If you want to see which interfaces are configured as “Trunk” ports, the above command will show you just this. Port Vlans in spanning tree forwarding state and not pruned Port Vlans allowed and active in management domain Port Mode Encapsulation Status Native vlan Let’s now see another useful show interface command on switches: However, if the total number of errors is a big percentage compared to the number of packets, then you should investigate for possible interface problems. If you see a small number of errors among millions of packets, then you don’t need to worry.
NOTE: The number of errors shown on each interface is a cumulative number which shows statistics (input/output errors etc) from the time the device was booted up. The above counters are also useful to watch how much traffic has passed through the interface, if there were any errors or frame collisions, buffer failures etc. The above counters are useful to check how much traffic has passed through the interface the last 5 minutes. If you have interface errors the reliability factor will decrease. Reliability 255/255: If you have reliability 255/255 it means that there are no input and output errors on the interface. Hardware is Lance, address is 000b.be66.0b01 (bia 000b.be66.0b01):Here you can see the MAC (hardware) address of the interface. The most important data you need to take into consideration are the following:įastEthernet0/1 is up, line protocol is up (connected): This shows that the specific interface is connected (both physical access and line protocol are up), so it is ready to pass traffic. The “Show Interface” command above which includes the specific interface number (FastEthernet 0/1), shows much more information. Received 956 broadcasts, 0 runts, 0 giants, 0 throttlesĠ input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abortĠ input packets with dribble condition detectedĢ357 packets output, 263570 bytes, 0 underrunsĠ output errors, 0 collisions, 10 interface resetsĠ output buffer failures, 0 output buffers swapped out Input queue: 0/75/0/0 (size/max/drops/flushes) Total output drops: 0ĥ minute input rate 0 bits/sec, 0 packets/secĥ minute output rate 0 bits/sec, 0 packets/secĩ56 packets input, 193351 bytes, 0 no buffer Last clearing of “show interface” counters never Input flow-control is off, output flow-control is off Switch0# show interfaces FastEthernet 0/1įastEthernet0/1 is up, line protocol is up (connected) Now if you want to dive deeper in the counters for each physical interface, we can be more specific as shown below:
Command to find mac address on cisco switch update#
The above gives me a quick status update of each available interface on the switch, on which VLAN it belongs, speed settings etc. I usually start first with the following command:įa0/4 notconnect 1 auto auto 10/100BaseTXįa0/5 notconnect 1 auto auto 10/100BaseTXįa0/6 notconnect 1 auto auto 10/100BaseTXįa0/7 notconnect 1 auto auto 10/100BaseTXįa0/8 notconnect 1 auto auto 10/100BaseTX On a Layer 2 switch we can check the status and various other counters and metrics for each physical ethernet interface or for every interface on the device. Here is the topology used to gather the various output data for each device in this article: In this article we will discuss and explain the “ show interface” command on both routers and switches, so let’s get started.
This command works on both Cisco Switches and Cisco Routers and has the same functionality on both types of devices. It can be very useful at troubleshooting connectivity issues and physical port issues, check the status of physical ports, watch how much traffic is passing through the interface, which IP address is assigned to the interface (for Layer3 interfaces) etc.
One of the most useful and popular commands used on Cisco devices is the “ show interface” command.