2012 年 7 月 23 日 中午登录192.168.15.10思科2960交换机，发现VLAN17的两个端口仍然处于err-disabled状态，下面是解决办法。
User Access Verification
Password:
dabaicai10>enable
Password:
dabaicai10#sh int status err-d
dabaicai10#sh int status err-disabled
Port Name Status Reason Err-disabled Vlans
Gi0/17 err-disabled loopback
Gi0/27 err-disabled loopback
dabaicai10#sh errdisable detect
ErrDisable Reason Detection Mode
----------------- --------- ----
arp-inspection Enabled port
bpduguard Enabled port
channel-misconfig Enabled port
community-limit Enabled port
dhcp-rate-limit Enabled port
dtp-flap Enabled port
gbic-invalid Enabled port
inline-power Enabled port
invalid-policy Enabled port
link-flap Enabled port
loopback Enabled port
lsgroup Enabled port
mac-limit Enabled port
pagp-flap Enabled port
port-mode-failure Enabled port
psecure-violation Enabled port/vlan
security-violation Enabled port
sfp-config-mismatch Enabled port
small-frame Enabled port
storm-control Enabled port
udld Enabled port
vmps Enabled port
dabaicai10#sh errdisable recovery
ErrDisable Reason Timer Status
----------------- --------------
arp-inspection Disabled
bpduguard Disabled
channel-misconfig Disabled
dhcp-rate-limit Disabled
dtp-flap Disabled
gbic-invalid Disabled
inline-power Disabled
link-flap Disabled
mac-limit Disabled
loopback Disabled
pagp-flap Disabled
port-mode-failure Disabled
psecure-violation Disabled
security-violation Disabled
sfp-config-mismatch Disabled
small-frame Disabled
storm-control Disabled
udld Disabled
vmps Disabled
Timer interval: 300 seconds
Interfaces that will be enabled at the next timeout:
dabaicai10#conf t
Enter configuration commands, one per line. End with CNTL/Z.
dabaicai10(config)#errdisable recovery loop
dabaicai10(config)#errdisable recovery cause loopb
dabaicai10(config)#errdisable recovery cause loopback //err-disabled端口恢复添加环路这一项
dabaicai10(config)#errdisable recovery interval 30 //配置超时时间30秒
dabaicai10(config)#
如果没有配置超时恢复功能，或者想在超时之前使端口恢复正常，则需要在端口上shutdown和noshutdown，这样才能让端口恢复到forwarding正常状态。
dabaicai10#sh errdisable recovery
ErrDisable Reason Timer Status
----------------- --------------
arp-inspection Disabled
bpduguard Disabled
channel-misconfig Disabled
dhcp-rate-limit Disabled
dtp-flap Disabled
gbic-invalid Disabled
inline-power Disabled
link-flap Disabled
mac-limit Disabled
loopback Enabled
pagp-flap Disabled
port-mode-failure Disabled
psecure-violation Disabled
security-violation Disabled
sfp-config-mismatch Disabled
small-frame Disabled
storm-control Disabled
udld Disabled
vmps Disabled
Timer interval: 30 seconds
Interfaces that will be enabled at the next timeout:
现在重新查看处于err-disabled状态的端口，没有发现处于此状态的端口，如下：
dabaicai10#sh int status err-disabled
查看17号端口状况：
dabaicai10#sh int status err-disabled
dabaicai10#sh int gi0/17
GigabitEthernet0/17 is down, line protocol is down (notconnect)
Hardware is Gigabit Ethernet, address is b8be.bf4e .1f 91 (bia b8be.bf4e .1f 91)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Auto-duplex, Auto-speed, media type is 10/100/1000BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 1w0d, output 1w0d, 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: 0/0 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
93950698 packets input, 71258537104 bytes, 0 no buffer
Received 434636 broadcasts (56052 multicasts)
0 runts, 2 giants, 0 throttles
5 input errors, 3 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 56052 multicast, 0 pause input
0 input packets with dribble condition detected
93836379 packets output, 91682002748 bytes, 0 underruns
0 output errors, 0 collisions, 3 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
查看27号口：
dabaicai10#sh int gi0/27
GigabitEthernet0/27 is down, line protocol is down (notconnect)
Hardware is Gigabit Ethernet, address is b8be.bf4e .1f 9b (bia b8be.bf4e .1f 9b)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Auto-duplex, Auto-speed, media type is 10/100/1000BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 1w0d, output 1w0d, 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: 0/0 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
10364564242 packets input, 5588212311201 bytes, 0 no buffer
Received 1216372196 broadcasts (16084363 multicasts)
0 runts, 1 giants, 0 throttles
36 input errors, 35 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 16084363 multicast, 0 pause input
0 input packets with dribble condition detected
9735409446 packets output, 9222664589218 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
Gi0/17 与Gi0/27均已不是err-disabled状态。