31 Days Before Your CCNA Exam

66 31 Days Before Your CCNA ExamTable 25-1 LAN Switch Interface Status Codes continuedLine StatusProtocol Status Interface Status Typical Root CauseUp Down notconnect An interface up/down state is not expected onLAN switch interfaces. This indicates a Layer 2problem on Layer 3 devices.Down down (err-disabled) err-disabled Port security has disabled the interface. The networkadministrator must manually reenable theinterface.Up Up connect The interface is working.Duplex and Speed MismatchesOne of the more common problems is issues with speed and/or duplex mismatches. On switchesand routers, the speed {10 | 100 | 1000} interface subcommand and the duplex {half | full} interfacesubcommand set these values. Note that configuring both speed and duplex on a switch interfacedisables the IEEE-standard autonegotiation process on that interface.The show interfaces status and show interfaces commands list both the speed and duplex settingson an interface, as shown in Example 25-5.Example 25-5Commands to Verify Speed and Duplex SettingsS1#show interface statusPort Name Status Vlan Duplex Speed TypeFa0/1 connected trunk full 100 10/100BaseTXFa0/2 connected 1 half 100 10/100BaseTXFa0/3 connected 1 a-full a-100 10/100BaseTXFa0/4 disabled 1 auto auto 10/100BaseTXFa0/5 disabled 1 auto auto 10/100BaseTXFa0/6 notconnect 1 auto auto 10/100BaseTX!Remaining output omittedS1#show interface fa0/3FastEthernet0/1 is up, line protocol is up (connected)Hardware is Fast Ethernet, address is 001b.5302.4e81 (bia 001b.5302.4e81)MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,reliability 255/255, txload 1/255, rxload 1/255Encapsulation ARPA, loopback not setKeepalive set (10 sec)Full-duplex, 100Mb/s, media type is 10/100BaseTXinput flow-control is off, output flow-control is unsupportedARP type: ARPA, ARP Timeout 04:00:00Last input never, output 00:00:00, output hang neverLast clearing of “show interface” counters neverInput queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0Queueing strategy: fifo