我们有两个 cisco，c3850它们与光纤端口 10G 上行链路，我在该中继（上行链路）端口上看到此错误

[c3850]-----10G----[c3850]

TenGigabitEthernet1/1/4 is down, line protocol is down (err-disabled)

当我尝试关闭/不关闭端口时出现以下错误

*May 26 10:12:02.506: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/1/4, changed state to upsh int *May 26 10:12:04.405: %UDLD-4-UDLD_PORT_DISABLED: UDLD disabled interface Te1/1/4, unidirectional link detected *May 26 10:12:04.405: %PM-4-ERR_DISABLE: udld error detected on Te1/1/4, putting Te1/1/4 in err-disable state *May 26 10:12:05.409: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/1/4, changed state to down *May 26 10:12:06.405: %LINK-3-UPDOWN: Interface TenGigabitEthernet1/1/4, changed state to down

什么是 UDLD 为什么会导致此问题。

上周我们用最新的固件升级了其中一个交换机，3.6.x但仍然使用旧代码运行第二个交换机3.3.x

你认为这可能是版本不匹配的问题吗？

更新

开关1

Interface Te1/1/4
---
Port enable administrative configuration setting: Follows device default
Port enable operational state: Enabled
Current bidirectional state: Unknown
Current operational state: Link down
Message interval: 7000 ms
Time out interval: 5000 ms

Port fast-hello configuration setting: Disabled
Port fast-hello interval: 0 ms
Port fast-hello operational state: Disabled
Neighbor fast-hello configuration setting: Disabled
Neighbor fast-hello interval: Unknown

No neighbor cache information stored

开关2

Interface Te1/1/4
---
Port enable administrative configuration setting: Follows device default
Port enable operational state: Enabled
Current bidirectional state: Unidirectional
Current operational state: Disabled port
Message interval: 7000 ms
Time out interval: 5000 ms

Port fast-hello configuration setting: Disabled
Port fast-hello interval: 0 ms
Port fast-hello operational state: Disabled
Neighbor fast-hello configuration setting: Disabled
Neighbor fast-hello interval: Unknown

No neighbor cache information stored

更新 2

SW2#sh interfaces te1/1/4
TenGigabitEthernet1/1/4 is down, line protocol is down (err-disabled)
  Hardware is Ten Gigabit Ethernet, address is 6c99.8962.2938 (bia 6c99.8962.2938)
  Description: Connect_to_SW1
  MTU 1500 bytes, BW 10000000 Kbit/sec, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive not set
  Full-duplex, 10Gb/s, link type is auto, media type is SFP-10G-ACTIVE-CABLE
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 3d04h, output never, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/2000/0/0 (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
     825762 packets input, 163952509 bytes, 0 no buffer
     Received 173 broadcasts (121 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 121 multicast, 0 pause input
     0 input packets with dribble condition detected
     362 packets output, 42206 bytes, 0 underruns
     0 output errors, 0 collisions, 3 interface resets
     0 unknown protocol drops
     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

SW1：

SW1#sh int te1/1/4
TenGigabitEthernet1/1/4 is down, line protocol is down (notconnect)
  Hardware is Ten Gigabit Ethernet, address is 6c99.8962.38b8 (bia 6c99.8962.38b8)
  Description: Connect_to_SW2
  MTU 1500 bytes, BW 10000000 Kbit/sec, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive not set
  Full-duplex, 10Gb/s, link type is auto, media type is SFP-10GBase-CX1
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 3d04h, output never, output hang never
  Last clearing of "show interface" counters 2y4w
  Input queue: 0/2000/0/0 (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
     39504875093 packets input, 4530561503783 bytes, 0 no buffer
     Received 74817556 broadcasts (70452372 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 70452372 multicast, 0 pause input
     0 input packets with dribble condition detected
     5520672431 packets output, 1374955280906 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 unknown protocol drops
     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

更新：

与 cisco 支持人员交谈，他们进行了一些调试，但没有找到答案，我们更换了新电缆但没有运气。

但是一旦我们在接口上禁用 UDLD，接口就会启动。并且一旦您启用 UDLD 接口就会进入错误禁用模式。

Cisco TAC 这可能是生成树循环，真的吗？UDLD 在物理层上运行，生成树如何阻止或禁用该端口？