Reference Guide

– 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 Withdrawn routes are removed from history state.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 in FTOS 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 order in
which they arrived (starting with the most recent). Furthermore, in non-deterministic mode, the software may not
compare MED attributes though the paths are from the same AS.
• Change the best path selection method to non-deterministic.
Change the best path selection method to non-deterministic.
CONFIG-ROUTER-BGP mode
bgp non-deterministic-med
NOTE: When you change the best path selection method, path selection for existing paths remains unchanged
until you reset it by entering the clear ip bgp command in EXEC Privilege mode.
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