WHITE PAPER

Traffic Distribution over Time and Space

An Operator Focused Approach to Inter Cloud Scenarios

http://www.smartenit.eu

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1. SmartenIT at a Glance The massive adoption of the cloud computing paradigm and its broad portfolio of service offerings poses substantial challenges to different stakeholders playing in the cloud land-scape, more specifically Internet Service Providers (ISP), Data Center owners, and Cloud Service Providers (CSP). Most of these challenges derive from the fact that new services are offered according to the cloud principle of service transparency, where end-users are fully unaware of heterogeneous underlying cross-layer infrastructures and assets that compose the service purchased.

Today and at the state of art all stakeholders contributing to the service chain lack a unified and cooperative view on the end-to-end service to be exposed to the end-user, which results in the absence of a cross-layer, inter-domain approach to challenges posed by service composition and proper end-to-end Service Level Agreements (SLA) management. Major drawback of the depicted landscape is the unfair management of inter-cloud/ inter-domain traffic, with extra burden on ISP/CSP owned infrastructure.

Another key topic, which constitutes at the same time a challenge as well as an oppor-tunity, is the growth of traffic driven by social networks, which turns out for its unpredicta-bility and burstiness of network traffic to be running on an increasing number of energy de-manding end-user devices and network equipment. These energy awareness conside-rations play another important role. Cloud computing, by leveraging virtualization tech-nology, is inherently more energy-efficient than an older computing paradigm, but its full potential of savings has not been exploited yet. In this complex and multi-sided landscape SmartenIT’s main idea and approach developed is to innovate on two main aspects, which are strictly correlated: the first is related to the analysis of new business schemes, which are intended to forecast cross-layer and inter-domain cooperation with an incentive-based approach, the second is to develop new traffic management mechanisms, which leverage newly developed business schemes. More in detail SmartenIT’s innovation explored the possibility of embedding new traffic management solutions with main topics as inter-domain collaboration, energy-aware and social-awareness considerations, to provide a tangible impact on end-user devices and underlying networking infrastructure as well as application provisioning infrastructure of service providers.

Therefore, SmartenIT’s landscape has been divided in two macro perspectives, namely the Operator Focused Scenario (OFS) and the End-user Focused Scenario (EFS).

The first scenario is dedicated to the analysis of inter-relationships among service provi-ders, whose infrastructure is used to compose cloud services to be offered to end-users, with a major focus on the management of inter-domain traffic and on the analysis of mutual interests of those stakeholders involved.

The second scenario sees the end-user as its main focus, dealing with topics of end-user interaction in a social network landscape and Quality-of-Experience (QoE), when purchas-ing cloud services. By leveraging these two scenarios, SmartenIT has designed suitable in-centive-compatible cross-layer network management schemes to drive an efficient and be-neficial interaction among service providers and end-users.

The following sections of this white paper introduce SmartenIT’s approach and solutions across the OFS scenario domain.

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2. Overlay Applications in Cloud Scenarios: A New Challenge for Stakeholders

Internet services such as IPTV (Internet TV), video and gaming, are used by millions of geographically dispersed people. Clouds, Content Delivery Networks (CDN), and online social networks have resulted in complex services where resources, data and service points are virtualized and instantiated at/migrated to multiple locations so as to efficiently serve the users. At the same time, the Internet faces well-known inefficiencies.

Asymmetric information between the ISP and its customers (cloud providers, other ISPs) is a major issue, since ISP are not willing to disclose internal details and policies of owned infrastructure to other ISPs and cloud/application service providers, rendering inter-domain monitoring impossible. Furthermore, there are no reward schemes for ISPs willing to provide assured quality to inter-domain traffic since networks solely exchange data and BGP (Border Gateway Protocol) information, lacking standardized service-aware inter-pro-vider service coordination in both business and technical layer. This is also due to the fact that interconnections contracts pertain to large traffic aggregates, thus there is no service-specific overlay for optimizations, and provide only uptime guarantees and absolutely no guarantees on quality. This lack of end-to-end inter-provider Service Level Agreements and respective multi-provider service-aware connectivity products drives high quality out of the market: Since there are no quality guarantees, it is impossible for buyers to predict the quality of inter-domain flows, thus they expect – and bias their willingness to pay on – the average quality observed in the market, which essentially renders any higher-quality product unsustainable. ISPs’ opportunistic routing and prioritizing owned flows over inter-domain traffic further mitigates quality. Overall, these inefficiencies are due to the lack of service-aware coordination and cooperation among ISPs, clouds and ISPs, and clouds. This further renders inter-provider cloud and content service provisioning problematic and greatly affecting the end-users’ Quality-of-Experience (QoE). This is also of particular inte-rest to Europe and similar areas where there are typically multiple geographically-limited ISPs, datacenters and cloud service providers without global Information and Commu-nication Technology infrastructure, rendering intra-provider traffic management and cross-layer network-cloud layer optimization solutions inapplicable.

To this end, data centers, CDNs and proxy servers attempt to mitigate these inefficiencies to some extent and improve service performance by bringing data and services closer to the users. However, this requires continuously transferring potentially vast amounts of data among clouds and data centers/caches across multiple Internet locations and domains. In particular, inter-cloud communication constitutes a thriving business and is further growing due to the emerging federations of clouds and CDNs, such as CDNI (Content Delivery Net-works Interconnection), OnApp, XIFI, or Zentera, that enable their members to dynamically lease presence to multiple geographic regions when and for as long needed. This elastic way to provision cloud resources and inter-cloud data transfers complement the CDNs’ content caching for cloud applications requiring good QoE for end users, redundancy, fault-tolerance and reliability.

Those data transfers comprise the opaque to the users “back-office”, hence not visible to end-users, Web traffic that generates a large portion of the Internet inter-domain traffic, being up to 30% and occasionally 40-50% of the total traffic of popular Internet transit links. The main sources of this traffic, which is expected to increase due to video, have been

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identified to be mainly related to Web proxies/intermediaries, CDN servers, ad exchanges and Web crawlers. This large “back-office” portion of transit traffic is not time-critical for the end users since it is not directly associated to their flows and thus substantial transit cost savings can be attained for ISPs and also for clouds by applying smart traffic management. This motivates SmartenIT research on traffic management mechanisms that consider the peculiarities of inter-cloud communication and bring benefits for both ISPs and their business customers, including the cloud service providers.

Cloud applications are hosted either at enterprise-owned private clouds, provider-owned public and hybrid clouds platforms. With the exception of the enterprise private cloud, the role and importance of the ISP increases with the openness of the cloud. The provisioning of efficient and reliable network connectivity is crucial for the success of the end-to-end cloud service and greatly impacts the customer’s satisfaction and, thus, his willingness to pay. ISPs can play a significant role in managed virtual clouds, a new service proposition as evolution of Virtual Private Networks (VPN); this constitutes an additional service of their portfolio targeting their existing customer base. Inter-connecting the Cloud IT (Information Technology) infrastructure requires an active involvement of ISPs in large scale due to well-known inefficiencies of the Internet: by-passing inefficient BGP routes, provisioned resources to guarantee Quality-of-Service (QoS), or prioritizing traffic possibly also in inter-domain layers. There is potential for ISPs here to combine network and Information Tech-nology resources and act as brokers-integrators, exploiting existing business relationships (e.g., VPN clients), bundling cloud brokering offers with network connectivity services so as to provide complete solutions to Small and Medium Businesses with aggressive pricing.

The efficient management of the underlying traffic and the fair and efficient use of cloud resources, considering also energy efficiency, QoE and stakeholders’ costs and interests is the focus of the SmartenIT research agenda. SmartenIT has specified, simulated, evalu-ated and implemented a set of mechanisms that are tailored to the operators’ needs and take into account their existing business contracts and interactions. Since for some inter-cloud data transfers, such as data replication, there may be multiple candidate destina-tions, SmartenIT Operator-focused mechanisms can select the optimal destination for such transfers, considering the sender’s constraints and preferences, as well as the network and cloud current load and performance metrics. This allows for joint cross-layer optimization between the network and cloud layer. Invoking the functionality which is complementing the network layer inter-domain traffic management done by the SmartenIT traffic management mechanisms over the ISP transit link(s) is optional.

SmartenIT adopts design-for-tussle principles, respecting the scope of business decisions and control of the network and cloud layer. In particular, the SmartenIT mechanism design rationale is to perform “win-win'” traffic management in the network that respects and meets the business expectations and constraints of the cloud layer as well. The clear separation of decisions between the cloud and the network layer is intentional to ensure that SmartenIT is compliant with current and emerging business models without providing unfair power to some stakeholder, being in line with the “design-for-tussle" and fair competition best practices. Therefore, the clouds and data centers, rather than the ISP, take all the cloud-related decisions such as selection of the destination and marking of traffic, while there is built-in support for both federated and independent data centers and clouds. Henceforth and in the remainder of this whitepaper we restrict attention to the SmartenIT network-layer traffic management for which there is a working software prototype and whose implementation – along with a plethora of simulations already conducted prior to the actual implementation – have enabled to document the effectiveness and power of the SmartenIT traffic management and to quantify the tangible benefits attained for operators.

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3. SmartenIT for Operators: Traffic Distribution over Time and Space

SmartenIT Traffic Management solutions have been designed to tackle the needs for Inter-Cloud Communication (ICC) traffic management in an ISP-friendly way. The approach is to apply novel ICC optimization mechanisms, comprising both network and cloud layer logic. To this end, SmartenIT has specified, evaluated and implemented the DTM++ (Dynamic Traffic Management) mechanism, which combines the features of two simpler mechanisms also developed in the scope of the project, DTM and ICC. Proposed mechanisms use information from network (transport layer) about topology and traffic samples and overwrite typical traffic routing by cost-based steering decisions implemented thanks to specially established tunnels.

The key motivation for the DTM++ traffic management rules is to recognize and then decide, whether and to what extent it is beneficial to choose the path with lower cost (“distribution over space”) or possibly delay a fraction of the traffic (“distribution over time”). The former decision pertains to the DTM logic of the DTM++ mechanism, while the latter to that of ICC traffic management mechanism

ICC is the incentive-compatible traffic management for the cost-efficient use of transit links, relying on the fact that it is highly beneficial for the ISP to shape delay-tolerant, i.e., time-shiftable traffic such as inter-cloud bulk data transfers for back-ups, during peak epochs thus reducing the transit link utilization under 95th percentile rule. As also depicted in Figure 1, removing some time-shiftable portion of the traffic when it exceed a threshold value and subsequently transferring it when the link usage is lower can enforce that the ISP transit link 95th percentile will not exceed the desired threshold value set by the ISP. This operation can be performed only as long as there is enough time-shiftable traffic to be delayed. The delaying of the traffic is incentive-compatible, since the marking of the traffic that is to be delayed is performed by the ISP business customers (clouds or data centers) and are in turn compensated for the extra delays incurred by getting a cut of the ISP’s tran-sit cost savings.

We now proceed to present the DTM logic of DTM++, which comprises the main core of the DTM++ traffic management mechanism: The DTM mechanism uses concept of trans-port costs and flow-based approach. The generic concept of the DTM mechanisms, de-signed for the optimization of transit costs for multi-homed ISP architecture is intended to minimize the ISP’s costs related to the amount of traffic in the network by optimally utilizing the multiple transit links of a multi-homed ISP. The cost function defined by the ISP reflects its requirements and may represent any monetary or non-monetary costs related to the amount of transmitted traffic. The work on DTM specification, implementation and perfor-mance evaluation is focused on monetary costs for inter-domain traffic (e.g., paid by Tier-3 operator to Tier-2 operator).

The principle of DTM mechanism as described in Figure is explained using the following simple use-case. Let’s assume that network of ISP-A is multi-homed and the tariff schemas used on different inter-domain links differs. In such a case appropriate shifting of a portion of inter-domain traffic between them may result in lowering total costs. The overall traffic on each inter-domain link is composed of two types of traffic: manageable and non-mana-geable (background). The former can be influenced by DTM. In this sample use-case the manageable traffic is constituted by all transfers between remote Data Centers (DC).

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Without using DTM all traffic exchanged between DC-A and DC-B would follow a default BGP path and would traverse, e.g., link AB. When DTM is used, two tunnels (Generic Route Encapsulation or Multi-Packet Label Switching tunnels) are established between remote POI (Point-of-Interconnection) to which DCs are connected to. Tunnels pass dif-ferent inter-domain links. ISP-A may select tunnel 1 or tunnel 2 for the inter-DC traffic and as a result decide which inter-domain link is used. The decision on the link selection is taken by the ISP dynamically (e.g., every minute) according to the current situation and estimated cost of inter-domain traffic. DTM is designed to operate with those tariffs based on total traffic volume or the 95th percentile.

Figure 1: SmartenIT DTM++ Traffic Management

DTM consists of two main building blocks:

1. An algorithm to find the optimal solution to be achieved at the end of an accounting pe-riod. It makes a prediction for the next period and finds a better traffic distribution in which the ISP's cost is minimized.

2. The compensation procedure determines how the traffic distribution should be influ-enced at a given moment to achieve the optimal solution at the end of the accounting period, i.e., decides on selection of inter-domain link.

Shift in space (DTM)

Link 1

Link 2

5 min samples

5 min samples

nn–1 n+1 n+2 n+3 n+4

nn–1 n+1 n+2 n+3 n+4

TARGET traffic (cost) to be achieved in the current period

TARGET traffic (cost) to be achieved in the current period

Shift in time (ICC)

5 min samples

nn–1 n+1 n+2 n+3 n+4

TARGET traffic (cost) to be achieved in the current period

Non-manageable traffic

Manageable traffic

• Portion of the traffic not affected

• Portion of the traffic shifted in space or time

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The DTM++ concept integrates DTM with ICC, thus, allowing for optimizations over both the space (among multiple links – DTM) and time (shifting in time – ICC) axes. The rationale and role of both mechanisms can be summarized as follows:

• DTM is responsible for distributing manageable traffic among tunnels and what follows selects the inter-domain link used. Given the amount of background and manageable traffic in a previous billing period DTM finds such a traffic distribution that the cost of the (inbound) traffic is optimized for the ISP of the receiving domain. DTM does not delay the traffic or drops packets.

• ICC additionally influences manageable traffic (delay tolerant component) on each link independently, performing traffic shaping so that the resulting aggregate rate is limited trying to keep it below a threshold, which is set for DTM++ to a reference threshold related to that link.

Figure 1: SmartenIT DTM++ Traffic Management Mechanism Deployment

SmartenIT’s DTM++ traffic management mechanism defines a consistent strategy to recog-nize opportunities to manage traffic in a multi-domain, multi-operator cloud framework, based on topology recognition and traffic measurements, which provide traffic adjustments over different links to achieve a proper targeted at link cost utilization.

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4. SmartenIT Solutions Matters to Operators In order to highlight the efficiency of the SmartenIT Operator-focused Traffic Management (TM) mechanisms, relevant and realistic (from a business perspective) Use Cases (UC) have been defined, such as: Bulk data transfers for clouds, Resource allocation in cloud federations, Video content transfer among clouds, IoT data transfers for clouds. Those UCs involve Cloud Service Providers/Data Center Operators, possibly in the form of a federation and ISPs offering the underlying traffic management. These UCs highlight aspects of the inter-cloud communication paradigm, for which ICC, DTM and DTM++ have been de-signed. The SmartenIT UCs developed and studied within SmartenIT relies on the provi-sion of proper incentives and the providing tangible benefits to all the stakeholders, so as to achieve a win-win situation. Those benefits include the minimization of costs in terms of inter-connection charges due to traffic generated by cloud services and applications for ISPs, operating costs in terms of connectivity charges and energy costs for Cloud Service Providers/Data Center Operators. The SmartenIT UCs and traffic management mecha-nisms are well in line with the existing and emerging business trends and business models in the context of cloud and Internet services.

More in detail, the SmartenIT Operator-focused mechanisms and DTM++ in particular con-stitute powerful tools of service differentiation and QoE enhancement, reducing transit and energy costs, as well as ISPs’ and clouds’ operating costs. They are applicable over the Best Effort Internet and also in the context of Future Internet, where some form of quality of service could be provisioned at inter-domain level. The SmartenIT Operator-focused me-chanisms are applicable under various business models, thus contributing to the operators’ agility and competitiveness: Such concrete business models are the TM Forum Repeatable Digital Services Provisioning or the Federation and the ISP Managed Services business models. The Repeatable Digital Services Provisioning model is a TM Forum attempt to adapt the Amazon repeatable retail business model to cloud and Internet services based on a middleware, the Ecosystem Enablement Platform, providing rich functionality to digital service providers: DTM++ could constitute a smart traffic management module of this platform. The Federation model is also a direct match, since SmartenIT mechanisms, namely ICC and DTM++, have by design a cloud layer facilitating optimal destination selection of bulk data transfers which explicitly considers the inter-cloud communication needs and inherent features. Finally, the ISP Managed Services model is also an excellent match since DTM++ could be an integral part of this paradigm as a whole and also for particular managed services such as Virtual Private Cloud and Managed Storage and Backup; in the latter cases SmartenIT intelligence could be integrated and used for the bulk data transfers among the Virtual Private Cloud end points and in order to perform scheduled managed back-ups. Also, SmartenIT relates to additional business models to emerge due to the different forms of customer ownership, brokering, intermediation and control, and form of the inter-operator business agreements.

Overall, the SmartenIT Operator-focused Traffic Management mechanisms are effective, incentive-compatible, and in line with best practices and recent evolutions in business models and networking and cloud services. Their design and features can also be extended to near-future paradigms, including assured-quality inter-domain connectivity, Software-Defined Networking/Network Function Virtualization and 5G. Thus, the SmartenIT mechanisms constitute very good solutions leading to significant benefits also in practical cases involving commercial networks and application/cloud service providers.

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Abbreviations

BGP Border Gateway Protocol

CDN Content Delivery Network

CDNI Content Delivery Networks Interconnection

CSP Cloud Service Provider

DC Data Center

DTM Dynamic Traffic Management

DTM++ Dynamic Traffic Management with extensions

EFS End-user Focused Scenario

ICC Inter-Cloud Communication

ISP Internet Service Provider

IT Information Technology

OFS Operator Focused Scenario

POI Point-of-Interconnection

QoE Quality-of-Experience

QoS Quality-of-Service

SLA Service Level Agreements

TM Traffic Management

UC Use Case

VPN Virtual Private Network

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The SmartenIT Consortium University of Zürich, UZH, Switzerland Athens University of Economics and Business - Research Center, AUEB-RC, Greece Julius-Maximilians Universität Würzburg, UniWue, Germany Technische Universität Darmstadt, TUD, Germany Akademia Gorniczo-Hutnicza im. Stanislawa Staszica w Krakowie, AGH, Poland Intracom S.A. Telecom Solutions, ICOM, Greece Alcatel Lucent Bell Labs, ALBLF, France Instytut Chemii Bioorganiicznej Pan, PSNC, Poland Interroute S.P.A, IRT, Italy Telkom Deutschland GmbH, TDG, Germany © Copyright 2015, the Members of the SmartenIT Consortium For more information on this document or the SmartenIT project, please contact: Prof. Dr. Burkhard Stiller Universität Zürich, CSG@IFI Binzmühlestrasse 14 CH—8050 Zürich Switzerland Phone: +41 44 635 4331 Fax: +41 44 635 6809 E-mail: info@smartenit.eu Mr. Matteo Biancani Enterprise Sales Director, Cloud Infrastructure Sales Interoute S.P.A. Via Cornelia, 498, Roma RM Italy Phone: +39 06 615 2401 Fax: + +39 06 6152 40 99 E-mail: matteo.biancani@interoute.com Further information on SmartenIT and its traffic management mechanisms as well as its prototypes and results achieved can be found in the two sections “Overview” and “Publica-tions” of the project’s home page http://www.smartenit.eu/.