• 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 [vrf vrf-name] dampening [ip-address mask]
• View all flap statistics or for specific routes meeting the following criteria.
EXEC or EXEC Privilege mode
show ip bgp [vrf vrf-name] 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 Dell Networking OS 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.
Examples of Configuring a Route and Viewing the Number of Dampened Routes
To view the BGP configuration, use the show config command in CONFIGURATION ROUTER BGP mode or
the
show running-config bgp command in EXEC Privilege mode.
The following example shows how to configure values to reuse or restart a route. In the following example,
default = 15 is the set time before the value decrements, bgp dampening 2 ? is the set re-advertise
value, bgp dampening 2 2000 ? is the suppress value, and bgp dampening 2 2000 3000 ? is the time
to suppress a route. Default values are also shown.
Dell(conf-router_bgp)#bgp dampening ?
<1-45> Half-life time for the penalty (default = 15)
route-map Route-map to specify criteria for dampening
<cr>
Dell(conf-router_bgp)#bgp dampening 2 ?
Border Gateway Protocol IPv4 (BGPv4) 259
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