Configuring MBGP Route Dampening
Configuring MBGP route dampening suppresses unstable MBGP routes.
Usage Scenario
MBGP route dampening is designed to suppress unstable routes. After MBGP route dampening is configured, an MBGP device does not add any unstable routes to its MBGP routing table or advertise them to its MBGP peers.
A primary cause of route instability is route flapping. A route is considered to be flapping when it repeatedly appears and then disappears in the routing table. MBGP is applied to complex networks where routes change frequently. Frequent route flapping consumes bandwidth and CPU resources and even seriously affects network operations. To prevent the impact of frequent route flapping, MBGP uses route dampening to suppress unstable routes.
Specified-requirement route dampening is a type of route dampening that is used to differentiate routes based on routing policies. This allows MBGP to use different route dampening parameters to suppress unstable routes. Different route dampening parameters can also be configured for different nodes in the same route-policy. When route flapping occurs, MBGP can use specific route dampening parameters to suppress the routes that match the route-policy. For example, on a network, a long dampening period of time can be set for routes with a long mask, and a short dampening period of time is set for routes with a short mask (such as an 8-bit mask).
Procedure
- Run system-view
The system view is displayed.
- Run bgp as-number
The BGP view is displayed.
- Run ipv4-family multicast
The BGP-IPv4 multicast address family view is displayed.
- Run dampening [ half-life-reach reuse suppress ceiling | route-policy route-policy-name ] * [ update-standard ]
MBGP route dampening parameters are set.
The value of suppress must be greater than that of reuse and smaller than that of ceiling.
If routes are differentiated based on policies and the dampening command is run to reference a route-policy, MBGP allows you to use different route dampening parameters to suppress different routes.
- Run commit
The configuration is committed.
Checking the Configurations
After the configuration is complete, you can check whether the configuration has taken effect.
Run the display bgp multicast routing-table dampened command to check dampened MBGP routes.
Run the display bgp multicast routing-table dampening parameter command to check configured MBGP route dampening parameters.
Run the display bgp multicast routing-table flap-info [ ip-address [ mask [ longer-match ] | mask-length [ longer-match ] ] | as-path-filter { as-path-filter-number | as-path-filter-name } | regular-expression as-regular-expression ] command to check MBGP route flapping statistics.