High-speed packet networks will begin to support services that need Quality-of-Service (QoS) guarantees. Guaranteeing QoS typically translates to reserving resources for the duration of a call. We propose a statedependent routing scheme that builds on any base stateindependent routing scheme, by routing flows which are blocked on their primary paths (as selected by the state-independent scheme) onto alternate paths in a manner that is guaranteed---under certain Poisson assumptions---to improve on the performance of the base state-independent scheme. Our scheme only requires each node to have state information of those links that are incident on it. Such a scheme is of value when either the base state-independent scheme is already in place and a complete overhaul of the routing algorithm is undesirable, or when the state (reserved flows) of a link changes fast enough that the timely update of state information is infeasible to all possible call-originators. The performance improvements ...

Abstract. Two highly visible public communication networks are the publicswitched telephone network (PSTN) and the Internet. While they typically provide different services and the basic technologies underneath are different, both networks rely heavily on routing for communication between any two points. In this paper, we present a brief overview of routing mechanisms used in the PSTN and the Internet from a historical perspective. In particular, we discuss the role of management for the different routing mechanisms, where and how one is similar or different from the other, as well as where the management aspect is heading in an inter-networked environment of the PSTN and the Internet where voice over IP (VoIP) services are offered. 1

Abstract—In the signaling plane of an IMS (IP Multimedia Subsystem) network, the interrogating Call/Session Control Function (I-CSCF) is required to choose the serving CSCF (S-CSCF) for user requests arriving at the proxy CSCFs (P-CSCF). This requires S-CSCF selection in such a way that the response time is minimized. However, in an overloaded situation, the P-CSCF entry points for arriving requests must balance between rejecting new requests and having an acceptable response time from S-CSCF for those that are allowed to enter. In this setting, we consider a number of controls for congestion avoidance that work in conjunction with S-CSCF selection in an IMS Network. For balancing between rejection of requests and the response time, we also propose a composite metric. Through our studies on grid topologies, we observe that one of the avoidance algorithms, the bang-bang control, generally shows to be the most promising toward striking a good balance between rejection of requests and the response time. I.

A dynamic window model is developed which provides admission control for circuit switched networks through the signalling network. This model incorporates distributed processing while achieving desired global congestion control effects. It reflects the interaction between the circuit switched path in the telephone network and the packet switched path in the signalling network. The model is solved by applying the concept of parametric analysis to study the whole circuit switching subnetwork as a composite server. The variant service rate is derived for the composite server of the circuit switch trunk in the context of a closed chain where the arrival of call services is finite. To avoid the overtlow and the combinatorial complex problems, the computation is reduced into the Erlang recursive fm. Mean value analysis formulae are derived for the model. Examples are given to demonstrate the validation of the analysis. 1.