show interface status command.
Swtch1>show interface status Port Name Status Vlan Duplex Speed Type Fa0/1 err-disabled 1 auto auto 10/100BaseTX Fa0/2 notconnect 1 auto auto 10/100BaseTX Fa0/3 notconnect 1 auto auto 10/100BaseTX Fa0/4 notconnect 1 auto auto 10/100BaseTX Fa0/5 notconnect 1 auto auto 10/100BaseTX Fa0/6 notconnect 1 auto auto 10/100BaseTX Fa0/7 notconnect 1 auto auto 10/100BaseTX Fa0/8 notconnect 1 auto auto 10/100BaseTX Fa0/9 notconnect 1 auto auto 10/100BaseTX Fa0/10 connected 1 a-full a-100 10/100BaseTX Fa0/11 notconnect 1 auto auto 10/100BaseTX Fa0/12 connected 1 a-full a-100 10/100BaseTX Fa0/13 notconnect 1 auto auto 10/100BaseTX Fa0/14 notconnect 1 auto auto 10/100BaseTX Fa0/15 notconnect 1 auto auto 10/100BaseTX Fa0/16 connected 1 a-half a-10 10/100BaseTX Fa0/17 notconnect 1 auto auto 10/100BaseTX Fa0/18 connected 1 a-full a-100 10/100BaseTX Fa0/19 connected 1 a-full a-100 10/100BaseTX Fa0/20 notconnect 1 auto auto 10/100BaseTX Fa0/21 notconnect 1 auto auto 10/100BaseTX --More-- Port Name Status Vlan Duplex Speed Type Fa0/22 notconnect 1 auto auto 10/100BaseTX Fa0/23 notconnect 1 auto auto 10/100BaseTX Fa0/24 notconnect 1 auto auto 10/100BaseTX
In this case port 1, i.e., Fast Ethernet 0/1, is in the err-disabled state.
You can see further information the port using the show interface
port_designator command, e.g.,
show interface fa0/1.
Swtch1>show interface fa0/1
FastEthernet0/1 is down, line protocol is down (err-disabled)
Hardware is Fast Ethernet, address is 0009.e897.d281 (bia 0009.e897.d281)
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 3/255, rxload 28/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Auto-duplex, Auto-speed, media type is 100BaseTX
input flow-control is unsupported output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:05:22, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 148000 bits/sec, 59 packets/sec
3922390118 packets input, 2836932384 bytes, 0 no buffer
Received 173810 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
2946274033 packets output, 3308865164 bytes, 0 underruns
1816 output errors, 219858312 collisions, 4 interface resets
0 babbles, 0 late collision, 549016730 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
Swtch1>To bring the port back up, you can take the following steps:
enable command and then provide
the enable secret.
Swtch1>enable Password: Swtch1#
configure command and hit Enter to
accept the default value of terminal when prompted to configure
from terminal, memory, or network.
Swtch1#configure Configuring from terminal, memory, or network [terminal]? Enter configuration commands, one per line. End with CNTL/Z.
Or you can just enter configure t to skip the prompt.
interface followed by the port designator.
Swtch1(config)#interface fa0/1
shutdown command followed by no
shutdown.
Swtch1(config-if)#shutdown Swtch1(config-if)#no shutdown
exit twice
Swtch1(config-if)#exit Swtch1(config)#exit
If you then enter the show interface command for that
particular port, you will see it is up.
Hoggle#show interface fa0/1
FastEthernet0/1 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0009.e897.d281 (bia 0009.e897.d281)
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Half-duplex, 10Mb/s, media type is 100BaseTX
input flow-control is unsupported output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
3922390145 packets input, 2935343150 bytes, 0 no buffer
Received 173837 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
2 input errors, 0 CRC, 2 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
2946317008 packets output, 3313196356 bytes, 0 underruns
1831 output errors, 219862940 collisions, 10 interface resets
0 babbles, 0 late collision, 549025392 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped outIf you have not addressed the underlying problem that caused the port to be placed in an err-disabled status, though, the problem is likely to reoccur.
In this particular case I found that shortly after I issued the no
shutdown command the port would go back into the err-disabled state.
The status for the port was showing a lot of collisions. At
Errdisable Port State Recovery on the Cisco IOS Platforms,
Cisco lists excessive collisons as being one of the reasons a port will
go into the err-disabled state.
This feature was first implemented to handle special collision situations in which the switch detected excessive or late collisions on a port. Excessive collisions occur when a frame is dropped because the switch encounters 16 collisions in a row. Late collisions occur after every device on the wire should have recognized that the wire was in use.
Only half-duplex configurations should experience collisions.
A port duplex misconfiguration is a common cause of the errors because of failures to negotiate the speed and duplex properly between two directly connected devices (for example, a NIC that connects to a switch). Only half-duplex connections should ever have collisions in a LAN. Because of the carrier sense multiple access (CSMA) nature of Ethernet, collisions are normal for half duplex, as long as the collisions do not exceed a small percentage of traffic.
When I checked the port's status I saw that it was showing
a-half for the duplex seeting and a-10 for
the speed setting.
Swtch1#show interface fa0/1 status Port Name Status Vlan Duplex Speed Type Fa0/1 connected 1 a-half a-10 10/100BaseTX
That meant that the duplex and speed settings were being autonegotiated to 10 Mbs half-duplex. I thought the settings should have been 100 Mbs full-duplex. However, after it went into the err-disabled state, I would see the following.
Swtch1>show interface fa0/1 status Port Name Status Vlan Duplex Speed Type Fa0/1 err-disabled 1 auto auto 10/100BaseTX
To resolve that problem, I configured the port so the speed was set to 100 Mbs and the duplex to full duplex.
Swtch1>enable Password: Swtch1#configure Configuring from terminal, memory, or network [terminal]? Enter configuration commands, one per line. End with CNTL/Z. Swtch1(config)#interface fa0/1 Swtch1(config-if)#speed 100 Swtch1(config-if)#duplex full Swtch1(config-if)#shutdown Swtch1(config-if)#no shutdown Swtch1(config-if)#exit Swtch1(config)#exit Swtch1#show interface fa0/1 status Port Name Status Vlan Duplex Speed Type Fa0/1 notconnect 1 full 100 10/100Base
But, after seeing the status listed as notconnect, I realized
the device to which it connected was only capable of supporting the 10 Mbs
speed, so I reset the port speed and then saved the configuration changes.
Swtch1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Swtch1(config)#exit Swtch1#show interface fa0/1 status Port Name Status Vlan Duplex Speed Type Fa0/1 notconnect 1 full 100 10/100BaseTX Swtch1#enable Swtch1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Swtch1(config)#interface fa0/1 Swtch1(config-if)#speed 10 Swtch1(config-if)#shutdown Swtch1(config-if)#no shutdown Swtch1(config-if)#exit Swtch1(config)#exit Swtch1#show interface fa0/1 status Port Name Status Vlan Duplex Speed Type Fa0/1 connected 1 full 10 10/100BaseTX Hoggle#write Building configuration... [OK]
That resolved the problem; I did not see a reoccurence of the problem.
If you have enabled errdisable recovery, you can determine the
reason for the errdisable status if you issue the show errdisable
recovery command.
For this switch, when I checked the settings, I found that
errdisable recovery was disabled.
Swtch1#show errdisable recovery ErrDisable Reason Timer Status ----------------- -------------- udld Disabled bpduguard Disabled security-violatio Disabled channel-misconfig Disabled vmps Disabled pagp-flap Disabled dtp-flap Disabled link-flap Disabled psecure-violation Disabled gbic-invalid Disabled dhcp-rate-limit Disabled unicast-flood Disabled loopback Disabled Timer interval: 300 seconds Interfaces that will be enabled at the next timeout:
The errdisable recovery command allows you to choose the
type of errors that automatically reenable the ports after a specified
amount of time. See
Errdisable Port State Recovery on the Cisco IOS Platforms for further
information.
References:
Created: Tuesday March 22, 2011