Flexible WAN protocol call admission control algorithm

摘要

An intermediate network node is configured to drop or reject new client sessions when its available resources are below a predetermined level. In this manner, the intermediate node can efficiently process a large number of new session attempts at substantially the same time. The intermediate node monitors the availability of its resources by calculating a load metric. The load metric is based on one or more partial load metrics, each corresponding to a different system resource. The load metric is compared with a predetermined value to determine whether the node has enough available resources to continue establishing new client sessions. Alternatively, the intermediate node rejects new client sessions when a total number of allocated “abstract resource units” rises above a predetermined level. That is, client sessions are assigned a predetermined number of abstract resource units on a per-protocol basis and a resource counter stores the number of abstract resource units allocated by the intermediate node. Each protocol is assigned a different time interval for a timing wheel, after which time the number of abstract resource units assigned for the protocol is subtracted from the resource counter. The intermediate node actively or passively rejects new client sessions until the timing wheel sufficiently decreases the counter below the predetermined level.