AP关联失败原因分析报告20110412

1、H3CIT©IP解关冇熹甘專AF关联失败原因分析报告.一、关联过程关联主要指 Station 发送Association Request 给AP, Association Request 中携带了一下协商信息，包括加密方式、支持的速率、支持的功率以前其他的一些特性。AP如果对这些协商信息没有异议且都支持的话，则回应携带OK信息AssociationResponse给Station同意其接入。至此，关联成功。Station可以继续发送正常的数据报文。1: Assodoiion一I y>Client图1.关联过程但如果AP对Station的协商信息有异议，则会发送携带错误码的 As

2、sociation Response给Station，以拒绝其接入。.二、关联失败的原因：关联失败的主要原因有：1.AC资源不足2.IE非法,包括加密算法等3. 不支持的功率4. 不支持的速率5. 其他不支持的功能通常我们常见的失败原因有2/3/4条。需要注意的是，通常Station在关联失败的情况下，会不断的尝试重新关联，这个频率是很快的，甚至达到每分钟2次。如果不去管Station，那么这个Station 一天下来就会产生大约2800的关联失败。而一台AL般接入10-15个Station，算上正常的上下线以及重关联，关联成功次数也就是最多几百次。但如果存在一个不断关联的Station，那么

3、关联失败率就会显的很高了。三、关联成功率：计算公式：关联成功率= 关联成功次数/关联请求数量以下为两个节点的OID:关联成功h3cDot11C不包含重关联成功次h3cDot11Ap1.3.6.1.4.1.2011.10.2.75.次数urAPID数Stati onAss ocSum2.2.3.1.1关联请求h3cDot11Ch3cDot11ApStationAsh3cDot11Ap1.3.6.1.4.1.2011.10.2.75.数量urAPIDsocReqSum =Stati onAss2.2.3.1.9h3cDot11ApStationAs socSum + h3cDot11ApStati

4、onAs socFailSumocReqSum四、关联协议标准:协议中定义的reasoncode,对于 association关注以disassociated 开头的原因协议内容截取：723.3 Disassociation frame formatThe frame body of a management frame of subtype Disassociation contains the information shown inTable 7-9.Order Information1 Reason code2 One or more vendor-specific informati

5、on elements may appear in this frame.7.3.1.7 Reason Code fieldThis Reason Code field is used to indicate the reason that an unsolicited notification management frame oftype Disassociation, Deauthentication, DELTS, DELBA, or DLS Teardown was generated. The length of theReason Code field is 2 octets.

6、The Reason Code field is illustrated in Figure 7-25.The reason codes are defined in Table 7-22.Table 7-22 Reason codesReason code Meaning0 Reserved1 Unspecified reason2 Previous authentication no longer valid3 Deauthenticated because sending STA is leaving (or has left) IBSS or ESS4 Disassociated du

7、e to inactivity5 Disassociated because AP is unable to handle all currently associated STAs6 Class 2 frame received from nonauthenticated STAClass 3 frame received from nonassociated STA7 Disassociated because sending STA is leaving (or has left) BSS8 STA requesting (re)association is not authentica

8、ted with responding STA9 Disassociated because the information in the Power Capability element is unacceptable10 Disassociated because the information in the Supported Channels element is unacceptable11 Reserved12 Invalid information element, i.e., an information element defined in this standard for

9、which the content does not meet the specifications in Clause 713 Message integrity code (MIC) failure14 4-Way Handshake timeout15 Group Key Handshake timeout16 Information element in 4-Way Handshake different from (Re)Association Request/Probe Response/Beacon frame17 Invalid group cipher18 Invalid p

10、airwise cipher19 Invalid AKMP20 Unsupported RSN information element version21 Invalid RSN information element capabilities22 IEEE 802.1X authentication failed23 Cipher suite rejected because of the security policy25-31 Reserved32 Disassociated for unspecified, QoS-related reason33 Disassociated beca

11、use QoS AP lacks sufficient bandwidth for this QoS STA34 Disassociated because excessive number of frames need to be acknowledged, but are not acknowledged due to AP transmissions and/or poor channel conditions35 Disassociated because STA is transmitting outside the limits of its TXOPs36 Requested from peer STA as the STA is leaving the BSS (or resetting)37 Requested from peer STA as it does not want to use the mechanism3