How to stop PorthChannel flappings?

[lichu6444]

Good afternoon,

I have a problem with 2 links (1 Gbps each) that form a PorthChannel (2 switches, one at each end). We are paying to a carrier for those links.

The problem is that sometimes one of the 2 links starts flapping (flappings of 1 or two seconds)  so then, our applications start losing synchronization.

I need somehow to solve this to shutdown the port that starts flapping.

I want to know if there is a solution (may be udld, or use spanning tree instead of the PorthChannel) that can shutdown the port when the flapping starts.

Thanks.

Regards,

Cristian.

[glen.grant]

  This switch should put it into err-disabled if it's flapping. 

Link-flap error

Link flap means that the interface continually goes up and down. The           interface is put into the errdisabled state if it flaps more than five times in           10 seconds. The common cause of link flap is a Layer 1 issue such as a bad           cable, duplex mismatch, or bad Gigabit Interface Converter (GBIC) card. Look at           the console messages or the messages that were sent to the syslog server that           state the reason for the port shutdown.

%PM-4-ERR_DISABLE: link-flap error detected on Gi4/1, putting Gi4/
1 in err-disable state

Issue this command in order to view the flap values:

cat6knative#show errdisable flap-values!--- Refer to show errdisable flap-values for more information on the command.ErrDisable Reason    Flaps    Time (sec)
-----------------    ------   ----------
pagp-flap              3       30
dtp-flap               3       30
link-flap              5       10

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a00806cd87b.shtml

[Leo Laohoo]

What kind of links are they?  Are they fibre or copper?

If you have link flapping, do NOT use UDLD.  It'll only make matters worst.