System and method for load balancing a communications network

• US 20060069776A1
• Filed: 09/15/2004
• Published: 03/30/2006
• Est. Priority Date: 09/15/2004
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Shim, Choon B., Xie, Liehua
• Granted Patent: US 7,805,517 B2
• Time in Patent Office: Days
• US Class Current: 709/225
• 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

Abstract

The invention relates to a system and method for load-balancing multiple servers in a communications network. Instead of using round robin or other predetermined scheme, SIP messages are forwarded to one of multiple SIP servers according to a performance score that is calculated from measured performance data. Advantageously, the disclosed system and method decreases signaling latency, improving overall communications speed. Moreover, where performance data indicates that a SIP server has failed, the performance score for the failed SIP server is zero, and the load balancer will not forward SIP messages to the failed SIP server. System uptime is also improved.

Claims

1. A method for load-balancing a Session Initiation Protocol (SIP) network, comprising:

receiving a SIP request from a source device;

selecting one of a plurality of SIP servers based on a plurality of performance scores, each of the plurality of performance scores associated with a corresponding one of the plurality of SIP servers; and

forwarding the SIP request to the selected SIP server.

2. The method of claim 1, further comprising:

before the selecting, determining whether the SIP request is a registration request; and

if the SIP request is a registration request, routing the SIP request to all SIP servers.

3. The method of claim 1, further comprising:

before the selecting, extracting a session signature from the SIP request;

determining whether a SIP session exists based on the extracted session signature;

if the SIP session exists, forwarding the SIP request to a SIP server associated with the existing SIP session.

4. The method of claim 1, wherein selecting one of a plurality of SIP servers includes generating a random integer;

the random integer having a value greater than zero, the random integer having a value less than or equal to a sum of performance scores for the plurality of SIP servers.

5. The method of claim 4 further including identifying a server j satisfying the condition (S₀+ . . . +S_j−

1)<

X≦

(S₀+ . . . +S_j), where S₀, S<sub>j−

1</sub>, and S_j are the performance scores for servers 0, j−

1, and j, respectively, and where X is the random integer.

6. The method of claim 1, wherein selecting one of a plurality of SIP servers includes determining the plurality of performance scores.

7. The method of claim 6, wherein determining the plurality of performance scores includes setting one of the plurality of performance scores equal to zero if a CPU usage is greater than a predetermined threshold.

8. The method of claim 6, wherein determining the plurality of performance score includes setting the performance score equal to zero if an amount of available memory is less than a predetermined threshold.

9. The method of claim 6, wherein determining the plurality of performance scores is based, at least in part, on a CPU percentage usage parameter and a memory availability parameter.

10. The method of claim 9, wherein determining the plurality of performance scores includes:

assigning a first weight to the CPU percentage usage parameter; and

assigning a second weight to the memory availability parameter.

11. The method of claim 10, wherein the determining the plurality of performance scores includes solving S_i=100(W₀(1−

C_i)+W₁M_i/Σ

M_k)/W₀+W₁), where;

S_i is the performance score of an ith SIP server;

W₀ is the first weight assigned to the CPU percentage usage parameter;

W₁ is the second weight assigned to the memory availability parameter;

C_i is a CPU percentage usage of an ith SIP server;

M_i is an amount of available memory of the ith SIP server; and

Σ

M_k is a sum of available memory of the plurality of SIP servers having non-zero performance scores.

12. The method of claim 6, wherein determining the plurality of performance scores is based, at least in part, on a call volume for each of the SIP servers.

13. The method of claim 6, wherein determining the plurality of performance scores is based, at least in part, on data associated with the failure of at least one of the plurality of SIP servers.

14. A method for polling a SIP server for performance data, comprising:

receiving a data request for the performance data in a performance server;

creating a persistent performance client in the performance server;

opening a connection to an agent running on the SIP server; and

issuing a request from the persistent performance client to the agent.

15. The method of claim 14, further comprising:

receiving a reply from the agent in the performance server, the reply responsive to the request from the persistent performance client;

transmitting the reply from the performance server; and

caching the persistent performance client in the performance server.

16. A method responsive to a data request, comprising:

creating a first controller, the first controller being configured to gather and cache performance data; and

creating a server socket, the server socket being configured to determine whether a connection request has been received, the server socket being further configured to transmit the performance data.

17. The method of claim 16, further comprising creating a second controller, the second controller configured to read the performance data, the second controller further configured to determine whether the performance data exceeds a predetermined threshold, the second controller further configured to issue a notification if the performance data exceeds a predetermined threshold.

18. A method for load-balancing a Session Initiation Protocol (SIP) network, comprising:

receiving a SIP request;

generating a routing request based on the SIP request;

generating a performance score request for each of a plurality of SIP servers based on the routing request;

generating a performance data query to each of the plurality of SIP servers based on the performance score request; and

receiving the performance data query in an agent in each of the plurality of SIP servers.

19. The method of claim 18, further comprising:

responding with performance data in response to the performance data query;

calculating a performance score for each of the plurality of SIP servers based on the performance data;

selecting a SIP server from the plurality of SIP servers based on the performance score for each of the plurality of SIP servers; and

forwarding the SIP request to the selected SIP server.

20. A machine-readable medium having instructions stored thereon for execution by a processor to perform a method comprising:

receiving a SIP request from a source device;

selecting one of a plurality of SIP servers based on a plurality of performance scores, each of the plurality of performance scores associated with a corresponding one of the plurality of SIP servers; and

forwarding the SIP request to the selected SIP server.

21. A machine-readable medium having instructions stored thereon for execution by a processor to perform a method comprising:

receiving a data request for the performance data in a performance server;

creating a persistent performance client in the performance server;

opening a connection to an agent running on the SIP server; and

issuing a request from the persistent performance client to the agent.

22. A machine-readable medium having instructions stored thereon for execution by a processor to perform a method comprising:

creating a first controller, the first controller being configured to gather and cache performance data; and

creating a server socket, the server socket being configured to determine whether a connection request has been received, the server socket being further configured to transmit the performance data.

23. A machine-readable medium having instructions stored thereon for execution by a processor to perform a method comprising:

receiving a SIP request;

generating a routing request based on the SIP request;

generating a performance score request for each of a plurality of SIP servers based on the routing request;

generating a performance data query to each of the plurality of SIP servers based on the performance score request; and

receiving the performance data query in an agent in each of the plurality of SIP servers.

24. A communication system, comprising:

an interface to a source device;

a load balancer coupled to the interface;

a plurality of Session Initiation Server (SIP) servers coupled to the load balancer; and

a performance server coupled to the load balancer and the plurality of SIP servers, the performance server configured to collect performance data from the plurality of SIP servers, the load balancer configured to calculate a plurality of performance scores, each of the plurality of performance scores associated with one of the plurality of SIP servers, the plurality of performance scores based on the performance data, the load balancer further configured to direct a SIP request received from the first interface to a selected one of the plurality of SIP servers based on the plurality of performance scores.

25. The system of claim 24, wherein the load balancer includes:

a SIP forwarding module configured to forward the SIP request to the selected one of the plurality of SIP servers;

a SIP routing module coupled to the SIP forwarding module, the SIP routing module configured to select the selected one of the plurality of SIP servers based on the performance score for each of the plurality of SIP servers;

a server load computation module coupled to the SIP routing module, the server load module configured to calculate the performance score for each of the plurality of SIP servers based on the collected performance data; and

a server performance query module coupled to the server load computation module, the server performance query module configured to fetch the performance data from the performance server.

26. The system of claim 24, wherein each of the plurality of SIP servers include a performance agent, the performance agent configured to provide the performance data to the performance server.