D-Link DGS-3630 Emulator 1 - Page 194

DGS-3630 Layer 3 Stackable Managed Switch CLI Reference Guide bgp dampening [HALF-LIFE REUSE SUPPRESS MAX-SUPPRESS-TIME UN-REACHABILTY-HALF-TIME | route-map MAP-NAME] no bgp dampening [route-map] Parameters HALF-LIFE REUSE SUPPRESS MAX-SUPPRESS-TIME UN-REACHABILITY-HALFLIFE route-map MAP-NAME (Optional) Specifies the time (in minutes) after which the accumulated penalty of the route is decreased by half. The range of the half-life period is 1 to 45 minutes. (Optional) Specifies the penalty that is decreased and falls below the reuse threshold, the route will be re-entered the routing table as a normal route. The range of the reuse value is from 1 to 20000. (Optional) Specifies the penalty that is increased and cross the suppress threshold, the route will become a dampening route and will not be advertised. The range is from 1 to 20000 (Optional) Specifies the maximum time (in minutes) that a route can be in the dampened state. The range is from 1 to 255. (Optional) Specifies the time (in minutes) after which the penalty of the unreachable routes is decreased by half. The range is 1 to 45. (Optional) Specifies the name of route map to control the routes for dampening. Default Half-life: 15 minutes. Reuse: 750. Suppress: 2000. Max-suppress-time: 4 times half-life. Un-reachability-half-life: 15 minutes. Command Mode Router Configuration Mode. Address Family Configuration Mode (IPv4 Unicast, IPv4 Multicast, IPv6 Unicast, and VRF). Command Default Level Level: 12. Usage Guideline The purpose of this command is to eliminate the advertising of the unstable routes and thus to avoid unstable of the network caused by flapping routes. When a prefix is removed or is added, BGP increases the penalty of the route by 1000. When the attribute of a received route has changes, BGP increases the penalty of the route by 500. Supposed that half-life is configured as 15 min, reuse is 800, and suppress is 1500. When a route flaps (from up to down), 1000 is added to the penalty of the route. Since the penalty is smaller than the suppress value, the route works normally. A withdraw message (an update message) is sent to the neighbors. As the half-life timer expired, the penalty of the route becomes 500. If another flaps occur, the penalty of the route keep being increased. If it is larger than the suppress value, the route will be dampened. BGP will not advertise message for the dampened route. As the time passed, the penalty of the route decreased. If the penalty of the route falls below the reuse threshold, the route will be restored as a normal route and update message will be sent for the route. If a route map is configured but the route map doesn't exist, it acts as all routes are enabled for dampening. 189