link-flap err-disabled

[Carpua]

hi all

i have a port that keeps going into err-disabled mode and shutdown. i configured err-disabled recovery on the switch but the port still doesn't get back up. below is a log results and err-disabled configuration

Aug 29 07:09:20.628: %PM-4-ERR_DISABLE: link-flap error detected on Gi0/42, putting Gi0/42 in err-disable state
Aug 29 07:09:45.517: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/35, changed state to down
Aug 29 07:09:50.626: %PM-4-ERR_RECOVER: Attempting to recover from link-flap err-disable state on Gi0/42
Aug 29 07:10:19.835: %PM-4-ERR_DISABLE: link-flap error detected on Gi0/42, putting Gi0/42 in err-disable state
Aug 29 07:10:49.833: %PM-4-ERR_RECOVER: Attempting to recover from link-flap err-disable state on Gi0/42
Aug 29 07:13:59.122: %PM-4-ERR_DISABLE: link-flap error detected on Gi0/42, putting Gi0/42 in err-disable state
Aug 29 07:14:29.120: %PM-4-ERR_RECOVER: Attempting to recover from link-flap err-disable state on Gi0/42

ErrDisable Reason Timer Status
----------------- --------------
bpduguard Enabled
channel-misconfig Enabled
dhcp-rate-limit Enabled
dtp-flap Enabled
gbic-invalid Enabled
inline-power Enabled
link-flap Enabled
mac-limit Enabled
loopback Enabled
pagp-flap Enabled
port-mode-failure Enabled
psecure-violation Enabled
security-violation Enabled
sfp-config-mismatch Enabled
small-frame Enabled
storm-control Enabled
udld Enabled
vmps Enabled

Timer interval: 30 seconds

Interfaces that will be enabled at the next timeout:

 

[chieftan]

Do you know what device is actually attached to this interface?

What does "show mac address-table" show you?
"show arp" or "show ip arp"?

 

[VinceWhirlwind]

Rather than worrying about recovering from err-disable, I'd personally focus more on preventing it from happening in the first place.

Show run interface - what is it configured as? Has somebody been silly and disabled auto-negotiate?
Show interface - what kind of errors are you getting? What kind of throughput is it getting when it's up?
If it's running at 1Gb, slow it down to 100Mb. If the errors disappear, then replace the cabling and try setting it to 1Gb again.

 

[Carpua]

Chieftan

its connected to an HP docking station.

VinceWhirlwind

GigabitEthernet0/42 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 18ef.6396.2b2c (bia 18ef.6396.2b2c)
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)
Full-duplex, 100Mb/s, 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 never, output 00:00:01, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 267508
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 261000 bits/sec, 220 packets/sec
20412486 packets input, 9020840366 bytes, 0 no buffer
Received 92875 broadcasts (56309 multicasts)
0 runts, 106 giants, 0 throttles
346 input errors, 238 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 56309 multicast, 368 pause input
0 input packets with dribble condition detected
59573239 packets output, 19365989605 bytes, 0 underruns
0 output errors, 0 collisions, 5 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

interface GigabitEthernet0/42
switchport access vlan 115
switchport mode access
end

 

[chieftan]

When you complete a "show ver" what is the uptime of the switch?

You have a fw CRC errors there which could indicate a duplex / speed issue. As the port is set to 100/FULL in Auto mode (In other words you have not configured these settings manually), it might be an idea to check what the speed and duplex settings are on the laptop that normally resides in the docking station.

The reason I ask about what is attached is the norm is for a port to err-disable when security is enabled on the specific port (via mac address or amount of failures allowed before shutting down and err-disabled)

You also have some "Giants", which are packets larger than the 1500 MTU and are dropped by the switch and not forwarded as these packets are not fragmented.

It may be a good idea to mirror the port and, in promiscouos mode, get a wireshark trace to see what packets are causing the Giants.

The reason I ask for the uptime of the switch is to try and ascertain if these CRC's and giants are over a short space of time or a longer period.

You could also take a snapshot of the current interface counter statistics and then reset the counters for the interface and monitor. See what erros occur before the interface goes back into err-disabled.

After all of this, you may even find that there is a hardware fault with that interface.

 

[chieftan]

Apologies, should have asked this as well......

Are you running a default STP setup (in other words, just attaching the switch to the network and allowing it to sort itself out) or are you actually running a pre-configured STP topology that has been designed by yourself or the Architect?

BPDUGuard could also cause the port to go err-disable.

 

[VinceWhirlwind]

From that information, I would be looking at the docking station. Do you have a spare? Or swap it with somebody else's - move this docking station to somebody else's desk and see if the problem travels with it.