Configuring Route Dampening - Cisco ME 3400 Software Configuration Manual

Configuring BGP
Usually a cluster of clients have a single route reflector, and the cluster is identified by the route reflector
router ID. To increase redundancy and to avoid a single point of failure, a cluster might have more than
one route reflector. In this case, all route reflectors in the cluster must be configured with the same 4-byte
cluster ID so that a route reflector can recognize updates from route reflectors in the same cluster. All
the route reflectors serving a cluster should be fully meshed and should have identical sets of client and
nonclient peers.
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 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.
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
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
35-60
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.
Chapter 35 Configuring IP Unicast Routing
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