交換機(jī)端口錯(cuò)包排查方法

1、.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-1dis int eth 0/1 Ethernet0/1 current state : UP IP Sending Frames Format is PKTFMT_ETHNT_2,

2、Hardware address is 000f-e21d-bedc Description: to gujiao_33-192.168.86.161 The Maximum Transmit Unit is 1500 Media type is twisted pair, loopback not set Port hardware type is 100_BASE_TX 100Mbps-speed mode, full-duplex mode Link speed type is force link, link duplex type is force link Flow-control

3、 is not enabled Port-flow-constrain has not been configured completely The Maximum Frame Length is 1536 Broadcast MAX-ratio: 100% PVID: 10 Mdi type: auto Port link-type: hybrid Tagged VLAN ID : , 99 Untagged VLAN ID : , 10, 458 Last 300 seconds input:0 packets/sec 11 bytes/sec Last 300 seconds outpu

4、t:7 packets/sec 520 bytes/sec Input(total):11864483 packets, 6684922188 bytes 66707 broadcasts, 9522 multicasts Input(normal):- packets, - bytes - broadcasts, - multicasts Input:0 input errors, 0 runts, 0 giants,- throttles, 0 CRC 0 frame,- overruns, 0 aborts, 0 ignored, - parity errors Output(total

5、): 12008069 packets, 5178275457 bytes 3638352 broadcasts, 288120 multicasts, 0 pauses Output(normal): - packets, - bytes - broadcasts, - multicasts, - pauses Output: 0 output errors,- underruns, - buffer failures 0 aborts, 0 deferred, 0 collisions, 0 late collisions 0 lost carrier, - no carrier 如上紅字

6、所示： 輸入錯(cuò)誤數(shù)，input errors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)。 1.Runts: discarded packets that are smaller than the mediums minimum packet size. ( Receive Byte Count 64 and NOT CRC Error orReceive Byte Count 1518 and NOT CRC Error orReceive Byte Count 1522 and Tag Packet and NOT CRC Error， 沒有vl

7、an tag，數(shù)據(jù)段大于1518字節(jié)，小于最大幀長(zhǎng)度，而且沒有CRC校驗(yàn)錯(cuò)誤的幀，和有vlan tag，數(shù)據(jù)段大于1522字節(jié)，小于最大幀長(zhǎng)度，而且沒有CRC校驗(yàn)錯(cuò)誤的幀。) 3.Throttles: discarded packets that are incomplete frames. ( 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。) 4.CRC: discarded packets with checksum error. ( Receive Packet CRC err

8、or，幀長(zhǎng)度在正常范圍（不帶tag，長(zhǎng)度在64到1518之間，或帶tag，長(zhǎng)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)。) 5.Frame: discarded packets with frame pad/sequence/alignment error, out of frame etc. （不是整數(shù)字節(jié)，而是多17bit，因此不對(duì)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: the receiver hardware is unable to hand receiveddata to a hardware bu

9、ffer because the input rate exceeds the receiversability to handle the data. （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(duì)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: Input abnormal frames that are discarded. ( 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: packets tha

10、t are discarded because the interface hardware does not have enough internal buffers. ( 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: Frames w

11、ith parity error. ( Receive Packet parity error,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)，output errors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)。 1.Underruns: There are no data in the output queue. ( Transmit under run，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。) 2.B

12、uffer failures: Hardware does not have enough internal buffers. (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(duì)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 Input IgnoredError，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)。) 3.Aborts: Output abnormal frames that are discarded. （ 在半雙工模式下，由于沖突檢測(cè)，延遲發(fā)送超過15次的幀，被丟棄

13、，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)） 4.Deferred: The packets could not be sent out for collision under half-duplex mode. ( 半雙工模式下，由于檢測(cè)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。) 5.Collisions: Statistic of collision detection under half-duplex mode. ( 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(cè)到?jīng)_突，當(dāng)時(shí)沒有發(fā)出的包。) 6.Late

14、collisions: Statistic of collision with GE port sendingpackets less than 512 bytes and 10/100M port less than 64 bytes. ( 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(cè)到?jīng)_突，當(dāng)時(shí)沒有發(fā)出的包。) 7.Lost carrier: Statistic of losing the carrier. （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(duì)于交換機(jī)，通常是由于線路中斷造成。） 8.No carrier: Statistic

15、 of no carrier. （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(duì)于交換機(jī)，通常是由于線路中斷造成。） 如果“input errors”和“output errors”非“0”并且數(shù)字在增長(zhǎng)，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,show run set port 1 description To_702 s

16、et port 1 auto disable set port 1 speed 10 set port 1 pvid 541 set port 1 macaddress on 1 set port 1 unit-statistics enable 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)#sh port 1 statistics PortId: 1 PortName: ReceivedFrames : 128998658 ReceivedBroadcastFrames: 1815 ReceivedBytes: 741746864 ReceivedMu

17、lticastFrames: 0 CrcError : 4934296 InPause: 0 InMACRcvErr: 0 Jabber : 2 Fragments: 6447228 UndersizeFrames: 0 Frames64Bytes: 1232457 Frames65_127Bytes: 84450478 Frames128_255Bytes : 7180773 Frames256_511Bytes : 2203985 Frames512_1023Bytes: 4738336 Frames1024_UpBytes : 29192629 OversizeFrames : 0 Se

18、ndUnicastFrames: 127249246 SendBytes: 4270894316 SendNoneUnicastFrames: 1892514 SendFrames : 129141760 SendBroadcastFrames: 1035165 SendMulticastFrames: 857349 SendSingleCollision: 0 SendMultiCollision : 0 SendLateCollision: 0 SendExcessCollision: 0 SendCollision: 0 SendDefferTrans: 0 OutPause : 0 可

19、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(zhǎng)，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10M set port 1 auto enable set port 1 speedadvertise speed10 fullDuplex 更改后端口配置 set port 1 description To_702 set port 1 pvid 541 set port 1 speedadvertise speed10 FullDuplex set port 1 macaddress on 1 set port 1 unit

20、-statistics enable 清除原端口1數(shù)據(jù)包統(tǒng)計(jì)，NJ-A-CFDS-Z2826S_2(1#7F)(cfg)#clear port 1 statistics ，再多次查看端口狀態(tài) NJ-A-CFDS-Z2826S_2(1#7F)(cfg)#sh port 1 statistics PortId: 1 PortName: ReceivedFrames : 2377ReceivedBroadcastFrames: 0 ReceivedBytes: 174972ReceivedMulticastFrames: 0 CrcError : 0 InPause: 0 InMACRcvErr:

21、0 Jabber : 0 Fragments: 0 UndersizeFrames: 0 Frames64Bytes: 4 Frames65_127Bytes: 2371 Frames128_255Bytes : 2 Frames256_511Bytes : 0 Frames512_1023Bytes: 0 Frames1024_UpBytes : 0 OversizeFrames : 0 SendUnicastFrames: 4293SendBytes: 6461573 SendNoneUnicastFrames: 6 SendFrames : 4299 SendBroadcastFrame

22、s: 4 SendMulticastFrames: 2 SendSingleCollision: 0 SendMultiCollision : 0 SendLateCollision: 0 SendExcessCollision: 0 SendCollision: 0 SendDefferTrans: 0 OutPause : 0 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。 總結(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 交換機(jī)端口原來

23、配置 S2403EIdis cu int eth 0/1 interface Ethernet0/1 description to_101 speed 10 duplex full broadcast-suppression 5 mac-address max-mac-count 1 port access vlan 456 交換機(jī)端口原來數(shù)據(jù)包統(tǒng)計(jì) S2403EI-2dis int eth 0/1 Ethernet0/1 current state : UP IP Sending Frames Format is PKTFMT_ETHNT_2, Hardware address is 000

24、f-e22a-45fc Description: to_101 The Maximum Transmit Unit is 1500 Media type is twisted pair, loopback not set Port hardware type is 100_BASE_TX 10Mbps-speed mode, full-duplex mode Link speed type is force link, link duplex type is autonegotiation Flow-control is not enabled Port-flow-constrain has

25、not been configured completely The Maximum Frame Length is 1518 Broadcast MAX-ratio: 5% PVID: 456 Mdi type: normal MAX mac-address learning count: 1 Port link-type: access Tagged VLAN ID : none Untagged VLAN ID : 456 Last 300 seconds input:29 packets/sec 5729 bytes/sec Last 300 seconds output:22 pac

26、kets/sec 3705 bytes/sec Input(total):33659824 packets, 8999990068 bytes 16038 broadcasts, 175 multicasts Input(normal):33659823 packets, - bytes 16038 broadcasts, 175 multicasts Input:1102 input errors, 0 runts, 0 giants,- throttles, 112 CRC 0 frame,- overruns, 0 aborts, 2637 ignored, - parity error

27、s Output(total): 36569492 packets, 12321086583 bytes 1404710 broadcasts, 5025215 multicasts, 0 pauses Output(normal): 36569492 packets, - bytes 1404710 broadcasts, 5025215 multicasts, - pauses Output: 0 output errors,- underruns, - buffer failures 19947 aborts, 0 deferred, 0 collisions, 0 late colli

28、sions - lost carrier, - no carrier 端口有1102個(gè)“input errors”，說明端口匹配有問題，需要進(jìn)行排查。 更改端口匹配模式，改成端口指定10M，duplex自適應(yīng) duplex auto 更改后端口配置 interface Ethernet0/1 description to_101 speed 10 broadcast-suppression 5 mac-address max-mac-count 1 port access vlan 456 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 S2403EIquit res

29、et counters int eth 0/1 S2403EIdis int eth 0/1 Ethernet0/1 current state : UP IP Sending Frames Format is PKTFMT_ETHNT_2, Hardware address is 000f-e22a-45fc Description: to_101 The Maximum Transmit Unit is 1500 Media type is twisted pair, loopback not set Port hardware type is 100_BASE_TX 10Mbps-spe

30、ed mode, full-duplex mode Link speed type is force link, link duplex type is autonegotiation Flow-control is not enabled Port-flow-constrain has not been configured completely The Maximum Frame Length is 1518 Broadcast MAX-ratio: 5% PVID: 456 Mdi type: normal MAX mac-address learning count: 1 Port l

31、ink-type: access Tagged VLAN ID : none Untagged VLAN ID : 456 Last 300 seconds input:28 packets/sec 5804 bytes/sec Last 300 seconds output:27 packets/sec 4880 bytes/sec Input(total):33672483 packets, 9002467028 bytes 16038 broadcasts, 175 multicasts Input(normal):33672482 packets, - bytes 16038 broa

32、dcasts, 175 multicasts Input:0 input errors, 0 runts, 0 giants,- throttles, 0 CRC 0 frame,- overruns, 0 aborts, 0 ignored, - parity errors Output(total): 36580860 packets, 12322962080 bytes 1404792 broadcasts, 5025466 multicasts, 0 pauses Output(normal): 36580860 packets, - bytes 1404792 broadcasts,

33、 5025466 multicasts, - pauses Output: 0 output errors,- underruns, - buffer failures 0 aborts, 0 deferred, 0 collisions, 0 late collisions - lost carrier, - no carrier 如果再多次查看端口狀態(tài)，看到“input errors”為“0”，此時(shí)用戶上網(wǎng)速度才正常。 3CISCO二層交換機(jī)端口錯(cuò)包排查方法，以C2950為例進(jìn)行說明 交換機(jī)端口原來配置 2950#sh ru int fa0/3 interface FastEthernet

34、0/3 description test switchport access vlan 100 no ip address duplex full speed 100 end 交換機(jī)端口原來數(shù)據(jù)包統(tǒng)計(jì), 2950#sh int fa0/3 FastEthernet0/3 is up, line protocol is up (connected) Hardware is Fast Ethernet, address is 000d.bd98.1c43 (bia 000d.bd98.1c43) Description: test MTU 1500 bytes, BW 100000 Kbit, D

35、LY 1000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Full-duplex, 100Mb/s input flow-control is off, output flow-control is off ARP type: ARPA, ARP Timeout 04:00:00 Last input never, output 00:00:01, output hang never Last clearing

36、 of show interface counters 21w6d Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue :0/40 (size/max) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute ouxtput rate 0 bits/sec, 0 packets/sec 330574221 packets input, 78353246 bytes, 0 no bu

37、ffer 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 input 0 input packets with dribble condition detected 307917156 packets output, 176359999 bytes, 0 underruns 0 output errors, 0 collisions, 0 inter

38、face resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier, 0 PAUSE output 0 output buffer failures, 0 output buffers swapped out 端口有3540個(gè)“input errors”，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) duplex auto 更改后端口配置 2950#sh ru int fa0/3 interface FastEthernet0/3 description t

39、est switchport access vlan 100 no ip address speed 100 end 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#clear counters fa0/3 Clear show interface counters on this interface confirm 回車確認(rèn) sw4-idc#sh int fa0/3 FastEthernet0/3 is up, line protocol is up (connected) Hardware is Fast Ethernet, address is 000d.bd98.1c43 (bi

40、a 000d.bd98.1c43) Description: HeHai-SyslogServer-218.104.84.114_5#B03 MTU 1500 bytes, BW 100000 Kbit, DLY 1000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Full-duplex, 100Mb/s input flow-control is off, output flow-control is off

41、 ARP type: ARPA, ARP Timeout 04:00:00 Last input never, output 00:00:01, output hang never Last clearing of show interface counters 00:01:40 Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue :0/40 (size/max) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 105000 bits/se