RESEARCH ARTICLE Overload management with regard to fairness in session initiation protocol networks by holonic multiagent systems Mehdi Khazaei | Nasser Mozayani School of Computer Engineering, Iran University of Science and Technology, Tehran, Iran Correspondence Mehdi Khazaei, School of Computer Engineering, Iran University of Science and Technology, Tehran 16846‐13114, Iran. Email: khazaei84@gmail.com Summary Session initiation protocol (SIP) is a widely used standard protocol for multimedia applications and IP multimedia subsystems. Internet protocol multimedia subsystem was introduced by the 3GGP signaling foundation as part of a set of next generation network architectures. Despite having useful practical features, SIP does not have suitable mechanisms to handle overload. This challenge creates a sharp drop in qual- ity of service for next generation network users. Because a distributed SIP network is a complex system composed of subsystems interacting with one another, multiagent system is an appropriate method to model network interactions and to solve overload in SIP networks. In this paper, holonic organization is applied to reduce the multiagent system complexity in modeling a large SIP network. Holonic organization is a hierarchical structure in which each holon covers a geographical area of the SIP network at the first level. At the second level, upper‐level holons con- trol the first‐level holons, and so on. Overload control is achieved by communication and the exchange of knowledge between the intelligent holons. Experimental results show that the proposed method prevents overload in the SIP network. The method also increases total throughput, reduces delay, and considers fairness in the SIP network. 1 | INTRODUCTION Session initiation protocol (SIP) is the most important signaling protocol for the application layer. Session initiation protocol is standardized by the Internet Engineering Task Force in RFC 3261. The protocol is used to manage sessions in many Internet applications such as voice over IP (VoIP), instant messaging, and video conferencing. IP networks provide a variety of services; different technologies gravitate toward integration networks and next generation networks. 1 In next generation networks, SIP undoubtedly plays a key role. 2 Overload occurs when the rate of incoming requests to the SIP server exceeds the server capacity. 3 The overload occurs under certain conditions such as disasters, emergency calls, TV shows, and congestion after a server reset. In the overloaded SIP server, transaction delay is increased and, consequently, responses are not received timely. Therefore, the retransmission mechanisms are triggered. This process increases the load not only on the overloaded server but also on its neighbor servers. As a result, the overload can spread out in the network and down the network completely. In SIP, the retransmission mechanism is used to compensate for lost messages when they are transmitted on an unreliable transport layer protocol such as user datagram protocol. Clearly, it is not economical to consider the worst case of overload in network design because that case requires a tre- mendous amount of resources (CPU and memory) whenever it occurs. The network is usually designed and engineered based on certain assumptions and user requirements. 4 As a result, the overload problem is not completely avoidable, and SIP should be equipped with an overload control mecha- nism to the extent possible. Session initiation protocol typi- cally uses 503 responses (service unavailable) to control the Received: 10 December 2015 Revised: 4 September 2016 Accepted: 1 February 2017 DOI 10.1002/nem.1969 Int J Network Mgmt. 2017;e1969. https://doi.org/10.1002/nem.1969 Copyright © 2017 John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/nem 1 of 18