While blockchains and smart contracts are primarily known for their use as the technologies underlying cryptocurrencies like Bitcoin and Ethereum, these technologies also have applicability in other areas. In this paper, we present an application of smart contracts running on a permissioned distributed ledger (essentially a private blockchain where only credentialed participants are allowed to read and write) to managing tenant and service accounts in a cloud computing data center. The system is called Saranyu and it supports four services: identity management, authentication, authorization, and charging. Identity management and authentication are handled using client-generated public/private key pairs in the usual fashion. Authorization is handled as a contract from a grantee of service access rights to a recipient which is a tenant or other service. Charging is supported by Saranyu integration with payment gateways for payments related to service resource usage. We describe an implementation of Saranyu on top of the Quorum blockchain system. We believe the security, non-repudiation, tamper-resistance, and easy transaction history access brought by blockchain technology will increase transparency and trust in cloud tenant and service management and that the fundamentally distributed nature of the blockchain will make Saranyu an excellent match with developing distributed cloud architectures.

Orchestration and management of cloud computing entities necessitate measuring and analysis of real-time monitored performance metrics. However, decision making in current management platforms are addressed separately in different cloud stack layers. These isolated active management decisions may degrade the total performance of the cloud system. Since, cloud computing platforms lack an integrated analytics and management capability, in this paper, we propose an integrated platform to detect and predict situations where corrective actions are required. First, a Dynamic Bayesian Network (DBN) is trained and updated by collected data to calculate the causal dependencies among various entities in different cloud service layers. The correlation values are then fed into a Long Short-Term Memory (LSTM) neural network to predict the future states. States that violate the Service Level Agreement(SLA) of cloud services are learned with training data, and if the forecasted states threaten the SLA of cloud services, associated events are generated to trigger management actions. Next, management actions are assigned a different set of events using a reinforcement learning approach. A set of experiments based on collected data from a real cloud service environment is conducted to validate the proposed approach. Experimental results indicate that the proposed method outperforms the current management solutions and improves web request response time by up to 7% and decreases SLA violation by 79% in the context of web application auto-scaling.

Software Defined Networking (in short SDN, which is also an acronym for Software Defined Network), has emerged as a response to the limitations and complexities of traditional network architectures. At the heart of SDN lies the idea to consolidate the control over network devices into a logically centralized (software) controller separated from the data plane. The separation of the control plane and the data plane is realized via an open programming interface between the data plane switches and the SDN controller. The decoupling allows the control plane to evolve independently of the data plane, which enables faster innovation since software often exceeds hardware in innovation speed. Furthermore, logical centralization has the potential to simplify network operation and management by providing a single focal point where the consequences of management actions can be assessed, and possibly rejected if they would lead to some violation of operational constraints. OpenFlow, the standard SDN protocol today, is based on a simple match-action paradigm which results in great flexibilities, e.g., in terms of traffic engineering, definition of flows, as well as in-band network control functionalities.

Software defined networking (SDN) and Network Function Virtualization (NFV) are new approaches to next generation network architecture for operator networks that have received much discussion in the research literature and in new forums organized to standardize their interfaces. While these approaches to network architecture are important, they only cover part of the problem. A fundamental property required from any next generation architecture is support for rapid, cross-domain service innovation. In this paper, we discuss Service Provider SDN (SP-SDN), an architectural approach to rapid service innovation based on exposure of functionality for cross-domain control at the service layer. The functionality is exposed through Web-style interfaces that feature abstractions crafted by suppressing detail irrelevant for the majority of the created services. The control spans mobile, fixed and cloud operator networks, allowing the rapid and flexible provisioning of services across all three domains. We compare this approach to SDN and NFV, and find that SP-SDN complements rather than competes with the two. We present two examples of prototype systems built with SP-SDN.

One of the primary principles of Software Defined Networking (SDN) is that representing networks as a collection of simple abstractions implemented as an API - rather than as a collection of standardized and proprietary protocols and command line interfaces - will lead to networks that are easier to build and manage. Application of this principle has advanced furthest in cloud computing, where the OpenStack Quantum network service provides tenants in a data center with an abstraction of an enterprise LAN. The Quantum API implements a virtual network through a plug-in, which might in fact require protocols and command line interfaces to drive the physical hardware. However, existing OpenStack support for wide area connectivity is restricted to L3 IPsec and SSL VPNs which do not in general support quality of service (QoS). In this paper, we present Cloud Atlas, a SDN abstraction and API extending the Quantum virtual network into the WAN. Cloud Atlas is built on top of existing WAN network services (L1-, L2-, and L3VPNs) that do support QoS. Cloud Atlas makes these services available to OpenStack through a tight integration with Quantum. We discuss two prototypes we have built of Cloud Atlas, one based on command line scripts and one based on a network management system. We conclude the paper with some observations on applying the cloud service model to networking and the value of SDN abstractions in supporting such a service model.

In the OpenFlow based split architecture, data-plane forwarding is separated from control and management functions. Forwarding elements make only simple forwarding decisions based on flow table entries populated by the controller. While OpenFlow does not specify how topology monitoring is performed, the centralized controller can use Link-Layer Discovery Protocol (LLDP) messages to discover link and node failures and trigger restoration actions. This monitoring and recovery model has serious scalability limitations because the controller has to be involved in the processing of all of the LLDP monitoring messages. For fast recovery, monitoring messages must be sent with millisecond interval over each link in the network. This poses a significant load on the controller. In this paper we propose to implement a monitoring function on OpenFlow switches, which can emit monitoring messages without posing a processing load on the controller. We describe how the OpenFlow 1.1 protocol should be extended to support the monitoring function. Our experimental results show that data plane fault recovery can be achieved in a scalable way within 50 milliseconds using this function.

This paper discusses the benefits of applying software defined networking (SDN) to circuit based transport networks. It first establishes the need for SDN in the context of transport networks. This paper argues that the use of SDN in the transport layers could be the enabler for both packet-optical integration and improved transport network applications. Then, this paper proposes extensions to OpenFlow 1.1 to achieve control of switches in multi-technology transport layers. The approach presented in this paper is simple, yet it distinguishes itself from similar work by its friendliness with respect to the current transport layer control plane based on generalized multiprotocol label switching (GMPLS). This is important as it will enable an easier and gradual injection of SDN into existing transport networks. This paper is completed with a few use case applications of SDN in transport networks.

In this paper, we describe an evolution of the mobile Evolved Packet Core (EPC) utilizing Software Defined Networking (SDN) that allows the EPC control plane to be moved into a data center. The EPC is a mobile aggregation network standardized by 3GPP for deployment of fixed and 4G mobile broadband services, having interoperability features for 3G and 2G mobile services. While mobile networks already deploy a considerable amount of software control, the ability of OpenFlow to decouple the control and data planes for IP routing provides the opportunity to simplify the configuration and maintenance of mobile aggregation networks by eliminating the distributed IP routing control plane. We extend OpenFlow 1.2 with two vendor extensions, one defining virtual ports to allow encapsulation and decapsulation and another to allow flow routing using the GTP Tunnel Endpoint Identifier (TEID). The result enables an architecture where the GTP control plane can be lifted up out of network elements such as the Serving Gateway and the Packet Data Network Gateway (PDN Gateway) and moved into a controller running in a virtual machine in a data center. The EPC network elements then run a simplified OpenFlow control plane, enhanced with GTP TEID routing extensions. We discuss a few new features that are enabled with GTP TEID routing and the status of a prototype.

Media flows coexist with TCP-based data traffic on the Internet and are required to be TCP-friendly. The TCP protocol slowly increases its sending rate until episodes of congestion occur, and then it quickly reduces its rate to remove congestion. However, media flows can be sensitive to even brief episodes of congestion. In this paper, we are interested in protecting media flows from TCP-induced congestion while maintaining their TCP friendliness. In particular, we consider media flows carried over the TCP-Friendly Rate Control (TFRC) protocol and we design algorithms that dynamically adapt the level of forward error correction (FEC) based on the congestion state of the network. To this end, first, we investigate the loss and delay characteristics of TFRC flows in several TCP-induced congestion scenarios, and we develop novel predictors of loss events based on packet delay information. Second, we use these predictors to dynamically adapt the level of FEC protection based on the predicted level of congestion. We show that this technique can significantly improve the overhead versus reliability trade-off compared to fixed FEC. Third, we select the FEC and original media packets within each FEC block, in a rate-distortion optimized way, and we show that this technique significantly improves media quality.

We propose an admission control policy that admits users into a public access network as soon as possible while limiting the overall security impact on the network and other users. In our model, each user has a particular reputation level when first requesting network access. Before admitting a user into the network, the initial risk of a user is assessed by the admission control system using past history and a scanning of the user's device which delays the user's admission into the network and updates the user's reputation level accordingly. We formulate the trade-off between the admission delay and security risk as a convex optimization problem, which can be solved for an admission control policy. The evaluation suggests that our approach can substantially increase the system security for public access networks while minimizing admission delay, in contrast to current approaches widely used in enterprise networks. The proposed framework extends the traditional quality of service- based admission control mechanisms with a well-defined notion of quality of security.

In network-based localized mobility management (NETLMM), a mobile node is not involved in signalling related to mobility support, and keeps the same IP address after handoff from one link to another. The mobile node's current access router acts as a mobility access gateway by sending Proxy Local Binding Updates to the local mobility anchor on behalf of the mobile node. Due to some properties of the NETLMM domain, implementing it efficiently using IEEE 802.11 radio access networks is not straightforward. This paper presents the challenges involved with such an implementation, presents solutions to them, and analyze the overall performance of the complete system.

Fast mobile IPv6 (FMIP) and hierarchical mobile IPv6 (HMIP) are enhancements to the standard mobile IPv6 (SMIP) protocol for reducing handover latency and data loss, and for localized mobility management. In this paper, we present scalability and robustness analysis of the three protocols and two hybrid protocols of FMIP and HMIP, using a large-scale simulation. The simulation results indicate that FMIP achieves the best handover performance. HMIP incurs considerably less per-handover signaling overhead than FMIP on the wireless link, but HMIP data traffic has a fixed and permanent overhead even after handover. Hybrid protocols achieve FMIP-like handover performance and improve handover signaling overhead but cannot remove tunneling overhead. Hybrid protocols are also more robust to access router and home agent failures.

Ad hoc networks have been proposed for a variety of applications where support for real time, multimedia services may be necessary. This requires that the network is able to offer quality of service (QoS) appropriate for the latency and throughput bounds needed to meet the real time constraint. An important component for QoS provisioning is resource estimation and quality prediction. The paper describes a model-based resource prediction (MBRP) mechanism to support real time communication in multi-hop wireless networks. Specifically, we develop an analytical model for differentiated MAC scheduling protocols. The model can predict per-flow and system-wide throughput and delivery latency, thereby enabling admission control of the flows and providing an efficient network management utility. After describing the basic model, we propose enhanced MBRP (EMBRP) for realistic network environments. Our proposed quality prediction method is beneficial in the deployment of a real ad hoc network where knowledge of resource allocation and consumption is needed to meet the service requirements. Analytical and simulation results show that EMBRP provides accurate flow quality prediction. The results also demonstrate the effectiveness of EMBRP as an admission control solution in multi-hop ad hoc networks.

Cellular telephones save power by switching to a low power or dormant mode when there is no active traffic. In dormant mode, the telephone periodically checks for a beacon, and if the beacon indicates that the phone has moved to a new paging area, the telephone performs a paging area update. Paging area update signaling requires considerably less power than is required to move an active traffic channel. When a call comes in, the network pages the telephone by flood signaling the paging area on a special channel, and the telephone brings up an active traffic channel. Recent work has attempted to extend paging to IP networks, in particular, networks running the Mobile IP mobility management protocol. In this paper, we compare mobile IPv6 and IP paging for dormant mode location updating. Simulations are presented for a typical macrocellular scenario and a hotspot scenario, where broadband microcells supplement the narrowband macrocells. The results show that Mobile IPv6 dormant mode location management is roughly comparable to IP paging.

Mobile IPv6 provides comprehensive mobility management for the IPv6 protocol. Yet, it has been known for some time that the default mobile IPv6 protocol for handover between subnets can result in packet drops, which cause a user-perceptible deterioration in a real time traffic. Recent work has defined several new algorithms for Mobile IPv6 handover. These algorithms consist of two components: preconfiguring the care of address when it is known, and establishing a source route-based tunnel between the old access router and the new so that the mobile node can continue to receive its traffic on the new link under its old care of address. In this paper, we present measurements of the fast Mobile IPv6 (FMIPv6) handover algorithms on a handover emulator. While the algorithms can reduce the number of packet drops, some amount of buffering helps smooth handover. In addition, algorithms differ in their ability to reduce handover packet drops, depending on the wireless link characteristics.

Solo is a portable window interface written in the Common Lisp Object System (CLOS) object-oriented programming language. Solo provides a virtual window machine which is targeted to a host window system by implementing a set of host window system specific classes and methods for Solo's host window system driver protocol. The interface presented by Solo to an application insulates it from differences in the host window system, facilitating application portability. Solo distinguishes itself from other object-oriented window systems by exploiting certain features of CLOS. CLOS method combination simplifies initialization of windows while preserving easy extensibility of the basic classes. Generic dispatch on multiple arguments, a feature unique to CLOS, allows a simpler and more flexible input event dispatching protocol. A powerful event description language simplifies the specification of keyboard and mouse events. A prototype implementation runs on the server based XII and NeWS host systems, and on the frame buffer based Lucid Window Toolkit.

CommonLoops is an object-oriented language embedded in Common Lisp. It is one of two such languages selected as starting points for the Common Lisp Object System (CLOS) which is currently being designed as a standard object-oriented extension to Common Lisp. This paper reports on experiences using the existing Portable CommonLoops (PCL) implementation of CommonLoops. The paper is divided into two parts: a report on the development of a window system application using the CommonLoops programming language, and a description of the implementation of another object-oriented language (CommonObjects) on top of the CommonLoops metaclass kernel, paralleling the two aspects of CommonLoops: the programming language and the metaclass kernel. Usage of the novel features in CommonLoops is measured quantitatively, and performance figures comparing CommonLoops, CommonObjects on CommonLoops, and the native Lisp implementation of CommonObjects are presented. The paper concludes with a discussion about the importance of quantitative assessment for programming language development.