Configuring Route Dampening - Cisco IE-4000 Software Configuration Manual

Configuring IP Unicast Routing
Configuring BGP
router bgp 5
neighbor 172.16.70.24 route-reflector-client

Configuring Route Dampening

Route flap dampening minimizes 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.
BEFORE YOU BEGIN
Enable BGP routing as described in the
DETAILED STEPS
Command
1. configure terminal
2. router bgp autonomous-system
3. bgp dampening
4. bgp dampening half-life reuse suppress
max-suppress [route-map map]
5. end
6. show ip bgp flap-statistics [{regexp
regexp} | {filter-list list} | {address mask
[longer-prefix]}]
7. show ip bgp dampened-paths
8. clear ip bgp flap-statistics [{regexp
regexp} | {filter-list list} | {address mask
[longer-prefix]}
9. clear ip bgp dampening
10. copy running-config startup-config
To disable flap dampening, use the no bgp dampening router configuration command without keywords. To set
dampening factors back to the default values, use the no bgp dampening router configuration command with values.
EXAMPLE
In the following example, BGP dampening is applied to prefixes filtered through the route-map named BLUE:
Switch(config)# ip prefix-list RED permit 10.0.0.0/8
Switch(config)# !
Switch(config)# route-map BLUE
Switch(config-route-map)# match ip address ip prefix-list RED
Switch(config-route-map)# exit
Enabling BGP Routing, page
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.
(Optional) Clear BGP flap statistics to make it less likely
that a route will be dampened.
(Optional) Clear route dampening information, and
unsuppress the suppressed routes.
(Optional) Save your entries in the configuration file.
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