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flapping, or change the path selection from the default mode (deterministic) to non-deterministic, use the
following commands.
•
Enable route dampening.
CONFIG-ROUTER-BGP mode
bgp dampening [half-life | reuse | suppress max-suppress-time] [route-map map-
name]
Enter the following optional parameters to configure route dampening parameters:
•
half-life: the range is from 1 to 45. Number of minutes after which the Penalty is decreased. After
the router assigns a Penalty of 1024 to a route, the Penalty is decreased by half after the half-life
period expires. The default is 15 minutes.
•
reuse: the range is from 1 to 20000. This number is compared to the flapping route's Penalty value.
If the Penalty value is less than the reuse value, the flapping route is once again advertised (or no
longer suppressed). Withdrawn routes are removed from history state. The default is 750.
•
suppress: the range is from 1 to 20000. This number is compared to the flapping route's Penalty
value. If the Penalty value is greater than the suppress value, the flapping route is no longer
advertised (that is, it is suppressed). The default is 2000.)
•
max-suppress-time: the range is from 1 to 255. The maximum number of minutes a route can be
suppressed. The default is four times the half-life value. The default is 60 minutes.
•
route-map map-name: name of a configured route map. Only match commands in the configured
route map are supported. Use this parameter to apply route dampening to selective routes.
•
Enter the following optional parameters to configure route dampening.
CONFIG-ROUTE-MAP mode
set dampening half-life reuse suppress max-suppress-time
•
half-life: the range is from 1 to 45. Number of minutes after which the Penalty is decreased. After
the router assigns a Penalty of 1024 to a route, the Penalty is decreased by half after the half-life
period expires. The default is 15 minutes.
•
reuse: the range is from 1 to 20000. This number is compared to the flapping route's Penalty value.
If the Penalty value is less than the reuse value, the flapping route is once again advertised (or no
longer suppressed). The default is 750.
•
suppress: the range is from 1 to 20000. This number is compared to the flapping route's Penalty
value. If the Penalty value is greater than the suppress value, the flapping route is no longer
advertised (that is, it is suppressed). The default is 2000.
•
max-suppress-time: the range is from 1 to 255. The maximum number of minutes a route can be
suppressed. The default is four times the half-life value. The default is 60 minutes.
•
Clear all information or only information on a specific route.
EXEC Privilege
clear ip bgp dampening [ip-address mask]
•
View all flap statistics or for specific routes meeting the following criteria.
EXEC or EXEC Privilege mode
show ip bgp flap-statistics [ip-address [mask]] [filter-list as-path-name]
[regexp regular-expression]
•
ip-address [mask]: enter the IP address and mask.
•
filter-list as-path-name: enter the name of an AS-PATH ACL.
•
regexp regular-expression: enter a regular express to match on.
By default, the path selection is deterministic, that is, paths are compared irrespective of the order of their
arrival. You can change the path selection method to non-deterministic, that is, paths are compared in the
Border Gateway Protocol IPv4 (BGPv4)
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Troubleshooting
