What Can I Do If Interconnected Optical Modules on Different CloudEngine Series Data Center Switches Cannot Communicate with Each Other?
Context
Theoretically, optical modules of the same connector type can be connected. In practice, pay attention to the transmit and receive power ranges and transmission distance. Table 1-6 lists the main factors that affect optical module interconnection.
Factor |
Description |
---|---|
Wavelength |
Do not interconnect optical modules with different wavelengths. Since optical modules with different wavelengths have different transmission loss and dispersion in a fiber, the transmission distances of such optical modules are different even at the same rate. Therefore, you need to select the optical modules with the same wavelength for interconnection. |
Transmission distance |
Optical modules interconnected must have the matching transmission distance. The connector specifications of optical modules vary greatly according to the transmission distance. Long-distance optical modules are expensive. When long-distance and short-distance optical modules are interconnected, optical attenuators must be used. To prevent an optical module from being burnt, the distance supported by the optical module should be longer than the length of the optical fiber connected to it. |
Rate |
The nominal rate of an optical module must be the same as the actual link rate. Low-rate optical modules are prohibited from transmitting high-rate signals. The nominal rate of an optical module must be greater than the interface rate. |
Mode |
Optical fibers and optical modules used together must work in the same mode. That is, single-mode optical fibers are used for single-mode optical modules, and multimode optical fibers are used for multimode optical modules. |
Fault Symptom
Two optical interfaces on different switches are interconnected through optical fibers. The local optical interface is Down, leading to a communication failure between the two corresponding optical modules.
Possible Causes
- The optical modules used on the switches are not certified for Huawei data center switches.
- The optical modules and optical fibers do not match.
- The local optical interface is shut down.
- The transmit power of the local optical module is too low or too high.
- The receive power of the local optical module is too low or too high.
- The two optical modules do not match.
Troubleshooting Procedure
- Check whether the optical module of the Down interface has been certified for Huawei data center switches. CloudEngine series switches must use optical modules certified for Huawei data center switches. Those that are not certified for Huawei data center switches cannot ensure service reliability, and the corresponding optical interfaces may fail to go Up.
- Check whether optical modules and optical fibers match.
- A single-mode optical module (typically with a center wavelength of 1310 nm or 1550 nm) must be used with single-mode optical fibers (typically yellow).
- A multimode optical module (typically with a center wavelength of 850 nm) must be used with multimode optical fibers (typically orange).
- Run the display interface transceiver command to check whether any alarm information has been generated for the optical module.
<HUAWEI> display interface 10ge 1/0/1 transceiver 10GE1/0/1 transceiver information: ------------------------------------------------------------------- Common information: Transceiver Type :10GBASE_SR Connector Type :LC Wavelength (nm) :850 Transfer Distance (m) :30(62.5um/125um OM1) 80(50um/125um OM2) 300(50um/125um OM3) 400(50um/125um OM4) Digital Diagnostic Monitoring :YES Vendor Name :HUAWEI Vendor Part Number :02318169 Ordering Name : ------------------------------------------------------------------- Manufacture information: Manu. Serial Number :AQG269Y Manufacturing Date :2013-10-20 Vendor Name :HUAWEI ------------------------------------------------------------------- Alarm information: -------------------------------------------------------------------
If the LOS alarm is displayed, the local optical interface does not receive signals from the remote interface. Run the display this command in the interface view to check whether the two interfaces have been shut down. If an interface is shut down, run the undo shutdown command on the interface.
- Run the display interface transceiver verbose command to check diagnostic information about the optical module on the local interface. Specifically, check whether the diagnostic information contains alarms about abnormal transmit or receive power.
<HUAWEI> display interface 10ge 1/0/1 transceiver verbose 10GE1/0/1 transceiver information: ------------------------------------------------------------------- Common information: Transceiver Type :10GBASE_SR Connector Type :LC Wavelength (nm) :850 Transfer Distance (m) :30(62.5um/125um OM1) 80(50um/125um OM2) 300(50um/125um OM3) 400(50um/125um OM4) Digital Diagnostic Monitoring :YES Vendor Name :HUAWEI Vendor Part Number :02318169 Ordering Name : ------------------------------------------------------------------- Manufacture information: Manu. Serial Number :AQG269Y Manufacturing Date :2013-10-20 Vendor Name :HUAWEI ------------------------------------------------------------------- Alarm information: ------------------------------------------------------------------- Diagnostic information: Temperature (Celsius) :33.68 Voltage (V) :3.29 Bias Current (mA) :7.97 Bias High Threshold (mA) :13.20 Bias Low Threshold (mA) :4.00 Current RX Power (dBm) :-2.15 Default RX Power High Threshold (dBm) :1.00 Default RX Power Low Threshold (dBm) :-11.90 Current TX Power (dBm) :-2.07 Default TX Power High Threshold (dBm) :1.00 Default TX Power Low Threshold (dBm) :-9.30 -------------------------------------------------------------------
The display interface transceiver verbose command displays the current transmit and receive power values of the optical module, as well as the default maximum and minimum power values.
- If RxPower Low is displayed, the strength of signals received by the local optical module is too low. As a result, the local interface may not go Up or discard packets after it is Up. In this case, check whether the distance between the two switches exceeds the maximum transmission distance of the remote optical module. If the distance is within the transmission distance of the remote optical module, check whether the optical module and optical fiber on the interface are damaged.
- If RxPower High is displayed, the strength of signals received by the local optical module is too high. The possible reason is that the distance between the two switches is short but a long-distance optical module is used on the remote end. In this case, install an optical attenuator on the remote optical module to protect the local optical module.
- If TxPower Low is displayed, the strength of signals sent from the local optical module is too low, or the optical module is faulty. This may cause low receive power on the remote optical module. Then, the remote interface may not go Up or discard packets after it is Up. In this case, contact technical support engineers.
- If TxPower High is displayed, the strength of signals sent from the local optical module is too high. This may cause high receive power on the remote optical module. If the high receive power lasts for a long time, the remote optical module will be burnt. The local optical module may have failed and you are advised to replace it.
To ensure normal communication between two interconnected interfaces that have optical modules installed, check for transmit and receive power alarms. Ensure that the transmit and receive power values of the two optical modules are in the normal ranges. Otherwise, traffic forwarding on the optical interfaces may be abnormal or the optical modules may be damaged.
- If no transmit and receive power alarms are displayed on the two ends but the interface is still Down, collect detailed information and logs about the optical modules, and then replace the optical modules or optical fibers. If the interface can go Up, the original optical modules or optical fibers are faulty. If the interface is still Down, contact technical support engineers.
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