交換機(jī)端口錯(cuò)包排查方法

一、重要性：從網(wǎng)維排查的用戶反應(yīng)網(wǎng)速慢的故障中，相當(dāng)一部分是由于交換機(jī)和交換機(jī)端口、交換機(jī)端口和用戶路由器端口、交換機(jī)端口和光電轉(zhuǎn)換器端口、交換機(jī)端口和用戶網(wǎng)卡匹配不當(dāng)，產(chǎn)生錯(cuò)包引起的。該問題雖然比較常見，但只要按交換機(jī)開局來配置，通常能降低故障發(fā)生率，即使還存在端口錯(cuò)包問題，也能通過改端口速度和雙工狀態(tài)來徹底解決。二、交換機(jī)端口錯(cuò)包說明：以華為交換機(jī)端口為例進(jìn)行說明：[NJ-A-GJXC-S3026C-1]disinteth0/1Ethernet0/1currentstate:UPIPSendingFrames'FormatisPKTFMT_ETHNT_2,Hardwareaddressis000f-e21d-bedcDescription:togujiao_33-192.168.86.161TheMaximumTransmitUnitis1500Mediatypeistwistedpair,loopbacknotsetPorthardwaretypeis100_BASE_TX100Mbps-speedmode,full-duplexmodeLinkspeedtypeisforcelink,linkduplextypeisforcelinkFlow-controlisnotenabledPort-flow-constrainhasnotbeenconfiguredcompletelyTheMaximumFrameLengthis1536BroadcastMAX-ratio:100%PVID:10Mditype:autoPortlink-type:hybridTaggedVLANID:,99UntaggedVLANID:,10,458Last300secondsinput:0packets/sec11bytes/secLast300secondsoutput:7packets/sec520bytes/secInput(total):11864483packets,6684922188bytes66707broadcasts,9522multicastsInput(normal):-packets,-bytes-broadcasts,-multicastsInput:0inputerrors,0runts,0giants,-throttles,0CRC0frame,-overruns,0aborts,0ignored,-parityerrorsOutput(total):12008069packets,5178275457bytes3638352broadcasts,288120multicasts,0pausesOutput(normal):-packets,-bytes-broadcasts,-multicasts,-pausesOutput:0outputerrors,-underruns,-bufferfailures0aborts,0deferred,0collisions,0latecollisions0lostcarrier,-nocarrier如上紅字所示：輸入錯(cuò)誤數(shù)，inputerrors等于各種重要錯(cuò)誤信息的總和。不同的產(chǎn)品可以根據(jù)具體情況增加其它參數(shù)，或減少不能實(shí)現(xiàn)的參數(shù)。Runts:discardedpacketsthataresmallerthanthemedium'sminimumpacketsize.（ReceiveByteCount<64andNOTCRCErrororReceiveByteCount<64andTagPacketandNOTCRCError，無論是否有vlantag,數(shù)據(jù)段小于64字節(jié)，而且沒有CRC校驗(yàn)錯(cuò)誤的幀。）Giants:discardedpacketsthatarelargerthanthemedium'smaximumpacketsize.（ReceiveByteCount>1518andNOTCRCErrororReceiveByteCount>1522andTagPacketandNOTCRCError,沒有vlantag，數(shù)據(jù)段大于1518字節(jié)，小于最大幀長度，而且沒有CRC校驗(yàn)錯(cuò)誤的幀，和有vlantag，數(shù)據(jù)段大于1522字節(jié)，小于最大幀長度，而且沒有CRC校驗(yàn)錯(cuò)誤的幀。）Throttles:discardedpacketsthatareincompleteframes.（交換機(jī)察覺緩存或CPU過載，關(guān)閉接口接收器的情形稱為throttle，是cisco路由器上的一個(gè)概念,我們的交換機(jī)目前不具備這個(gè)功能,一般應(yīng)該顯示為不支持。）CRC:discardedpacketswithchecksumerror.（ReceivePacketCRCerror,幀長度在正常范圍（不帶tag,長度在64到1518之間，或帶tag，長度在64到1522之間），而且CRC校驗(yàn)錯(cuò)，如果支持此項(xiàng)，則不支持奇偶校驗(yàn)錯(cuò)誤項(xiàng)。）Frame:discardedpacketswithframepad/sequence/alignmenterror,outofframeetc.（不是整數(shù)字節(jié)，而是多1~7bit，因此不對齊，或亂序或空幀，而且CRC校驗(yàn)錯(cuò)誤，但是不計(jì)入CRC錯(cuò)誤。）6.Overrun:thereceiverhardwareisunabletohandreceiveddatatoahardwarebufferbecausetheinputrateexceedsthereceiver'sabilitytohandlethedata.（由于接口輸入速率超過接受方處理能力，導(dǎo)致丟包，由于我們的交換機(jī)一般是線速轉(zhuǎn)發(fā)，這項(xiàng)一般應(yīng)該為0,只有部分交換機(jī)對上傳CPU或三層線速轉(zhuǎn)發(fā)的幀有接口帶寬限制，或是通過ACL實(shí)現(xiàn)的帶寬限制，因此被丟棄的幀，計(jì)入此項(xiàng)。）7.Aborts:Inputabnormalframesthatarediscarded.（除其他錯(cuò)誤之外，產(chǎn)品認(rèn)為有必要統(tǒng)計(jì)的錯(cuò)誤，例如前導(dǎo)碼異常的幀，計(jì)入此項(xiàng)。）8.Ignored:packetsthatarediscardedbecausetheinterfacehardwaredoesnothaveenoughinternalbuffers.（Packetignored,由于接口內(nèi)部buffer滿，丟棄的幀，與由于主系統(tǒng)緩存空間缺乏，導(dǎo)致的丟棄幀不同。線速轉(zhuǎn)發(fā)的幀，在多接口滿帶寬輸入，單接口輸出等情況下,由于輸出接口的帶寬不足,數(shù)據(jù)幀將內(nèi)部緩存占滿,導(dǎo)致從接口輸入的幀在進(jìn)入內(nèi)部緩存之前被丟棄,以及進(jìn)入內(nèi)部緩存的幀超時(shí)無法輸出,計(jì)入此項(xiàng),上傳到CPU的幀，由于CPU處理能力限制，toCPU的緩存滿，導(dǎo)致被丟棄，也計(jì)入此項(xiàng)。）9.Parity:Frameswithparityerror.（ReceivePacketparityerror,如果支持此項(xiàng)，則不支持CRC錯(cuò)誤項(xiàng)。）輸入丟棄數(shù)/輸入錯(cuò)誤數(shù)，outputerrors等于各種重要錯(cuò)誤信息的總和。不同的產(chǎn)品可以根據(jù)具體情況增加其它參數(shù)，或減少不能實(shí)現(xiàn)的參數(shù)。Underruns:Therearenodataintheoutputqueue.（Transmitunderrun,與Overrun相反，輸出接口的緩存從輸出隊(duì)列中取以太網(wǎng)幀時(shí)，沒有幀，是一種非常少見的硬件異常。有的交換機(jī)就沒有單獨(dú)的接口輸出緩存，與接口輸出隊(duì)列是同一塊緩存。）Bufferfailures:Hardwaredoesnothaveenoughinternalbuffers.（內(nèi)部緩存滿，如果輸出隊(duì)列滿，輸出的以太網(wǎng)幀將在內(nèi)部緩存中暫時(shí)存儲(chǔ)，由于內(nèi)部緩存滿，導(dǎo)致幀丟棄。由于交換機(jī)對線速轉(zhuǎn)發(fā)的數(shù)據(jù)幀發(fā)生的這種異常，認(rèn)為只是到達(dá)內(nèi)部緩存而沒有到達(dá)出接口，是個(gè)輸入幀，因此計(jì)入InputIgnoredError,只有從CPU發(fā)出的幀，由于內(nèi)部緩存滿，導(dǎo)致幀丟棄，計(jì)入此項(xiàng)。）Aborts:Outputabnormalframesthatarediscarded.（在半雙工模式下,由于沖突檢測,延遲發(fā)送超過15次的幀,被丟棄,計(jì)入此項(xiàng)。除其他錯(cuò)誤之外,產(chǎn)品認(rèn)為有必要統(tǒng)計(jì)的錯(cuò)誤,例如添加前導(dǎo)碼異常的幀,也計(jì)入此項(xiàng)）Deferred:Thepacketscouldnotbesentoutforcollisionunderhalf-duplexmode.（半雙工模式下,由于檢測到載波正在被聲明,當(dāng)時(shí)沒有發(fā)出的包,延時(shí)一次計(jì)數(shù)加一。）Collisions:Statisticofcollisiondetectionunderhalf-duplexmode.（半雙工模式下,在以太網(wǎng)幀數(shù)據(jù)部分的前64字節(jié)進(jìn)入線路前,由于檢測到?jīng)_突,當(dāng)時(shí)沒有發(fā)出的包。）Latecollisions:StatisticofcollisionwithGEportsendingpacketslessthan512bytesand10/100Mportlessthan64bytes.（半雙工模式下，在以太網(wǎng)幀數(shù)據(jù)部分的前64字節(jié)進(jìn)入線路后，由于檢測到?jīng)_突，當(dāng)時(shí)沒有發(fā)出的包。）Lostcarrier:Statisticoflosingthecarrier.（載波丟失，一般適用于串行WAN接口，發(fā)送過程中，每丟失一個(gè)載波，此計(jì)數(shù)加一，對于交換機(jī)，通常是由于線路中斷造成。）Nocarrier:Statisticofnocarrier.（無載波，一般適用于串行WAN接口，當(dāng)試圖發(fā)送幀時(shí)，如果沒有載波出現(xiàn)，此計(jì)數(shù)加一，對于交換機(jī)，通常是由于線路中斷造成。）如果“inputerrors”和“outputerrors”非“0"并且數(shù)字在增長，通常情況下可能存在端口匹配問題，必須進(jìn)行端口狀態(tài)調(diào)整。其它廠商，cisco和中興的二層交換機(jī)錯(cuò)包類型相似，可以類推。三、錯(cuò)包問題排查方法下面分別說下中興、華為和CISCO二層交換機(jī)排查常用命令。1中興交換機(jī)端口排查方法，以Z2826S為例進(jìn)行說明；交換機(jī)端口原來配置,showrunsetport1descriptionTo_702setport1autodisablesetport1speed10setport1pvid541setport1macaddresson1

setport1unit-statisticsenable交換機(jī)端口原來數(shù)據(jù)包統(tǒng)計(jì)NJ-A-CFDS-Z2826S_2(1#7F)(cfg)#shport1statisticsPortId:1 PortName:ReceivedFramesReceivedBytesCrcErrorInMACRcvErrReceivedFramesReceivedBytesCrcErrorInMACRcvErrFragmentsFrames64Bytes:1232457Frames128_255Bytes:7180773Frames512_1023Bytes:4738336OversizeFrames:0SendUnicastFrames:127249246SendNoneUnicastFrames:1892514SendBroadcastFrames:1035165:128998658ReceivedBroadcastFrames:1815:741746864ReceivedMulticastFrames:0:4934296InPause:0:0Jabber:2:6447228UndersizeFrames:0Frames65_127Bytes:84450478Frames256_511Bytes:2203985Frames1024_UpBytes:29192629SendBytes:4270894316SendFrames:129141760SendMulticastFrames:857349SendSingleCollision:0SendSingleCollision:0SendLateCollision:0SendCollision :0OutPause :0SendMultiCollision:0SendExcessCollision:0SendDefferTrans:0可以看到端口有大量“CrcError”錯(cuò)包，并且多次查看端口信息，可以看到錯(cuò)包在增長，該用戶當(dāng)前的上網(wǎng)速度肯定會(huì)慢，需要整改

更改端口匹配模式，改成端口自適應(yīng)，主動(dòng)宣告10Msetport1autoenablesetport1speedadvertisespeed10fullDuplex更改后端口配置setport1descriptionTo_702setport1pvid541setport1speedadvertisespeed10FullDuplexsetport1macaddresson1setport1unit-statisticsenable清除原端口1數(shù)據(jù)包統(tǒng)計(jì)，NJ-A-CFDS-Z2826S_2(1#7F)(cfg)#clearport1statistics，再多次查看端口狀態(tài)NJ-A-CFDS-Z2826S_2(1#7F)(cfg)#shport1statisticsPortId:1PortName:ReceivedFrames:2377ReceivedBytes:174972ReceivedFrames:2377ReceivedBytes:174972CrcError :0InMACRcvErr :0Fragments :0Frames64Bytes :4Frames128_255Bytes:2Frames512_1023Bytes:0ReceivedBroadcastFrames:0ReceivedMulticastFrames:0InPause :0Jabber :0UndersizeFrames:0Frames65_127Bytes:2371Frames256_511Bytes :0Frames1024_UpBytes :0OversizeFramesSendUnicastFrames:4293SendBytes:6461573SendNoneUnicastFrames:6SendUnicastFrames:4293SendBytes:6461573SendNoneUnicastFrames:6SendFrames:4299SendBroadcastFrames:4SendBroadcastFrames:4SendMulticastFrames:2SendSingleCollision:0SendSingleCollision:0SendMultiCollisionSendLateCollisionSendExcessCollisionSendLateCollisionSendExcessCollisionSendCollisionSendDefferTransSendCollisionSendDefferTransOutPause可以發(fā)現(xiàn)用戶端口“CrcError”一直為“0”，此時(shí)用戶上網(wǎng)才是正常的?？偨Y(jié)，只要2826端口有“CrcError”錯(cuò)誤，一定要進(jìn)行排查，直到“CrcError”錯(cuò)誤為“0”2?華為二層交換機(jī)端口錯(cuò)包排查方法，以S2403H-EI為例進(jìn)行說明①交換機(jī)端口原來配置[S2403EI]discuinteth0/1interfaceEthernet0/1descriptionto_101speed10duplexfullbroadcast-suppression5mac-addressmax-mac-count1portaccessvlan456交換機(jī)端口原來數(shù)據(jù)包統(tǒng)計(jì)[S2403EI-2]disinteth0/1Ethernet0/1currentstate:UPIPSendingFrames'FormatisPKTFMT_ETHNT_2,Hardwareaddressis000f-e22a-45fcDescription:to_101TheMaximumTransmitUnitis1500Mediatypeistwistedpair,loopbacknotsetPorthardwaretypeis100_BASE_TX10Mbps-speedmode,full-duplexmodeLinkspeedtypeisforcelink,linkduplextypeisautonegotiationFlow-controlisnotenabledPort-flow-constrainhasnotbeenconfiguredcompletelyTheMaximumFrameLengthis1518BroadcastMAX-ratio:5%PVID:456Mditype:normalMAXmac-addresslearningcount:1Portlink-type:accessTaggedVLANID:noneUntaggedVLANID:456Last300secondsinput:29packets/sec5729bytes/secLast300secondsoutput:22packets/sec3705bytes/secInput(total):33659824packets,8999990068bytes16038broadcasts,175multicastsInput(normal):33659823packets,-bytes16038broadcasts,175multicastsInput:1102inputerrors,0runts,0giants,-throttles,112CRC0frame,-overruns,0aborts,2637ignored,-parityerrorsOutput(total):36569492packets,bytes1404710broadcasts,5025215multicasts,0pausesOutput(normal):36569492packets,-bytes1404710broadcasts,5025215multicasts,-pausesOutput:0outputerrors,-underruns,-bufferfailures19947aborts,0deferred,0collisions,0latecollisions-lostcarrier,-nocarrier端口有1102個(gè)“inputerrors”，說明端口匹配有問題，需要進(jìn)行排查。③更改端口匹配模式，改成端口指定10M,duplex自適應(yīng)duplexauto更改后端口配置interfaceEthernet0/1descriptionto_101speed10broadcast-suppression5mac-addressmax-mac-count1portaccessvlan456④清除原端口1數(shù)據(jù)包統(tǒng)計(jì)，再多次查看端口狀態(tài)，需要從“#”模式退到“>”模式[S2403EI]quit<S2403EI>resetcountersinteth0/1[S2403EI]disinteth0/1Ethernet0/1currentstate:UPIPSendingFrames'FormatisPKTFMT_ETHNT_2,Hardwareaddressis000f-e22a-45fcDescription:to_101TheMaximumTransmitUnitis1500Mediatypeistwistedpair,loopbacknotsetPorthardwaretypeis100_BASE_TX10Mbps-speedmode,full-duplexmodeLinkspeedtypeisforcelink,linkduplextypeisautonegotiationFlow-controlisnotenabledPort-flow-constrainhasnotbeenconfiguredcompletelyTheMaximumFrameLengthis1518BroadcastMAX-ratio:5%PVID:456Mditype:normalMAXmac-addresslearningcount:1Portlink-type:accessTaggedVLANID:noneUntaggedVLANID:456Last300secondsinput:28packets/sec5804bytes/secLast300secondsoutput:27packets/sec4880bytes/secInput(total):33672483packets,9002467028bytes16038broadcasts,175multicastsInput(normal):33672482packets,-bytes16038broadcasts,175multicastsInput:0inputerrors,0runts,0giants,-throttles,0CRC0frame,-overruns,0aborts,0ignored,-parityerrorsOutput(total):36580860packets,bytes1404792broadcasts,5025466multicasts,0pausesOutput(normal):36580860packets,-bytes1404792broadcasts,5025466multicasts,-pausesOutput:0outputerrors,-underruns,-bufferfailures0aborts,0deferred,0collisions,0latecollisions-lostcarrier,-nocarrier如果再多次查看端口狀態(tài)，看到“inputerrors”為“0”，此時(shí)用戶上網(wǎng)速度才正常。3.CISCO二層交換機(jī)端口錯(cuò)包排查方法，以C2950為例進(jìn)行說明①交換機(jī)端口原來配置2950#shruintfa0/3interfaceFastEthernet0/3descriptiontestswitchportaccessvlan100noipaddressduplexfullspeed100end②交換機(jī)端口原來數(shù)據(jù)包統(tǒng)計(jì),2950#shintfa0/3FastEthernet0/3isup,lineprotocolisup(connected)HardwareisFastEthernet,addressis000d.bd98.1c43(bia000d.bd98.1c43)Description:testMTU1500bytes,BW100000Kbit,DLY1000usec,reliability255/255,txload1/255,rxload1/255EncapsulationARPA,loopbacknotsetKeepaliveset(10sec)Full-duplex,100Mb/sinputflow-controlisoff,outputflow-controlisoffARPtype:ARPA,ARPTimeout04:00:00Lastinputnever,output00:00:01,outputhangneverLastclearingof"showinterface"counters21w6dInputqueue:0/75/0/0(size/max/drops/flushes);Totaloutputdrops:0Queueingstrategy:fifoOutputqueue:0/40(size/max)5minuteinputrate0bits/sec,0packets/sec5minuteouxtputrate0bits/sec,0packets/sec330574221packetsinput,78353246bytes,0nobufferReceived372broadcasts,0runts,0giants,0throttles3540inputerrors,3540CRC,0frame,0overrun,0ignored0watchdog,0multicast,0pauseinput0inputpacketswithdribbleconditiondetected307917156packetsoutput,176359999bytes,0underruns0outputerrors,0collisions,0interfaceresets0babbles,0latecollision,0deferred0lostcarrier,0nocarrier,0PAUSEoutput0outputbufferfailures,0outputbuffersswappedout端口有3540個(gè)“inputerrors”，說明端口匹配有問題，需要進(jìn)行排查。更改端口匹配模式，改成端口雙工狀態(tài)duplex自適應(yīng)duplexauto更改后端口配置2950#shruintfa0/3interfaceFastEthernet0/3descriptiontestswitchportaccessvlan100noipaddressspeed100end清除原端口1數(shù)據(jù)包統(tǒng)計(jì)，再多次查看端口狀態(tài)2950#clearcountersfa0/3Clear"showinterface"countersonthisinterface[confirm][回車確認(rèn)]sw4-idc#shintfa0/3FastEthernet0/3isup,lineprotocolisup(connected)HardwareisFastEthernet,addressis000d.bd98.1c43(bia000d.bd98.1c43)Description:HeHai-SyslogServer-218.104.84.114_5#B03MTU1500bytes,BW100000Kbit,DLY1000usec,reliability255/255,txload1/255,rxload1/255EncapsulationARPA,loopbacknotsetKeepaliveset(10sec)Full-duplex,100Mb/sinputflow-controlisoff,outputflow-controlisoffARPtype:ARPA,ARPTimeout04:00:00Lastinputnever,output00:00:01,outputhangneverLastclearingof"showinterface"counters00:01:40

Inputqueue:0/75/0/0(size/max/drops/flushes);Totaloutputdrops:0Queueingstrategy:fifoOutputqueue:0/40(size/max)5minuteinputrate0bits/sec,0packets/sec5minuteoutputrate105000bits/sec,1packets/sec4278packetsinput,3722881bytes,0nobuffer