Interface and Hardware Components Configuration Guide, Cisco IOS XE 17.16.x (Catalyst 9500 Switches)

Restrictions for Link Debounce Timer

The following are restrictions for configuring link debounce timer:

On Cisco Catalyst 9500 Series Switches - High Performance, link debounce configuration is supported at port level.
On Cisco Catalyst 9500X Series Switches, link debounce configuration is supported only on the global level, port level configuration is not supported.
If you have configured StackWise Virtual Link (SVL) and Dual-Active Detection (DAD) on an interface, then configuring link debounce globally can cause instability in SVL and DAD links.
To ensure optimal link stability and minimize the impact on upper-layer protocols during PSM switchover, it is recommended to configure the Link Debounce Timer to 1200ms on all interfaces that are directly connected between Cisco Catalyst 9500 Series Switches - High Performance and Cisco ONS DWDM PSM modules.

Information About Link Debounce Timer

The Link Debounce Timer delays notification of a link up or down status change. Delayed notification of a link status change can decrease traffic loss due to network reconfiguration when network ethernet port experiences minor faults in the link.

If the status of a link changes quickly from up to down and then back to up, the Link Debounce Timer suppresses the link down status notification. If the link transitions from up to down, but does not come back up, the Link Debounce Timer delays the link down status notification until the debounce timer expires.

Delayed link status notification allows a quick port status change and recovery without triggering any of the changes that are necessary when a port status changes (up or down). The normal operation of Dense Wavelength Division Multiplexing (DWDM) links includes quick port status changes and recovery during DWDM network reconvergence. Delayed link status notification can also be used to mitigate link flaps because of bad cabling.

Note

Enabling the port debounce timer causes link up or down detections to be delayed, resulting in loss of traffic during the debouncing period. This situation might affect the convergence and reconvergence of some Layer 2 and Layer 3 protocols.

Recommendations for deploying the Link Debounce Timer on Catalyst 9500 Series Switches-High Performance

We recommend that you set the Link Debounce Timer to 1200 ms on Catalyst 9500 Series Switches-High Performance interfaces that connect to DWDM Protection Switch Modules (PSMs) to avoid link or port flaps during PSM failover events. Due to hardware limitations, increasing the timer value beyond 1200 ms is not recommended.

Even if the flap between both connections takes 50 ms, 100 ms, or 150 ms, the PHY may be unable to recover in time due to hardware limitations, and you may still receive notifications about the link going down.

Configuring Link Debounce Timer

To configure Link Debounce Timer on Cisco Catalyst 9500 Series Switches - High Performance port, perform this task:

Procedure

	Command or Action	Purpose
Step 1	enable Example: `Device> enable`	Enables privileged EXEC mode. Enter your password, if prompted.
Step 2	configure terminal Example: `Device# configure terminal`	Enters global configuration mode.
Step 3	interface `interface` `interface-id` Example: `Device(config)# interface fortygigabitEthernet 1/0/10`	Enters interface configuration mode and selects the link to configure.
Step 4	link debounce [time `debounce-time`] Example: `Device(config-if)# link debounce time 360`	Configures the debounce timer in milli seconds. Maximum allowed timer is 1200 ms.
Step 5	end Example: `Device(config-if)# end`	Returns to privileged EXEC mode.
Step 6	show interface `interface-id` debounce or show interface debounce Example: `Device# show interface debounce`	Verifies the configuration.

Configuring Link Debounce Up Timer

To configure Link Debounce Up Timer for Cisco Catalyst 9500X Series Switches globally, perform this task:

Procedure

Command or Action Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode. Enter your password, if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

system debounce link-up debounce-time

Example:

Device(config)# system debounce link-up 360

Enables and configures the debounce up timer in milli seconds. The timer range is from 120ms to 10000ms.

Note

Link debounce up timer is disabled by default.

Configuring Link Debounce Down Timer

To configure Link Debounce Down Timer for Cisco Catalyst 9500X Series Switches globally, perform this task:

Procedure

Command or Action Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode. Enter your password, if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

system debounce link-down debounce-time]

Example:

Device(config)# system debounce link-down 360

Enables and configures the debounce down timer in milli seconds. The timer range is from 120ms to 10000ms.

Note

Link debounce down timer is disabled by default.

Example: Configuring the Link Debounce Timer

The following example shows how to enable Link Debounce Timer on a FortygigabitEthernet port for Cisco Catalyst 9500 Series Switches - High Performance.

Device(config)# interface fortygigabitEthernet 1/0/10
Device(config-if)# link debounce time 360
Warning: Enabling debounce feature causes link down detection to be delayed

The following examples show how to verify the Link Debounce Timer configuration for Cisco Catalyst 9500 Series Switches - High Performance.

Device# show interface fortygigabitEthernet 1/0/10 debounce 

Port         Debounce time   Value(ms)
Fo1/0/10     enable               360

Device# show interfaces debounce

Port         Debounce time   Value(ms)
Fo1/0/1      disable         
Fo1/0/2      disable         
Fo1/0/3      enable          1200 
Fo1/0/4      disable         
Fo1/0/5      disable         
Fo1/0/6      disable         
Fo1/0/7      disable         
Fo1/0/8      disable         
Fo1/0/9      disable         
Fo1/0/10     enable          360  
Fo1/0/11     disable         
Fo1/0/12     enable          240  
Fo1/0/13     disable

Feature History for Link Debounce Timer

This table provides release and related information for the features explained in this module.

These features are available in all the releases subsequent to the one they were introduced in, unless noted otherwise.


Release	Feature	Feature Information
Cisco IOS XE Bengaluru 17.6.1	Link Debounce Timer	The Link Debounce Timer feature delays notification of a link down status change. Delayed notification of a linkdown status change can decrease traffic loss due to network reconfiguration when network ethernet portexperiences minor faults in the link. Support for this feature was introduced only on the C9500-32C, C9500-32QC, C9500-48Y4C, and C9500-24Y4C models of the Cisco Catalyst 9500 Series Switches.
Cisco IOS XE Dublin 17.12.4	Link Debounce Up/Down Timer	The Link Debounce Up/Down Timer feature delays notification of a link from down to up status change. Delayed notification of a linkdown status change can decrease traffic loss due to network reconfiguration when network ethernet portexperiences minor faults in the link. Support for this feature was introduced only on Cisco Catalyst 9500X Series Switches in global configuration mode.
Cisco IOS XE 17.15.1	Link Debounce Up/Down Timer	The Link Debounce Up/Down Timer feature delays notification of a link from down to up status change. Delayed notification of a linkdown status change can decrease traffic loss due to network reconfiguration when network ethernet portexperiences minor faults in the link. Support for this feature was introduced only on Cisco Catalyst 9500X Series Switches in global configuration mode.

Use the Cisco Feature Navigator to find information about platform and software image support. To access Cisco Feature Navigator, go to Cisco Feature Navigator.

Bias-Free Language

Book Title

Interface and Hardware Components Configuration Guide, Cisco IOS XE 17.16.x (Catalyst 9500 Switches)

Chapter Title

Configuring Link Debounce Timer

Results

Chapter: Configuring Link Debounce Timer

Configuring Link Debounce Timer

Restrictions for Link Debounce Timer

Information About Link Debounce Timer

Recommendations for deploying the Link Debounce Timer on Catalyst 9500 Series Switches-High Performance

Configuring Link Debounce Timer

Procedure

Example:

Example:

Example:

Example:

Example:

Example:

Configuring Link Debounce Up Timer

Procedure

Example:

Example:

Example:

Configuring Link Debounce Down Timer

Procedure

Example:

Example:

Example:

Example: Configuring the Link Debounce Timer

Feature History for Link Debounce Timer

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