WO2013041033A1

WO2013041033A1 - Access points to access an access controller in a wireless local area network

Info

Publication number: WO2013041033A1
Application number: PCT/CN2012/081654
Authority: WO
Inventors: Zhe JI; Guoxiang XU
Original assignee: Hangzhou H3C Technologies Co., Ltd.
Priority date: 2011-09-21
Filing date: 2012-09-20
Publication date: 2013-03-28
Also published as: CN102316549B; CN102316549A

Abstract

The disclosure relates to access points APs to access an access controller AC in a wireless local area network. It comprises: receiving, by said AC, a discovery request message sent by any AP; sending by said AC to the AP a discovery response message carrying a waiting time so as to inform said AP to randomly select a waiting time within said carried waiting time, and to send a Datagram Transport Layer Security DTLS connection request for accessing when the randomly selected waiting time expires after a discovery process performed by the AP is finished, wherein said carried waiting time is determined based on a CPU load of the AC and an association priority of the AP.

Description

ACCESS POINTS TO ACCESS AN ACCESS CONTROLLER IN A WIRELESS LOCAL AREA

NETWORK

BACKGROUND

In a large-scale Wireless Local Access Network WLAN, an access controller AC often needs to manage thousands of access points APs. In such a network, when the network needs to be restarted, thousands of APs are associated with said AC at the same time and said AC needs to authenticate each AP and establish a session with it.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various examples of various aspects of the present disclosure. It will be appreciated that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. It will be appreciated that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of another element may be implemented as an external component and vice versa.

Fig. 1 is a flow chart of a method for APs to access an AC according to an example;

Fig. 2 is a schematic drawing of format of Control And Provisioning of Wireless Access Points CAPWAPs message according to an example;

Fig. 3 is a structural diagram of said AC according to an example; and Fig. 4 is a structural diagram of said AP according to an example.

DETAILED DESCRIPTION

As used herein, the term "includes" means includes but not limited to, the term "including" means including but not limited to. The term "based on" means based at least in part on. In addition, the terms "a" and "an" are intended to denote at least one of a particular element.

In the following, certain examples are described in detail with reference to the drawings.

With the reference to Fig. 1, Fig. 1 is a flow chart of a method for APs to access an AC according to an example.

At block 101, said method comprises receiving by said AC a discovery request message sent by any AP.

The AC will receive said discovery request messages sent by a lot of APs, the disclosure has the same processing for any the AP. Each AC in said WLAN network will receive discovery request messages from a plurality of APs, and each AP will receive discovery response messages sent by a plurality of ACs and then will select an AC with high priority to perform Datagram Transport Layer Security DTLS connection and further access it.

In this context, a situation in which a number of APs will access one AC is taken as an example.

At this block 101 , the discovery request message sent by the AP and received by the AC carries the model of the AP as well as the software and hardware information of the AP. This is the same as the existing implementation.

At block 102, said method comprises sending by the AC a discovery response message carrying a waiting time to the AP so as to inform said AP to randomly select a waiting time within said carried waiting time, and to send a DTLS connection request for accessing when the randomly selected waiting time expires after a discovery process performed by AP is finished, wherein the carried waiting time is determined based on a Central Processing Unit CPU load of the AC itself and an association priority of the AP. In this context, the phrase "an association priority of the AP" refers to a priority of AP while associating with AC, which is known as "an association priority of the AP" for short.

At this block 102, the discovery response message sent by the AC to the AP carries software and hardware version of the AC, name of the AC as well as a waiting time that is determined based on a CPU load of the AC and an association priority of the AP. Wherein, the association priority of each AP is pre-configured on the AC. Said carried waiting time is realized through a type length value TLV in the message, and the specific content of TLV is value of the carried waiting time. The unit of the carried waiting time is generally set to be second, or set according to the specific application.

The specific way for determining the carried waiting time based on a CPU load of the AC and an association priority of the AP is as follows:

If the CPU load of the AC is higher than a first preset value and lower than a second preset value and when the association priority of the AP is a high priority, the carried waiting time is determined to be Wo.

If the CPU load of the AC is higher than a first preset value and lower than a second preset value and when the association priority of the AP is a low priority, the carried waiting time is determined to be Wi, wherein the first preset value is smaller than the second preset value and Wo<Wi.

If the CPU load of the AC is lower than the first preset value, said discovery response message is sent to the AP to inform the AP to directly send a DTLS connection request for accessing after the discovery process performed by the AP is finished, namely, this AP can directly access the AC without waiting.

If the CPU load of the AC is higher than the second preset value, which means that the CPU of the AC is busy, the discovery response message is not sent to the AP. Since the CPU of the AC is busy and can not allow access by any new AP, no discovery response message is sent to the AP.

This block 102 mentions "after the discovery process performed by the AP is finished", which means that the AP has collected all the discovery response messages and has ready to access the AC when a timer expires at an interval of discovery process. In the example, the AP does not immediately send the DTLS connection request after the discovery process is finished, but it waits for said randomly selected waiting time to initiate the DTLS connection. The AC receives the DTLS connection request sent by any AP and if it determines, according to the CPU load condition of the AC, that said AP is allowed to establish the DTLS connection, the DTLS connection request of the AP will be responded to enable the AP to access the AC; otherwise, it will record a number of times the DTLS connection request is not responded to and if the number of times reaches a preset number, the DTLS connection request of the AP will preferentially be responded to enable the AP to access the AC.

The AC receives a DTLS connection request sent by any AP. If the CPU load of the AC is lower than the second preset value, the DTLS connection request of the AP will be responded to enable the AP to access the AC; otherwise, a DTLS connection response will not sent to the AP, and it will record a number of times the DTLS connection request is not responded to and if the number of times reaches a preset number, the DTLS connection request of the AP will preferentially be responded to enable the AP to access the AC.

When the AC determines, according to the CPU load condition of the

AC, that the DTLS connection request of any AP will not be responded to, the specific implementation is as follows:

The AC simultaneously records the number of times the DTLS connection request of each AP is not responded to, i.e. Failed DTLS Session Count, and preferentially responds to the DTLS connection request of the AP whose number of times has reached the max Failed DTLS session Retry Count minus 1 , thus preventing the AP from entering a long time sulking state.

The AC receives a join request message sent by any AP. If the CPU load of the AC is higher than the second preset value, the AC sends a join response message to the AP, in which the value of the RESULT CODE in the join response message is set to be AC CPU busy, so as to inform the AP to resend the join request message for joining when the randomly selected waiting time expires. As for other situations of failure of joining, they are the same as the existing situation.

With the reference to Fig. 2, Fig. 2 is a schematic drawing of format of Control And Provisioning of Wireless Access Points CAPWAPs message according to an example. In Fig. 2, an example of setting the value of the RESULT CODE to be AC CPU busy will be described in detail below through said message formats. In Fig. 2, when the value of Message Type in Control Header field is 4, it means that said message is a Join Response message. Message Elements field refer to one or more Message Elements, format of each Message Element is a TLV format. With respect to the Result Code, the value of Type is 33 and the value of Length is 4, and meanings of Value are as follows:

0 represents Success; 1 represents Failure (AC List Message Element MUST Be Present); 2 represents Success (NAT Detected); 3 represents Join Failure (Unspecified); 4 represents Join Failure (Resource Depletion); 5 represents Join Failure (Unknown Source), etc.

One value for Value of RESULT CODE is added in the example, which represents that the Value of RESIULT CODE is set to be AC CPU busy. Wherein, said added value is identified by a value not adopted in the existing protocol standards or not used in the example.

The AP receives the join response message sent by the AC. If the value of the RESULT CODE in the join response message is set to be AC CPU busy, AP will not enter the DTLS Teardown state and will records the number of times it has sent the request message; and will resend the join request message to the AC when the randomly selected waiting time expires; if the value of RESULT CODE in the join response message is set to be AC CPU busy and the number of times that the AP has sent the join request message has reached a preset number of repetition, the AP will directly enter a DTLS Teardown state, thus avoiding entering an endless loop in case any fault occurs in the AC. If at the discovery process, the discovery response message sent by the AC does not carry the waiting time, the AP will directly resend the join request message without waiting upon receiving a join response message which indicates AC CPU busy. If no join response success message is received from the AC after sending the join request message four times by AP, the AP will directly enter a DTLS Teardown state. Wherein, the number of four times of sending the join request message is a number specified by the standard protocol, but it can be adjusted properly during application.

According to the same concept as that of the above method, the present disclosure provides AC for use in the WLAN, as shown in Fig. 3. With the reference to Fig. 3, Fig. 3 is a structural diagram of said AC 300 according to an example. Said AC 300 comprises: a receiving unit 301, a determining unit 302 and a sending unit 303.

The receiving unit 301 is to receive a discovery request message sent by any AP.

The determining unit 302 is to determine a waiting time based on a

CPU load of said AC and an association priority of the AP after the receiving unit 301 receives said discovery request message sent by any AP, .

The sending unit 303 is to send to the AP a discovery response message carrying the waiting time determined by said determining unit 302 to the AP so as to inform said AP to randomly select a waiting time within said carried waiting time, and to send a DTLS connection request for accessing when the randomly selected waiting time expires after a discovery process performed by AP is finished.

In an example, the determining unit 302 is further to determine the carried waiting time to be W₀ if the CPU load of the AC is higher than a first preset value and lower than a second preset value and when the association priority of the AP is a high priority; and determine the carried waiting time to be Wi if the CPU load of the AC is higher than a first preset value and lower than a second preset value and when the association priority of the AP is a low priority, wherein the first preset value is smaller than the second preset value and W₀<Wi.

The sending unit 303 is further to send to the AP a discovery response message if the CPU load of the AC is lower than the first preset value so as to inform the AP to directly send a DTLS connection request for accessing without waiting after the discovery process performed by the AP is finished; and not send the discovery response message to the AP if the CPU load of the AC is higher than the second preset value.

In another example, said AC further comprises a recording unit 304.

The receiving unit 301 is further to receive a DTLS connection request sent by any AP.

The determining unit 302 is further to not allow the AP to establish a

DTLS connection if the CPU load of the AC is higher than the second preset value; otherwise, allow the AP to establish a DTLS connection.

The recording unit 304 is to record a number of times the DTLS connection request of the AP is not responded to, if the determining unit 302 determines that the AP is not allowed to establish a DTLS connection.

The sending unit 303 is further to respond to the DTLS connection request of the AP to enable the AP to access AC if the determining unit 302 determines that the AP is allowed to establish the DTLS connection; and preferentially respond to the DTLS connection request of the AP to enable the AP to access AC if the determining unit 302 determines that the AP is not allowed to establish a DTLS connection and the number of times recorded by the recording unit 304 that the DTLS connection request is not responded to reaches a preset number.

In still another example, the receiving unit 301 is further to receive a join request message sent by any AP.

The sending unit 303 is further to send a join response message to the AP if the determining unit 302 determines that the CPU load of the AC is higher than the second preset value, and set the value of the RESULT CODE in the sent response message to be AC CPU busy to inform the AP to resend the join request message when the randomly selected waiting time expires.

The disclosure also provides an AP 400 for use in a WLAN, referring to Fig. 4, which is a structural diagram of said AP according to an example. Said AP 400 comprises a receiving unit 401, a determining unit 402 and a sending unit 403.

The receiving unit 401 is to receive a discovery response message carrying a waiting time sent by an AC. The determining unit 402 is to determine the waiting time carried in the discovery response message received by the receiving unit 401 , wherein the carried waiting time is determined based on CPU load of AC and an association priority of the AP, and said determining unit is further to randomly select a waiting time within said carried waiting time.

The sending unit 403 is to send a DTLS connection request for accessing to the AC when the waiting time randomly selected by the determining unit 402 expires after the discovery process performed by the AP is finished.

In an example, the receiving unit 401 is further to receive a join response message sent by the AC.

The determining unit 402 is further to determine that an AP will not enter the DTLS Teardown state if the value of the RESULT CODE in the join response message received by the receiving unit 401 is AC CPU busy and the number of times that the AP sends the join request message does not reach a preset number of repetition; otherwise, the AP will directly enter the DTLS teardown state if the number of times that the AP sends the join request message reaches a preset number of repetition.

The sending unit 403 is further to resend a join request message to the AC when the waiting time randomly selected by the determining unit 402 expires.

The units mentioned in the above examples can be integrated together or deployed separately, they can be combined into one unit or be further divided into multiple sub-units.

In summary, the AC in the disclosure informs the AP of waiting time before initiating connection in the discovery process, and said waiting time is determined based on the CPU load of the AC at the time and association priority of the AP. After receiving said information, the AP randomly selects a waiting time within the informed waiting time and initiates a DTLS connection request when the randomly selected waiting time expires after the discovery process is finished. Since each AP selects a random waiting time, the APs can orderly be associated with the AC, thus avoiding the impact brought about by a great number of APs associating with the AC simultaneously and facilitating network maintenance.

The AC responds or refuses the connection of AP in the DTLS Setup stage according to the CPU load of the AC and the association priority of the AP. If the number of times of refusing reaches a preset number, said AP will be responded to in preference to prevent the AP from entering a long time Sulking state.

The AC refuses the Join request of the AP in the Join stage according to the CPU load of AC and the association priority of the AP, and the AP can wait according to the newly defined error code instead of entering into the DTLS teardown state. Only when the number of times of retry reaches a certain number, will a failure be confirmed and the AP enters the DTLS teardown state, thus avoiding entering an endless loop in case any fault occurs in the AC.

The above examples can be implemented by hardware, software or firmware or a combination thereof. For example the various methods, processes and functional units described herein may be implemented by a processor (the term processor is to be interpreted broadly to include a CPU, processing unit, ASIC, logic unit, or programmable gate array etc.). The processes, methods and functional units may all be performed by a single processor or split between several processers; reference in this disclosure or the claims to a 'processor' should thus be interpreted to mean One or more processors'. The processes, methods and functional modules be implemented as machine readable instructions executable by one or more processors, hardware logic circuitry of the one or more processors or a combination thereof. Further the teachings herein may be implemented in the form of a software product. The computer software product is stored in a storage medium and comprises a plurality of instructions for making a computer device (which can be a personal computer, a server or a network device such as a router, switch, access point etc.) implement the method recited in the examples of the present disclosure.

The drawings are merely schematic drawings of an example, and the modules or flows in the drawings are not necessary essential for carrying out the disclosure.

The modules in the device in the examples can be distributed in the device in the examples according to the descriptions of the example, or they can be changed so as to be in one or more devices that are different from that in the examples. The modules in the above examples can be either combined into one module or further divided into several sub-modules.

The above sequential numbers mentioned are only for facilitating description, but they are not used to represent which example is more advantage.

The above description includes examples. Any modification, equivalent substitution and improvement made that are according to the spirit and principle of the examples shall be included in the protection scope.

Claims

1. A method for access points APs to access an access controller AC in a wireless local area network, wherein said method comprises:

receiving, by said AC, a discovery request message sent by any AP; sending by said AC to the AP a discovery response message carrying a waiting time so as to inform said AP to randomly select a waiting time within said carried waiting time, and to send a Datagram Transport Layer Security DTLS connection request for accessing when the randomly selected waiting time expires after a discovery process performed by the AP is finished, wherein said carried waiting time is determined based on a CPU load of the AC and an association priority of the AP.

2. The method of claim 1 , further comprising:

if the CPU load of the AC is higher than a first preset value and lower than a second preset value and when the association priority of the AP is a high priority, determining the carried waiting time to be Wo;

if the CPU load of the AC is higher than a first preset value and lower than a second preset value and when the association priority of the AP is a low priority, determining the carried waiting time to be Wi, wherein the first preset value is smaller than the second preset value and Wo<Wi .

3. The method of claim 2, further comprising:

if the CPU load of the AC is lower than the first preset value, sending to the AP a discovery response message to inform the AP to directly send a DTLS connection request for accessing without waiting after the discovery process is finished;

if the CPU load of the AC is higher than the second preset value, not sending the discovery response message to the AP.

4. The method of claim 2, further comprising:

receiving, by the AC, a DTLS connection request sent by any AP; if the CPU load of the AC is lower than the second preset value, responding to the DTLS connection request of the AP to enable the AP to access the AC; if the CPU load of the AC is higher than the second preset value, not sending a DTLS connection response to the AP and recording a number of times the DTLS connection request of the AP is not responded to; and

if the number of times reaches a preset number, responding to the DTLS connection request of the AP to enable the AP to access the AC .

5. The method of claim 2, further comprising:

receiving, by the AC, a join request message sent by any AP;

if the CPU load of the AC is higher than the second preset value, sending by the AC to the AP a join response message, with the value of RESULT CODE in the join response message being set to be AC CPU busy, so as to inform the AP to resend the join request message for joining when the randomly selected waiting time expires.

6. The method of claim 5, further comprising:

receiving, by the AP, said join response message sent by the AC;

if the value of RESULT CODE in the join response message is set to be AC CPU busy, the AP not entering a DTLS teardown state, and recording a number of times the AP sends the join request message;

resending said join request message to the AC when the randomly selected waiting time expires; and

directly entering the DTLS teardown state if the value of RESULT

CODE in the join response message is set to be AC CPU busy and the number of times that said AP sends the join request message reaches a preset number of repetition.

7. An access controller AC for use in a wireless local area network, wherein said AC comprises a receiving unit, a determining unit and a sending unit;

wherein said receiving unit is to receive a discovery request message sent by any access point AP;

said determining unit is to determine a waiting time based on a CPU load of the AC and an association priority of the AP after the receiving unit receives said discovery request message sent by any AP;

said sending unit is to send to the AP a discovery response message carrying the waiting time determined by said determining unit to inform said AP to randomly select a waiting time within said carried waiting time and to send a Datagram Transport Layer Security DTLS connection request for accessing when the randomly selected waiting time expires after a discovery process performed by the AP is finished.

wherein said receiving unit, said determining unit and said sending unit are implemented by a processor.

8. The access controller of claim 7, wherein said determining unit is further to:

determine the carried waiting time to be Wo if the CPU load of the

AC is higher than a first preset value and lower than a second preset value and when the association priority of the AP is a high priority;

determine the carried waiting time to be Wi if the CPU load of the AC is higher than a first preset value and lower than a second preset value and when the association priority of the AP is a low priority, wherein the first preset value is smaller than the second preset value and Wo<Wi;

said sending unit is further to:

send to the AP a discovery response message if the CPU load of the AC is lower than the first preset value so as to inform the AP to directly send a DTLS connection request for accessing with waiting after the discovery process is finished; and

not send the discovery response message to the AP if the CPU load of the AC is higher than the second preset value.

9. The access controller of claim 8, wherein said AC further comprises a recording unit;

said receiving unit is further to receive a DTLS connection request sent by any AP;

said determining unit is further to determine that the AP is not allowed to establish a Datagram Transport Layer Security DTLS connection if the CPU load of the AC is higher than the second preset value; otherwise, the AP is allowed to establish said DTLS connection if the CPU load of the AC is lower than the second preset value? said recording unit is to record a number of times the DTLS connection request of the AP is not responded to if the determining unit determines that the AP is not allowed to establish said DTLS connection; said sending unit is further to: respond to the DTLS connection request of the AP to enable the AP to access AC if the determining unit determines that the AP is allowed to establish the DTLS connection; and preferentially respond to the DTLS connection request of the AP to enable the AP to access AC if the determining unit determines that the AP is not allowed to establish a DTLS connection and the number of times recorded by the recording unit that the DTLS connection request is not responded to reaches a preset number.

10. The access controller of claim 8, wherein,

said receiving unit is further to receive a join request message sent by any AP;

said sending unit is further to: send a join response message to the AP if the determining unit determines that the CPU load of the AC is higher than the second preset value, and set the value of RESULT CODE in the sent join response message to be AC CPU busy to inform the AP to resend the join request message when the randomly selected waiting time expires.

11. An access point AP for use in a wireless local area network, wherein said AP comprises a receiving unit, a determining unit and a sending unit;

wherein said receiving unit is to receive a discovery response message carrying a waiting time sent by an access controller AC;

said determining unit is to determine the waiting time carried in the discovery response message received by the receiving unit, wherein the carried waiting time is determined based on a CPU load of the AC and an association priority of the AP, and said determining unit is further to randomly select a waiting time within said carried waiting time;

said sending unit is to send to the AC a Datagram Transport Layer

Security DTLS connection request for accessing when the waiting time randomly selected by the determining unit expires after a discovery process performed by the AP is finished;

12. The access point of claim 11 , wherein,

said receiving unit is further to receive a join response message sent by the AC;

said determining unit is further to determine that if the value of RESULT CODE in the join response message received by the receiving unit is AC CPU busy and the number of times that the AP sends a join request message does not reach a preset number of repetition, the AP does not enter the DTLS teardown state; otherwise, if the number of times that the AP sends a join request message reaches a preset number of repetition, the AP directly enters the DTLS teardown state;

said sending unit is further to resend a join request message to the AC when the waiting time randomly selected by the determining unit expires.