交换机端口错包排查方法

1、一、重要性：从网维排查的用户反应网速慢的故障中，相当一部分是山于交换机和交换机端 口、交换机端口和用户路山器端口、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-1dis int eth 0/1Ethernet0/1 current state : UPIP Sen ding Frames Format is PKTFMT_ETHNT_2, Ha

2、rdware address is 000f-e21d-bedcDescription: to gujiao_33-192.168.86.161The Maximum Transmit Unit is 1500Media type is twisted pair, loopback not setPort hardware type is 100_BASE_TX100Mbps-speed mode, full-duplex modeLink speed type is force link，link duplex type is force linkFlow-control is not en

3、abledPort-flow-constrain has not been configured completelyThe Maximum Frame Length is 1536Broadcast MAX-ratio: 100%PVID: 10Mdi type: autoPort link-type: hybridTagged VLAN ID : , 99Untagged VLAN ID : , 10, 458Last 300 sec onds in put: 0 packets/sec 11 bytes/secLast 300 sec onds output: 7 packets/sec

4、 520 bytes/secInput(total): 11864483 packets, 6684922188 bytes66707 broadcasts, 9522 multicastslnput(normal): packets, bytes broadcasts, multicastsInput: 0 in put errors, 0 runts, 0 giants, throttles, 0 CRC0 frame, overruns，0 aborts, 0 ignored, parity errorsOutput(total): 12008069 packets, 517827545

5、7 bytes3638352 broadcasts, 288120 multicasts, 0 pausesOutputfnormal): packets, bytes broadcasts, multicasts, - pausesOutput: 0 output errors, underruns, buffer failures0 aborts, 0 deferred, 0 collisions, 0 late collisions0 lost carrier, no carrier如上红字所示：输入错误数，input errors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

6、增加其它参数，或减少不能实现的参数。1. Runts: discarded packets that are smaller than the mediums minimum packet size.（Receive Byte Count 64 and NOT CRC Erroror Receive Byte Count 1518 and NOT CRC Erroror Receive Byte Count 1522 and Tag Packet and NOT CRC Error,没有vlan tag,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vlan tag

7、,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。）3. Throttles: discarded packets that are in complete frames.（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H前不具备这个功能，一般应该显示为不支 持。）4. CRC: discarded packets with checksum error.（Receive Packet CRC error,帧长度在正常范圉（不带tag,长度在64到1518 之间，或带tag,长度在64到1522之间），

8、而且CRC校验错，如果支持此项， 则不支持奇偶校验错误项。）5. Frame: discarded packets with frame pad/sequence/alignment error, out of frame etc.（不是整数字节，而是多17bit,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。）6.0verrun: the receiver hardware is unable to hand receiveddata to a hardware buffer because the in put rate exceeds the receiversa

9、bility to handle the data.（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，讣入此 项。）7. Aborts: Input abnormal frames that are discarded.（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.lg no red: packets t hat are discarded because the in terface hardware

10、 does not have eno ugh in ter nal buffers.（Packetignored,山于接口内部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，山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岀，计入此 项，上传到CPU的帧，曲于CPU处理能力限制，toCPU的缓存满，导致被丢弃, 也计入此项。）9.Parity: Frames with parity error（Receive Packet parity er

11、ror,如果支持此项，则不支持CRC错误项。）输入丢弃数/输入错误数，output errors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。1Underruns: There are no data in the output queue（Transmit under run,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。）2. Buffer failures: Hardware does not have eno ugh in

12、ter nal buffers （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，山 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Input IgnoredError,只有从CPU发出的帧，山于内部缓存满，导致帧丢弃，计入此项。）3. Aborts: Output abnormal frames that are discarded（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，产品认为有必要统讣的错误，例如添加前导码异常的帧, 也计入此项）4.

13、Deferred: The packets could not be sent out for collision under half-duplex mode （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。）5. Collisions: Statistic of collision detection under half-duplex mode.（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。）6丄ate collisions: Statistic of collision with GE port send

14、ingpackets less than 512 bytes and 10/1 OOM port less than 64 bytes.（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。）7. Lost carrier: Statistic of losing the carrier.（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。）8. No carrier: Statistic of no carrier.（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

15、数加一，对于交换机，通常是由于线路中断造成。）如果“input errors”和“output errors”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，cisc。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,show runset port 1 description To_702set port 1 auto disableset port 1 speed 10set port 1 pvid

16、541set port 1 macaddress on 1set port 1 unit-statistics enable 交换机端口原来数据包统计NJ-A-CFDS-Z2826S_2(1#7F)(cfg)#sh port 1 statisticsPortld: 1 PortName:ReceivedFramesReceived Bytes CrcError InMACRcvErr Fragme nts Frames64Bytes:128998658 ReceivedBroadcastFrames: 1815:741746864 ReceivedMulticastFrames: 0:4934

17、296 InPause: 0:0Jabber: 2:6447228 UndersizeFrames : 0Frames128_255Bytes : 7180773Frames512_1023Bytes : 4738336OversizeFrames : 0Frames256_511 Bytes: 2203985Framesl 024_UpBytes: 29192629SendllnicastFrames : 127249246 SendNonellnicastFrames: 1892514 SendBroadcastFrames : 1035165Sen d BytesSen dFrames:

18、4270894316:129141760SendMulticastFrames : 857349SendSingleCollision : 0SendLateCollision : 0SendCollision: 0OutPause: 0SendMultiCollision: 0SendExcessCollision : 0SendDefferTrans: 0:1232457 Frames65_127Bytes : 84450478可以看到端口有大量“CrcErr。严错包，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

19、宣告10Mset port 1 auto enableset port 1 speedadvertise speedlO fullDuplex更改后端口配置set port 1 description To_702set port 1 pvid 541set port 1 speedadvertise speedlO FullDuplexset port 1 macaddress on 1set port 1 unit-statistics enable 清除原端口 1 数据包统计，NJ-A-CFDS-Z2826S_2(1#7F)(cfg)#clear port 1 statistics,再多

20、次查看端口状态NJACFDSZ2826S_2(1#7F)(cfg)#sh port 1 statisticsPortld: 1 PortName:ReceivedFrames : 2377 ReceivedBroadcastFrames: 0Received Bytes: 174972ReceivedMulticastFrames: 0CrcError: 0In Pause: 0InMACRcvErr : 0 Fragments: 0Frames64Bytes : 4 Framesl28_255Bytes: 2Frames512_1023Bytes : 0 OversizeFrames : 0

21、 SendUnicastFrames : 4293 SendNonellnicastFrames: 6 SendBroadcastFrames : 4 SendSingleCollision : 0 SendLateCollision : 0 SendCollision: 0OutPause: 0Jabber: 0UndersizeFrames: 0Frames65_127Bytes : 2371Frames256_511 Bytes: 0Framesl 024_UpBytes: 0SendBytes: 6461573SendFrames: 4299SendMulticastFrames :

22、2SendMultiCollision: 0SendExcessCollision : 0Sen dDefferTra ns可以发现用户端口CrcError一直为“OS此时用户上网才是正常的。总结，只要2826端口有“CrcErro严错误，一定要进行排查，直到“CrcErro严 错误为“0”O2. 华为二层交换机端口错包排查方法，以S2403H-EI为例进行说明 交换机端口原来配置S2403EIdis cu int eth 0/1interface Ethernet0/1description to_101speed 10duplex fullbroadcast-suppression 5ma

23、c-address maxmac-count 1port access vlan 456 交换机端口原来数据包统讣S2403EI-2dis int eth 0/1Ethernet0/1 current state : UPIP Sending Frames Format is PKTFMT_ETHNT_2, Hardware address is 000f-e22a-45fcDescription: to_101The Maximum Transmit Unit is 1500Media type is twisted pair, loopback not setPort hardware t

24、ype is 100_BASE_TX10Mbps-speed mode, full-duplex modeLink speed type is force link，link duplex type is autonegotiationFlow-control is not enabledPort-flow-c on strai n has not bee n con figured completelyThe Maximum Frame Length is 1518Broadcast MAX-ratio: 5%PVID: 456Mdi type: normalMAX mao address

25、Lear ning count: 1Port link-type: accessTagged VLAN ID : noneUntagged VLAN ID : 456Last 300 sec onds in put: 29 packets/sec 5729 bytes/secLast 300 seconds output: 22 packets/sec 3705 bytes/secInput(total): 33659824 packets, 8999990068 bytes16038 broadcasts, 175 multicastsIn put (n ormal): 33659823 p

26、ackets, bytes16038 broadcasts, 175 multicastsInput: 1102 input errors, 0 runts, 0 giants, throttles, 112 CRC0 frame, overruns，0 aborts, 2637 ignored， parity errorsOutput(total): 36569492 packets, bytes1404710 broadcasts, 5025215 multicasts, 0 pausesOutput(normal): 36569492 packets, bytes1404710 broa

27、dcasts, 5025215 multicasts, pausesOutput: 0 output errors, underruns, buffer failures19947 aborts, 0 deferred, 0 collisions, 0 late collisions lost carrier, no carrier端口有1102个“input errors”，说明端口匹配有问题，需要进行排查。 更改端口匹配模式，改成端口指定10M, duplex自适应duplex auto更改后端口配置interface Ethernet0/1description to_101speed

28、10broadcast-suppression 5mac-address maxmac-count 1port access vlan 456 清除原端口 1数据包统汁，再多次查看端口状态，需要从“#”模式退到“”模 式S2403EIquit reset counters int eth 0/1S2403EIdis int eth 0/1Ethernet0/1 current state : UPIP Sending Frames Format is PKTFMT_ETHNT_2, Hardware address is000f-e22a-45fcDescription: to_101The

29、Maximum Transmit Unit is 1500Media type is twisted pair, loopback not setPort hardware type is 100_BASE_TX10Mbps-speed mode, full-duplex modeLink speed type is force link, link duplex type is autonegotiation Flow-control is not enabledPort-flow-constrain has not been configured completelyThe Maximum

30、 Frame Length is 1518Broadcast MAX-ratio: 5%PVID: 456Mdi type: normalMAX macaddress Learning count: 1Port link-type: accessTagged VLAN ID : noneUntagged VLAN ID : 456Last 300 sec onds in put: 28 packets/sec 5804 bytes/secLast 300 sec onds output: 27 packets/sec 4880 bytes/secInput(total): 33672483 p

31、ackets, 9002467028 bytes16038 broadcasts, 175 multicastsInput(normal): 33672482 packets, bytes16038 broadcasts, 175 multicastsIn put: 0 in put errors, 0 run ts, 0 gian ts, throttles, 0 CRC0 frame, - overruns，0 aborts, 0 ignored, parity errors Output(total): 36580860 packets, bytes1404792 broadcasts,

32、 5025466 multicasts, 0 pausesOutput(normal): 36580860 packets, bytes1404792 broadcasts, 5025466 multicasts, pausesOutput: 0 output errors, underruns, buffer failures0 aborts, 0 deferred, 0 collisions, 0 late collisions lost carrier, no carrier如果再多次查看端口状态，看到“input errors为“0”，此时用户上网速度才正常。3. CISCO二层交换机

33、端口错包排查方法，以C2950为例进行说明 交换机端口原来配置2950#sh ru int fa0/3interface FastEthernet0/3description testswitchport access vlan 100no ip addressduplex fullspeed 100end 交换机端口原来数据包统汁，2950#sh intfa0/3FastEthernet0/3 is up，line protocol is up (connected)Hardware is Fast Ethernet, address is 000d.bd98.1c43 (bia 000d.

34、bd9&1c43) Description: testMTU 1500 bytes, BW 100000 Kbit, DLY 1000 usee,reliability 255/255, txload 1/255, rxload 1/255Encapsulation ARPA, loopback not setKeepalive set (10 sec)Full-duplex, 100Mb/sin put flow-c ontrol is off, output flow-c on trol is offARP type: ARPA, ARP Timeout 04:00:00Last in p

35、ut n ever, output 00:00:01, output hang n everLast clean ng of show interface counters 21w6dIn put queue: 0/75/0/0 (size/max/drops/f lushes); Total output drops: 0 Queueing strategy: fifoOutput queue :0/40 (size/max)5 minute in put rate 0 bits/sec, 0 packets/sec5 minute ouxtput rate 0 bits/sec, 0 pa

36、ckets/sec330574221 packets input, 78353246 bytes, 0 no buffer Received 372 broadcasts, 0 runts, 0 giants, 0 throttles 3540 input errors, 3540 CRC, 0 frame, 0 overrun, 0 ignored 0 watchdog, 0 multicast, 0 pause in put0 in put packets with dribble condition detected307917156 packets output, 176359999

37、bytes, 0 underruns0 output errors, 0 collisions，0 interface resets0 babbles, 0 late collision，0 deferred0 lost carrier, 0 no carrier, 0 PAUSE output0 output buffer failures, 0 output buffers swapped out端口有3540个“input errors”，说明端口匹配有问鼠 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duplex auto更改后端口配置2950#sh ru in

38、t fa0/3interface FastEthernet0/3description test switchport access vlan 100 no ip address speed 100 end 清除原端口1数据包统计，再多次查看端口状态2950#clear counters fa0/3Clear show interface counters on this interface confirm回车确认 sw4-idc#sh int faO/3FastEthernet0/3 is up； line protocol is up (connected)Hardware is Fast

39、 Ethernet, address is 000d.bd98.1c43 (bia 000d.bd98.1c43) Description: HeHai-SyslogServer-218.104.84.114_5#B03MTU 1500 bytes, BW 100000 Kbit, DLY 1000 usee,reliability 255/255, txload 1/255, rxload 1/255Encapsulation ARPA, loopback not setKeepalive set (10 sec)Full-duplex, 100Mb/sin put flow-c on tr

40、ol is off, output flow-c on trol is offARP type: ARPA, ARP Timeout 04:00:00Last in put n ever, output 00:00:01, output hang n everLast clearing of show interface counters 00:01:40In put queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0Queueing strategy: fifoOutput queue :0/40 (size/max)5 minute in put rate 0 bits/sec, 0 packets/sec5 minute output rate 105000 bits/sec, 1