Per-flow QoS support over a stateless Differentiated Services IP domain

This paper consists of two parts. In the first part, we propose an admission control paradigm, called Gauge & Gate Reservation with Independent Probing (GRIP), devised to operate over a stateless Differentiated Services IP domain. GRIP admits a new flow upon the successful and timely delivery, through the domain, of probing packets independently generated by the end-points. Failed reception of probing packets is interpreted as congestion in the network. Our solution is fully distributed and scalable, as admission control decisions are taken at the edge nodes, and requires no coordination between routers, which are stateless and remain oblivious to individual flows. An interesting feature of the GRIP operation is its backward compatibility (at the expense of experienced performance) with existing routers. The performance of GRIP is related to the capability of routers to locally take decisions about the degree of congestion, and suitably block probing packets when congestion conditions are detected. In the second part of the paper we describe a specific GRIP implementation, characterized by the capability of providing strict Quality of Service guarantees, thanks to suitable assumptions made on the supported traffic and on the traffic control mechanisms, in a specific domain.