Brocade Virtual ADX Switch and Router Guide (Supporting ADX v03.1.00) - Manual (Page 278)

264 Brocade Virtual ADX Switch and Router Guide
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Filtering
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• Maximum suppression time – Specifies the maximum number of minutes a route can be
suppressed regardless of how unstable the route has been before this time. You can set the
parameter to a value from 1 – 20000 minutes. The default is four times the half-life. When the
half-life value is set to its default (15 minutes), the maximum suppression time defaults to 60
minutes.
You can configure route flap dampening globally or for individual routes using route maps. If you
configure route flap dampening parameters globally and also use route maps, the settings in the
route maps override the global 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.
Using a route map to configure route flap dampening for a specific neighbor
You can use a route map to configure route flap dampening for a specific neighbor by performing
the following tasks:
• Configure an empty route map with no match or set clauses. This route map does not specify
particular routes for dampening but does allow you to enable dampening globally when you
refer to this route map from within the BGP4 configuration level.
• Configure another route map that explicitly enables dampening. Use a set clause within the
route map to enable dampening. When you associate this route map with a specific neighbor,
the route map enables dampening for all routes associated with the neighbor. You also can use
match clauses within the route map to selectively perform dampening on some routes from the
neighbor.
NOTE
You still need to configure the first route map to enable dampening globally. The second route
map does not enable dampening by itself; it just applies dampening to a neighbor.
• Apply the route map to the neighbor.
To enable route flap dampening for a specific BGP4 neighbor, enter commands such as the
following.
Virtual ADX(config)# route-map DAMPENING_MAP_ENABLE permit 1
Virtual ADX(config-routemap DAMPENING_MAP_ENABLE)# exit
Virtual ADX(config)# route-map DAMPENING_MAP_NEIGHBOR_A permit 1
Virtual ADX(config-routemap DAMPENING_MAP_NEIGHBOR_A)# set dampening
Virtual ADX(config-routemap DAMPENING_MAP_NEIGHBOR_A)# exit
Virtual ADX(config)# router bgp
Virtual ADX(config-bgp-router)# dampening route-map DAMPENING_MAP_ENABLE
Virtual ADX(config-bgp-router)# neighbor 10.10.10.1 route-map in
DAMPENING_MAP_NEIGHBOR_A
In this example, the first command globally enables route flap dampening. This route map does not
contain any match or set clauses. At the BGP4 configuration level, the dampening route-map
command refers to the DAMPENING_MAP_ENABLE route map created by the first command, thus
enabling dampening globally.