Configuring Route Dampening - Cisco WS-C3560-48PS-S Software Configuration Manual

Chapter 30 Configuring IP Unicast Routing
Beginning in privileged EXEC mode, use these commands to configure a route reflector and clients:
Command
Step 1
configure terminal
Step 2
router bgp autonomous-system
Step 3
neighbor ip-address | peer-group-name
route-reflector-client
Step 4 bgp cluster-id cluster-id
Step 5 no bgp client-to-client reflection
Step 6 end
Step 7
show ip bgp
Step 8
copy running-config startup-config

Configuring Route Dampening

Route flap dampening is a BGP feature designed to minimize the propagation of flapping routes across
an internetwork. A route is considered to be flapping when it is repeatedly available, then unavailable,
then available, then unavailable, and so on. When route dampening is enabled, a numeric penalty value
is assigned to a route when it flaps. When a route's accumulated penalties reach a configurable limit,
BGP suppresses advertisements of the route, even if the route is running. The reuse limit is a
configurable value that is compared with the penalty. If the penalty is less than the reuse limit, a
suppressed route that is up is advertised again.
Dampening is not applied to routes that are learned by IBGP. This policy prevents the IBGP peers from
having a higher penalty for routes external to the AS.
Beginning in privileged EXEC mode, use these commands to configure BGP route dampening:
Command
Step 1
configure terminal
Step 2 router bgp autonomous-system
Step 3 bgp dampening
Step 4
bgp dampening half-life reuse suppress
max-suppress [route-map map]
Step 5
end
Step 6 show ip bgp flap-statistics [{regexp regexp} |
{filter-list list} | {address mask [longer-prefix]}]
Step 7
show ip bgp dampened-paths
78-16156-01
Purpose
Enter global configuration mode.
Enter BGP router configuration mode.
Configure the local router as a BGP route reflector and the
specified neighbor as a client.
(Optional) Configure the cluster ID if the cluster has more than
one route reflector.
(Optional) Disable client-to-client route reflection. By default,
the routes from a route reflector client are reflected to other
clients. However, if the clients are fully meshed, the route
reflector does not need to reflect routes to clients.
Return to privileged EXEC mode.
Verify the configuration. Display the originator ID and the
cluster-list attributes.
(Optional) Save your entries in the configuration file.
Purpose
Enter global configuration mode.
Enter BGP router configuration mode.
Enable BGP route dampening.
(Optional) Change the default values of route dampening
factors.
Return to privileged EXEC mode.
(Optional) Monitor the flaps of all paths that are flapping. The
statistics are deleted when the route is not suppressed and is
stable.
(Optional) Display the dampened routes, including the time
remaining before they are suppressed.
Catalyst 3560 Switch Software Configuration Guide
Configuring BGP
30-61