The POS port of the switch is prone to problems. When checking for faults, we should first check whether the line connecting to the POS port of the recovery switch is faulty, and then analyze other aspects. In the process of using a switch to control the network, we sometimes encounter the phenomenon of restoring the physical status of the switch POS port to "down". How is this fault caused, how can we restore the working status of this port?
In the event of this abnormal phenomenon, we conduct two checks, one is to check whether the physical connection of the corresponding port is normal, and the other is to check whether the connection settings of the corresponding port are normal, in particular, check the clock setting parameters for restoring the POS port of the switch.
First, check whether the line connecting to the POS port of the recovery switch is faulty. Generally, we should use two fiber cables to connect to the switch, one of which is used to receive data signals, another optical fiber cable is used to send data signals and cannot be reversed.
In addition, if the sender and receiver of the same optical fiber cable are accidentally connected to the POS port of the recovery switch at the same time, even if the network loop function of the corresponding port is not enabled, when executing the string command "display interface pos", we can also see prompts like "loopback detected.
When we confirm that the line connection is correct, we also need to check whether the internal clock is set between the local recovery switch POS port and the peer recovery switch POS port. When the two switches use a direct connection, we should set one of the POS port clock parameters of the recovery switch to an internal clock, and the other POS port clock parameters of the recovery switch to the default line clock.
If the above check cannot restore the physical status of the POS port of the switch, we can try to restore the scrambling parameter of the POS port of the switch for inspection, check whether the local and peer scrambling Parameters match. If not, adjust them in time.
Configure duplex mode to ensure that the data port mode matches
If we want a data port of the switch to send data packets externally and accept data packets from outside, we can consider setting the duplex mode of the switch port to full duplex mode, if you only want a data port to receive packets from outside or send packets at a certain time point. Then we can try to adjust the duplex mode parameter of the data port to the half duplex mode. Of course, we can also set the target switching port to the automatic negotiation status, at this time, the port duplex status is determined by the negotiation between the local port and the peer port.
When configuring the duplex mode parameters of a target switch port, we can log on to the backend Management system of the switch and execute the string command "system" in the command line status ", switch to the Global System View Mode of the switch system. In this mode, enter the "interface e0/6" string command in the command line state, click the Enter key, and switch to the configuration mode of the target switch port.
If you continue to execute the "duplex full" string command in this state, the duplex mode of the target switching port will be changed to full duplex mode, and the "duplex half" string command will also be executed, you can change the duplex parameter of the target switching port to the half duplex mode.
If you want to change the port duplex parameter of the switch to the default setting, you can enter the "duplex auto" string command, or the "undo duplex" string command, and click the Enter key, the destination switch port duplex parameter is changed to the default setting.
We only need to remind you that the 10/100 Mbps Ethernet port can work in both the automatic negotiation mode and the half-duplex mode and the full-duplex mode. We can configure the port according to the actual situation; the 10/100/1000Mbps Ethernet port can also work in Automatic negotiation mode, half duplex mode, and full duplex mode.
However, when the switching port is at the transmission speed of 1000 Mbit/s, we can only change the duplex parameter of the port to automatic negotiation mode or full duplex mode. If the destination Ethernet Optical port is Mbps or Mbps, the POS port of the recovery switch can only be set to full duplex mode.