server reply; and

wherein the first flag value signals that the first packet contains the send path list.

3. A router as recited in claim 1, further comprising sequences of instructions which, when executed by the processor, cause the processor to perform:

setting a second flag value in each of the one or more subsequent packets; and

wherein the second flag value instructs nodes to use the send path list for routing the one or more subsequent packets for server load balancing.

4. A router as recited in claim 1, further comprising sequences of instructions which, when executed by the processor, cause the processor to perform:

setting a first flag value in the first packet of the server reply; and

wherein the first flag value signals that the first packet contains the send path list and comprises an IP-RECORD-ROUTE-OPTION-FOR-SLB flag value in a header of the first packet.

5. A router as recited in claim 1, further comprising sequences of instructions which, when executed by the processor, cause the processor to perform:

setting a second flag value in each of the one or more subsequent packets; and

wherein the second flag value instructs nodes to use the send path list for routing the one or more subsequent packets and comprises an IP-STRICT-ROUTE-OPTION-FOR-SLB flag value in a header of the subsequent packets.

6. A router as recited in claim 1, further comprising sequences of instructions which, when executed by the processor, cause the processor to perform selecting one of the plurality of servers to respond to the client request in response to receiving a first packet of the client request at a first node in a network associated with the client.

7. A router as recited in claim 1, further comprising sequences of instructions which, when executed by the processor, cause the processor to perform storing the send path list in a mapping at the last node when the first packet reaches the last node, wherein the mapping comprises an association of send path lists and client identifying information.

8. A router as recited in claim 1, further comprising sequences of instructions which, when executed by the processor, cause the processor to perform storing the send path list in a mapping at the last node when the first packet reaches the last node, wherein the mapping comprises an association of send path lists and packet flow identifying information.

9. A router as recited in claim 1, further comprising sequences of instructions which, when executed by the processor, cause the processor to perform storing one or more identifiers of ingress interfaces on which the first packet of the client request arrives, in a return path list, as the first packet of the client request is routed from a first node to the last node using hop-by-hop decisions, based on setting an IP-RECORD-ROUTE-OPTION-FOR-SLB flag value in the first packet of the client request.

10. A router as recited in claim 9, wherein the route is a first router, and the router further comprises sequences of instructions which, when executed by the processor, cause the processor to perform:

receiving one or more subsequent packets of the server reply;

setting an IP-STRICT-ROUTE-OPTION-FOR-SLB flag value in each of the one or more subsequent packets of the server reply; and

forwarding the one or more subsequent packets of the server reply to the client on a second route that is defined only by the return path list and without hop-by-hop routing decisions.

11. A router as recited in claim 9, further comprising sequences of instructions which, when executed by the processor, cause the processor to perform storing the return path list in a mapping at the first node when the first packet reaches the first node, wherein the mapping comprises an association of return path lists and server identifiers.

12. A router as recited in claim 11, further comprising sequences of instructions which, when executed by the processor, cause the processor to perform popping a server identifier from the send path list and forwarding the first packet to a server on an IP address contained in the server identifier.

13. A router as recited in claim 11, further comprising sequences of instructions which, when executed by the processor, cause the processor to perform popping a server identifier from the send path list, performing network address translation on the server identifier to determine where to forward the first packet, and forwarding the first packet to a server on an IP address determined by the network address translation.

14. A router as recited in claim 11, wherein:

the first node and last node are load-balancing routers that participate as multicast nodes; and

the selected server is a load-balanced server.

15. An apparatus, comprising:

means for receiving, at a last node associated with a selected server among a plurality of servers, a first packet of a server reply to a client request from a client;

means for storing one or more identifiers of ingress interfaces on which the first packet arrives, in a send path list, as the first packet of the server reply is routed from the selected server to the client using hop-by-hop decisions;

means for receiving one or more subsequent packets of the client request;

means for forwarding the one or more subsequent packets to the selected server on a route that is defined by the send path list and without hop-by-hop routing decisions.

16. An apparatus as recited in claim 15, further comprising:

means for setting a first flag value in the first packet of the server reply; and

wherein the first flag value signals that the first packet contains the send path list.

17. An apparatus as recited in claim 15, further comprising:

means for setting a second flag value in each of the one or more subsequent packets; and

wherein the second flag value instructs nodes to use the send path list for routing the one or more subsequent packets for server load balancing.

18. An apparatus as recited in claim 15, further comprising:

means for setting a first flag value in the first packet of the server reply; and

wherein the first flag value signals that the first packet contains the send path list and comprises an IP-RECORD-ROUTE-OPTION-FOR-SLB flag value in a header of the first packet.

19. An apparatus as recited in claim 15, further comprising:

means for setting a second flag value in each of the one or more subsequent packets; and

wherein the second flag value instructs nodes to use the send path list for routing the one or more subsequent packets and comprises an IP-STRICT-ROUTE-OPTION-FOR-SLB flag value in a header of the subsequent packets.

20. An apparatus as recited in claim 15, further comprising means for selecting one of the plurality of servers to respond to the client request in response to receiving a first packet of the client request at a first node in a network associated with the client.

21. An apparatus as recited in claim 15, further comprising means for storing the send path list in a mapping at the last node when the first packet reaches the last node, wherein the mapping comprises an association of send path lists and client identifying information.

22. An apparatus as recited in claim 15, further comprising means for storing the send path list in a mapping at the last node when the first packet reaches the last node, wherein the mapping comprises an association of send path lists and packet flow identifying information.

23. An apparatus as recited in claim 15, further comprising means for storing one or more identifiers of ingress interfaces on which the first packet of the client request arrives, in a return path list, as the first packet of the client request is routed from a first node to the last node using hop-by-hop decisions, based on setting an IP-RECORD-ROUTE-OPTION-FOR-SLB flag value in the first packet of the client request.

24. An apparatus as recited in claim 23, wherein the route is a first route, and the apparatus further comprises:

means for receiving one or more subsequent packets of the server reply;

means for setting an IP-STRICT-ROUTE-OPTION-FOR-SLB flag value in each of the one or more subsequent packets of the server reply; and

means for forwarding the one or more subsequent packets of the server reply to the client on a second route that is defined only by the return path list and without hop-by-hop routing decisions.

25. An apparatus as recited in claim 23, further comprising means for storing the return path list in a mapping at the first node when the first packet reaches the first node, wherein the mapping comprises an association of return path lists and server identifiers.

26. An apparatus as recited in claim 25, further comprising means for popping a server identifier from the send path list and forwarding the first packet to a server on an IP address contained in the server identifier.

27. An apparatus as recited in claim 25, further comprising means for popping a server identifier from the send path list, performing network address translation on the server identifier to determine where to forward the first packet, and forwarding the first packet to a server on an IP address determined by the network address translation.

28. An apparatus as recited in claim 25, wherein:

the first node and last node are load-balancing routers that participate as multicast nodes; and

the selected server is a load-balanced server.