通过命令：show interfaces et-0/0/2 extensive,显示input error以及CRC错误。
状态显示：
Physical interface: et-0/0/2, Enabled, Physical link is Up
Interface index: 942, SNMP ifIndex: 516, Generation: 676
Link-level type: Ethernet, MTU: 1514, Speed: 40Gbps, BPDU Error: None, MAC-REWRITE Error: None, Loopback: Disabled, Source filtering: Disabled, Flow control: Disabled, Media type: Fiber
Device flags : Present Running
Interface flags: SNMP-Traps Internal: 0x4000
Link flags : None
Input errors:
Errors: 771731, Drops: 0, Framing errors: 771415, Runts: 0, Policed discards: 0, L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0, FIFO errors: 0, Resource errors: 0
Output errors:
Carrier transitions: 3, Errors: 0, Drops: 0, Collisions: 0, Aged packets: 0, FIFO errors: 0, HS link CRC errors: 0, MTU errors: 0, Resource errors: 0
…………………………
MAC statistics: Receive Transmit
Total octets 1216533781969 1073277356863
Total packets 1669078594 1462519491
Unicast packets 1633851744 1398747806
Broadcast packets 361455 27733729
Multicast packets 34865395 36037956
CRC/Align errors 771415 0
FIFO errors 0 0
初步排查，影响的原因有可能是以下几点：
1. 接口模块
2. 光线或网线
3. 两边接口是否全双工
解决办法：
经换模块，CRC显示正常，input error恢复正常。 开Case，对模块进行RMA处理。
Juniper QFX5100交换机et接口input error及CRC/Align errors
原文：http://blog.51cto.com/8019770/2093193