Towards an SDN network control application for differentiated traffic routing

In the last years, Software Defined Networking has emerged as a promising paradigm to foster network innovation and address the issues coming from the ossification of the TCP/IP architecture. The clean separation between control and data plane, the definition of northbound and southbound interfaces are key features of the Software Defined Networking paradigm. Moreover, a centralised control plane allows network operators to deploy advanced control and management strategies. Effective traffic engineering and resources management policies allow to achieve a better utilisation of network resources and improve endto- end service performance. This paper deals with the architectural design and experimental validation of a control application that enables differentiated routing for traffic flows belonging to different service classes. The new control application makes routing decisions leveraging on OpenFlow network statistics, i.e., taking advantage of real-time network status information. Moreover, a Deep Packet Inspection module has been developed and integrated in the control application to detect VoIP traffic with Session Initiation Protocol signalling, enforcing this way policies for a differentiated treatment of VoIP traffic. Finally, a functional validation is performed in emulated environment.This work was supported by the EPSRC INTERNET Project EP/H040536/1.This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/ICC.2015.724925

Slicing in WiFi networks through airtime-based resource allocation

Network slicing is one of the key enabling technologies for 5G networks. It allows infrastructure owners to assign resources to service providers (tenants), which will afterwards use them to satisfy their end-user demands. This paradigm, which changes the way networks have been traditionally managed, was initially proposed in the wired realm (core networks). More recently, the scientific community has paid attention to the integration of network slicing in wireless cellular technologies (LTE). However, there are not many works addressing the challenges that appear when trying to exploit slicing techniques over WiFi networks, in spite of their growing relevance. In this paper we propose a novel method of proportionally distributing resources in WiFi networks, by means of the airtime. We develop an analytical model, which shed light on how such resources could be split. The validity of the proposed model is assessed by means of simulation-based evaluation over the ns-3 framework.This work has been supported in part by the European Commission and the Spanish Government (Fondo Europeo de desarrollo Regional, FEDER) by means of the EU H2020 NECOS (777067) and ADVICE (TEC2015-71329) projects, respectively

Experimental evaluation of two open source solutions for wireless mesh routing at layer two

The paper reports the outcome of an experimental evaluation of two open source solutions for realising a Wireless Mesh Network (WMN). Both works at layer two of the ISO/OSI stack and are transparent to the IP layer, i.e. they allow keeping the existing TCP/IP stack unchanged and avoid dealing with the complex IP configuration and management tasks. The first solution is the upcoming IEEE 802.11s standard, as implemented by the open80211s project, and the other is the B.A.T.M.A.N. routing protocol, in its layer-2 version. We compared them in a small experimental testbed, with main focus on their behaviour in typical mesh situations. We found that both have strengths and shortcomings, but none can be claimed to be completely mature

Estimation of token bucket parameters for aggregated VoIP sources

The paper presents an analytical study aimed to establish a dimensioning procedure for the token bucket algorithm, used as a meter in a Differentiated Services network architecture, when a stochastic model for the multiplexed traffic is available. In the work, we propose an equivalent queueing system method to 'on line' estimate the linear bounded arrival processes (LBAP) parameters when a non-zero probability of non-conforming packets is accepted. Then, we validate our approach considering an aggregation of fluidic On-Off processes with exponentially distributed sojourn time in each state, used to model telephone sources with voice activity detection (VAD). To test the goodness of our analytical results, we employ discrete event simulations, which have highlighted the accuracy of the proposed dimensioning procedure in a voice over IP (VoIP) scenario. Moreover, we investigate the multiplexing gain and the effect of different parameters on the LBAP characterization of the VoIP traffic, taking into account a non-zero probability of non-conforming packets. Copyright (C) 2002 John Wiley Sons, Ltd

Implementation frameworks for IEEE 802.11s systems

The standardisation process of IEEE 802.11s requires some effort to be devoted to assess the effectiveness of the proposed solutions. Specifically, the path selection and forwarding facilities, embodied by the Hybrid Wireless Mesh Protocol (HWMP), are the major and most delicate components. A working prototype can be profitably used to experimentally evaluate such features, thus returning immediate and significant feedback. In this scenario, the paper offers a threefold contribution. First, we review the current 802.11s implementation efforts, such as the Open 802.11s and One Laptop Per Child projects, highlighting the pros and cons of each solution. Then, we describe a prototype IEEE 802.11s Mesh Access Point (MAP) we developed starting from common off-the-shelf hardware and software. The main innovation of this prototype is the support of both modes of operation of HWMP. Conversely to the other projects, which implement only the reactive mode, our device also supports the proactive mode, and runs it in the same way as suggested by the draft standard, thus becoming a more complete evaluation platform. As a final contribution, we provide some Simulation results to assess the behaviour of the mixed proactive-reactive mode, From this evaluation, we can confirm that employing the proactive algorithm can bring some benefits to the operation of the 802.11s network, even though a careful approach must be taken to avoid some drawbacks. (C) 2009 Elsevier B.V. All rights reserved

A joint experimental and simulation study of the IEEE 802.11s HWMP protocol and airtime link metric

One of the main features of the upcoming IEEE 802.11s standard is the path selection procedure, which is performed by the Hybrid Wireless Mesh Protocol by means of thetextitairtime link metric (ALM). Through a small experimental testbed, and using the open80211s code, which provides one of the most compliant draft implementations, we analysed the impact that the implementation choices of the developers have on the system performance. The analysis revealed that even small deviations from the specified routines (or different choices in the estimation of the parameters used in the online calculation of the ALM) can lead to noteworthy performance degradations. We thus realized some fixes to improve the performance of the system and verified the effectiveness of such amendments in a realistic simulation environment. We then compared the performance of the modified version to the original one. The outcome of the test highlighted the remarkable advantage achieved by the proposed fixes

Experimental study on QoS provisioning to heterogeneous VoIP sources in diffServ environment

The work presents a research activity focused on the experimental study of three different issues related to the provision of VoIP services with QoS guarantee in DiffServ networks. Firstly the study deals with the analysis of two dissimilar strategies for the setting of the parameters of a traffic control module in a DiffServ network node. Using these results, secondly the effectiveness of static and dynamic SLAs strategies for QoS provisioning in DiffServ environment is experimentally evaluated. This analysis is carried out considering aggregation of voice sources adopting two distinct codecs, i.e. G723.1 and G729. These codecs produce traffic with different statistical features (variable and constant bit rate respectively). Hence, this approach allows assessing the impact on the single sources' performance of the multiplexing of heterogeneous VoIP sources in a single class

On synchronization techniques: performance and impact on time metrics monitoring

The paper presents an experimental comparison of device synchronization strategies to monitor quality of service (QoS) time metrics, such as the one-way delay and the delay variation. The compared strategies are based on global positioning system (GPS), public Internet network time protocol (NTP) servers and ad hoc GPS-based NTP servers with different treatments of the NTP traffic. The presented experimental results allow to quantitatively evaluate the level of performance achievable using each synchronization technique. Finally, considering a satellite test bed, we focus our analysis on two relevant aspects of time metrics monitoring: the impact of the synchronization errors on the metrics observation and the different values that can be measured when a metric is monitored at the application or data link level. Copyright (C) 2003 John Wiley Sons, Ltd

On the relevance of correlation dependencies in ON/OFF characterization of broadband traffic

The paper presents joint measurements of IP and ATM traffic over an MPOA based campus network. The search for parsimonious realistic modeling of heterogeneous aggregated traffic has led to the generalization of on/off modeling schemes. Even a single on/off pattern with Pareto-geometric distributions of the sojourn times in each state determines a hyperbolic decay of the autocovariance function corresponding to long range dependence (LRIB). Hence, adequate on/off models can fit real traces corresponding to the multiplexing of several heterogeneous connections. In the paper, the on/off behavior of the traffic is evidenced at the ATM level. The relevant feature of the traces is that either the on and the off sojourn times could be well approximated by a light tailed distribution. The observed LRD behavior is due to the presence of correlation in the sequence of on (as well as off) periods lengths. In order to confirm this hypothesis, different synthetic traces were considered, verifying the LRD behavior by means of wavelet analysis. Implications of such state correlations on queueing behavior are then compared by means of discrete event simulation