TY - BOOK T1 - IPv6: The protocol, transition and porting mechanisms T2 - Ellinika Grammata Y1 - 2006 A1 - Christos Bouras A1 - Apostolos Gkamas A1 - Kostas Stamos A1 - Dimitris Primpas A1 - A Karaliotas A1 - Petros Ganos JF - Ellinika Grammata ER - TY - JOUR T1 - Architecture and Performance Evaluation for Redundant Multicast Transmission Supporting Adaptive QoS JF - Tools and Applications, Kluwer Academic Publishers, Vol. 25, No. 1 Y1 - 2005 A1 - Christos Bouras A1 - Apostolos Gkamas A1 - Kostas Stamos A1 - A Karaliotas AB -

In this paper we describe the architecture of an application that was developed for the transmission of multimedia data, using the multicast mechanism, over the Internet. There are two major issues that have to be considered when designing and implementing such a service, the fairness and the adaptation schemes. The fairness problem results from the fact that Clients with different capabilities have to be served. In our application we use a mechanism that categorizes the Clients into a number of groups according to each Client’s capabilities and (the mechanism) serves each group of Clients with a different multicast stream. With the term “capabilities” we do not only mean the processing power of the Client, but also the capacity and the condition of the network path towards that Client. Because of today’s Internet heterogeneity and the lack of Quality of Service (QoS) support, the Server cannot assume that the Clients will permanently be able to handle a specific bit rate.We have therefore implemented an additional mechanism for the intra-stream bit rate adaptation. The proposed mechanism uses a “friendly” to the network users congestion control policy to control the transmission of the data. We evaluate the adaptive multicast transmission mechanism through a number of experiments and a number of simulations in order to examine its behaviour to a heterogeneous group of Clients and its behaviour against TCP and UDP data streams.

ER - TY - CONF T1 - QoS issues in the Research and Academic Networks: The case of GRnet T2 - Industrial Conference on Multi-Provider QoS/SLA Internetworking (MPQSI 2005), Tahiti, French Polynesia Y1 - 2005 A1 - Christos Bouras A1 - Dimitris Primpas A1 - A Karaliotas A1 - Mixalis Paraskevas A1 - M Oikonomakos A1 - C Sintoris AB -

This paper describes the design and the implementation of QoS services in a high speed backbone network as well as a management tool for the service. The services were designed taking advantage of features provided by the MPLS technology and also by using the DiffServ architecture. The supported QoS services include the IP Premium that tries to provide zero packet loss as well as minimum delay and jitter and the Less Than Best Effort service. In addition we implemented a management tool for the service. The scope of this tool is to allow the users to manage their QoS requests (make a new one, edit, delete or view a request). Also the tool performs admission control and produces the necessary configuration that must be applied on the network in order to implement every service’s request.

JF - Industrial Conference on Multi-Provider QoS/SLA Internetworking (MPQSI 2005), Tahiti, French Polynesia ER - TY - JOUR T1 - The deployment of IPv6 in an IPv4 world and Transition Mechanisms JF - Internet Research: Electronic Networking, Applications and Policy, Emerald, Volume 13, Number 2 Y1 - 2003 A1 - Christos Bouras A1 - A Karaliotas A1 - Petros Ganos AB - It is stated that the new version of the IP protocol, IPv6, is the answer to the majority of the problems that were raised during the enormous expansion of the Internet and its transformation to a global communication platform with commercial scope. At the same time it is also stated that IPv6 dominance will not be easy and there will be a period when the two versions of the protocol will co-exist. In this paper we describe some of the main transition mechanisms that can be deployed in order to facilitate the transition process to the new version of the IP protocol. Furthermore, the presented mechanisms are discussed regarding their usability, usefulness and manageability. Describes the way some of these mechanisms were applied to the Greek Research & Technology Network (GRNET). ER - TY - CONF T1 - Issues for the Performance Monitoring of an Open Source H.323 Implementation Ported to IPv6 – Enabled Networks with QoS Characteristics T2 - The 2003 International Conference in Internet Computing (IC 2003), Las Vegas, Nevada, USA Y1 - 2003 A1 - Christos Bouras A1 - Apostolos Gkamas A1 - Kostas Stamos A1 - Dimitris Primpas A1 - A Karaliotas AB - OpenH323 is an open source H.323 implementation that has been ported to IPv6. It therefore presents an opportunity to perform experiments and compare the performance of an H.323 application when using the IPv4 stack and when using the IPv6 stack. In this paper we initially introduce briefly the porting procedure and the methodology we used in order to achieve it. We then present the appropriate experiments that have to be performed in order to comparatively evaluate the IPv4 and IPv6 protocol stacks. We also present the results of some initial experiments comparing IPv4 and IPv6 performance and the conclusions that they can lead us to. JF - The 2003 International Conference in Internet Computing (IC 2003), Las Vegas, Nevada, USA ER - TY - JOUR T1 - Wireless School Network JF - Learning Technology Newsletter – IEEE Learning Technology Task Force(on line), Vol. 5, Issue 2 Y1 - 2003 A1 - Christos Bouras A1 - A Karaliotas A1 - Mixalis Paraskevas A1 - V Papoutsis A1 - Christos Ntokos A1 - N Drosopoulos AB - The architecture of the wireless network consists of 3 main parts. The wireless infrastructure, the connection of the wireless island to the rest network and the interconnection between the neighboring schools a near one participating in the wireless network. The wireless connection supports Point-to-Multipoint technology [3] and uses the frequency band 2,4 Ghz to 2,4835 Ghz. The reserved bandwidth of this wireless LAN is order of magnitude 11 Mbps. In each school the bridge device is connected to a newly equipped Fast Ethernet switch interconnecting the internal schools network to the wireless network. Between the schools a fast Ethernet network is built using copper and Fiber optic cabling. The interconnection of the wireless network upstream to the backbone is achieved with the use of the link between the E.A.O and the local main distribution node of the EDUNET network. This link had to be upgrade because it will carry the traffic from the wireless network too. The selected solution was the VDSL technology by engaging the appropriate modems over a two-wire leased line between the E.A.O and the main node. We have a selected point in each school unit that wireless bridge and antenna will be installed. The wireless bridge must stand near to antenna because long cabling distances will produce noise in the transmission signal. The wireless bridge will be housed at waterproof cabinet, which offers all the necessary specifications for protection and electric feeding. The waterproof cabinet is installed at the antenna pylon. ER - TY - CONF T1 - Behaviour Investigation using Simulation for Redundant Multicast Transmission Supporting Adaptive QoS T2 - 10th IEEE International Conference on Networks (ICON 2002), Singapore Y1 - 2002 A1 - Christos Bouras A1 - Apostolos Gkamas A1 - Kostas Stamos A1 - A Karaliotas AB - In this paper we describe a mechanism for redundant multicast transmission of multimedia data supporting adaptive QoS over the Internet and we investigate its behaviour using simulation. There are two major issues that have to be considered when designing and implementing such a mechanism, the fairness, which is the ability to cope with receiver heterogeneity, and the adaptation schemes. The proposed mechanism uses a friendly to the network users congestion control policy to control the transmission of the data. We evaluate the adaptive multicast transmission mechanism through a number of simulations in order to examine its behaviour to a heterogeneous group of receivers and its behaviour against TCP and UDP data streams. Main conclusion of the simulation was that the proposed mechanism has friendly behaviour against the dominant traffic types of today’s Internet and treats a heterogeneous group of receivers with fairness. JF - 10th IEEE International Conference on Networks (ICON 2002), Singapore ER - TY - CONF T1 - Transition Strategies from IPv4 to IPv6: The case of GRNET T2 - 3rd International Network Conference-INC 2002, Plymouth, UK Y1 - 2002 A1 - Christos Bouras A1 - A Karaliotas A1 - Petros Ganos AB - In this paper we describe the results that came out from the project of employing the IPv6 protocol over the Greek Research & Technology Network (GRNET). In the way of this process one of the big issues that had to be considered was the transition strategy that would be deployed. The main goals of a transition strategy are to be smooth enough and therefore to put the less of configuration overhead to the end users and the network administrators. JF - 3rd International Network Conference-INC 2002, Plymouth, UK ER - TY - CONF T1 - Architecture and Performance Evaluation for Redundant Multicast Transmission Supporting Adaptive QoS T2 - 9th International Conference on Software, Telecommunications and Computer Networks (SoftCom 2001) Split, Dubrovnik(Croatia), Ancona, Bari (Italy), vol II Y1 - 2001 A1 - Christos Bouras A1 - Apostolos Gkamas A1 - Kostas Stamos A1 - A Karaliotas AB -

In this paper we describe the architecture of an application that was developed for the transmission of multimedia data, using the multicast mechanism, over the Internet. There are two major issues that have to be considered when designing and implementing such a service, the fairness and the adaptation schemes. In our application we use a mechanism that categorizes the receivers into a number of groups according to each receiver’s capabilities and (the mechanism) serves each group of users with a different multicast stream. We have also implemented an additional mechanism for the intra-stream bit rate adaptation. The proposed mechanism uses a “friendly” to the network users congestion control policy to control the transmission of the data. We evaluate the adaptive multicast transmission mechanism through a number of experiments in order to examine its behaviour to a heterogeneous group of receivers and its behaviour against TCP and UDP data streams.

JF - 9th International Conference on Software, Telecommunications and Computer Networks (SoftCom 2001) Split, Dubrovnik(Croatia), Ancona, Bari (Italy), vol II ER - TY - CONF T1 - An Architecture for Redundant Multicast Transmission Supporting Adaptive QoS T2 - 7th International WORKSHOP ON MULTIMEDIA SYSTEMS, Capri, Italy Y1 - 2001 A1 - Christos Bouras A1 - Apostolos Gkamas A1 - Kostas Stamos A1 - A Karaliotas AB - In this paper we describe the architecture and the implementation of an application that was developed for the transmission of multimedia data, using the multicast mechanism, over the Internet. There are two major issues that have to be considered when designing and implementing such a service, the fairness and the adaptation schemes. The fairness problem results from the fact that receivers with different capabilities have to be served. In our application we use a mechanism that categorizes the receivers into a number of groups according to each receiver’s capabilities and (the mechanism) serves each group of users with a different multicast stream. With the term “capabilities” we do not only mean the processing power of the client, but also the capacity and the condition of the network path towards that client. Because of today’s Internet heterogeneity and the lack of Quality of Service (QoS) support, the sender cannot assume that the receivers will permanently be able to handle a specific bit rate. We have therefore implemented an additional mechanism for the intra-stream bit rate adaptation. JF - 7th International WORKSHOP ON MULTIMEDIA SYSTEMS, Capri, Italy ER -