一台Dell机，网卡为1000M网卡，接上Cisco交换机，遇到err-disabled错误，原因是link-flap,即短时间内网卡up,down过于频繁。换了一个交换机接口，没有再出现这个错误。原因不明。

一点关于link-flap的说明：

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