User manual

Chapter 5 Troubleshooting

If there are any problems during installation and operation, please try to solve them according to the

following suggestions. If the problems still exist, please contact distributors for help.

z Power (PWR): indicator OFF

Answer

 Please check if there is any fault with power supply.

z Loss-of-Signal (LOS) alarm in E1 link: indicator ON

Answer: LOS alarm caution that your E1 interface cannot receive signal. Please check if the input

cable is properly connected. If using 120Ω twisted-pair interface, please check if the line sequence

is correct. Please also check if transmitting and receiving cables are reversely connected, and avoid

hot swapping. Process local loop-back test, if there is still alarm, thus it indicates that the E1

interface of converter has been damaged.

z E1 receiving signal error alarm (LER): indicator ON

Answer: LER alarm may be caused by the uplink E1 link alarm (AIS), loss of frame (LOF) or

cyclic redundancy check (CRC). This indicates that there are errors in E1 receiving link. Please

check the of E1 receiving link and E1 frame parameter of equipment on opposite site, such as

PCM30/31 and CRC enable/disable.

z Remote alarm (RAL): indicator ON

Answer: RAL at local end caused by LOS or LER at remote (opposite) end equipment. This

indicates that there is error at E1 receiving link of remote equipment, i.e. transmitting link of local

equipment.

z Severe packet loss of DTE equipment

Answer: The possible reasons for severe packet loss are.

1. Incorrect clock mode setting.

2. Check V.35 interface status of the Router, if there are data errors of input and output, then it

indicates that TX CLKand RX CLK phase relationship need to be adjusted. This problem can

be located by doing local V.35 interface loop-back test.

3. Cable loose at E1 port or wrong line sequence.

z Connecting with DTE equipment in transparent mode, there are few packet losses occurring

when using default phase.

Answer: It is needed to adjust the phase. Normally you only need to adjust the 1st bit of dip-switch,

i.e. adjust TX CLK from positive (deault) to negative.

z Compatibility with equipment of other brands

Answer: RC903-V35FE1 can cooperate with similar products of other brands, and also can

cooperate with Routers with fractional E1 interface. It is needed to ensure they are using same time