分类：
2012-08-22 13:45:56
现象：
按照租用电路合同要求，如期为某大客户开通全地区几十条电路，当日全部测试正常，三天后客户投诉全部电路均出现多少不等的丢包现象。
测试方法：
远端和局端各个办公地点，各自安装好配置相同的cisco2811一台，互联端口配置同网段IP地址各一个，从局端登录到配置模式下， 使用扩展PING命令，PING大小为2048k的包1000个。
Router#
Router#show int s0/0/1:0
Serial0/0/1:0 is up, line protocol is up
Hardware is GT96K Serial
Internet address is 1.1.1.1/30
MTU 1500 bytes, BW 2048 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input 00:00:02, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 1536 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
130 packets input, 10324 bytes, 0 no buffer
Received 115 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
138 packets output, 10715 bytes, 0 underruns
0 output errors, 0 collisions, 6 interface resets
0 output buffer failures, 0 output buffers swapped out
2 carrier transitions
Timeslot(s) Used: UNFRAMED, SCC: 1, Transmitter delay is 0 flags
Router#ping ip
Target IP address: 1.1.1.2 //对端地址
Repeat count [5]: 1000 //重复发包次数
Datagram size [100]: 2048 //报文大小
Timeout in seconds [2]:
Extended commands [n]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 1000, 2048-byte ICMP Echos to 1.1.1.2, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!
!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!
!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!
!!!!!!!!!!.!!!!!!!!!
Success rate is 98 percent (985/1000), round-trip min/avg/max = 16/18/32 ms
Router#
组网示意图：
解决方法：
思路1：将远端和中心机房的路由器同时更换对应的端口，即更换传输电路的方式。
思路2：配置相同的cisco2811路由器两台，使用同轴电缆将它们背对背互联，互相进行连通性测试，待测试正常后，将其中一台拿到选取的接入点 代替原工作中路由器进行测试。
故障恢复结论：
经询问该大客户网络管理员得知，在A运营商的电路先行开通后，B运营商提供的所有电路开通后出现丢包现象。几日前A运营商的电路已开始承载业务，不 方便采用更换传输电路的方式测试，因此实际操作中采用了思路2的方法，后经现场测试发现路由器时钟设置错误，当两路运营商的电路同时启用，由于全部选用了 跟踪线路时钟，因而导致了B运营商电路启用出现了丢包现象。
由此推论：当所有点电路开通后，出现大量设备故障的可能小较小，应该在故障和时侧重于软件方面上的测试
