Priority Transmission of SIP Signaling Flows in Case of IP Link Congestion

Conceptual framework of Next Generation Network (NGN) is based on Internet Protocol (IP) transport technology, which is generally accepted as the optimal solution for delivering of next generation multimedia services. Although packet-switched networks are in the mainstream, decades of experience with circuit-switched networks still set expectations when it comes to Quality of Service (QoS). As opposed to circuit-switched networks, signaling flow and media flow of NGN services are mixed in transmission. That makes it difficult for an IP network node to guarantee the signaling flow packet is not discarded in case of the congestion, which results in an impossibility to trigger the framework of dynamic QoS negotiation and implement service reachability. Since the service reachability is guaranteed in the signaling flow transmission aspect, it is necessary to consider the possibility of IP network to fulfill expectations regarding the straightway and reliable transmission of signaling flows. In this paper, the link congestion effect on critical performance metrics of Session Initiation Protocol (SIP) signaling flows is investigated by performing extensive simulation study. Our results indicate that IP network is able to guarantee transmission criteria of SIP signaling flows even in case of critical link congestion when the highest priority is assigned to them.