Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 - Manual (Page 373)

Brocade ICX 6650 Layer 3 Routing Configuration Guide 355
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Route flap dampening configuration
Globally configuring route flap dampening
To enable route flap dampening using the default values, enter the following command.
Brocade(config-bgp-router)#dampening
Syntax: dampening [half-life reuse suppress max-suppress-time]
The half-life parameter specifies the number of minutes after which the route penalty becomes half
its value. The route penalty allows routes that have remained stable for a while despite earlier
instability to eventually become eligible for use again. The decay rate of the penalty is proportional
to the value of the penalty. After the half-life expires, the penalty decays to half its value. Thus, a
dampened route that is no longer unstable can eventually become eligible for use again. You can
configure the half-life to be from 1 - 45 minutes. The default is 15 minutes.
The reuse parameter specifies how low a route penalty must become before the route becomes
eligible for use again after being suppressed. You can set the reuse threshold to a value from 1
through 20000. The default is 750 (0.75, or three-fourths, of the penalty assessed for a one
“flap”).
The suppress parameter specifies how high a route penalty can become before the Layer 3 switch
suppresses the route. You can set the suppression threshold to a value from 1 through 20000. The
default is 2000 (two “flaps”).
The max-suppress-time parameter specifies the maximum number of minutes that a route can be
suppressed regardless of how unstable it is. You can set the maximum suppression time to a value
from 1 through 20000 minutes. The default is four times the half-life setting. Thus, if you use the
default half-life of 15 minutes, the maximum suppression time is 60 minutes.
The following example shows how to change the dampening parameters.
Brocade(config-bgp-router)#dampening 20 200 2500 40
This command changes the half-life to 20 minutes, the reuse threshold to 200, the suppression
threshold to 2500, and the maximum number of minutes a route can be dampened to 40.
NOTE
To change any of the parameters, you must specify all the parameters with the command. If you want
to leave some parameters unchanged, enter their default values.
Using a route map to configure route flap dampening
for specific routes
Route maps enable you to fine tune route flap dampening parameters for individual routes. To
configure route flap dampening parameters using route maps, configure BGP4 address filters for
each route you want to set the dampening parameters for, then configure route map entries that
set the dampening parameters for those routes. The following sections show examples.
To configure address filters and a route map for dampening specific routes, enter commands such
as the following.