Congestion-Avoidance Algorithms

Because the queue's tail drops, even in managed queue environments, and because it can induce global synchronization, there is a great deal of merit in environments that do not allow congestion in the first place. Covered here are two ways to accomplish this. The first is a combination of three features: CAR, Weighted Random Early Detection (WRED), and BGP policy propagation; the second is RSVP, a fully integrated bandwidth-management feature.

Although CAR and WRED are stateless policy propagation techniques, they become soft-state when combined with BGP. In other words, the information carried by the BGP routing protocol determines the level of service provided to all traffic.

RSVP, on the other hand, is the ...

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