Introduction to Switch Fault Analysis and Network Troubleshooting
Today, we explore Switch Fault Analysis and troubleshooting strategies to address common issues with network switches. This guide is designed to help network administrators and IT professionals efficiently handle faults and maintain network stability.
1. Physical Layer Switch Fault Analysis
In switch fault analysis, physical layer failures typically include problems with the switch hardware or the physical connections. This can involve:
a. Hardware failure
Hardware failures of the device include: device interface or hardware damage, incorrect or unsupported Boot ROM or VRP software version, incorrect optical module interface type, PC card failure or incorrect configuration. Usually one or some interface switches are disconnected, and other interfaces will gradually disconnect.
b. Physical line failure (fault)
Faults of the physical lines connected to the switch include: physical damage to the network cable or optical fiber line itself, incorrect cable type (except MDI/MDI-X automatic sensing), incorrect optical fiber transmission and reception, and intermediate transmission equipment (such as photoelectric converters and protocol converters) Faults or failures, the maximum transmission length and maximum rate supported by the interface cable are beyond the scope of use. Moreover, the matching between the working rate, working mode, frame format negotiation and device interface can also cause faults on the physical layer.
For the above problems, we can find some problems such as:
1. Initial sentence with device interface status. Router maintenance and repair A router is a device that connects the local area networks and wide area networks in the Internet. It automatically selects and sets routes according to the channel conditions, and sends signals in the best path and in a forward and backward order. If the indicator light is off, it means that no data is being sent or received. If the indicator light flashes, it means that data is being sent or received.
2. Check the output of the port display command, such as display interface ethernet0/1.
3. Determine using the replacement method. Including lines, cables and optical fibers, boards, slots, machines, switching lines, such as transceivers.
4. Configure interface loopback on the switch. Set the port for loopback test: loopback { external | internal }.
2. Port negotiation and self-loop failure
The problem of port negotiation is caused by different interface parameters of different manufacturers or different devices of the same manufacturer using different hardware chips, which leads to weak negotiation ability between devices and mismatch of parameters such as working rate and working mode. Or the default parameters of the devices at both ends are inconsistent, which leads to the failure of port automatic negotiation. The port works normally but cannot communicate normally. At this time, it is necessary to manually adjust the parameters of the port and set up to ensure the parameters of both parties.
You can use the display loopback-detection command to check whether loopback occurs at the output of the switch. Most switches support loopback detection. You can enable the loopback detection function on the switch. Most switches now support the Loopback-Detection function.
3. Troubleshooting VLAN faults
Vlan technology is mainly used to isolate network storms and improve network security; different users send data frames, etc., because the ports are divided into Vlan ACCESS ports, TRUNK ports and HYBRID ports. Firewall maintenance and repair The so-called firewall refers to a protective barrier composed of software and hardware devices, constructed on the boundary between the internal network and the external network, and between the private network and the public network. It is a figurative statement of a method to obtain security. It is a combination of computer hardware and software. For Vlan failures, it is mainly due to improper configuration (deploy), involving spanning tree, VTP, port type, etc., and allowing the use of Vlan, etc.
4. Device Compatibility Switch Fault Analysis
At present, the phenomenon of network device interconnection is very common, and device compatibility issues are inevitable. Device compatibility failures can be roughly divided into:
1. Use different protocols to implement the same functions of devices and communicate with each other during negotiation. For this failure, the use of a unified international standard (IETF standards organization) can be used.
2. Devices that use the same protocol specification but use different methods to implement communication with each other in the negotiation. This failure can be solved by first confirming that the protocol implementation has a standard interface, and then accurately configuring the parameters of the protocol interface to ensure the success of the negotiation.
3. Devices that use the same protocol specification and the same method but different default parameters communicate with each other for consultation. In this case, only the parameters of the protocol interface can be configured to ensure successful negotiation.
5. Other troubleshooting (Remove)
Network failures are complex and variable. In addition to the problems caused by the failures, there are other failures, such as network viruses and network topology defects. These failures are not unique to the rules that can be found. Only by testing your own experience and using network tools can you solve them.
The above analysis and troubleshooting methods of switch faults can help us sort out and solve faults in the network. Switch maintenance and repair A switch has multiple ports, each of which has a bridging function and can connect a local area network or a high-performance server or workstation. In fact, switches are sometimes called multi-port bridges. In addition to the relevant theoretical knowledge of network fault diagnosis and resolution, it is also necessary to accumulate experience to help us find the root cause of the problem as soon as possible.