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Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
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Chapter38 Configuring IP Unicast Routing Configuring BGP
When the route reflector receives an advertised route, it takes one of these actions, depending on the
neighbor:
•A route from an external BGP speaker is advertised to all clients and nonclient peers.
•A route from a nonclient peer is advertised to all clients.
•A route from a client is advertised to all clients and nonclient peers. Hence, the clients ne ed not be
fully meshed.
Usually a cluster of clients have a single route reflector, and the cluster is identified by the r oute 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 update s from rout e ref lect ors in th e same clust er. 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 refl ect or a nd clie nts:
Configuring Route Dampening
Route flap dampening is a BGP feature designed to minimize t he 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.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 router bgp autonomous-system Enter BGP router configuration mode.
Step3 neighbor ip-address | peer-group-name
route-reflector-client Configure the local router as a BGP route reflector and the
specified neighbor as a client.
Step4 bgp cluster-id cluster-id (Optional) Configure the cluster ID if the cluster has more than
one route reflector.
Step5 no bgp client-to-client reflection (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.
Step6 end Return to privileged EXEC mode.
Step7 show ip bgp Verify the configuration. Display the originator ID and the
cluster-list attributes.
Step8 copy running-config startup-config (Optional) Save your entries in the configuration file.