Therefore, you can use either a crossover or a straight-through cable for connections to a copper 10/100, 10/100/1000, or 1000BASE-T SFP module port on the switch, regardless of the type of device on the other end of the connection. When the Auto-MDIX feature is enabled, the switch detects the required cable type for copper Ethernet connections and configures the interfaces accordingly. Note, the automatic medium-dependent interface crossover (Auto-MDIX) feature is enabled by default on switches running Cisco IOS Release 12.2(18)SE or later. SW1# show controllers ethernet-controller fastEthernet 1/0/1 phy. You can use the following command to see the operating state of auto-mdix. If that switch port is connect to another switch, it would need a crossover cable but if you have Straight-Through it wont work unless the auto-mdix feature kicks in, BUT the auto-MDIX feature work only when the speed and duplex are set to auto.īasically, if you are using the wrong cable type and rely on auto-mdix to get connectivity, you must keep the speed and duplex to auto. If only protocol is down, then check if this interface on other connecting device is UP, duplex & speed is matching, encapsulation on both ends is same. It seems weird, since the port was working good before changing the speed. If it is 'ethernet down, line protocol down', then a physical layer problem like cable not connected. That fact that is show down down(not connect) mean a physical issue. I suspect that if someone physically checks the connection that they will find that the interface is not connected to a switch or anything. I run into the same issue in my home lab and found the cause. In my experience when a cable is not plugged in the Ethernet/Fast Ethernet will show to be line up line protocol down, which is the exact symptom that you report. Reliability 255/255, txload 1/255, rxload 73/255įull-duplex, 100Mb/s, media type is 10/100BaseTXįastEthernet1/0/47 is up, line protocol is up (connected) Any recommendations on getting this port back up, short of rebooting the switch in the end cabinet (I can't connect to the switch)Įven after resetting the speed, I'm getting:įastEthernet1/0/47 is down, line protocol is down (notconnect) Incorrect subnets in case of Layer 3 ports. physical layer is up), there is a mismatch between the connected links (Layer 2 or 3). I've tried setting the speed back to 100, and shutting down/starting the port again, but it never reconnects. Answer: That would mean that even though line is connected (i.e. As a quick fix, I set the speed on the main switch to be 10Mbps for the port that connects to the switch in the cabinet.Īfter doing that however, the port now shows down (notconnect). I recently had someone in one cabinet start consuming 100% of the bandwidth in my network. In my network, I have a main Cisco 2950 that connects to my outside bandwidth, then individual Cisco 2950s in each cabinet that connect back to the main one.
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