The Internet of Things (IoT) aims to gather valuable data from our surroundings through resource-constrained networks and devices. For this reason, efficient and lightweight communication protocols are required to be developed and adopted. CORECONF, a network management protocol designed for constrained environments, provides a promising solution for IoT device configuration. This work introduces pycoreconf, an open-source implementation of CORECONF, with the goal of testing the protocol and making it more accessible to researchers and developers by enabling its use in real-world scenarios and experimental setups. In this paper, we evaluate its performance and applicability as a southbound interface in an SDN-based architecture, demonstrating its potential for configuring security contexts between IoT devices. Potential for other use cases remains to be explored in future work. Our results suggest that pycoreconf is a viable tool for those interested in exploring and adopting CORECONF in IoT scenarios.

The Internet of Things (IoT) aims to gather valuable data from our surroundings through resource-constrained networks and devices. For this reason, efficient and lightweight communication protocols are required to be developed and adopted. CORECONF, a network management protocol designed for constrained environments, provides a promising solution for IoT device configuration. This work introduces pycoreconf, an open-source implementation of CORECONF, with the goal of testing the protocol and making it more accessible to researchers and developers by enabling its use in real-world scenarios and experimental setups. In this paper, we evaluate its performance and applicability as a southbound interface in an SDN-based architecture, demonstrating its potential for configuring security contexts between IoT devices. Potential for other use cases remains to be explored in future work. Our results suggest that pycoreconf is a viable tool for those interested in exploring and adonting CORECONF in IoT scenarios.

The Industrial Internet of Things (IIoT) covers a wide range of use cases with different requirements. Among them, critical use case are distinguished by their need for extremely low latency and high reliability. Similarly, 5G networks are designed to support diverse use cases that meet the requirements of IIoT applications. However, achieving ultra-low latency remains a challenge. On the other hand, the Static Context Header Compression (SCHC) mechanism, designed to address the issue of large protocol overhead in IoT, has demonstrated its effectiveness in reducing latency by compressing the packet header across various LPWAN technologies. Consequently, integrating SCHC into 5G networks will enhance the low-latency capabilities necessary to effectively support these critical IIoT use cases. This paper proposes an integration architecture of SCHC compression mechanisms within the 5G core network. Based on 3GPP specifications, the proposed solution ensures compatibility with existing 5G standards while optimizing communication efficiency and reducing protocol over-head for IIoT applications in 5G networks.

The longevity of the protocols used by Domain Name System (DNS) is a testament to its relevance in establishing an efficient mapping between identifiers. Recent attempts to integrate DNS into the REST (REpresentational State Transfer) paradigm have paved the way for its future evolution. However, this “RESTification” made a reality by protocols such as DNS-over-HTTPS (DoH) or DoQ (DNS-over-QUIC), increases the latency and verbosity of the DNS. We propose to reduce such negative impacts of RESTIfication while maintaining the benefits it brings to the DNS. A new binary format based on the Concise Binary Object Representation (CBOR) called Efficient CBOR (e-CBOR) is introduced making the DNS message representation more compact and flexible. The tests carried out on our implementation show more than 57% reduction for DNS/DNSSEC queries. In the case of responses, we obtain a reduction of up to 16% in the size of messages encoded in the traditional format.

In current sensor-based monitoring solutions, each application involves a specified deployment and requires significant configuration efforts to adapt to changes in the sensor field. In this paper, we propose a generic solution that relies on the massive deployment of battery-powered sensors. More precisely, we present a solution for LPWAN sensors emissions scheduling to ensure overall regular sensor data emissions over time (at a rate chosen by the user) while limiting management costs incurred by sensors’ arrivals and departure. Our objectives include monitoring quality that we evaluate through a "diversity" metric encompassing that information value depletes with time, plus management cost quantified by the number of orders sent to sensors. Modeling arrivals and departures as random processes, we compute those performance metrics as functions of the overall data reception period selected and evaluate them against alternative scheduling methods. We show that our solution is better suited for Massive IoT contexts.

We are witnessing an exponential increase in IoT applications resting on global mobility of objects. Mobility requires moreover roaming to allow any device to move from one IoT network operator to another. The solutions proposed in the literature are however neither scalable nor secure. The consequences for devices’ owners with large fleets of roaming objects may seriously impact the economic benefits of the involved services. We tackle these issues starting from IoTRoam a compliant open-source implementation of the LoRaWAN roaming architecture. This one based on regular DNS resolutions suffers from the limitations indicated above. We propose to modify IoTRoam by introducing a new entity called DNS Broker responsible for orchestrating in a decentralised fashion roaming between different operators using private and secure DNS resolutions. We experimentally show the feasibility of our approach. A preliminary performance evaluation of our implemented architecture shows equal performances for a more flexible, scalable and secure architecture.

In today’s monitoring solutions, each application involves custom deployment and requires significant configuration efforts to accommodate sensor changes. In contrast, in this paper, we consider a massive deployment of battery-powered sensors to propose a more versatile monitoring solution that is not tied to the physical deployment of devices.First, we define a framework for the definition of a monitoring strategy, for which we propose a generic monitoring accuracy metric, which, weighted to the lifetime of the monitoring network, allows the characterization of a multi-objective problem.We then introduce a specific two-parameter instantiation for the period update function, that ensures strictly periodic emissions from sensors even when new sensors join the system over time. We show through simulations how the two parameters– target emission period and number of jointly used sensors–can be chosen according to the objectives for the monitoring, by highlighting the Pareto front for accuracy and energy-efficiency.1

The Internet of Things (IoT) paradigm brings together various applications and use cases, in several domains such as Smart City, e-Health, Industrial IoT, etc. The characteristics of these applications range from high-data rate streams to sporadic transmissions of small packets, including critical and low-latency traffic. Some of them such as telemetering, smart agriculture, asset tracking and environment monitoring also require an extended coverage and a long battery life (up to 10 years). Both non-3GPP and 3GPP technologies, such as Sigfox, LoraWAN, NB-IoT and LTE-M, were specifically designed to meet these specific requirements, by reducing for instance the bandwidth and the achievable data rate. These networks are so constrained that it is very challenging for them to support a standard, interoperable network stack, including security protocols. Nevertheless, these features would be highly desirable in order to ease and accelerate the deployment of IoT solutions involving various types of devices, from very constrained low-power sensors to high data rate cameras and critical actuators. In this paper, we study standard, interoperable and secure solutions and we show how Static Context Header Compression (SCHC), a generic compression and fragmentation mechanism, can be used to enable their support over constrained IoT networks. With our implementation, typical messages are shrunk from 80-100 bytes down to as little as 20-30 bytes.

Context: Internet-of-Things (IoT) systems are increasingly deployed in the real world, but their security lags behind the state of the art of non-IoT systems. Moving target defense (MTD) is a cyberdefense paradigm, successfully implemented in conventional systems, that could improve IoT security. Objective: Identify and synthesize existing MTD techniques for IoT and validate the feasibility of MTD as a cybersecurity paradigm suitable for IoT systems. Method: We use a systematic literature review method to search and analyze existing MTD for IoT techniques up to July 2020. We evaluated the existing techniques in terms of security foundations and real-world deployability using the evidence they provide. We define and use entropy-related metrics to categorize them. This is the first MTD survey to use Shannon's entropy metric empirically. Results: Thirty-two distinct MTD for IoT techniques exist: 54% are Network-layer-based, 50% present strong evidence about their real-world deployment, and 64% have weak security foundations. Conclusion: MTD for IoT is a feasible cyberdefense approach. A variety of proposals exist, with evidence about their implementation and evaluation. Nevertheless, the MTD for IoT state of the art is still immature: the security foundations of most existing proposals are weak. Novel techniques should prioritize providing convincing security foundations and real-world deployment evidence.

The Internet of Things (IoT) is more and more present in fundamental aspects of our societies and personal life. Billions of objects now have access to the Internet. This networking capability allows for new beneficial services and applications. However, it is also the entry-point for a wide variety of cyber-attacks that target these devices. The security measures present in real IoT systems lag behind those of the standard Internet. Security is sometimes completely absent. Moving Target Defense (MTD) is a 10-year-old cyber-defense paradigm. It proposes to randomize components of a system. Reasonably, an attacker will have a higher cost attacking an MTD-version of a system compared with a static-version of it. Even if MTD has been successfully applied to standard systems, its deployment for IoT is still lacking. In this paper, we propose a generic MTD framework suitable for IoT systems: IANVS (pronounced Janus). Our framework has a modular design. Its components can be adapted according to the specific constraints and requirements of a particular IoT system. We use it to instantiate two concrete MTD strategies. One that targets the UDP port numbers (port-hopping), and another a CoAP resource URI. We implement our proposal on real hardware using Pycom LoPy4 nodes. We expose the nodes to a remote Denial-of-Service attack and evaluate the effectiveness of the IANVS-based port-hopping MTD proposal.

The amount of data transferred in a smart grid system, and its reliability impose to add new communication technologies to the power line communication network using the electricity infrastructure. RPL, a well-known routing protocol in smart grid application, has been specially designed to support the constraints of low power and lossy networks. In this paper we propose to study the impact of combining a radio and a PLC interface in a smart metering architecture, by modifying RPL to handle both available interface. Using discrete event simulation, we show how the network can be more resilient to failure while the overall quality of service can be significantly increased.

Up to recently, two main approaches were used for connecting the “things” in the growing Internet of Things (IoT) - one based on multi-hop mesh networks, using short-range technologies and unlicensed spectrum, and the other based on long-range cellular network technologies using corresponding licensed frequency bands. New type of connectivity used in Low-Power Wide Area networks (LPWAN), challenges these approaches by using low-rate long-range transmission technologies in unlicensed sub-GHz frequency bands. In this paper, we do performance testing on one such star-topology network, based on Semtech's LoRa™ technology, and deployed in the city of Rennes - LoRa FABIAN. In order to check the quality of service (QoS) that this network can provide, generally and in given conditions, we conducted a set of performance measurements. We performed our tests by generating and then observing the traffic between IoT nodes and LoRa IoT stations using our LoRa FABIAN protocol stack. With our experimental setup, we were able to generate traffic very similar to the one that can be used by real application such as sensor monitoring. This let us extract basic performance metrics, such as packet error rate (PER), but also metrics related specifically to the LoRa physical layer, such as the Received Signal Strength Indicator (RSSI) and Signal to Noise ratio (SNR), within various conditions. Our findings provide insight about the performance of LoRa networks, but also about evaluation methods for these type of networks. We gathered measurement data that we make freely available together with the tools we used.

The extension of communication devices and the proliferation of transmission medium in home network contribute to increase the electromagnetic noise in home environment in general and in some area more specifically. To date, no scientific study has yet raised health issues, although public questions still exist. Whereas, lots of actions focus only on base stations of cellular networks. In order to respond to some potential customers concern, we want to minimize such emissions whenever it is possible within home environment. In this regard, we extend Wi-Fi radiation study [1] by considering involuntary emissions from power lines while carrying data in high frequencies. We first propose a PLC radiation model based on antenna theory. We demonstrate then a link-adaptive radiant exposure path cost that can fit any shortest path algorithm in order to keep electromagnetic radiation under control within a specific area. The goal of this work is to estimate the radiated power generated jointly fromWi-Fi and PLC links within a heterogeneous network and then reduce it using a routing algorithm.

This paper presents and evaluates a method to localize devices that communicate using a wireless network. The distances that separate a blind node, willing to determine its position, and a set of anchor nodes, that know their locations, are evaluated using the signal attenuation (RSSI) measured on data packets. However, multipath effects, frequent in an indoor scenario, introduce randomness in signal propagation, reducing localization accuracy. We propose to use a maximum likelihood estimator on a two-modes Gaussian Mixture model approach to detect and exclude outlier measurements. We evaluate and compare this method using experimental measurements.

As the IPv4 address pool is being exhausted, it becomes urgent to find a way to migrate IPv4 network architectures to IPv6, or to reduce the use of IPv4 addresses. In this paper, we discuss a strategy known as “Address + Port” translation, which consists in several users sharing the same IPv4 address and being distinguished by a range of port numbers. Of critical importance for the feasibility of such a mechanism is the knowledge of the minimum number of ports to allocate to users so that no service degradation is perceived. To that extent, we analyse the port consumption of the most port-consuming Internet applications, Web browsing, and present some aggregate port consumption curves for the student population of our campus. Our results suggest that a port range of 1000 ports is totally transparent to users (which would allow to share a single IPv4 address among 64 users), while 400 ports (i.e., 150 users per address) is sufficient for most of users. Finally, the number of users per address could be further improved by benefiting from statistical multiplexing, i.e., using dynamical instead of fixed port range allocation.

The 6LoWPAN layer was recently introduced as a means to enable the transmission of IPv6 datagrams over Low-power and Lossy Networks (LLNs). That layer provides schemes for fragmenting the network-layer datagrams and reassembling link-layer fragments. However, the loss of one fragment of the original datagram will lead to the loss of the latter, and eventually the retransmission of all the fragments, which is not energy-efficient. Simple Frame Forwarding and Recovery (SFFR), introduced by Thubert and Hui, is a simple end-to-end scheme for coping with MAC-layer losses in multi-hop LLNs. In this paper, we study the performance of SFFR in multi-hop wireless networks, in terms of energy consumption. Numerical results show that SFFR offers an efficient alternative to classical, hop-by-hop error-control schemes like ARQ (Automatic Repeat Request).

This paper presents an experimental study of TCPHC, a novel algorithm for compressing the Transmission Control Protocol (TCP) header to reduce its overhead in IPv6-enabled Low-power and Lossy Networks (6LoWPANs). Results show that TCPHC outperforms TCP both in low-loss and high-loss networks. In fact, TCPHC can reduce the TCP header to 6 bytes in more than 95% of the cases. Moreover, experimental results show that our TCP header compression algorithm reduces the energy consumption by up to 15%.

A number of studies show that most of current probing tools, for available bandwidth, exhibit low accuracy, and slow convergence in Home Networks. Some reasons of this behavior include the high queuing variability of probing flows, which is induced by multiple-access mechanisms, time-variant capacity links of hybrid paths, and the instability of beta probing tools. Considering these constrains of the measurement process and the limitations of probing-tools, this paper proposes using Iperf in a lightweight mode to obtain maximum throughput of non-disruptive TCP flows to estimate the available bandwidth. Our experimental results show that Iperf doubles the accuracy of the estimates compared with IGI/PTR, Pathchirp and Wbest, on representative hybrid paths. We also show that due to the low bandwidth delay products (BDP), of home network paths, we can keep low overhead using TCP flows with convenient probing/polling intervals, which reduces the intrusiveness associated to the default Iperf usage.

Deploying a security policy may prove difficult whenever the system does not embed all necessary security functionalities. Some specific functionalities are required to accurately evaluate the contexts viewed as constraints in which some security requirements are to be met. Dynamic or contextual requirements are problematic since they rely on specific functionalities which are not always available in the system or are even impossible to acquire given the current technologies. Therefore, it is essential to ensure that the contextual requirements are always managed and well deployed taking into account the existent functionalities in the system. We present a solution to cope with the following issue: ensuring that the contextual security requirements are always best deployed within the set of functionalities in the system.

The successful deployment of a security policy is closely related not only to the complexity of the security requirements but also to the capabilities/functionalities of the security devices. The complexity of the security requirements is additionally increased when contextual constraints are taken into account. Such situations appear when addressing the dynamism of some security requirements or when searching a finer granularity for the security rules. The context denotes those specific conditions in which the security requirements are to be met. (Re)deploying a contextual security policy depends on the security device functionalities: either (1) the devices include all functionalities necessary to deal with a context and the policy is consequently deployed for ensuring its automatic changes or (2) the devices do not have the right functionalities to entirely interpret a contextual requirement. We present a solution to cope with this issue: the (re)deployment of access control policies in a system that lacks the necessary functionalities to deal with contexts.

IPv6 is an attractive technology for innovative services such as health care monitoring, alarm systems, peer to peer applications, virtual machine systems and so on. The generalization of end to end paradigm, possible due to the length of IPv6 addresses, eases the deployment of such services. Nevertheless end to end connection can be a threat since application can be easily accessible from outside and thus a compromised application may endanger others. In this paper, we study some of the advantages of using the IPv6 protocol in home networks but most particularly how to improve the security of home networks. We present an architecture allowing the definition of a partition between groups of applications and where communication between these groups is not permitted if there is no explicit delegation. We overview the key points of the current implementation and some initial results of our approach.

The VoIP suite of protocols are extended to propose a computer network capable of terrestrially storing in real time the flight data records and cockpit voice records of every commercial flight. The design process took into account the satellite access, the aviation, the black box manufacturing and the VoIP industriespsila recent developments. As a result, a system architecture development framework and a transport-signaling protocol are proposed. The economic feasibility of the proposal is finally addressed.

Recent years have seen significant growth in the use of IP based multimedia and streaming applications over wireless network links, which are characterized by low (or shared) capacity, appreciable delay and variable (sometimes high BER). This has motivated the development of innovative design techniques and protocols to increase the amount of bandwidth per user, improving perceived quality and using the available energy efficiently. This paper presents experimental quantitative and qualitative performance metrics using H.264 and ROHC for a multicast video streaming. The simulation results show that the proposed Cross-Layer ROHC compression outperforms IP/UDP/RTP and ROHC U-Mode strategies by offering the highest video quality and reducing both, the bandwidth usage and the average delay to start video reproduction.

The enormous growth in the use of the IP-based multimedia and other applications has increased the need to use the available communication technologies including satellite and radio links efficiently. These wireless links generally induce high bit error rates and long delays. Moreover, the deployment of IP protocols over these links leads to significant header overhead. IP tunneling mechanisms, widely used in the network security, IPv4-to-IPv6 transition, and mobile networks also have long delay characteristics. This paper studies the behavior of one of the most commonly used Robust Header Compression (ROHC) mechanism over such long delay links and tunnels. We show the impact of long delay, high bit error rate, and packet reordering on ROHC performance. Some of the experiments have been conducted over L2TP tunnel between France and Korea. The results show that ROHC compression can be used over long delay links to reduce header overheads with certain limitations. The results presented in this paper will provide the basis for further designing header compression schemes specifically suited for links and tunnels with long delays.

High speed downlink packet access (HSDPA) is a packet-based data service in UMTS networks that supports data rates of several Mbit/s, making it suitable for data applications ranging from file transfer to multimedia streaming. In spite of the fairly high data rates that HSDPA offers, the shared downlink radio channel used in HSDPA is a challenging environment for delay- and loss-sensitive applications. It is relatively easy to partition resources over wired links with known link capacity. Nevertheless, such partitioning is complex for wireless links with variable capacity; due to the dynamic nature of the link, it is difficult to effectively allocate the resources (i.e., time slots) between users who may be paying different prices for different services. In this paper we study the general problem of resource partitioning for shared wireless links like HSDPA. We consider different QoS classes or user groups, and the use of MAC-layer scheduling for resource partitioning between groups and between individual users. We propose a variant of an existing HSDPA scheduler called required activity detection (RAD) scheduler. The proposal is studied using a detailed UMTS/HSDPA simulator.

In this work, we study the flow allocation problem in Next Generation Internet (NGI) networks. Given a capacitated network, flow allocation consists of a simultaneous routing and bandwidth allocation problem for flows realizing a set of source-destination demands. We consider the case where demands are elastic and the flow realizing one demand can be arbitrary split over multiple paths. Moreover, we ensure that the allocated flows are survivable to network failures using path protection. We investigate the possibility of sharing backup capacity, thus enabling more efficient resource consumption. Depending on the optimization objective, we provide two different approaches to the problem. The first approach maximizes the total allocated volume and the second one maximizes the minimum allocated volume. We build mathematical formulations based on generalizations of the maximum multicommodity flow and the maximum concurrent flow problems. Moreover, we provide new approximation algorithms based on a primal-dual approach. These algorithms compute a solution that is within a guaranteed factor of the optimal. Numerical results enable to get deeper insights on the quality and compared performance of the different approaches.

Many networked applications use end-to-end congestion control protocols to avoid the occurrence of congestion collapse phenomena. However, such transport protocols may suffer from link underutilization when there are wireless links along the path: the inability to distinguish wireless losses from congestion losses often results in unnecessary throughput decreases. Since networks are becoming increasingly heterogeneous, a mix of wired and wireless links, it is important to have some means of identifying the cause of a packet loss and to adapt the response of the transport protocol. In this paper, we present an end-to-end solution to this problem and propose a novel method for wireless loss estimation in IP DiffServ networks (WLED). WLED aims at enhancing the performance of equation-based rate control protocols for multimedia applications, by means of directly estimating the wireless and congestion loss rates. We discuss the integration of WLED with a recent, equation-based rate control protocol and we evaluate WLED's performance through simulation. Our results illustrate a new benefit of using DiffServ-like differentiation mechanisms for multimedia streaming in wireless networks, like UMTS, that support quality of service (QoS).

The use of ROHC (robust header compression) for multimedia applications as VoIP over 3G radio links has shown a good performance in reducing the overhead of RTP encapsulation. Some efforts have been made to use ROHC over IEEE 802 links, but the solution needs to be optimized. The use of ROHC out of its operating assumptions adds some additional problems. These problems occur when the padding is used within small packets. This paper introduces an optimized solution to send ROHC packets over IEEE 802 links

This paper outlines the concept of auto-organization in IPv6 networks. If the auto-configuration of hosts is defined by IPv6 and mandatory, these mechanisms can not be assimilated to a fully plug and play feature as IPv6 routers still have to be manually configured. In order to succeed in new domains such as SOHO, a full auto-configuration feature must be offered. Indeed, the configuration of 64 bits IPv6 prefixes and the numbering of links are not really friendly and are error prone especially in home networking. This paper tackles the issues that arise, reviews actual solutions and proposes a totally distributed protocol named NAP for IPv6 routers auto-configuration.

In this paper, we present a novel polynomial time framework for the off-line flow allocation problem in MPLS-traffic engineering (MPLS-TE) networks. This framework, named FATE (flow allocation for traffic engineering), encom-passes different objectives that illustrate the operator needs for traffic engineering and provides advanced control over the quality of the solution. Typically, we consider minimizing congestion, bandwidth consumption and operational costs. FATE is based on linear programming and presents an efficient solution for the problem both in terms of computational complexity and approximation guarantees. Simulation results show that we can get an efficient trade-off between congestion and bandwidth consumption while having a reduced number of label switched paths (LSPs) for various known topologies

The header compression mechanisms have been defined to work on a peer-to-peer noisy links, nevertheless the interest to integrate these schemes in multicast diffusion is increasing because this option will offer bandwidth savings. In this paper, ROHC unidirectional mode is used as a current possibility to make header compression to multicast packets. In a multicast distribution service users join the group at any time. Thus, the use of ROHC header compression will create a waiting time to start receiving the application information because all the header information is sent in a periodical time. A context recovery process (CRP) is proposed to improve ROHC multicast performance. This CRP reduces the waiting time to receive the context and may decrease the probability of context damage in a noisy link. The waiting time to receive the context is a new indicator to be considered in addition to ROHC performance indicators, when studying ROHC multicast performance. Our solution is evaluated by simulation means

The use of IPv6 in the third generation of cellular networks leads to weak performance of the network systems because the IPv6 header size sent in each packet represents more than twice the payload normally used in video or audio applications. The IETF ROHC (robust header compression) working group has defined a new header compression mechanism to reduce the transmission time and increment the use of the bandwidth in networks with scarce resources. The present version of ROHC considers a static configuration of the ROHC implementation parameters and at the same time does not negotiate some of the link parameters. This paper proposes a dynamic configuration for UMTS radio networks through negotiation. Dynamic configuration enables ROHC to improve its efficiency and robustness based on radio link parameters.

ROHC Bormann C., et al. (2001) is the new standard for header compression proposed by the IETF (Internet engineering task force) to compress different protocol headers. ROHC needs to be configured to afford the changes in the characteristics of the UMTS radio link and to enable a better compression of the IPv6 flows. In this document we will introduce the characteristics and the behavior of ROHC. Also we study the compression parameters that are recommended as implementation dependent in the ROHC specification and we show how to configure them. This study can help to improve the efficiency and robustness of ROHC when it is used in scarce resources links, such as UMTS.

With the emergence of new multimedia applications and the large standardization effort of packet telephony products, a large volume of small packet traffic flows in the network. It is expected to get worse with the popularity of VoIP applications. To mitigate the impact of small packets we propose the aggregation of packets present in the output queue and which have the same forwarding equivalence class, such as those which will leave a routing domain from the same node (an egress node). The set of aggregated packets will be subsequently treated as a single packet, thus requiring smaller processing overhead at intermediate routers. We report the results of several simulations that evaluate the performance benefits of aggregation. We note that aggregation keeps the same behavior as pure FIFO. Thus it doesn't disturb the aggregator router behavior. It saves CPU processing time and buffer space at intermediate routers, thus improving the overall network performance.

The future Internet networks are expected to use IPv6 version rather than the IPv4 one. This is mainly due to the limitations of IPv4 in terms of addresses, routing and security QoS issues developed by the Internet community are also tailored for both versions and will be easily deployed in both sides. Since a huge amount of sub-networks are already installed for the v4 version, it is difficult to imagine ISPs starting deploying the v6 version without some assurance that old legacy networks will still be able to connect to the Internet. In this paper we present some mechanisms that have been proposed to ease this transition especially for v4 users that still want to communicate with their old applications. We present also an IPv6 tunneling mechanism that has some advantages over the other models. We show how one could use such a mechanism to transparently establish hybrid communications between two worlds in both ways and discuss some important issues like scalability and performance.

The paper describes the Prism distributed multimedia platform. The paper is divided in three parts. The first part resumes the main components of the platform. The authors show the different planes that interact with both multimedia applications and network resources. The second part describes a different approach being developed for the platform to ease the distribution of multimedia objects. It is based on fragmented objects. The third part enumerates two different applications that have been developed for and on that platform. The first is a specific multimedia protocol and the second is a whiteboard used for tele-teaching.

Many current approach to access control assume all external access are dangerous. As a consequence they stop all communication and check for authorisation. We present an optimistic approach to provide security services in a network environment that do not interject the security services into the operational sequence, rather, the security services are established as a parallel set of services/steps. This optimistic approach let go the communication and checks in parallel for authorization, illegal communication will be stopped latter. Provided that the checking is fast enough the potential danger may be kept as low as necessary. This presentation exhibits the concepts, properties, advantages of an optimistic access control. An implementation called “Network Security Probe” NSP is described.