Common failure phenomena and causes

1. When docking failure occurs, the common failure phenomena are:

(1) Docking service is not available;

(2) The Ethernet service status is abnormal, such as: slow speed, large delay, service with packet loss, sending or receiving data with error packets, etc.

(3) Abnormal status of 2M service, such as: slow speed, large delay, service with frame loss, sending or receiving data with error codes, etc.

2. Fault causes:

Fault category	Fault cause
External causes	Poor cable or fiber contact
	Cable or fiber connection error
	Network cable production is not standardized
	Docking signal attenuation is too large or does not meet the standard requirements
	Incorrect service configuration of the docking device
	Failure of docking equipment
	Network cable or fiber optic transmission length exceeds the specification
	Serious environmental electromagnetic interference, affecting the network cable transmission
	Problems with the negotiation between the two ends of the equipment
	Incorrect selection of the optical port (single-mode or multi-mode) of the docking device
Equipment reasons	Incorrect setting of commodity attributes (Tag attribute, default VLAN)
	Routing configuration error
	Inconsistent number of 2Ms in the bound communication bundle at both ends
	Docking signals work in different modes (full-duplex or half-duplex)
	Ambient temperature or subrack temperature is too high
	Ethernet board failure
	Abnormal physical characteristics of the optical interface (too low luminous power, too much jitter, etc.)
	SDH part of the service configuration error
	SDH failure (line board cross board failure, reversal failure, line error code, etc.)

Common fault processing steps

Comprehensive client failure analysis, involving optical equipment failure causes are mainly divided into four: transmission line damage, optical or board card damage, optical or port drop dead, interconnection equipment port mode mismatch.

1、Transmission line damage

Examine the cause of the failure and locate the transmission line failure point.

Step 1: Examine the supporting lines of the client, and contact the monitoring room to check whether there is any alarm on the faulty line. If there is any ET ___ LOS alarm, it is judged to be caused by power loss of the client or loose lines of the Ethernet port, and the line connector is replaced if the power supply of the equipment is normal;

Step 2: Replace the line connector after the fault still exists, replace the equipment interconnection line;

Step 3: Observe the optical interface board indicator (red), the indicator is bright, indicating that the optical interface does not receive light signals, preliminary judgment for fiber damage, check whether the pigtail is normal, contact the optical cable transmission to assist in troubleshooting the entire fiber, if the fiber is broken, contact the optical cable maintenance to assist in the timely melting of the fiber.

Step 4: After melting the fiber to observe the optical interface board indicator (red), the indicator light does not indicate that the optical interface to receive a normal light signal, the use of optical power meter to test the light attenuation is whether or not in the permissible range of error, are normal and then re-test.

2、Optical or board card damage

Check the client equipment, power supply is normally connected to the case found in the optical transmitter power indicator does not light, restart the power switch after the device still can not start, the judgment that the equipment is damaged; equipment is running normally, the corresponding board can not be started, restart the device, the board is still in a sleep state, the judgment for the equipment board is damaged. Contact the equipment manufacturer to replace the equipment or board, and retest after replacement.

Replacement method:

Step 1, turn off the device power switch and disconnect the power supply;

The second step is to replace the device or board card with the same model;

Step 3, turn on the power for 30 seconds and turn on the power switch. Observe the device indicator, and retest the device after it has stabilized operation.

3、Optical transceiver or port drop dead

Contact the transmission network manager, see the client device is "managed", judge the optical terminal or port drop dead, need to restart the device.

The first step is to turn off the power switch of the device;

Step 2: Turn on the power switch of the device after 30 seconds;

The third step is to observe the indicator light of the device and re-test the device after its operation is stabilized.

4、Interconnection device port mode mismatch

Use a pc to ping test the ip of the other end, packet loss is serious, and it is judged to be caused by the mismatch of the port mode of the interconnection equipment. If one end is a fixed mode (either 10M, 100M), the other end is a self-negotiation mode, even if the negotiation is successful, self-negotiation of the end will only work in half-duplex mode; if one end works in full-duplex mode, the other end works in half-duplex mode (including self-negotiation out of the half-duplex, but also deal with the same), ping the small packet is not a problem, the flow of small times do not have any problem, traffic reaches about 15%, there is no problem. Any problem, when the traffic reaches about 15% or more, there will be conflicts, wrong packets, and ultimately affect the performance of the work!

Set the interconnected device ports in the same port mode, and it is recommended to set it to full duplex mode for business testing.

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