你沒有規定dlci，我就自己假設了，RTA-SWITCH DLCI=10;

RTB-SWITCH DLCI=20;

RTC-SWITCH DLCI=30;

FR-SWITCH配置如下

fr switching

interface serial 6/0

link-protocol fr

fr interface-type dce

fr dlci 10

interface serial 7/1

link-protocol fr

fr interface-type dce

fr dlci 30

interface serical 7/0

link-protocol fr

fr interface-type dce

fr dlci 20

fr dlci-switch 10 interface serial 7/0 dlci 20

fr dlci-switch 10 interface serial 7/1 dlci 30

fr dlci-switch 20 interface serial 6/0 dlci 10

fr dlci-switch 20 interface serial 7/1 dlci 30

fr dlci-switch 30 interface serial 6/0 dlci 10

fr dlci-switch 30 interface serial 7/0 dlci 20