Preethi Natarajan

Fog Computing: A Platform for Internet of Things and Analytics

Internet of Things (IoT) brings more than an explosive proliferation of endpoints. It is disruptive in several ways. In this chapter we examine those disruptions, and propose a hierarchical distributed architecture that extends from the edge of the network to the core nicknamed Fog Computing. In particular, we pay attention to a new dimension that IoT adds to Big Data and Analytics: a massively distributed number of sources at the edge.

PIE: A lightweight control scheme to address the bufferbloat problem

Bufferbloat is a phenomenon where excess buffers in the network cause high latency and jitter. As more and more interactive applications (e.g. voice over IP, real time video conferencing and financial transactions) run in the Internet, high latency and jitter degrade application performance. There is a pressing need to design intelligent queue management schemes that can control latency and jitter; and hence provide desirable quality of service to users. We present here a lightweight design, PIE (Proportional Integral controller Enhanced), that can effectively control the average queueing latency to a reference value. The design does not require per-packet extra processing, so it incurs very small overhead and is simple to implement in both hardware and software. In addition, the design parameters are self-tuning, and hence PIE is robust and optimized for various network scenarios. Simulation results, theoretical analysis and Linux testbed results show that PIE can ensure low latency and achieve high link utilization under various congestion situations.

Improving Web Sites Performance Using Edge Servers in Fog Computing Architecture

In this paper, we consider web optimization within Fog Computing context. We apply existing methods for web optimization in a novel manner, such that these methods can be combined with unique knowledge that is only available at the edge (Fog) nodes. More dynamic adaptation to the users conditions (eg. network status and devices computing load) can also be accomplished with network edge specific knowledge. As a result, a users web page rendering performance is improved beyond that achieved by simply applying those methods at the web server or CDNs.

LISP-MN: Mobile Networking Through LISP

The current Internet architecture was not designed to easily accommodate mobility because IP addresses are used both to identify and locate hosts. The Locator/Identifier Separation Protocol (LISP) decouples them by considering two types of addresses: EIDs that identify hosts, and RLOCs that identify network attachment points and are used as routing locators. LISP, with such separation in place, can also offer native mobility. LISP-MN is a particular case of LISP which specifies mobility. In this paper we provide a comprehensive tutorial on LISP-MN, showing its main features and how it compares to existing mobility protocols.

SCTP: an innovative transport layer protocol for the web

We propose using the Stream Control Transmission Protocol (SCTP), a recent IETF transport layer protocol, for reliable web transport. Although TCP has traditionally been used, we argue that SCTP better matches the needs of HTTP-based network applications. This position paper discusses SCTP features that address: (i) head-of-line blocking within a single TCP connection, (ii) vulnerability to network failures, and (iii) vulnerability to denial-of-service SYN attacks. We discuss our experience in modifying the Apache server and the Firefox browser to benefit from SCTP, and demonstrate our HTTP over SCTP design via simple experiments. We also discuss the benefits of using SCTP in other web domains through two example scenarios ? multiplexing user requests, and multiplexing resource access. Finally, we highlight several SCTP features that will be valuable to the design and implementation of current HTTP-based client-server applications.

Non-Renegable Selective Acknowledgments (NR-SACKs) for SCTP

In both TCP and SCTP, selectively acked (SACKed) out-of-order data is implicitly renegable; that is, the receiver can later discard SACKed data. The possibility of reneging forces the transport sender to maintain copies of SACKed data in the send buffer until they are cumulatively acked. In this paper, we investigate the situation where all out-of-order data is non-renegable, such as when the data has been delivered to the application, or when the receiver simply never reneges. Using simulations, we show that SACKs result in inevitable send buffer wastage, which increases as frequency of loss events and loss recovery durations increase. We introduce a fundamentally new ack mechanism, Non-Renegable Selective Acknowledgments (NR-SACKs), for SCTP. Using NR-SACKs, an SCTP receiver can explicitly identify some or all out-of-order data as being non-renegable, allowing the sender to free up send buffer sooner than if the data were only SACKed. Simulation comparisons show that NR-SACKs enable efficient utilization of a transport senderpsilas memory. Further investigations show that NR-SACKs also improve throughput in Concurrent Multipath Transfer (CMT) [4].

Concurrent multipath transfer using SCTP multihoming: introducing the potentially-failed destination state

Previously, we identified the failure-induced receive buffer (rbuf) blocking problem in Concurrent Multipath Transfer using SCTP multihoming (CMT), and proposed CMT with a Potentially-failed destination state (CMTPF) to alleviate rbuf blocking. In this paper, we complete our evaluation of CMT vs. CMT-PF. Using ns-2 simulations we show that CMT-PF performs on par or better than CMT during more aggressive failure detection thresholds than recommended by RFC4960. We also examine whether the modified sender behavior in CMT-PF degrades performance during non-failure scenarios. Our evaluations consider: (i) realistic loss model with symmetric and asymmetric path loss, (ii) varying path RTTs. We find that CMT-PF performs as well as CMT during non-failure scenarios, and interestingly, outperforms CMT when the paths experience asymmetric rbuf blocking conditions. We recommend that CMT be replaced by CMT-PF in future CMT implementations and RFCs.

Programmable Overlays via OpenOverlayRouter

OpenOverlayRouter (OOR) is an open source software router to deploy programmable overlay networks. OOR leverages the Locator/ID Separation Protocol (LISP) to map overlay identifiers to underlay locators, and to dynamically tunnel overlay traffic through the underlay network. LISP overlay state exchange is complemented with NETCONF remote configuration and VXLANGPE encapsulation. OOR aims to offer a flexible, portable, and extensible overlay solution via a user-space implementation available for multiple platforms (Linux, Android, and OpenWrt). In this article, we describe the OOR software architecture and how it overcomes the challenges associated with a user-space LISP implementation. Furthermore, we present an experimental evaluation of OOR performance in relevant scenarios.

Location and identity privacy for LISP-MN

The current Internet architecture was not designed to easily accommodate mobility because IP addresses are used both to identify and locate hosts. The Locator/Identifier Separation Protocol (LISP) decouples them by considering two types of addresses: Endpoint IDentifiers (EIDs) to identify hosts, and Routing LOCators (RLOCs) that identify network attachment points. LISP, with such separation in place, also offers native mobility. In this context, LISP-MN is a particular case of LISP and specifies mobility. Mobility protocols have an inherent issue with privacy since some users may not want to reveal their location or their identity. In this paper, we present an overview of LISP-MN and propose solutions to enable privacy, both in terms of location and identity.

Hierarchical IP flow clustering

The analysis of flow traces can help to understand a networks usage patterns. We present a hierarchical clustering algorithm for network flow data that can summarize terabytes of IP traffic into a parsimonious tree model. The method automatically finds an appropriate scale of aggregation so that each cluster represents a local maximum of the traffic density from a block of source addresses to a block of destination addresses. We apply this clustering method on NetFlow data from an enterprise network, find the largest traffic clusters, and analyze their stationarity across time. The existence of heavy-volume clusters that persist over long time scales can help network operators to perform usage-based accounting, capacity provisioning and traffic engineering. Also, changes in the layout of hierarchical clusters can facilitate the detection of anomalies and significant changes in the network workload.