53 research outputs found
Time-varying resilient virtual network mapping for multi-location cloud data centers
Optical networks constitute a fundamental building block that has enabled the success of cloud computing. Virtualization, a cornerstone of cloud computing, today is applied in the networking field: physical network infrastructure is logically partitioned into separate virtual networks, thus providing isolation between distinct virtual network operators (VNOs). Hence, the problem of virtual network mapping has arisen: how to decide which physical resources to allocate for a particular virtual network? In a cloud context, not just network connectivity is required, but also data center (DC) resources located at multiple locations, for computation and/or storage. Given the underlying anycast routing principle, the network operator has some freedom to which specific DC to allocate these resources.
In this paper, we solve a resilient virtual network mapping problem that optimally decides on the mapping of both network and multi-location data center resources resiliently using anycast routing, considering time-varying traffic conditions. In terms of resilience, we consider the so-called VNO-resilience scheme, where resilience is provided in the virtual network layer. To minimize physical resource capacity requirements, we allow reuse of both network and DC resources. The failures we protect against include both network and DC resource failures: we hence allocate backup DC resources, and also account for synchronization between primary and backup DC.
As optimization criteria, we not only consider resource usage minimization, but also aim to limit virtual network reconfigurations from one time period to the next. We propose a scalable column generation approach to solve the dynamic resilient virtual network mapping problem, and demonstrate it in a case study on a nationwide US backbone network
Let there be Chaining: How to Augment your IGP to Chain your Services
Ever since Network Functions Virtualization has replaced dedicated appliances, ISPs have been able to add a degree of flexibility in their traffic engineering. However, it also has increased the complexity of the optimization problem, because it is now necessary to place virtual functions and route traffic jointly. Insofar, a logically centralized approach has been taken, where a so-called orchestrator, having full knowledge of the network, the virtual functions, and the traffic, run complex algorithms to find a suitable solution to the problem. The outcome of the algorithms are then translated to network configurations to be pushed to all of the appliances. We argue that there is no need to fully centralize every decision, rather we can leverage existing network intelligence to achieve the same goal. In particular we propose to augment the routing layer with the notion of services, so to rely on the robustness and scalability of Interior Gateway Protocols (IGP). Our solution leverages on existing distributed routing protocols where, in addition, autonomous nodes announce information about the virtual services they provide. Our design is modular and incrementally deployable and has been implemented in what we call a NFV Router. In our evaluation, we show that (i) NFV Routers distributed chaining decisions are close to optimal centrally-computed paths, (ii) on a large scale testbed deployment, NFV Routers efficiently steer traffic through chains and only add a small overhead to control traffic and (iii) our distributed system, because of its local control loop, has a faster reaction to network events than centralized solutions
Opportunistic Routing and Synchronous Transmissions Meet TSCH
Low-power wireless networking commonly uses either Time-Slotted Channel Hopping (TSCH), synchronous transmissions, or opportunistic routing. All three of these different, orthogonal approaches strive for efficient and reliable communication but follow different trajectories. With this paper, we combine these concepts into one protocol: AUTOBAHN.AUTOBAHN merges TSCH scheduling with opportunistically routed, synchronous transmissions. This opens the possibility to create long-term stable schedules overcoming local interference. We prove the stability of schedules over several days in our experimental evaluation. Moreover, AUTOBAHN outperforms the autonomous scheduler Orchestra under interference in terms of reliability by 13.9 percentage points and in terms of latency by a factor of 9 under a minor duty cycle increase of 2.1 percentage points
Adaptive load balancing routing algorithms for the next generation wireless telecommunications networks
This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel UniversityWith the rapid development of wireless networks, mesh networks are evolving as a new important technology, presenting a high research and commercial interest. Additionally, wireless mesh networks have a wide variety of applications, offering the ability to provide network access in both rural and urban areas with low cost of maintenance. One of the main functionalities of a wireless mesh network is load balancing routing, which is the procedure of finding the best, according to some criteria, routes that data need to follow to transfer from one node to another. Routing is one of the state-of-the-art areas of research because the current algorithms and protocols are not efficient and effective due to the diversity of the characteristics of these networks. In this thesis, two new routing algorithms have been developed for No Intra-Cell Interference (NICI) and Limited Intra-Cell Interference (LICI) networks based on WiMAX, the most advanced wireless technology ready for deployment. The algorithms created are based on the classical Dijkstra and Ford-Fulkerson algorithms and can be implemented in the cases of unicast and multicast transmission respectively.State scholarships foundation of Greece
Latency-Based Anycast Geolocation: Algorithms, Software, and Datasets
International audienceUse of IP-layer anycast has increased in the last few years beyond the DNS realm. Yet, existing measurement techniques to identify and enumerate anycast replicas exploit specifics of the DNS protocol, which limits their applicability to this particular service. With this paper, we not only propose and thoroughly validate a protocol-agnostic technique for anycast replicas discovery and geolocation, but also provide the community with open source software and datasets to replicate our experimental results, as well as facilitating the development of new techniques such as ours. In particular, our proposed method achieves thorough enumer-ation and city-level geolocalization of anycast instances from a set of known vantage points. The algorithm features an iterative workflow, pipelining enumeration (an optimization problem using latency as input) and geolocalization (a classification problem using side channel information such as city population) of anycast replicas. Results of a thorough validation campaign show our algorithm to be robust to measurement noise, and very lightweight as it requires only a handful of latency measurements
Time-varying Resilient Virtual Networking Mapping for Multi-location Cloud Data Centers
Abstract
In the currently dominant cloud computing paradigm, applications are being served in data
centers (DCs), which are connected to high capacity optical networks. For bandwidth and
consequently cost efficiency reasons, in both DC and optical network domains, virtualization
of the physical hardware is exploited. In a DC, it means that multiple so-called virtual
machines (VMs) are being hosted on the same physical server. Similarly, the network is
partitioned into separate virtual networks, thus providing isolation between distinct virtual
network operators (VNOs). Thus, the problem of virtual network mapping arises: how to
decide which physical resources to allocate for a particular virtual network? In this thesis,
we study that problem in the context of cloud computing with multiple DC sites. This
introduces additional flexibility, due to the anycast routing principle: we have the freedom
to decide at what particular DC location to serve a particular application. We can exploit
this choice to minimize the required resources when solving the virtual network mapping
problem.
This thesis solves a resilient virtual network mapping problem that optimally decides
on the mapping of both network and data center resources, considering time-varying traffic
conditions and protecting against possible failures of both network and DC resources. We
consider the so-called VNO resilience scheme: rerouting under failure conditions is provided
in the virtual network layer. To minimize physical resource capacity requirements, we allow
reuse of both network and DC resources: we can reuse the same resources for the rerouting
under failure scenarios that are assumed not to occur simultaneously. Since we also protect
against DC failures, we allocate backup DC resources, and account for synchronization
between primary and backup DCs. To deal with the time variations in the volume and geographical
pattern of the application traffic, we investigate the potential benefits (in terms
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of overall bandwidth requirements) of reconfiguring the virtual network mapping from one
time period to the next. We provide models with good scalability, and investigate different
scenarios to check whether it is worth to change routing for service requirement between time
periods. The results come up with our experiments show that the benefits for rerouting is
very limited.
Keywords: Cloud Computing, Optical Networks, Virtualization, Anycast, VNO resilienc
Formal Validation of Security Properties of AMT's Three-Way Handshake
Multicasting is a technique for transmitting the same information to multiple receivers over IP networks. It is often deployed on streaming media applications over the
Internet and private networks. The biggest problem multicast introduces today is that it is an all or nothing solution. Every element on the path between the source and the receivers (links, routers, firewalls) requires multicast protocols to be enabled. Furthermore, multicast has a conceptual business model, and therefore is not an easy case to make. These factors, embedded deep in technology, but ultimately shaped by economics, led to a lack of multicast deployment. To address this problem, the AMT (Automatic IP Multicast without explicit Tunnels) specification has been
developed by the Network Working Group at the IETF. This specification is designed to provide a mechanism for a migration path to a fully multicast-enabled backbone.
It allows multicast to reach unicast-only receivers without the need for any explicit tunnels between the receiver and the source. We have formally validated the three-way
handshake in the AMT specification using AVISPA against two main security goals: secrecy and authentication. We have demonstrated that the authentication goal is not met: an attacker can masquerade as an AMT relay, and the AMT gateway (at the end user) cannot distinguish a valid relay from an invalid one. Another attack was also found where an intruder can disconnect or shutdown a valid session for a valid end-user using a replay attack
Content-centric wireless networks with limited buffers: when mobility hurts
We analyze throughput–delay scaling laws of mobile ad hoc networks under a content-centric traffic scenario, where users are mainly interested in retrieving contents cached by other nodes. We assume limited buffer size available at each node and Zipf-like content popularity. We consider nodes uniformly visiting the network area according to a random-walk mobility model, whose flight size varies from the typical distance among the nodes (quasi-static case) up to the edge length of the network area (reshuffling mobility model). Our main findings are: 1) the best throughput–delay tradeoffs are achieved in the quasi-static case: increasing the mobility degree of nodes leads to worse and worse performance; ii) the best throughput–delay tradeoffs can
be recovered by power control (i.e., by adapting the transmission range to the content) even in the complete reshuffling case
Survey of Transportation of Adaptive Multimedia Streaming service in Internet
[DE] World Wide Web is the greatest boon towards the technological advancement of modern era. Using the benefits of Internet globally, anywhere and anytime, users can avail the benefits of accessing live and on demand video services. The streaming media systems such as YouTube, Netflix, and Apple Music are reining the multimedia world with frequent popularity among users. A key concern of quality perceived for video streaming applications over Internet is the Quality of Experience (QoE) that users go through. Due to changing network conditions, bit rate and initial delay and the multimedia file freezes or provide poor video quality to the end users, researchers across industry and academia are explored HTTP Adaptive Streaming (HAS), which split the video content into multiple segments and offer the clients at varying qualities. The video player at the client side plays a vital role in buffer management and choosing the appropriate bit rate for each such segment of video to be transmitted. A higher bit rate transmitted video pauses in between whereas, a lower bit rate video lacks in quality, requiring a tradeoff between them. The need of the hour was to adaptively varying the bit rate and video quality to match the transmission media conditions. Further, The main aim of this paper is to give an overview on the state of the art HAS techniques across multimedia and networking domains. A detailed survey was conducted to analyze challenges and solutions in adaptive streaming algorithms, QoE, network protocols, buffering and etc. It also focuses on various challenges on QoE influence factors in a fluctuating network condition, which are often ignored in present HAS methodologies. Furthermore, this survey will enable network and multimedia researchers a fair amount of understanding about the latest happenings of adaptive streaming and the necessary improvements that can be incorporated in future developments.Abdullah, MTA.; Lloret, J.; Canovas Solbes, A.; GarcĂa-GarcĂa, L. (2017). Survey of Transportation of Adaptive Multimedia Streaming service in Internet. Network Protocols and Algorithms. 9(1-2):85-125. doi:10.5296/npa.v9i1-2.12412S8512591-
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