carrier-delay
To delay the processing of hardware link down or up notifications, use the carrier-delay command in interface configuration mode.
carrier-delay {down milliseconds [up milliseconds] | up milliseconds [down milliseconds]}
Syntax Description
down milliseconds |
Length of time, in milliseconds, to delay the processing of hardware link down notifications. Range is from 0 through 2147483647. |
up milliseconds |
Length of time, in milliseconds, to delay the processing of hardware link up notifications. Range is from 0 through 2147483647. |
Command Default
-
The carrier-delay up timer has a default value of 200 ms. There is a delay of 200 ms before the upper layer protocols are notified when a physical link goes up.
-
The carrier-delay down timer does not have a default value. The upper layer protocols are notified as quickly as possible when a physical link goes down.
Command Modes
Interface configuration
Command History
Release |
Modification |
---|---|
Release 7.0.12 |
This command was introduced. |
Release 24.2.11 |
A default value of 200 ms was introduced for the carrier-delay up timer. |
Usage Guidelines
When you delay the processing of hardware link down notifications, the higher layer routing protocols are unaware of a link until that link is stable.
If the carrier-delay down milliseconds command is configured on a physical link that fails and cannot be recovered, link down detection is increased, and it may take longer for the routing protocols to re-route traffic around the failed link.
In the case of very small interface state flaps, running the carrier-delay down milliseconds command prevents the routing protocols from experiencing a route flap.
Although the router accepts a value between 0 to 2147483647 milliseconds, the minimum value that is configured to the interface is 10 milliseconds, so as to avoid overloading the linecard control stack. We recommend that if your router has a value below 10 milliseconds, reconfigure the value to a minimum of 10 milliseconds, and if required assign a higher value.
Note |
Enter the show interface command to see the current state of the carrier-delay operation for an interface. No carrier-delay information is displayed if carrier-delay has not been configured on an interface. |
Task ID
Task ID |
Operations |
---|---|
interface |
read, write |
Examples
This example shows how to delay the processing of hardware link down notifications:
RP/0/RP0/CPU0:router(config-if)# carrier-delay down 10
The following example shows how to delay the processing of hardware link up and down notifications:
RP/0/RP0/CPU0:router(config-if)# carrier-delay up 100 down 100