After specification of Integrated Services for Internet, some doubts arose about its scalability, because per flow state information has to be kept in every router on the path from sender to receiver. Aggregation of traffic into best effort class, assured class and premium class Premium class needs a corresponding Expedited Forwarding Behavior. Need policing and admission control for this class.
Assured service permits a statistical guaranteed rate.
Packets that exceed the negotiated rate are either marked as best effort or dropped. The overall dropping probability is considerably lower than the best effort packets. Packets are classified and marked for a corresponding service category At the edges of the network or at the hosts, we need traffic conditioning functions such as classification, policing and shaping Nodes in the backbone network only need to distinguish between different per-hop forwarding behaviors by looking at a mark in the packet header, and they need to provide corresponding forwarding mechanisms.