交换机端口错包排查方法

一、重要性：从网维排查的用户反应网速慢的故障中，相当一部分是由于交换机和交换机端口、交换机端口和用户路由器端口、交换机端口和光电转换器端口、交换机端口和用户网卡匹配不当，产生错包引起的。该问题虽然比较常见，但只要按交换机开局来配置，通常能降低故障发生率，即使还存在端口错包问题，也能通过改端口速度和双工状态来彻底解决。二、交换机端口错包说明：以华为交换机端口为例进行说明：[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如上红字所示：输入错误数，inputerrors等于各种重要错误信息的总和。不同的产品可以根据具体情况增加其它参数，或减少不能实现的参数。Runts:discardedpacketsthataresmallerthanthemedium'sminimumpacketsize.（ReceiveByteCount<64andNOTCRCErrororReceiveByteCount<64andTagPacketandNOTCRCError，无论是否有vlantag,数据段小于64字节，而且没有CRC校验错误的帧。）Giants:discardedpacketsthatarelargerthanthemedium'smaximumpacketsize.（ReceiveByteCount>1518andNOTCRCErrororReceiveByteCount>1522andTagPacketandNOTCRCError,没有vlantag，数据段大于1518字节，小于最大帧长度，而且没有CRC校验错误的帧，和有vlantag，数据段大于1522字节，小于最大帧长度，而且没有CRC校验错误的帧。）Throttles:discardedpacketsthatareincompleteframes.（交换机察觉缓存或CPU过载，关闭接口接收器的情形称为throttle，是cisco路由器上的一个概念,我们的交换机目前不具备这个功能,一般应该显示为不支持。）CRC:discardedpacketswithchecksumerror.（ReceivePacketCRCerror,帧长度在正常范围（不带tag,长度在64到1518之间，或带tag，长度在64到1522之间），而且CRC校验错，如果支持此项，则不支持奇偶校验错误项。）Frame:discardedpacketswithframepad/sequence/alignmenterror,outofframeetc.（不是整数字节，而是多1~7bit，因此不对齐，或乱序或空帧，而且CRC校验错误，但是不计入CRC错误。）6.Overrun:thereceiverhardwareisunabletohandreceiveddatatoahardwarebufferbecausetheinputrateexceedsthereceiver'sabilitytohandlethedata.（由于接口输入速率超过接受方处理能力，导致丢包，由于我们的交换机一般是线速转发，这项一般应该为0,只有部分交换机对上传CPU或三层线速转发的帧有接口带宽限制，或是通过ACL实现的带宽限制，因此被丢弃的帧，计入此项。）7.Aborts:Inputabnormalframesthatarediscarded.（除其他错误之外，产品认为有必要统计的错误，例如前导码异常的帧，计入此项。）8.Ignored:packetsthatarediscardedbecausetheinterfacehardwaredoesnothaveenoughinternalbuffers.（Packetignored,由于接口内部buffer满，丢弃的帧，与由于主系统缓存空间缺乏，导致的丢弃帧不同。线速转发的帧，在多接口满带宽输入，单接口输出等情况下,由于输出接口的带宽不足,数据帧将内部缓存占满,导致从接口输入的帧在进入内部缓存之前被丢弃,以及进入内部缓存的帧超时无法输出,计入此项,上传到CPU的帧，由于CPU处理能力限制，toCPU的缓存满，导致被丢弃，也计入此项。）9.Parity:Frameswithparityerror.（ReceivePacketparityerror,如果支持此项，则不支持CRC错误项。）输入丢弃数/输入错误数，outputerrors等于各种重要错误信息的总和。不同的产品可以根据具体情况增加其它参数，或减少不能实现的参数。Underruns:Therearenodataintheoutputqueue.（Transmitunderrun,与Overrun相反，输出接口的缓存从输出队列中取以太网帧时，没有帧，是一种非常少见的硬件异常。有的交换机就没有单独的接口输出缓存，与接口输出队列是同一块缓存。）Bufferfailures:Hardwaredoesnothaveenoughinternalbuffers.（内部缓存满，如果输出队列满，输出的以太网帧将在内部缓存中暂时存储，由于内部缓存满，导致帧丢弃。由于交换机对线速转发的数据帧发生的这种异常，认为只是到达内部缓存而没有到达出接口，是个输入帧，因此计入InputIgnoredError,只有从CPU发出的帧，由于内部缓存满，导致帧丢弃，计入此项。）Aborts:Outputabnormalframesthatarediscarded.（在半双工模式下,由于冲突检测,延迟发送超过15次的帧,被丢弃,计入此项。除其他错误之外,产品认为有必要统计的错误,例如添加前导码异常的帧,也计入此项）Deferred:Thepacketscouldnotbesentoutforcollisionunderhalf-duplexmode.（半双工模式下,由于检测到载波正在被声明,当时没有发出的包,延时一次计数加一。）Collisions:Statisticofcollisiondetectionunderhalf-duplexmode.（半双工模式下,在以太网帧数据部分的前64字节进入线路前,由于检测到冲突,当时没有发出的包。）Latecollisions:StatisticofcollisionwithGEportsendingpacketslessthan512bytesand10/100Mportlessthan64bytes.（半双工模式下，在以太网帧数据部分的前64字节进入线路后，由于检测到冲突，当时没有发出的包。）Lostcarrier:Statisticoflosingthecarrier.（载波丢失，一般适用于串行WAN接口，发送过程中，每丢失一个载波，此计数加一，对于交换机，通常是由于线路中断造成。）Nocarrier:Statisticofnocarrier.（无载波，一般适用于串行WAN接口，当试图发送帧时，如果没有载波出现，此计数加一，对于交换机，通常是由于线路中断造成。）如果“inputerrors”和“outputerrors”非“0"并且数字在增长，通常情况下可能存在端口匹配问题，必须进行端口状态调整。其它厂商，cisco和中兴的二层交换机错包类型相似，可以类推。三、错包问题排查方法下面分别说下中兴、华为和CISCO二层交换机排查常用命令。1中兴交换机端口排查方法，以Z2826S为例进行说明；交换机端口原来配置,showrunsetport1descriptionTo_702setport1autodisablesetport1speed10setport1pvid541setport1macaddresson1

setport1unit-statisticsenable交换机端口原来数据包统计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”错包，并且多次查看端口信息，可以看到错包在增长，该用户当前的上网速度肯定会慢，需要整改

更改端口匹配模式，改成端口自适应，主动宣告10Msetport1autoenablesetport1speedadvertisespeed10fullDuplex更改后端口配置setport1descriptionTo_702setport1pvid541setport1speedadvertisespeed10FullDuplexsetport1macaddresson1setport1unit-statisticsenable清除原端口1数据包统计，NJ-A-CFDS-Z2826S_2(1#7F)(cfg)#clearport1statistics，再多次查看端口状态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可以发现用户端口“CrcError”一直为“0”，此时用户上网才是正常的。总结，只要2826端口有“CrcError”错误，一定要进行排查，直到“CrcError”错误为“0”2•华为二层交换机端口错包排查方法，以S2403H-EI为例进行说明①交换机端口原来配置[S2403EI]discuinteth0/1interfaceEthernet0/1descriptionto_101speed10duplexfullbroadcast-suppression5mac-addressmax-mac-count1portaccessvlan456交换机端口原来数据包统计[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个“inputerrors”，说明端口匹配有问题，需要进行排查。③更改端口匹配模式，改成端口指定10M,duplex自适应duplexauto更改后端口配置interfaceEthernet0/1descriptionto_101speed10broadcast-suppression5mac-addressmax-mac-count1portaccessvlan456④清除原端口1数据包统计，再多次查看端口状态，需要从“#”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状态，看到“inputerrors”为“0”，此时用户上网速度才正常。3.CISCO二层交换机端口错包排查方法，以C2950为例进行说明①交换机端口原来配置2950#shruintfa0/3interfaceFastEthernet0/3descriptiontestswitchportaccessvlan100noipaddressduplexfullspeed100end②交换机端口原来数据包统计,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个“inputerrors”，说明端口匹配有问题，需要进行排查。更改端口匹配模式，改成端口双工状态duplex自适应duplexauto更改后端口配置2950#shruintfa0/3interfaceFastEthernet0/3descriptiontestswitchportaccessvlan100noipaddressspeed100end清除原端口1数据包统计，再多次查看端口状态2950#clearcountersfa0/3Clear"showinterface"countersonthisinterface[confirm][回车确认]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