BGP: Difference between revisions
→BGP Route Dampening
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= BGP Route Dampening =
Source: [https://www.noction.com/blog/bgp-dampening noction.com]
* The unstable route whose availability alters repeatedly is called a flap.
* When flaps occur, excessive number of BGP UPDATE messages are sent to BGP peers which in turn increases the load of the peers and excessively consumes CPU power.
* The goal of BGP route dampening when first introduced was to reduce the propagation of flapping routes without affecting the convergence time of the stable routes.
* It was designed to decrease the load on routers and increase the overall network stability, as the stable prefixes would still be advertised while the propagation of the flapping routes would remain suppressed until such routes become stable again.
* BGP Route dampening was applied locally on the routes learned by the eBGP peers.
* When the command bgp dampening is enabled without configuring any optional arguments, the default values are used.
* The default IOS dampening values are 15 750 2000 60.
;Config:
router bgp 64501
bgp dampening
neighbor 10.0.0.2 remote-as 64502
Verify:
R1# show ip bgp dampening parameters
R1# show ip bgp dampening flap-statistics
R1# debug ip bgp dampening
;The meaning of the default dampening parameters:
* The penalty will be reduced to half after 15 minutes (Half-life time).
* The routes will not be used when the Suppress penalty 2000 is reached.
* The dampened route will be reused when the penalty is decoyed into 750 (Reuse penalty).
* The routes experiencing route flaps should not be suppressed for more than 60 minutes (Max suppress time).
= EBGP vs IBGP =
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