Performance Evaluation of Datagram Congestion Control Protocol for SIP Signalling using NS-2 Simulation Agus Awaludin, Mohamad Fathurahman, Reza Primardiansyah, Riri Fitri Sari Depeartment of Electrical Engineering, Faculty of Engineering University of Indonesia, Depok 16424 E-mail : awaludin@ui.ac.id, mohamad.fathurahman91@ui.ac.id, reza.primardiansyah@ui.ac.id, riri@ui.ac.id Abstract - The use of Internet-Protocol (IP) Based, combine the transmission of multimedia communication service signalling with other internet based service within the same infrastructure. UDP as the default signaling transport protocol for SIP based mutlimedia communication signalling brings an issue of call drop possibilities during network congestion, leads to impossibility to realize reachibility of service. The paper aims to present the idea of using Datagaram Congestion Control Protocol as signaling transport protocol for SIP based call control protocol to overcome the issue of call drop regarding to network congestion. It assumed that DCCP has a solution to detect network congestion that leads the upper layer protocol from sending an application traffic when the congestion occurs. To proof the concept, the simulation study was performed to run SIP module on NS2 , with independently developed DCCP SIP module. The obtained result indicate that DCCP has been more reliable to avoid call drop event due to network congestion compared to UDP. On the other hand UDP as a transport signalling protocol still have a better performance regarding SIP call setup delay than DCCP. Key word : Signalling, VoIP, SIP, transport protocol, DCCP 1. INTRODUCTION The roadmap of telecommunication service defined the move from Switched Circuit Network (SCN) based infrastructure to Packet Switch Network which based on IP transport technology. Adopting the future multimedia services, the next genertation of fixed and mobile network evolved from Next Generation (NGN) and IP Multimedia Subsytem (IMS) framework to Evolved Packet System (EPS) as the meeting point of NGNs. SIP has a significant role as the main signalling and call control protocol on all next generation framework. Until now UDP is agreed as an optimal IP transport protocol for SIP. The unreliable characteristics of UDP brings an issue regarding the possibilites of call drop caused by the congestion on the network, leading the imposibility to implement reacheability of telecommunication service. The selection of UDP as signalling transport protocol for SIP is due to the fact that it has the lowest call setup delay. The problem rise when the network is congested, it increase the posibility of unsuccessfull call setup if one of the packet contain SIP message droped by the network devices such us router, because UDP donot have a congestion detection and packet retransmission mechanism. In this paper we propose an idea of using Datagaram Congestion Control Protocol as signaling transport protocol for SIP based call control protocol. We focus on analyzing the packet drop rate and call setup delay of SIP signalling on top of both UDP and DCCP transport signalling protocol. The paper is organized as follow. Subsection 2 will consist of literature study on NGN, SIP and DCCP. Subsection 3 will consist of performance evaluation simulation of SIP signalling over DCCP. Subsection 4 will consist of discussion on simulation result and comparison to other related research on SIP signalling performance evaluation over various signalling transport protocols.