功能：查看接口硬件的信息和电缆的类型以及时钟信息
实例：
chj#show controllers s1/0
M4T: show controller:
PAS unit 0, subunit 0, f/w version 3-101, rev ID 0x2800001, version 1
idb = 0x62379A70, ds = 0x6237B878, ssb=0x6237BC2C
Clock mux=0x0, ucmd_ctrl=0x1C, port_status=0x7B
Serial config=0x8, line config=0x200
maxdgram=1608, bufpool=48Kb, 96 particles
DCD=up DSR=up DTR=up RTS=up CTS=up
line state: up
cable type : V.11 (X.21) DCE cable, received clockrate 56000
# 线缆类型是DCE,时钟频率为56000
base0 registers=0x3C800000, base1 registers=0x3C802000
mxt_ds=0x629ECE00, rx ring entries=47, tx ring entries=64
rxring=0x3903580, rxr shadow=0x623824D4, rx_head=9
