Users Guide

Layer 2 Switching Commands 399
User Guidelines
The link bounce time configures a link bounce hysteresis on link loss of link.
Loss of link signal starts a link bounce timer. If the link is restored prior to
expiry of the timer, operation continues and the system is not notified that
that link connectivity has been lost. Hysteresis can be used to mitigate link
flaps caused by bad cabling or partially inserted optics or cables.
The debounce timer resolution is approximately 10 ms. Setting a value will
start the timer when loss of link is detected.
Ports operating at lower speeds may benefit from debounce values larger than
the default. Ports operating over fiber generally do not require larger
debounce times.
Use the show interfaces debounce command to display the link debounce
time or to display the link flap count (the number of notifications sent to the
system that link signal was lost). The link flap count is also displayed by the
show interfaces command (Link Debounce Flaps).
The link debounce counter is cleared by the clear counters command and the
clear counters interface-id command.
In general, a debounce time above 300 ms is recommended for copper
interfaces with link flaps.
Command History
Introduced in version 6.2.0.1 firmware.
Example
The following example disables the link debounce timer for interface gi1/0/1.
switch# conf t
console(config)#interface gi1/0/1
console(config-if-Gi1/0/1)#no link debounce time
The following example sets the link debounce timer for interface gi1/0/1 to
500 ms.
switch# conf t
console(config)#interface gi1/0/1
console(config-if-Gi1/0/1)#link debounce time 500