如何查询网络设备的接口是单工还是双工？
单工即半双工表示同一时刻，只能收或者发；
全双工表示同一时刻，可以同时收和发；
命令很简单：
Router>enable
Router#show interface g0/0
GigabitEthernet0/0 is administratively down, line protocol is down (disabled)
Hardware is CN Gigabit Ethernet, address is 0001.97c4.6501 (bia 0001.97c4.6501)
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, //该行即显示传输速率
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is RJ45 //该行即显示单工还是双工模式，Full-duplex为双工。
……
再举一例：
Switch>enable
Switch#show interface f0/1
FastEthernet0/1 is down, line protocol is down (disabled)
Hardware is Lance, address is 0001.97ab.de01 (bia 0001.97ab.de01)
BW 100000 Kbit, DLY 1000 usec, //该行即显示传输速率
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Half-duplex, 100Mb/s ////该行即显示单工还是双工模式，Half-duplex为单工。
……
是不是很简单！
工匠给个建议：不同类型的设备之间进行互联链路时，最好手动指定速率和双工，以免互联时设备间协商出问题！