 | Copyright © 2008, Juniper Networks, Inc. All rights reserved. Trademark Notice. | |
BGP route flapping describes the situation in which BGP systems send an excessive number of update messages to advertise network reachability information. BGP flap damping is a way to reduce the number of update messages sent between BGP peers, thereby reducing the load on these peers without adversely affecting the route convergence time.
Flap damping reduces the number of update messages by marking routes as ineligible for selection as the active or preferable route. Doing this leads to some delay, or suppression, in the propagation of route information, but the result is increased network stability. You typically apply flap damping to external BGP (EBGP) routes (that is, to routes in different ASs). You can also apply it within a confederation, between confederation member ASs. Because routing consistency within an AS is important, do not apply flap damping to internal BGP (IBGP) routes. (If you do, it is ignored.)
BGP flap damping is defined in RFC 2439, BGP Route Flap Damping.
To effect changes to the default BGP flap damping values, you define actions by creating a named set of damping parameters and including it in a routing policy with the damping action (described in Table 16). For the damping routing policy to work, you also must enable BGP route flap damping.
The following sections discuss the following topics:
| Copyright © 2008, Juniper Networks, Inc. All rights reserved. Trademark Notice. | |