DiffServ was designed to implement service provider quality of service (QoS) policies, where routers change and react upon the DiffServ Code Point (DSCP) in the IP header. However, nowadays, applications are beginning to directly set the DSCP themselves, in the hope that this will yield a more appropriate service for their respective video, audio and data streams. WebRTC is a prime example of such an application. We present measurements, for both IPv4 and IPv6, of what happens to DSCP values along Internet paths after an end system has set them without any prior agreement between a customer and a service provider. We find that the DSCP is often changed or zeroed along the path, but detrimental effects from using the DSCP are extremely rare; moreover, DSCP values sometimes remain intact (potentially having an effect on traffic) for several AS hops. This positive result motivates an analysis of the potential latency impact from such DSCP usage, for which we present the first measurement results. We find that routers at approximately 3% of more than 100,000 links differentiate between the WebRTC DSCP values (EF, AF42 and CS1) and consistently reduce delay in comparison with probes carrying a zero value (CS0) under congestion. In contrast, routers at around 2% of these links increase the delay by a comparable amount under congestion, uniformly for EF, AF42 and CS1.

In former times, it was necessary to operate and maintain powerful personal computers to run applications. Nowadays, many "normal" users just use laptops, tablet PCs or smartphones. Their applications are powered by cloud systems in the background, which are operated in data centres at remote locations and being connected over the Internet. This presentation first introduces the basics of cloud computing: virtualisation, virtual machines, containers, and software as a service. A challenge of using cloud computing is to deploy services to cloud providers, in order to operate them in a cost-efficient way while providing the best application experience to the users. The vision of the Multi-Cloud Execution-Ware for Large-scale Optimised Data-Intensive Computing (MELODIC) project is to enable federated cloud computing for data-intensive applications. Furthermore, it provides the user with an easy-to-use, unified cloud environment, which hides the complexity of a multi-cloud. The second part of this presentation therefore provides an overview of the basic ideas and application use cases of MELODIC.

A large fraction of the communication in the Internet is handled by the Transmission Control Protocol (TCP). Since the first deployments of this protocol more than 30 years ago, the spectrum of applications as well as the structure of the network have developed at a fast pace. For example, today's network devices, like smartphones and laptops – i.e.\ particularly many devices in the area of mobile computing – frequently have an interesting property: the existence of multiple IP addresses (IPv4 and/or IPv6). The addresses may even change due to mobility. This property, denoted as multi-homing, can be utilised for multi-path transport, i.e. the simultaneous usage of multiple paths in the network to improve performance. Multi-path transport is a hot topic in the Internet Engineering Task Force (IETF), which is the standardisation organisation for the Internet. This talk provides an overview of the work in the areas of multi-homing and multi-path transport, with focus on the area of the protocols TCP and Stream Control Transmission Protocol (SCTP) with their experimental extensions Multi-Path TCP (MPTCP) and Concurrent Multi-Path Transfer for SCTP (CMT-SCTP). It particularly shows the sequence of research and selected results, beginning from a simple simulation model, via lab setups and small Internet scenarios, up to the large-scale, international testbed project NorNet. NorNet, and particularly its landline network part NorNet Core, is furthermore described in some detail. Based on NorNet, it is finally possible to validate simulation results in real-world, multi-homed networks, in order to provide valuable input to the ongoing IETF standardisation processes of MPTCP and CMT-SCTP. Particularly, it will also show how the NorNet testbed can be utilised for research at Hainan University.

Cloud computing has revolutionized the way of application usage and deployment: applications run cost-effectively in remote data centers. With the increasing need for mobility and micro-services, particularly with the upcoming 5G mobile broadband networks, there is also a strong demand for mobile edge computing (MEC): applications run in small cloud systems in close proximity to the user, in order to minimize latencies. Both cloud and MEC have their advantages and disadvantages. Combining the two approaches in a unified multi-cloud, consisting of both traditional cloud services provisioned over heterogeneous cloud platforms and MEC systems, has the potential of obtaining the best out of both worlds. However, a comprehensive study is needed to evaluate the performance gains and the overheads involved for real-world cloud applications. In this paper, we introduce a baseline performance evaluation in order to identify the fallacies and pitfalls of combining multiple cloud systems and MEC into a unified MEC-multi-cloud platform. For this purpose, we analyze the basic, application-independent performance metrics of average round-trip time (RTT) and average application payload throughput in a setup consisting of two private and one public cloud systems. This baseline performance analysis confirms the feasibility of MEC-multi-cloud, and provides guidelines for designing an autonomic resource provisioning solutions, in terms of an extension proposed to our existing Melodic middleware platform for multi-cloud applications.