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This article showed you how to configure and troubleshoot the switch port. If you have found the article useful, we would really appreciate you sharing it with others. Thanks for choosing SPOTO .
Serial port troubleshooting
When the serial port has connectivity problems, in order to eliminate the serial port failure, it is generally started from the show interface serial command, analyzes its screen output report content, and finds out the problem. The interface status and line protocol status are provided at the beginning of the serial port report. The possible combinations of interfaces and line protocols are as follows:
1, serial port operation, line protocol operation, this is a complete working condition. The serial and line protocols have been initialized and are exchanging protocol survival information.
2. The serial port operation and the line protocol are closed. This display indicates that the router is connected to the device providing the carrier detection signal, indicating that the carrier signal appears between the local and remote modems, but the protocol survival information at both ends of the connection is not correctly exchanged. Possible failures occur in router configuration issues, modem operation problems, leased line interference, or remote router failures, clock problems with digital modems, and the two serial ports connected through the link are not on the same subnet.
3. The serial port and line protocol are all closed. It may be a line fault, cable fault or modem failure in the telecommunications department.
4. The serial port administrative shutdown and line protocol shutdown are the cases where the shutdown command is entered in the interface configuration. Turn on administrative shutdown by entering the no shutdown command.
In the case where both the interface and the line protocol are running, although the basic communication of the serial link is established, there are still many potential failure problems due to packet loss and packet error. Interface input or output packets should not be lost during normal communication, or the amount lost is very small and will not increase. If the packet loss increases regularly, it indicates that the traffic transmitted through the interface exceeds the amount of traffic that the interface can handle. The solution is to increase the line capacity. Look for packet loss for other reasons, see the status of the I/O hold queue in the output report for the show interface serial command. When it is found that the number of packets in the hold queue reaches the maximum allowable value of the information, the size of the hold queue setting can be increased.
Troubleshooting the Ethernet interface
Typical fault problems with Ethernet interfaces are excessive use of bandwidth; frequent collision collisions; use of incompatible frame types. Use the show interface ethernet command to view throughput, collision conflicts, packet loss, and frame type content for the interface.
1. You can check the bandwidth utilization of the network by checking the throughput of the interface. If the percentage of network broadcast packets is high, network performance begins to decline. Packets that are converted to the Ethernet segment by the fabric may overwhelm the Ethernet port. On the Internet, this can be done by optimizing the interface by using the no IP route-cache command on the Ethernet interface, disabling fast conversions, and adjusting buffer and hold queue settings.
2. When two interfaces attempt to transmit packets to the Ethernet cable at the same time, a collision will occur. Ethernet requires few collisions, and different network requirements are different. In general, it is found that conflicts should be found three or five times per second. Collision conflicts create congestion, which is often caused by over-used, over-utilized, or “聋” nodes. Ethernet networks should be considered in the physical design and laying of cable system management. Over-standard laying of cables may cause more conflicts.
3. If the interface and line protocol report the running status and the physical connections of the nodes are intact, they cannot communicate. The cause of the problem may also be that the two nodes use incompatible frame types. The solution to the problem is to reconfigure the same use.
Frame type. If two devices on the same network with different frame types are required to communicate with each other, you can use subinterfaces on the router interface and specify different encapsulation types for each subinterface.
Asynchronous communication port troubleshooting
In the operation of the interconnection network, the task of the asynchronous communication port is to provide reliable service for the user, but it is also a faulty part.
The general external factors for asynchronous communication port failure are poor performance of the dial-up link; connection quality problems of the telephone network switch; modem settings. Check the modems used at both ends of the link: There are not many problems connecting to the remote PC port modem, because the modem is usually initialized each time a new dialup is generated, and most communication programs can send the appropriate commands before issuing the dial command. Setting the string; There are more problems connecting the router port. This modem usually waits for a connection from a remote modem and does not receive the setup string before the connection. If the modem loses its settings, there should be a way to initialize the remote modem. The easy way is to use a modem that can be configured through the front panel; another method is to connect the modem to the asynchronous interface of the router, establish reverse telnet, and send a setup command to configure the modem.
The show interfaces async command, show line command is the tool that is most useful for diagnosing asynchronous communication port failures. In the show interface async command output report, the only case where the interface status report is closed is that the interface does not have a package typeset. The line protocol status display is the same as the serial line protocol display. The show line command displays the interface receive and transfer speed settings as well as the EIA status display. The show line command can be thought of as an extension of the interface command ( show interface async).
Check the EIA signal output by the show line command to determine the network status.
To determine the asynchronous communication port failure, generally use the following steps: Check the cable line quality; check the modem's parameter settings; check the modem connection speed; check if rxspeed and txspeed match the modem's configuration;
Use the show interface async command and the show line command to check the communication status of the port; check the EIA status display from the report of the show line command; check the interface encapsulation; check for packet loss and buffer loss.
