SATNAC 2007 Conference Papers

Network Engineering

Title:                   Evaluation of Multiple Interface Functionality and Flow Mobility

Authors:              Gareth Abrey (University of Cape Town),
Neco Ventura (University of Cape Town) 

Abstract:             The Internet and mobile communications are converging towards a single, globally connected network. The latest mobile devices are increasingly equipped with multiple access technologies. These interfaces will prove most useful if used in collaboration. The functionality possible with multiple interfaces is evaluated on a test-bed in this paper to determine the success of a typical multiple interface scheme. Our results show that there are distinct advantages in using multiple  interfaces for data flows, however some scenarios illustrate potential performance problems under certain conditions.


Title:                   Mapping the African Internet

Authors:              John Gilmore (University of Stellenbosch),

Anthony Krzesinski (University of Stellenbosch)

Abstract:             This paper describes the methods used to generate a router level map of the African Internet. The traceroute utility was used to collect router level information on the Internet. We developed software to automate the sending of traceroute probes to selected IP addresses, to store the information produced by the traceroute data and to transform the data into adjacency matrices. The adjacency matrices, together with geographical data concerning the location of the routers, were used to draw a map showing the Internet topology.


Title:                   A Distributed Scheme for Robust On-Line Network Engineering

Authors:              Johannes Goebel (University of Hamburg, Germany),
Anthony Krzesinski (University of Stellenbosch), Dieter Stapelberg (University of Stellenbosch)

Abstract:             This paper presents a model of an on-line network bandwidth management scheme: at random time instants bandwidth prices are computed and are used to adjust the bandwidths of the network paths in response to the traffic conditions. The distinguishing features of the scheme are that it works without centralised control and thus scales to large networks, and that rather than using traffic engineering to move network flows to where the network bandwidth is located, network engineering is used to move bandwidth to where the flows are located. Simulation results show that the reallocation scheme provides prompt and robust bandwidth provisioning.


Title:                   Investigation into Performance Metrics for Connection Admission Control in an MPLS Simulated Network

Authors:              Prathaban Moodley (University of the Witwatersrand),
Hu Hanrahan (University of the Witwatersrand) 

Abstract:             The future multiservice communication network will be packet based. Existing circuit switched telco networks have been designed on traffic engineering principles, ensuring guaranteed QoS for all classes of traffic within the network. Existing traffic models for circuit switched networks do not apply to a packetised network. Many packet based technologies do not address QoS. The traffic engineering feature of MPLS provides the best QoS function for packetised IP networks today (apart from legacy ATM). A Connection Admission Control function is required to ensure guaranteed services for class based or path based traffic over a packetised network. This paper addresses the question of whether information gathered from the network could be useful in informing the Connection Admission Control function. The network is represented by the NS-2 network simulator. Performance metrics (latency, jitter, and packet loss) are recorded during various simulated network conditions. These simulated network conditions include:- step load, dynamic load, busy hour and disaster events. Traffic classes include common telco traffic:- web, ftp, voice and video traffic. Performance metrics provide insight into the state of the network and is useful for informing the design and operation of the Connection Admission Control function.


Title:                   An Optimal Pricing Model for Wireless Community Mesh Networks

Authors:              Hai Ling Zhu (University of Johannesburg),
Wimpie Clarke (University of Johannesburg), Andre Nel (University of Johannesburg), Marco dos Santos (University of Johannesburg)

Abstract:             The development of wireless LAN technologies offers a novel platform for internet service resale via wireless community mesh networks that provide high network coverage and lower infrastructure cost. In a wireless community mesh network, access point functions as both the Internet service provider and Internet access provider to the mesh network neighbors (end-users) since the upstream Internet service providers of the access point is not able to monitor and bill for the resold traffic within the community mesh network. In this Internet service resale business, the access provider sets their pricing policy as an Internet reseller to maximize its revenue, while the end-users who are price sensitive, respond to this pricing policy by controlling their Internet usage. Using a queuing theory model, we propose an optimal pricing model to achieve revenue maximization for a mesh network access provider. The user’s sensitivity to the price is modeled in order to discover the optimal price. The effects of the price on the traffic load and the maximum number of users at the access point are explored since price is viewed as an additional strategy to encourage a better usage of the limited bandwidth resource. Monte Carlo simulation results are presented to verify the analytically optimal price based on the proposed pricing model.


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