Note that this interface is running in half duplex. This could indicate a layer 1 problem like a broken cable, wrong cable (crossover instead of straight-through) or maybe a bad NIC. Received 2407 broadcasts (1702 multicasts)Ġ input errors, 0 CRC, 0 frame, 0 overrun, 0 ignoredĠ watchdog, 1702 multicast, 0 pause inputĠ input packets with dribble condition detectedĤ2700 packets output, 8267872 bytes, 0 underrunsĠ output errors, 0 collisions, 1 interface resetsĠ lost carrier, 0 no carrier, 0 PAUSE outputĠ output buffer failures, 0 output buffers swapped outįastEthernet 0/1 is showing down. 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/secģ457 packets input, 309301 bytes, 0 no buffer Last clearing of "show interface" counters never Input flow-control is off, output flow-control is unsupported Half-duplex, Auto-speed, media type is 10/100BaseTX What’s the first thing we should check? Our interfaces of course! SW1# show interfaces fa0/1 FastEthernet0/1 is down, line protocol is down (notconnect) Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), Let’s try a ping: C:Documents and SettingsH1> ping 192.168.1.2 We’ll assume the computers are configured correctly and there are no issues there. Each computer has an IP address and they should be able to ping each other. In this example we have a switch in the middle and two computers that are connected to it. Let’s walk through a couple of scenarios… Duplex / speed issues
Interface up line protocol down how to#
In this lesson we’ll take a look how to troubleshoot a variety of interface issues.