How to Configure BGP Route Dampening скачать в хорошем качестве

How to Configure BGP Route Dampening

Configuring BGP Route Dampening Route dampening is a BGP feature designed to minimize the propagation of flapping routes across an internetwork. A route is considered to be flapping when its availability alternates repeatedly. BGP Route Dampening Terms: 1. Flap-A route whose availability alternates repeatedly. 2. History state-After a route flaps once, it is assigned a penalty and put into history state, meaning the router does not have the best path, based on historical information. 3. Damp state-In this state, the route has flapped so often that the router will not advertise this route to BGP neighbors. 4. Penalty-Each time a route flaps, the router configured for route dampening in another autonomous system assigns the route a penalty of 1000. Penalties are cumulative. The penalty for the route is stored in the BGP routing table until the penalty exceeds the suppress limit. At that point, the route state changes from history to damp. 5. Suppress limit-A route is suppressed when its penalty exceeds this limit. The default value is 2000. 6. Half-life-Once the route has been assigned a penalty, the penalty is decreased by half after the half-life period (which is 15 minutes by default). The process of reducing the penalty happens every 5 seconds. 7. Reuse limit-As the penalty for a flapping route decreases and falls below this reuse limit, the route is unsuppressed. That is, the route is added back to the BGP table and once again used for forwarding. The default reuse limit is 750. The process of unsuppressing routes occurs at 10-second increments. Every 10 seconds, the router finds out which routes are now unsuppressed and advertises them to the world. 8. Maximum suppress limit-This value is the maximum amount of time a route can be suppressed. The default value is four times the half-life. CONFIGURE: SUMMARY STEPS enable configure terminal router bgp as-number bgp dampening [half-life reuse suppress max-suppress-time ] [route-map map-name ] end Example: R1: conf t router bgp 1 bgp log-neighbor-changes network 1.1.1.1 mask 255.255.255.255 neighbor 10.10.12.2 remote-as 2 end wr R2: conf t router bgp 2 bgp log-neighbor-changes bgp dampening neighbor 10.10.12.1 remote-as 1 end wr VERIFY: show run all | include dampening show ip bgp dampening parameters show ip bgp dampening flap-statistics !Displays BGP flap statistics for all paths. clear ip bgp flap-statistics !Clears BGP flap statistics for all routes. ! show ip bgp dampening dampened-paths !Displays the dampened routes, including the time remaining before they will be unsuppressed. clear ip bgp dampening !Clears route dampening information and unsuppresses the suppressed routes. debug ip bgp dampening show ip bgp 1.1.1.1 !Check Dampinfo. NOTE: The flap statistics for a route are also cleared when a BGP peer is reset. Although the reset withdraws the route, there is no penalty applied in this instance, even if route flap dampening is enabled. 🔔 Subscribe to my YouTube channel:    / @ferdstechchannel   📺 Playlist of all my videos on BGP:    • BGP   Facebook Page:   / ferdsthenetworkguy   References: https://www.cisco.com/c/en/us/td/docs... BGP Route Dampening.....confused???: https://community.cisco.com/t5/networ... Configuring BGP Route Dampening: https://www.cisco.com/c/en/us/td/docs... BGP Dampening: https://ccieblog.co.uk/bgp/bgp-dampening #cisco #ccna #ccnp #ccie