下面顯示了 show cdp neighbors 命令的部分輸出:DevicID Local Intrfce Holdtme Capability Platform Port ID lab-7206 Eth 0 157 R 7206VXR Fas 0/0/0 lab- as5300-1 Eth 0 163 R AS5300 Fas 0 lab-as5300- 2 Eth 0 159 R AS5300 Eth 0 lab-as5300-3 Eth 0 122 R AS5300 Eth 0 lab- as5300-4 Eth 0 132 R AS5300 Fas 0/0 lab-3621 Eth 0 140 R S 3631- telcoFas 0/0as5300-4 Eth 0 132 R AS5300 Fas 0/0 lab-3621 Eth 0 140 R S 3631- telcoFas 0/0 008024 2758E0 Eth 0 132 T CAT3000 1/2 lab-400-1 Eth 0 130 r FH400 Fas 0/0 在此輸出中,"r "代表什麼?