Error disable Switch port

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Sep 22nd, 2010
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I had posted this on WAN forum,


I got issue on the switchport connecting to Wireless_outdoor_AP, all of a sudden the port becomes error_disable.

I shutdown the port and make the port default then it starts working again. Again after couple of days it goes off.

Cisco recommended to configure error-disable recovery and error-disable time but it doesnt help.

Can you expert can recommend solution to overcome this issue.

Switch : 2960 48 ports

Wireless_outdoor_AP : Wilan

show errdisable detect
ErrDisable Reason    Detection status
-----------------    ----------------
udld                 Enabled
bpduguard            Enabled
security-violatio    Enabled
channel-misconfig    Enabled
psecure-violation    Enabled
unicast-flood        Enabled
vmps                 Enabled
loopback             Enabled
unicast-flood        Enabled
pagp-flap            Enabled
dtp-flap             Enabled
link-flap            Enabled
sfp-config-mismat    Enabled
gbic-invalid         Enabled
dhcp-rate-limit      Enabled
storm-control        Enabled
arp-inspection       Enabled
community-limit      Enabled
invalid-policy       Enabled


sh interfaces status err-disabled

Port      Name               Status       Reason
Fa0/38                       err-disabled link-flap
Fa0/44                     err-disabled loopback

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Leo Laohoo Wed, 09/22/2010 - 15:34
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The question is "WHY" is your port going into error disable.

If it's a link-flap then there is a chance that you have a faulty cable.  The good part of this all is that you have a 2960 with in-build TDR (crude but good enough).

Use the command "test cable tdr int ", wait for about 8 seconds before invoke the result using the command "sh cable tdr int ".

NOTE:  If you are running IOS earlier than 12.2(46) this command is DISRUPTIVE.  IF you have IOS version newer to this, then it's OK.

Good result is "OK" or "Normal".  Anything else is bad.  Also, because you have a 10/100BaseTx, don't be alarm if the result is for the first two pairs.  This is normal.  If you have gig ports then you will have a result of all four pairs.

Hope this helps.

Souvik Ghosh Wed, 09/22/2010 - 17:36
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It would be better to check the speed/duplex settin as well.


anthony.dyne Thu, 09/23/2010 - 00:04
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I got this as output

Interface Speed Local pair Pair length        Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Fa0/45    100M  Pair A     10   +/- 15 meters Pair A      Normal             
                Pair B     10   +/- 15 meters Pair B      Normal             
                Pair C     N/A                Pair C      Not Supported      
                Pair D     N/A                Pair D      Not Supported

How do I overcome this issue.

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NickNac79 Thu, 09/23/2010 - 00:13
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Hi Antony,

This is connecting to an outside Wireless AP, is there any chance that the cable that is feeding the AP is loose outside and is flapping when the wind blows?  There may be a microbreak in the cable that only presents when the cable is in certain positions (i.e. when the wind is blowing hard and the cable is flapping)

Check to ensure it's properly secured.

Also, have you tried the AP connected to a different port on the switch?


anthony.dyne Thu, 09/23/2010 - 01:10
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Nick what you mentioned is very much possible. Can we bypass this for outdoor Wireless links.

I have checked on 5 different ports but its the same, even changed the switch with new IOS ; still the same

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