几天前，使用一台cisco 2950交换机和tp-link 24口的100mb端口的交换机级联。导致cisco 2950设备上的级联端口在使用一天后，第二天早上上班时发现端口显示err-disabled.网络不通。如何处理？

查看接口状况：

GX-SW-2950-01#sh interfaces f0/2

FastEthernet0/2 is down, line protocol is down (err-disabled)

  Hardware is Fast Ethernet, address is 0011.bb48.d4c2 (bia 0011.bb48.d4c2)

  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, 

     reliability 254/255, txload 1/255, rxload 1/255

  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 12:08:35, output 12:08:35, 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

     7828496 packets input, 3836732423 bytes, 0 no buffer

     Received 153627 broadcasts (0 multicast)

     0 runts, 0 giants, 0 throttles

     2 input errors, 1 CRC, 1 frame, 0 overrun, 0 ignored

     0 watchdog, 89124 multicast, 0 pause input

     0 input packets with dribble condition detected

     7809493 packets output, 2721732114 bytes, 0 underruns

     0 output errors, 0 collisions, 2 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

只有2 input errors, 1 CRC, 1 frame,2 interface resets。按道理不足以导致接口进入err-disabled状态。

没有办法，只能配置err-disabled。启用recovery功能。命令如下：

GX-SW-2950-01(config)#errdisable recovery interval 30

GX-SW-2950-01(config)#errdisable recovery cause all

经过几天测试，可以正常使用。可惜的事情，没有搞清楚为何进入err-disabled状态。原因有很多种可能。但不知道是哪个。下面是cisco默认提供的几种可能原因：

GX-SW-2950-01#show errdisable detect 

ErrDisable Reason    Detection status

-----------------    ----------------

udld                 Enabled

bpduguard            Enabled

security-violatio    Enabled

channel-misconfig    Enabled

psecure-violation    Enabled

dhcp-rate-limit      Enabled

unicast-flood        Enabled

vmps                 Enabled

pagp-flap            Enabled

dtp-flap             Enabled

link-flap            Enabled

gbic-invalid         Enabled

loopback             Enabled

dhcp-rate-limit      Enabled

unicast-flood        Enabled

其实可以单独测试每一条。以找出真正的原因，但有15种可能。想想还是算了。

cisco 2950级联tp-link，端口老是err-disabled。导致网络不通，如何处理？