- Network topology mapper bgp peering device how to#
- Network topology mapper bgp peering device install#
- Network topology mapper bgp peering device software#
In the output above, we can see that the penalty is slowly decreasing (decaying). penalty decayed to 924 after 60 second(s) penalty decayed to 958 after 60 second(s)ĮvD: accum. If you wait, you’ll also see some debug messages: R2#ĮvD: accum. In the output above, you can see that route 1.1.1.1/32 has flapped 1 time and now has a penalty of 1000. penalty 1000, flap count 1ĮvD: unsuppress item left in reuse timer array with penalty 1000īGP(0): charge penalty for 1.1.1.1/32 path 1 with halflife-time 15 reuse/suppress 750/2000īGP(0): flapped 1 times since 00:00:00. Now take a look at R2: R2# debug ip bgp dampeningĮvD: charge penalty 1000, new accum. To simulate a flapping route, we’ll shut the loopback interface of R1: R1(config)# interface Loopback 0 To see route dampening in action, I’ll enable a debug on R2: R2# debug ip bgp dampeningīGP dampening debugging is on for all address families Suppress penalty : 2000 Reuse penalty : 750 Max suppress penalty: 12000 Max suppress time: 60 mins Half-life time : 15 mins Decay Time : 2320 secs Or you can use this show command: R2# show ip bgp dampening parameters You can see them in the running configuration: R2# show run all | include dampening Let’s try whether route dampening works or not. Network Next Hop Metric LocPrf Weight Path RPKI validation codes: V valid, I invalid, N Not found Origin codes: i - IGP, e - EGP, ? - incomplete X best-external, a additional-path, c RIB-compressed, R RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter, Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, R2 has learned route 1.1.1.1/32 from R1: R2# show ip bgpīGP table version is 2, local router ID is 192.168.12.2 I’ll keep it simple and use the global option for now.
![network topology mapper bgp peering device network topology mapper bgp peering device](https://www.rogerperkin.co.uk/wp-content/uploads/2014/02/bgp-local-preference-rogers-ccie-blog.jpg)
R2(config-router)# bgp dampening route-map DAMPENING R2(config-route-map)# match ip address R1_L0 R2(config)# route-map DAMPENING permit 10 This way, you can specify which routes you want to enable dampening for: R2(config)# ip access-list standard R1_L0 The alternative is to include a route-map. R2(config-router)# bgp dampening Route-Map
Network topology mapper bgp peering device how to#
This is how to enable it: R2(config)# router bgp 2 When you enable BGP route dampening globally, it affects all routes. We have two options to configure BGP route dampening: R1 has a loopback interface that we advertise through BGP. There are two routers, each in their own AS.
Network topology mapper bgp peering device software#
I’m using IOSv Software version 15.9(3)M2. Let’s see how we configure BGP dampening. The maximum suppress time is 60 minutes by default. The maximum suppress limit ensures that a route won’t be dampened forever. When the penalty is below 50% of the reuse limit, the penalty is removed from the route. Once the penalty is below the reuse limit of 750, the route can be used again and advertised to other BGP routers.
![network topology mapper bgp peering device network topology mapper bgp peering device](https://engineering.fb.com/wp-content/uploads/2021/05/BGP_fabric.jpg)
![network topology mapper bgp peering device network topology mapper bgp peering device](https://www.cisco.com/c/dam/en/us/support/docs/ip/border-gateway-protocol-bgp/23675-27.gif)
Once the penalty is below 50% of the reuse limit, the penalty is removed completely.
Network topology mapper bgp peering device install#
To install or advertise the route again, the penalty has to be lower than a reuse limit.When half-life is reached, the penalty is reduced by 50%. When the router learns again about a route with a penalty, the half-life timer starts.Once the route is dampened, the router won’t install the route in the routing table nor advertise it to other BGP neighbors.When the route exceeds the suppress limit, the route is dampened.Each time a route flaps, the penalty is increased by 1000.I included the default values for Cisco IOS. Let’s take a look at how BGP route dampening works.