Hysteretic Control Technique for Overload Problem Solution in Network of SIP Servers

This paper contains research and development results concerning application of hysteretic control principles to solve SIP servers overload problem, which is known from a number of IETF standards and scientific papers published over the past few years. The problem is that SIP protocol, being the application layer protocol, by default has no build-in means of overload control, as, for example, SS7, MTP2 and MTP3 protocols. It was the SS7 network, where a threshold mechanism of hysteretic signalling load control was first implemented. In this paper we describe the main up-to-date solutions of an overload control problem in a signalling network, and develop analytical models of hysteretic control, which are useful in the development of load management functions of SIP servers. We also propose the design of Open SIP signalling Node (OSN) software architecture which is intended to be used for simulations and comparison of various overload control mechanisms

A Study over Registration Server System Simulation

This paper is a continuous study of the registration server system using a previous created real-time simulation application for my working product- T-Mobile Digits’ registration server system - an Enterprise-level solution ensembles Skype for Business, but with a sizable testing user pool. As a standard system design normally includes the hardware infrastructure, computational logics and its own assigned rules/configures, and as all the complex system, a well-set server structure is the kernel for no matter testing or commercial purpose. The challenges are real and crucial for both business success besides the concerns of access capability and security. It will begin with the discussion of the server-side architecture and the current functional workflows. However, the problematic project is facing stalling issues of the registration system whenever the automation tests deploys, or the pressure tests are happening. The project norms are based on my previous study, current study after architecture refactor and enterprise server function reporting tool: Splunk. I will create a new hypothesis of the mathematical model/formula towards the new architecture and will retrieve the most of simulation skeleton formed from last semester by introducing new variables and new model for the performance comparisons. This project will finalize the study from the last semester and evaluate the server performance under the new architecture. Also, I will try to explore and compare the performances before and after the structure level refactors in the server architecture design, which is in achieving to provide comparison to the system architects or other stakeholders and help them to explore the possible improvements of the current registration server system. The ultimate goal of the study remains the same: I am seeking opportunities to analyze over current problematic flows and achieving making betterments to the product and I expect to make theoretical suggestions to better for the current workflow and logic structure of the current registration server system so that the server would be more durable for automation tests and malicious attacks

Statistical Analysis of Message Delay in SIP Proxy Server, Journal of Telecommunications and Information Technology, 2014, nr 4

Single hop delay of SIP message going through SIP proxy server operating in carriers backbone network is being analyzed. Results indicate that message sojourn times inside SIP server in most cases do not exceed order of tens of milliseconds (99% of all SIP-I messages experience less than 21 ms of sojourn delay) but there were observed very large delays which can hardly be attributed to message specic processing procedures. It is observed that delays are very variable. Delay components distribution that is to identied are not exponentially distributed or nearly constant even per message type or size. The authors show that measured waiting time and minimum transit time through SIP server can be approximated by acyclic phase-type distributions but accuracy of approximation at very high values of quantiles depends on the number outliers in the data. This nding suggests that modeling of SIP server with queueing system of GjPHjc type may server as an adequate solution

Probe-based end-to-end overload control for networks of SIP servers

The Session Initiation Protocol (SIP) has been adopted by the IETF as the control protocol for creating, modifying and terminating multimedia sessions. Overload occurs in SIP networks when SIP servers have insufficient resources to handle received messages. Under overload, SIP networks may suffer from congestion collapse due to current ineffective SIP overload control mechanisms. This paper introduces a probe-based end-to-end overload control (PEOC) mechanism, which is deployed at the edge servers of SIP networks and is easy to implement. By probing the SIP network with SIP messages, PEOC estimates the network load and controls the traffic admitted to the network according to the estimated load. Theoretic analysis and extensive simulations verify that PEOC can keep high throughput for SIP networks even when the offered load exceeds the capacity of the network. Besides, it can respond quickly to the sudden variations of the offered load and achieve good fairness

A distributed end-to-end overload control mechanism for networks of SIP servers.

The Session Initiation Protocol (SIP) is an application-layer control protocol standardized by the IETF for creating, modifying and terminating multimedia sessions. With the increasing use of SIP in large deployments, the current SIP design cannot handle overload effectively, which may cause SIP networks to suffer from congestion collapse under heavy offered load. This paper introduces a distributed end-to-end overload control (DEOC) mechanism, which is deployed at the edge servers of SIP networks and is easy to implement. By applying overload control closest to the source of traf?c, DEOC can keep high throughput for SIP networks even when the offered load exceeds the capacity of the network. Besides, it responds quickly to the sudden variations of the offered load and achieves good fairness. Theoretic analysis and extensive simulations verify that DEOC is effective in controlling overload of SIP networks

Performance analysis of mobile networks under signalling storms

There are numerous security challenges in cellular mobile networks, many of which originate from the Internet world. One of these challenges is to answer the problem with increasing rate of signalling messages produced by smart devices. In particular, many services in the Internet are provided through mobile applications in an unobstructed manner, such that users get an always connected feeling. These services, which usually come from instant messaging, advertising and social networking areas, impose significant signalling loads on mobile networks by frequent exchange of control data in the background. Such services and applications could be built intentionally or unintentionally, and result in denial of service attacks known as signalling attacks or storms. Negative consequences, among others, include degradations of mobile network’s services, partial or complete net- work failures, increased battery consumption for infected mobile terminals. This thesis examines the influence of signalling storms on different mobile technologies, and proposes defensive mechanisms. More specifically, using stochastic modelling techniques, this thesis first presents a model of the vulnerability in a single 3G UMTS mobile terminal, and studies the influence of the system’s internal parameters on stability under a signalling storm. Further on, it presents a queueing network model of the radio access part of 3G UMTS and examines the effect of the radio resource control (RRC) inactivity timers. In presence of an attack, the proposed dynamic setting of the timers manage to lower the signalling load in the network and to increase the threshold above which a network failure could happen. Further on, the network model is upgraded into a more generic and detailed model, represent different generations of mobile technologies. It is than used to compare technologies with dedicated and shared organisation of resource allocation, referred to as traditional and contemporary networks, using performance metrics such as: signalling and communication delay, blocking probability, signalling load on the network’s nodes, bandwidth holding time, etc. Finally, based on the carried analysis, two mechanisms are proposed for detection of storms in real time, based on counting of same-type bandwidth allocations, and usage of allocated bandwidth. The mechanisms are evaluated using discrete event simulation in 3G UMTS, and experiments are done combining the detectors with a simple attack mitigation approach.Open Acces

Модель SIP-сервера с дисциплинами шлюзового и исчерпывающего обслуживания очередей

This paper investigates characteristics of the polling cycling models with exhaustive and gated service disciplines. We have derived mean queuing delays for suggested models and evaluated results.В статье исследуются характеристики СМО как системы поллинга с циклическим порядком опроса очередей, исчерпывающей и шлюзовой дисциплинами обслуживания. Представлены формулы в явном виде, характеризующие среднее время ожидания в очереди. Проведена реализация численного эксперимента

A Secured Load Mitigation and Distribution Scheme for Securing SIP Server

Managing the performance of the Session Initiation Protocol (SIP) server under heavy load conditions is a critical task in a Voice over Internet Protocol (VoIP) network. In this paper, a two-tier model is proposed for the security, load mitigation, and distribution issues of the SIP server. In the first tier, the proposed handler segregates and drops the malicious traffic. The second tier provides a uniform load of distribution, using the least session termination time (LSTT) algorithm. Besides, the mean session termination time is minimized by reducing the waiting time of the SIP messages. Efficiency of the LSTT algorithm is evaluated through the experimental test bed by considering with and without a handler. The experimental results establish that the proposed two-tier model improves the throughput and the CPU utilization. It also reduces the response time and error rate while preserving the quality of multimedia session delivery. This two-tier model provides robust security, dynamic load distribution, appropriate server selection, and session synchronization

Гистерезисное управление сигнальной нагрузкой в сети SIP-серверов

This review deals with the research of load control mechanisms in signaling networks that use three types of thresholds for congestion control. The main objective of this paper is toanalyze the congestion control mechanisms and mathematical models for SIP-servers. Thestudy is based on hysteresial techniques of flow control, which originally was developed forSignaling System 7. We propose general methods for describing hysteresis signaling flow control techniques. We study the current situation and problems of SIP built-in overloadcontrol mechanism, proposed by IETF. Our approaches to mathematical models constructionin the form of queuing systems with hysteresis control are presented.В статье, являющейся по сути обзором, исследуются механизмы управления нагрузкой в сетях сигнализации, которые используют три типа порогов для контроля перегрузок. Целью обзора является анализ механизмов и моделей контроля перегрузок SIP-серверов. В основе исследований лежит гистерезисное управление нагрузкой, которое исходно было разработано для общеканальной системы сигнализации №7. Разработаны унифицированные методы описания процедур гистерезисного управления сигнальной нагрузкой. Исследовано современное состояние и проблемы базового механизма контроля перегрузок SIP-серверов, предложенного комитетом IETF. Изложены подходы к построению математических моделей SIP-серверов в виде систем массового обслуживания с гистерезисным управлением