AP關(guān)聯(lián)失敗原因分析報告20110412

1、H3CIT©IP解關(guān)冇熹甘專AF關(guān)聯(lián)失敗原因分析報告.一、關(guān)聯(lián)過程關(guān)聯(lián)主要指 Station 發(fā)送Association Request 給AP, Association Request 中攜帶了一下協(xié)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如果對這些協(xié)商信息沒有異議且都支持的話，則回應(yīng)攜帶OK信息AssociationResponse給Station同意其接入。至此，關(guān)聯(lián)成功。Station可以繼續(xù)發(fā)送正常的數(shù)據(jù)報文。1: Assodoiion一I y>Client圖1.關(guān)聯(lián)過程但如果AP對Station的協(xié)商信息有異議，則會發(fā)送攜帶錯誤碼的 As

2、sociation Response給Station，以拒絕其接入。.二、關(guān)聯(lián)失敗的原因：關(guān)聯(lián)失敗的主要原因有：1.AC資源不足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們常見的失敗原因有2/3/4條。需要注意的是，通常Station在關(guān)聯(lián)失敗的情況下，會不斷的嘗試重新關(guān)聯(lián)，這個頻率是很快的，甚至達(dá)到每分鐘2次。如果不去管Station，那么這個Station 一天下來就會產(chǎn)生大約2800的關(guān)聯(lián)失敗。而一臺AL般接入10-15個Station，算上正常的上下線以及重關(guān)聯(lián)，關(guān)聯(lián)成功次數(shù)也就是最多幾百次。但如果存在一個不斷關(guān)聯(lián)的Station，那么

3、關(guān)聯(lián)失敗率就會顯的很高了。三、關(guān)聯(lián)成功率：計算公式：關(guān)聯(lián)成功率= 關(guān)聯(lián)成功次數(shù)/關(guān)聯(lián)請求數(shù)量以下為兩個節(jié)點(diǎn)的OID:關(guān)聯(lián)成功h3cDot11C不包含重關(guān)聯(lián)成功次h3cDot11Ap1.3.6.1.4.1.2011.10.2.75.次數(shù)urAPID數(shù)Stati onAss ocSum2.2.3.1.1關(guān)聯(lián)請求h3cDot11Ch3cDot11ApStationAsh3cDot11Ap1.3.6.1.4.1.2011.10.2.75.數(shù)量urAPIDsocReqSum =Stati onAss2.2.3.1.9h3cDot11ApStationAs socSum + h3cDot11ApStati

4、onAs socFailSumocReqSum四、關(guān)聯(lián)協(xié)議標(biāo)準(zhǔn):協(xié)議中定義的reasoncode,對于 association關(guān)注以disassociated 開頭的原因協(xié)議內(nèi)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