Improving reliability and availability of a load balanced server

• US 7,451,209 B1
• Filed: 10/22/2003
• Issued: 11/11/2008
• Est. Priority Date: 10/22/2003
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Schieber, Ami, Schwartzman, Sharon, Inbar, Vicktoria
• Primary Examiner(s): Etienne; Ario
• Assistant Examiner(s): Lai; Michael C
• Application Number:
  US10/692,428
• Time in Patent Office: 1,847 Days
• Field of Search: 709223-224, 718/105
• US Class Current: 709/224
• CPC Class Codes: G06F 11/2025 using centralised failover control functionality
• CPC Class Codes: H04L 41/5012 determining service availability, e.g. which services are available at a certain point in time
• 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 67/1012 based on compliance of requirements or conditions with available server resources
• CPC Class Codes: H04L 67/1023 based on a hash applied to IP addresses or costs
• CPC Class Codes: H04L 67/1029 using data related to the state of servers by a load balancer
• CPC Class Codes: H04L 67/1036 Load balancing of requests to servers for services different from user content provisioning, e.g. load balancing across domain name servers
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols

Abstract

The invention provides a method and apparatus for improving reliability and availability of a load balanced server. The apparatus performs and the method provides the steps of monitoring the server'"'"'s performance; detecting when the server'"'"'s performance is worse than a failover threshold; and sending a message to one or more clients indicating that the one or more clients should failover to an alternate server.

Claims

1. A method for improving reliability and availability of a load balanced server comprising the steps of:

monitoring the server'"'"'s performance,

wherein monitoring comprises measuring one or more parameters selected from the group consisting of a currently available number of threads, a maximum number of available threads, memory usage percentage, and a number of processes running;

detecting when the server'"'"'s performance is worse than a failover threshold;

sending a message to one or more clients indicating that said one or more clients should failover to an alternate server;

disconnecting a first set of one or more clients, wherein said first set of one or more clients comprise one or more clients from said one or more clients; and

connecting a second set of one or more clients, wherein the second set of one or more clients comprise one or more clients from said first set of one or more clients, and wherein the step of connecting said second set of one or more clients comprises the steps of;

connecting each client of said second set of one or more clients at a different time; and

initiating the step of connecting each client based on a timeout mechanism configured on each client.

2. The method of claim 1, wherein the server is an AAA server and the one or more clients are AAA clients.

3. The method of claim 1, wherein the step of sending a message comprises sending an ICMP Echo message.

4. The method of claim 1, wherein the step of monitoring further comprises measuring availability of services, wherein the services of which the availability is checked on the server comprise mandatory services and dependent services.

5. The method of claim 1, further comprising the step of determining the one or more clients to which to send the message based on a predefined list of clients.

6. The method of claim 1, further comprising the step of determining the one or more clients to which to send the message based on a network device group.

7. The method of claim 1, further comprising the step of determining the one or more clients to which to send the message based on network topology.

8. The method of claim 1, further comprising the step of determining the alternate server based on a list configured on each of said one or more clients.

9. The method of claim 1, wherein the message that is sent to said one or more clients comprises a list of one or more alternate servers to which said one or more clients can failover.

10. The method of claim 1, further comprising the step of checking authority of a message sent between a sender and a receiver by comparing a first hashed value, produced by the sender and sent with the message, with a second hashed value produced by the receiver.

11. The method of claim 10, further comprising the step of producing the first hashed value and the second hashed value using a one-way hash algorithm with a shared secret as a key and a combination of the server'"'"'s IP address and the client'"'"'s IP address as input.

12. The method of claim 10, further comprising the step of producing the first hashed value and the second hashed value using a one-way hash algorithm with a combination of a shared secret, the server'"'"'s IP address, and the client'"'"'s IP address as input.

13. The method of claim 1, further comprising the step of connecting with a second client.

14. The method of claim 13, further comprising the step of initiating the step of connecting with said second client based on a request from the second client.

15. The method of claim 14, further comprising the step of initiating the step of connecting with said second client based on a timeout mechanism configured on the second client.

16. The method of claim 13, further comprising the step of initiating the step of connecting with said second client based on a request by the server.

17. The method of claim 16, further comprising the step of initiating the step of connecting with said second client based on the server'"'"'s performance being better than a connection threshold.

18. The method of claim 17, wherein the step of initiating comprises the step of comparing the connection threshold with a function relating one or more parameters selected from the group consisting of server related parameters, system related parameters, and availability of services on the server.

19. The method of claim 18, wherein the server related parameters comprise a currently available number of threads and a maximum number of available threads.

20. The method of claim 18, wherein the system related parameters comprise CPU usage percentage, memory usage percentage, and number of processes running.

21. The method of claim 18, wherein the services of which the availability is checked on the server comprise services mandatory for correct functioning of the server and services needed for logging on the server.

22. The method of claim 1, wherein said one or more clients comprise all clients connected to said server.

23. The method of claim 1, wherein said one or more clients comprise a proper subset of all clients connected to said server.

24. The method of claim 1, further comprising the step of initiating the step of connecting said second set of one or more clients based on the server'"'"'s performance being better than a connection threshold, wherein the server'"'"'s performance is measured as a function relating one or more parameters selected from the group consisting of server related parameters, system related parameters, and availability of services on the server.

25. The method of claim 1, wherein said second set of one or more clients comprises multiple clients, and the step of connecting a second set of one or more clients comprises the steps of:

connecting a third set of one or more clients at a first time, wherein said third set of one or more clients comprises one or more clients from said multiple clients; and

connecting a fourth set of one or more clients at a second time, wherein said first time is different than said second time, and said second set of one or more clients comprises one or more clients from said multiple clients.

26. The method of claim 1, wherein said second set of one or more clients comprises all of said one or more clients.

27. A computer-readable storage medium carrying one or more sequences of instructions for improving reliability and availability of a load balanced server, which instructions, when executed by one or more processors, cause the one or more processors to carry out the steps of:

monitoring the server'"'"'s performance,

wherein monitoring comprises measuring one or more parameters selected from the group consisting of a currently available number of threads, a maximum number of available threads, memory usage percentage, and a number of processes running;

detecting when the server'"'"'s performance is worse than a failover threshold;

sending a message to one or more clients indicating that said one or more clients should failover to an alternate server;

disconnecting a first set of one or more clients, wherein said first set of one or more clients comprise one or more clients from said one or more clients; and

connecting a second set of one or more clients, wherein the second set of one or more clients comprise one or more clients from said first set of one or more clients, and wherein the step of connecting said second set of one or more clients comprises the steps of;

connecting each client of said second set of one or more clients at a different time; and

initiating the step of connecting each client based on a timeout mechanism configured on each client.

28. The computer-readable storage medium of claim 27, wherein the server is an AAA server and the one or more clients are AAA clients.

29. The computer-readable storage medium of claim 27, wherein the step of sending a message comprises sending an ICMP Echo message.

30. The computer-readable storage medium of claim 27, wherein the instructions, when executed, further cause the one or more processors to perform the step of checking authority of a message sent between a sender and a receiver by comparing a first hashed value, produced by the sender and sent with the message, with a second hashed value produced by the receiver.

31. The computer-readable storage medium of claim 27, wherein the instructions, when executed, further cause the one or more processors to perform the steps of:

initiating a connection with a second client, based on one or more of;

a request from the second client;

a timeout mechanism configured on the second client;

a request by the server; and

the server'"'"'s performance being better than a connection threshold,

wherein initiating the connection with the second client further comprises comparing the connection threshold with a function relating one or more parameters selected from the group consisting of server related parameters, system related parameters, and availability of services on the server; and

connecting with a second client.

32. An apparatus for improving reliability and availability of a load balanced server, comprising:

means for monitoring the server'"'"'s performance,

wherein monitoring comprises measuring one or more parameters selected from the group consisting of a currently available number of threads, a maximum number of available threads, memory usage percentage, and a number of processes running;

means for detecting when the server'"'"'s performance is worse than a failover threshold;

means for sending a message to one or more clients indicating that said one or more clients should failover to an alternate server;

means for disconnecting a first set of one or more clients, wherein said first set of one or more clients comprise one or more clients from said one or more clients; and

means for connecting a second set of one or more clients, wherein the second set of one or more clients comprise one or more clients from said first set of one or more clients, and wherein the means of connecting said second set of one or more clients comprises;

means for connecting each client of said second set of one or more clients at a different time; and

means for initiating the step of connecting each client based on a timeout mechanism configured on each client.

33. The apparatus of claim 32, wherein the server is an AAA server and the one or more clients are AAA clients.

34. The apparatus of claim 32, wherein the means for sending a message further comprises sending an ICMP Echo message.

35. The apparatus of claim 32, further comprising means for checking authority of a message sent between a sender and a receiver by comparing a first hashed value, produced by the sender and sent with the message, with a second hashed value produced by the receiver.

36. The apparatus of claim 32, further comprising:

means for initiating a connection with a second client, based on one or more of;

a request from the second client;

a timeout mechanism configured on the second client;

a request by the server; and

the server'"'"'s performance being better than a connection threshold,

wherein the means for initiating the connection with the second client further comprises means for comparing the connection threshold with a function relating one or more parameters selected from the group consisting of server related parameters, system related parameters, and availability of services on the server; and

means for connecting with a second client.

37. An apparatus for improving reliability and availability of a load balanced server, comprising:

a network interface that is coupled to the 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 carry out the steps of;

monitoring the server'"'"'s performance,

wherein monitoring comprises measuring one or more parameters selected from the group consisting of a currently available number of threads, a maximum number of available threads, memory usage percentage, and number of processes running;

detecting when the server'"'"'s performance is worse than a failover threshold;

sending a message to one or more clients indicating that said one or more clients should failover to an alternate server;

disconnecting a first set of one or more clients, wherein said first set of one or more clients comprise one or more clients from said one or more clients; and

connecting a second set of one or more clients, wherein the second set of one or more clients comprise one or more clients from said first set of one or more clients, and wherein the step of connecting said second set of one or more clients comprises the steps of;

connecting each client of said second set of one or more clients at a different time; and

initiating the step of connecting each client based on a timeout mechanism configured on each client.

38. The apparatus of claim 37, wherein the server is an AAA server and the one or more clients are AAA clients.

39. The apparatus of claim 37, wherein the step of sending a message further comprises sending an ICMP Echo message.

40. The apparatus of claim 37, further comprising the step of checking authority of a message sent between a sender and a receiver by comparing a first hashed value, produced by the sender and sent with the message, with a second hashed value produced by the receiver.

41. The apparatus of claim 37, further comprising the steps of:

initiating a connection with a second client, based on one or more of;

a request from the second client;

a timeout mechanism configured on the second client;

a request by the server; and

the server'"'"'s performance being better than a connection threshold,

wherein the step of initiating the connection with the second client further comprises comparing the connection threshold with a function relating one or more parameters selected from the group consisting of server related parameters, system related parameters, and availability of services on the server; and

connecting with a second client.