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Chapter 39
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 to minimize the propagation of flapping routes across an
internetwork. A route is 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 the accumulated penalties for a route reach the configured 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 autonomous system.
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
OL-13270-06
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.
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
Configuring BGP
39-67
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