Two R4001s interconnect through a 2M cable, and they connect with the network management server and the client respectively through Ethernet interfaces. The data configuration is correct (verified on other points). The 2M cE1 cable emits an RLOS alarm, so the router cannot work normally.
1) Check the data configuration, and there are no errors.
2) The RLOS indicator of the S1 interface is on after the two routers are interconnected through a 2M cE1 cable, so it indicates a problem on the transmission channel.
3) The clocks of the two routers need to be set as DTE and DCE modes respectively. Set the clock of one router to DCE mode, and perform the self-loop. The RLOS indicator is on, indicating that the clock module of this router is damaged.
4) Set the clock of the router with the damaged clock module to DTE, and that of the other router to DCE. Reconfigure the original data, and the two routers can work normally.
The possible causes are:
1) Wrong data configuration.
2) Transmission channel problems.
3) Hardware faults.