4

We have two cisco c3850 they are uplink with fiber port 10G and i am seeing this error on that trunk (uplink) port

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

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

when i try to shut / no shut port i got following error

*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

what is UDLD why it's causing this issue.

Last week we upgrade one of switch with latest firmware 3.6.x but still second switch running on older code 3.3.x

do you think it could be version mismatch issue?

UPDATE

SW1

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

SW2

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

UPDATE 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

Update:

Talk to cisco support and they did some debug but no answer found, we replaced new cable but no luck.

But as soon as we disable UDLD on interface, interface brought up. and as soon as you enable UDLD interface goes to err-disable mode.

Cisco TAC this this could be the spanning-tree loop, Really? UDLD run on physical layer how could spanning-tree can block or disable that port?

  • 1
    Can you post a show interface Te1/1/4 from both switches? This still looks like a physical issue to me. – zevlag May 27 '16 at 18:00
  • I have opened cisco case, they said change cable and see. – Satish May 29 '16 at 22:36
1

Solution:

We had two switches.

[SW1]------10G------[SW2]

We upgraded SW1 with latest version and after upgrade UDLD failed between two switch.

We disabled UDLD on that port and everything was working file data was flowing on link both direction.

Later on SW2 upgrade switch with latest and greatest software fixed all issue and we re-enable UDLD and all good.

0

This document on UDLD (UniDirectional Link Detection) would be a good review for you.

UDLD detects that both side can receive packets, not just a physical connection, before bringing a port up. So assuming that you have verified there are no cabling issues, crossed jumper, etc, then it's a configuration setting.

Likely, you have UDLD enabled on one switch but not the other.

Try troubleshooting beginning with show udld on both sides.

  • I have updated output, it was working last week and how it just stopped working after upgrade software code on SW2 – Satish May 26 '16 at 20:56
0

It may not be UDLD but spanning tree. Once in errdisable, clear that out bu shut down both interfaces, set

switchport mode trunk
switchport trunk encapsulation dot1

then unshut both interface.

  • I believe all recent switch/router default comes/enabled with dot1q encapsulation these days. – Satish Aug 2 '16 at 19:40

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