Overload protection for SIP servers

• US 20080031258A1
• Filed: 08/01/2006
• Published: 02/07/2008
• Est. Priority Date: 08/01/2006
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Tracey, John Michael, Wright, Charles P., Acharya, Arup, Wang, Xiping, Xiao, Zhen, Nahum, Erich M.
• Granted Patent: US 7,522,581 B2
• Time in Patent Office: Days
• US Class Current: 370/395.42
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/19 at layers above the network layer network arrangements for networked applications for scheduling or organising the servicing of application requests H04L67/60
• CPC Class Codes: H04L 47/2441 relying on flow classification, e.g. using integrated services [IntServ]
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames
• CPC Class Codes: H04L 47/801 Real time traffic
• CPC Class Codes: H04L 47/821 Prioritising resource allocation or reservation requests
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 65/1046 Call controllers; Call servers
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers

Abstract

A method for operating a server having a maximum capacity for servicing requests comprises the following steps: receiving a plurality of requests; classifying each request according to a value; determining a priority for handling the request according to the value, such that requests with higher values are assigned higher priorities; placing each request in one of multiple queues according to its priority value; and dropping the requests with the lowest priority when the plurality of requests are received at a rate that exceeds the maximum capacity. The server operates according to a session initiation protocol.

Classifying each request comprises running a classification algorithm. The classification algorithm comprising steps of: receiving a rule set, each rule comprising headers and conditions; creating a condition table by taking a union of all conditions in the rules; creating a header table by extracting a common set of headers from the condition table; extracting the relevant headers from the header table; determining a matching rule; creating a bit vector table; selecting the matching rule according to data in the bit vector table; and applying the rule to place the message in the appropriate queue.

Claims

1. A method for operating a server having a maximum capacity for servicing requests, the method-comprising steps of:

receiving a plurality of requests;

classifying each request according to a value;

determining a priority for handling the request according to the value, such that requests with higher values are assigned higher priorities;

placing each request in one of multiple queues according to its priority value; and

dropping the requests with the lowest priority when the plurality of requests are received at a rate that exceeds the maximum capacity.

2. The method of claim 1 wherein the server operates according to the session initiation protocol (SIP).

3. The method of claim 1 wherein classifying each request comprises running a classification algorithm, the classification algorithm comprising steps of:

receiving a rule set, each rule comprising headers and conditions;

creating a condition table by taking a union of all conditions in the rules;

creating a header table by extracting a common set of headers from the condition table;

extracting the relevant headers from the header table;

determining a matching rule;

creating a bit vector table;

selecting the matching rule according to data in the bit vector table; and

applying the rule to place the message in the appropriate queue.

4. The method of claim 1 wherein the request is for an SIP message session.

5. The method of claim 1 wherein the request is for a session setup for a voice over internet protocol session.

6. The method of claim 1 wherein the value of the request is based upon a plurality of message types, the message types comprising:

register message;

presence subscription and notification;

bye messages;

specific destinations;

source of the message;

whether the message belongs to a session-in-progress;

whether the message belongs to a new session setup; and

within a message, retransmission of a message vs. the first instance the message is being sent.

7. The method of claim 3 wherein headers are classified as one of:

simple headers, pseudo-headers, and derived headers.

8. The method of claim 7 wherein, in conjunction with user-defined derived headers, the user is allowed to specify complex data types such as structures and complex data variables such as associate arrays and pointers, as well as scalars.

9. The method of claim 3 wherein rules with a numerically higher priority value have precedence over rules with a lower value and wherein a first matching rule will be applied for rules with the same priority value.

10. The method of claim 9 wherein rules are sorted in decreasing order of priority such that the matching process can be stopped after the first matching rule is found.

11. The method of claim 1 wherein the requests comprise:

session initiation requests, session modification requests, and requests for binding a user to an address.

12. The method of claim 1 wherein queues comprise:

a high priority queue, a medium priority queue, and a low priority queue.

13. The method of claim 1 wherein the classification algorithm operates at run time.