SLA Policies. In a single-receiver SLA, the receiver can place constraints on how the traffic should be shared among the ingress points. These constraints can be used to assign static as well as dynamic shares. Static shares assign one time non- changing shares to the ingress nodes which often waste the resources of the network. However it would be nicer if these shares are dynamically assigned based on the current network load conditions as dictated by the SLA policies. This is achieved by allowing the SLA to place multiple constraints on the amount of traffic that different groups of ingress points can send to a particular egress under different network load conditions. So we provide the customer with a very simple and flexible scheme for specifying a number of constraints in the general form If condition then constraints This form can handle both static as well as dynamic resource sharing. For example if we want a static constraint like a policy that ingress point A should always be able to send at least LAX to egress X under a certain SLA, then we can specify this constraint as (SAX represents the share) If true then SAX >= LAX On the other end of the spectrum, one is able to specify much more complex constraints for certain conditions that may or may not hold. For example a policy requiring that when the aggregate incoming traffic to the network (T) is greater than the limit agreed upon in the SLA (BX), then each ingress should be assigned at least its weighted share of the receiver bandwidth. At the same time the combined share of traffic from ingress points A and B should be limited by LABX. This can be represented as If ΣTiX >= BX then For ∀i, SiX >= WiX*BX and SAX + SBX <= LABX Note that the customer and the service provider agree upon the weights in the SLA and even the weights can change for different load conditions. This simple way of representing share assigning policies gives the customer much more flexibility and freedom to customize the traffic policing constraints according to his own requirements. At the same time these enable the service provider a much richer framework to provide service differentiation for satisfying a large set of customer requirements. The service provider can have a different pricing structure for each policy and form customized packages by combining different policies to suit the requirements of different customers or even define certain high demand packages.
