The Solution of Optical Transceiver Connection Failure Between Data Center Switches

NADDOD Jason Data Center Architect Dec 12, 2022

During the use of optical transceivers, various problems will inevitably occur. Here, NADDOD summarizes two common problems of optical transceivers and the corresponding solutions.

The Main Reasons and Solutions for Optical Transceiver Docking Failure

Theoretically, the same interface standard type can be docked, but the actual use of the transceiver power range and transmission distance should be noted. The main factors affecting the docking of optical transceivers are shown below.

Wavelength: Docking of optical transceivers of different wavelengths is prohibited. Due to the different transmission loss and dispersion in the fiber, The transmission distance is different for different wavelengths at the same speed, so the optical transceiver of the same wavelength should be selected for docking.

Transmission Distance: Optical transceivers require peer-to-peer use, different distance optical transceiver interface indicators vary greatly, and the price of long-distance optical transceivers is also high, so long-distance optical transceivers and short-distance optical transceivers docking, must be docked by increasing the optical attenuator; In order to avoid not burning optical transceivers, it is recommended that the optical transceiver support distance is not less than the fiber length.

Rate: The nominal rate of the optical transceiver should be consistent with the actual link rate, and it is strictly forbidden for the low-rate optical transceiver to run high-speed signals. The nominal rate of the optical transceiver must be greater than the interface rate.

Mode: Optical fiber and optical transceiver should be used in pairs, i.e. single-mode optical transceiver using single-mode fiber and multi-mode optical transceiver using multi-mode fiber, do not mix.

Failure Situation

The two optical interfaces are docked through the fiber, the local port Down, the optical transceiver docking does not work.

Possible Causes

  • Incompatibility between the optical transceiver used and the equipment
  • Mismatch between optical transceiver and fiber
  • The port is shutdown
  • Transmitting optical power is too low or too high
  • Receiving optical power is too low or too high
  • Mismatch between the optical transceivers docked at both ends

Troubleshooting Steps

  1. Confirm whether the optical transceiver on Down’s port is compatible with the device. The main incompatibilities between modules and devices are as follows.
  • The transceiver is not recognized by the device, the transceiver is not responsive when inserted into the device, and the test does not come out with the information of the transceiver.
  • Insert the transceiver, the device pops up Not Supported, Unknown, No Qualified and other unsupported & alarm information.
  • When the transceiver is inserted, the device status light is abnormal, and the port cannot be connected.
  • The transceiver can be connected, but the information displayed is not normal; for example, the information displayed is unknown SFP, etc. The reliability of incompatible optical transceivers cannot be guaranteed.
  • The reliability of incompatible optical transceivers cannot be guaranteed and may cause the port to fail to UP.

  1. Check whether the optical transceiver and fiber match
  • Single-mode optical transceiver, generally wavelength 1310nm, 1550nm, corresponding to single-mode fiber, yellow.
  • The wavelength of multimode optical transceiver is generally 850nm, which corresponds to multimode fiber, orange, aqua blue or rose red.
  1. Take HUAWEI switch as an example, execute the command display interface transceiver to check whether there is alarm information of optical transceiver under “Alarminformation”. If there is an LOS Alarm warning, it means that no signal is sent from the other side. Execute the command display interface in interface mode to see if the ports at both ends are shutdown, and if the ports are shutdown, execute undo shutdown operation.

  2. Execute the command display interface transceiver verbose to view the diagnostic information of the optical transceiver and check whether the optical transceiver has alarm information about transmitting or receiving optical power.

    Diagnostic information

In the diagnostic information of the optical transceiver, you can check the current transmit and receive optical power values, as well as the default maximum and minimum power values.

  • If the receiving power is Low (RxPower Low) , it means that the signal received by this terminal is too low, then the port may not be UP or after UP messages are sent and received with discards. Please check whether the transmission distance is too far at this time, beyond the transmission distance of the optical transceiver, and then check the optical transceiver, optical fiber damage.
  • If the received power is high (RxPower High), it means that the signal received at this end is too high. The possible reason is that the optical transceiver at the opposite end is a long-range optical transceiver, and the actual transmission distance is too short, resulting in the signal not attenuated.
  • If the transmitting power is low (TxPower Low), it means that the transmitting signal of the local optical transceiver is bad or the optical transceiver itself is faulty, which may cause the receiving power at the opposite end to be low and cause the port not to UP or there is discard in the message sending and receiving after UP.
  • If the transmitting power is high (TxPower High), it means that the transmitting signal of the optical transceiver at this end is too strong, which may cause the receiving power at the opposite end to be high, and cause the optical transceiver at the opposite end to burn out due to the continuous high receiving power, which may be caused by the failure of the optical transceiver at this end, and it is recommended to replace the optical transceiver.

Therefore, after the port is inserted into the optical transceiver and docked successfully, the alarm information in terms of transmitting or receiving optical power should be checked to avoid abnormal traffic or optical transceiver status caused by too low or too high power.

  1. If there is no alarm at both ends, and the port is not UP, please first intercept the optical transceiver details and get the relevant logs, then try to replace another fiber or optical transceiver to see if it can UP normally. If it can UP, it means that the original fiber or optical transceiver itself has problems, please replace the new fiber or optical transceiver. If it still can not UP, please contact technical support staff.

The Main Causes of Optical transceiver Failure and Protective Measures

Optical transceivers must have a standardized method of operation in their application, and any irregular action may cause hidden damage or permanent failure.

The Main Causes of Optical Transceiver Failure

The main causes of optical transceiver failure are deterioration of optical transceiver performance due to ESD damage, and optical link failure due to optical port contamination and damage. Optical port contamination and damage are mainly due to the following reasons.

  • The optical port of the optical transceiver is exposed to the environment, and the optical port is contaminated by the entry of dust.
  • The end face of the optical fiber connector used has been polluted, which leads to the secondary contamination of the optical port of the optical transceiver.
  • The end face of optical connector with pigtail is used improperly, such as: end face scratches, etc.
  • Poor quality fiber optic connectors are used.
  • How to effectively protect the optical transceiver failure? Mainly divided into two kinds of ESD protection and physical protection.

ESD protection

ESD damage is a major problem that causes deterioration of optical device performance and even loss of device optoelectronic function. In addition, ESD damaged optical devices are not easy to test and screen, and it is difficult to locate them quickly if they fail.

Operating instructions

  1. Optical transceivers must be in anti-static packaging during transportation and transfer before use, and must not be removed or placed at will.
  2. Before contacting the optical transceiver, anti-static gloves and anti-static bracelets must be worn, and anti-static measures must be taken when installing optical devices (including optical transceivers).
  3. Test equipment or application equipment must have a good grounding wire.

Physical Protection

The laser and temperature control circuit (TEC) inside the optical transceiver are fragile and may break or fall off easily after impact, so physical protection should be paid attention to during transportation and use.

The optical port can be lightly wiped with a cleaning swab, but a non-special cleaning swab may cause damage to the optical port, and excessive force when using the swab may cause the metal in the swab to scratch the ceramic end face.

The insertion and extraction of the optical transceiver are designed to simulate manual operation, and the thrust and pull force are also designed to simulate manual operation, and no apparatus should be used during installation and removal.

Operation Instructions

  1. When using the optical transceiver, pay attention to lightly hold and gently put to prevent falling.
  2. When the optical transceiver is inserted, it can not be pushed by hand with other metal tools. The pull ring can be opened to the unlocking position before pulling the pull ring, and can not be done with other metal tools.
  3. When cleaning the optical port, use special cleaning cotton swabs and do not use other metal substances to insert into the optical port.