isis suppress-flapping peer hold-max-cost disable
Function
The isis suppress-flapping peer hold-max-cost disable command disables the Hold-max-cost mode.
The undo isis suppress-flapping peer hold-max-cost disable command enables the Hold-max-cost mode.
By default, the Hold-max-cost mode is enabled.
Format
isis suppress-flapping peer hold-max-cost disable
undo isis suppress-flapping peer hold-max-cost disable
Usage Guidelines
Usage Scenario
Flapping suppression works in either Hold-down or Hold-max-cost mode.
- Hold-down mode: In the case of frequent flooding and topology changes during neighbor relationship establishment, interfaces prevent neighbor relationship reestablishment during Hold-down suppression, which minimizes synchronization attempts and packet exchanges.
- Hold-max-cost mode: If the traffic forwarding path changes frequently, interfaces use the maximum value (16777214 for the wide mode and 63 for the narrow mode) as the cost of the flapping link during Hold-max-cost suppression, which prevents traffic from passing through the flapping link. If a device on a key path is isolated from the network due to IS-IS neighbor relationship flapping, the network is separated into two isolated parts. To prevent this problem, use the Hold-max-cost mode on the key path.
If the neighbor relationship does not go Down within successive resume-intervals, or the interval between two successive neighbor Down events is greater than or equal to resume-interval, the suppression in Hold-max-cost mode exits.
Flapping suppression can also work first in Hold-down mode and then in Hold-max-cost mode.
By default, the Hold-max-cost mode takes effect. To configure the Hold-down mode and set duration for this mode, run the isis suppress-flapping peer hold-down interval command.
Precautions
The Hold-max-cost mode takes effect only unidirectionally. If a remote device does not support IS-IS neighbor relationship flapping suppression, bidirectional traffic between the local and remote devices may travel along different paths.
