Border gateway protocol peer dampening
View Patent ↗A method is disclosed for preventing an unstable BGP Peer from repeatedly initializing unstable BGP connections. In one embodiment, BGP speakers are penalized for causing errors that result in BGP restarts. When a speaker accumulates enough penalty points, its peer notifies it that it has been dampened (prevented from establishing a BGP connection). A memory decay function allows the speaker to automatically attempt a new connection once a given amount of time has passed. The method allows at least two, and possibly more, BGP speakers to avoid network and processor costs from servicing unstable BGP peerings.
1. A method of operating a packet network router, the method comprising:
tracking, for a given peer with which the packet network router is configured to exchange routing information, at least one metric related to the stability of the routing peer relationship between the packet network router and the peer, the at least one tracking metric comprising accumulating penalties when the peer relationship is restarted;
basing a degree of the penalty on the type of event that causes the peer relationship to restart;
when the accumulated penalties comprising the at least one tracked metric are compared to exceed a first threshold, preventing the peer from exchanging routing information with the packet network router;
reducing the level of accumulated penalties with time, while the peer is prevented from exchanging routing information with the packet network router; and
comparing the reduced level of accumulated penalties to a second threshold, and automatically inactivating the routing information exchange prevention mechanism when the reduced level of accumulated penalties meets a preset criterion with respect to the second threshold.
2. The method of claim 1 , wherein penalties are accumulated for selected reset events that cause the peer relationship to restart.
3. The method of claim 1 , further comprising basing the degree of penalty assessed on the cost of restarting the peer relationship.
4. The method of claim 1 , wherein the significance of an accumulated penalty decays with time.
5. The method of claim 1 , wherein preventing the peer from exchanging routing information comprises placing a routing exchange mechanism in a dampened state from which connection attempts by the peer are ignored.
6. The method of claim 5 , further comprising notifying the peer that it has been dampened when entering the dampened state.
7. The method of claim 1 , further comprising using routing cost metrics to select between multiple possible routes to a given destination, and, when multiple possible routes to a given destination are tied based on routing cost metrics, attempting to break the tie based on comparing at least one of the metrics related to the stability of the peer relationship for each peer associated with one of the multiple possible routes.
8. The method of claim 7 , wherein comparing at least one of the metrics related to the stability of the peer relationship comprises comparing the number of times each peer has been prevented from exchanging routing information due to historical instability.
9. A packet network router comprising:
one or more processors;
means for the one or more processors to track, for a given peer with which the packet network router is configured to exchange routing information, at least one metric related to the stability of the routing peer relationship between the packet network router and the peer, the at least one tracked metric comprises accumulating penalties for selected reset events that cause the peer relationship to restart and basing a degree of the penalty on the type of event that causes the peer relationship to restart;
means for preventing the peer from exchanging routing information with the packet network router when the accumulated penalties comprising the at least one tracked metric are compared to exceed a first threshold;
means for reducing the level of accumulated penalties with time, while the peer is prevented from exchanging routing information with the packet network router; and
means for comparing the reduced level of accumulated penalties to a second threshold, and automatically inactivatng the routing information exchange prevention mechanism when the reduced level of accumulated penalties meets a preset criteria with respect to the second threshold.
10. The apparatus of claim 9 , wherein the means for preventing the peer from exchanging routing information comprises placing a routing exchange mechanism in a dampened state from which connection attempts by the peer are ignored.