??在IP網(wǎng)絡(luò)中，光纖鏈路出現(xiàn)故障是經(jīng)常出現(xiàn)的事情，光纖鏈路中間經(jīng)過ODF、傳輸設(shè)備等多個節(jié)點(diǎn)，所以需要掌握診斷、定位故障位置的方法，一般就是采用在光纖鏈路的不同節(jié)點(diǎn)上，向端點(diǎn)設(shè)備打環(huán)，通過在端點(diǎn)設(shè)備上查看打環(huán)效果，來確認(rèn)打環(huán)是否成功，如果打環(huán)成功，說明端點(diǎn)設(shè)備到打環(huán)節(jié)點(diǎn)之間的光路是正常。
??下面以cisco路由器為例，說明cisco路由器上使用哪些指令
一、查看收發(fā)光功率
??查看端口的收發(fā)光功率是否正常？如下，通過命令可以看到端口的發(fā)光功率為-5.9dBm，發(fā)光功率為-7.1dBm，都在正常范圍內(nèi)，沒有超過正常閾值；收發(fā)光功率在正常范圍內(nèi)，是打環(huán)測試的首要觀察對象，如果收光功率太低，則要在不同節(jié)點(diǎn)上打環(huán)，確認(rèn)哪個節(jié)點(diǎn)開始收光功率開始異常，來定位故障點(diǎn)；
C7609#show interface gigabitEthernet 1/11 transceiver detail
Transceiver monitoring is disabled for all interfaces.
ITU Channel not available (Wavelength not available),
Transceiver is internally calibrated.
mA: milliamperes, dBm: decibels (milliwatts), NA or N/A: not applicable.
++ : high alarm, + : high warning, - : low warning, -- : low alarm.
A2D readouts (if they differ), are reported in parentheses.
The threshold values are calibrated.
High Alarm High Warn Low Warn Low Alarm
Temperature Threshold Threshold Threshold Threshold
Port (Celsius) (Celsius) (Celsius) (Celsius) (Celsius)
--------- ----------------- ---------- --------- --------- ---------
Gi1/6 26.3 89.0 85.0 -5.0 -9.0
High Alarm High Warn Low Warn Low Alarm
Voltage Threshold Threshold Threshold Threshold
Port (Volts) (Volts) (Volts) (Volts) (Volts)
--------- ----------------- ---------- --------- --------- ---------
Gi1/6 3.32 3.59 3.50 3.09 3.00
High Alarm High Warn Low Warn Low Alarm
Current Threshold Threshold Threshold Threshold
Port (milliamperes) (mA) (mA) (mA) (mA)
--------- ----------------- ---------- --------- --------- ---------
Gi1/6 13.1 N/A N/A N/A N/A
Optical High Alarm High Warn Low Warn Low Alarm
Transmit Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
--------- ----------------- ---------- --------- --------- ---------
Gi1/6 -7.1 0.9 -3.0 -9.5 -13.5
Optical High Alarm High Warn Low Warn Low Alarm
Receive Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
--------- ----------------- ---------- --------- --------- ---------
Gi1/6 -5.9 0.9 -3.0 -19.0 -23.0
二、查看端口收發(fā)包數(shù)量
??有些設(shè)備支持在端口狀態(tài)下，直接查看是否檢測到環(huán)路，但有些設(shè)備就不支持，對于不支持的設(shè)備，可以通過觀察端口的收發(fā)包數(shù)量，來確認(rèn)是否正常環(huán)路。
??先完成“硬環(huán)”或“軟環(huán)”操作，“硬環(huán)”即物理上將某個ODF架或設(shè)備側(cè)的收發(fā)兩根尾纖使用法蘭盤連接起來，“軟環(huán)”即傳輸設(shè)備上向端點(diǎn)設(shè)備打環(huán)，完成打環(huán)操作后，就是端點(diǎn)設(shè)備上的操作了。
??首先，要將端口的計數(shù)器清零，使用命令clear counter gigabitEthernet 1/1，將端口各計數(shù)器都先清零。
C7609#clear counters gigabitEthernet 1/11
Clear "show interface" counters on this interface [confirm]y
C7609#show interfaces gigabitEthernet 1/11
GigabitEthernet1/11 is down, line protocol is down (notconnect)
Hardware is C7600 1Gb 802.3, address is c067.af4b.1440 (bia c067.af4b.1440)
Description: S9306_G6/0/0
Internet address is 192.168.87.146/30
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 0/255, rxload 0/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s
input flow-control is off, output flow-control is off
Clock mode is auto
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output never, output hang never
Last clearing of "show interface" counters 00:00:06
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 0 bits/sec, 0 packets/sec
L2 Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes
L3 in Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes mcast
L3 out Switched: ucast: 0 pkt, 0 bytes mcast: 0 pkt, 0 bytes
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
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
C7609#
??其次，正常情況下，設(shè)備會自動發(fā)送一些協(xié)商之類的報文，所以即使不人為手動發(fā)包，此時端口的發(fā)包數(shù)量也會不斷增加，假如打環(huán)正常的話，此時發(fā)包數(shù)量和收包數(shù)量是一致的，說明從打環(huán)位置到端點(diǎn)設(shè)備之間鏈路正常；如果此時收發(fā)包數(shù)量不一致，則說明打環(huán)異常，從打環(huán)的位置到端點(diǎn)設(shè)備之間鏈路有故障，需要將打環(huán)位置，往端點(diǎn)設(shè)備靠近，繼續(xù)打環(huán)測試。
??使用命令show interfaces gigabitEthernet 1/11后，觀察輸出結(jié)果中的下面這兩行；
C7609#show interfaces gigabitEthernet 1/11
xxx packets input, 0 bytes, 0 no buffer
xxx packets output, 0 bytes, 0 underruns
??最后，可以通過人為發(fā)ping包，確認(rèn)打環(huán)效果，本例中端口上配置的IP地址為192.168.87.146/30，而且端口狀態(tài)為up，所以在設(shè)備上向網(wǎng)段192.168.87.146/30其他主機(jī)IP發(fā)送ping包的話，報文會從這個端口發(fā)送出去，用來測試發(fā)出去的報文，是否會經(jīng)過環(huán)路返回。
??通過ping指令發(fā)送ping報文，觀察端口的收發(fā)報文數(shù)量，收報文數(shù)量可能會有一定的延遲，短時間收發(fā)包不一致，可能過幾秒就恢復(fù)一致；如果經(jīng)過ping包測試，端口的收發(fā)包數(shù)量還能保持一致，則說明環(huán)路正常。
C7609#ping 192.168.87.145 repeat 10
Type escape sequence to abort.
Sending 10, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
..........
Success rate is 0 percent (0/10)
C7609#show interfaces gigabitEthernet 1/11
xxx packets input, 0 bytes, 0 no buffer
xxx packets output, 0 bytes, 0 underruns
??以上鏈路打環(huán)診斷方法，絕大多數(shù)網(wǎng)絡(luò)設(shè)備都使用，不需要再為設(shè)備接口無法查看環(huán)回狀態(tài)而苦惱。
