Fog Computing and Its Role in the Internet of Things

1 Fog Computing and Its Role in the Internet of Things Flavio Bonomi, Rodolfo Milito, Jiang Zhu, Sateesh Addepalli Cisco Systems Inc. 170 W Tasman Dr. San Jose, CA 95134, USA. {flavio, romilito, jiangzhu, ABSTRACT nodes in the vicinity to meet their delay requirements. An Fog Computing extends the Cloud Computing paradigm to emerging wave of Internet deployments, most notably the the edge of the network, thus enabling a new breed of ap- Internet of Things (IoTs), requires mobility support and plications and services. Defining characteristics of the Fog geo-distribution in addition to location awareness and low are: a) Low latency and location awareness; b) Wide-spread latency. We argue that a new platform is needed to meet geographical distribution; c) Mobility; d) Very large number these requirements; a platform we call Fog Computing [1], of nodes, e) Predominant role of wireless access, f) Strong or, briefly, Fog, simply because the fog is a cloud close to presence of streaming and real time applications, g) Het- the ground.}

2 We also claim that rather than cannibalizing erogeneity. In this paper we argue that the above charac- Cloud Computing , Fog Computing enables a new breed of teristics make the Fog the appropriate platform for a num- applications and services, and that there is a fruitful inter- ber of critical Internet of Things (IoT) services and appli- play between the Cloud and the Fog, particularly when it cations, namely, Connected Vehicle, Smart Grid , Smart comes to data management and analytics. Cities, and, in general, Wireless Sensors and Actuators Net- This paper is organized as follows. In the second sec- works (WSANs). tion we introduce the Fog Computing paradigm, delineate its characteristics, and those of the platform that supports Fog services. The following section takes a close look at a few Categories and Subject Descriptors key applications and services of interest that substantiate [Computer-Communication Networks]: Com- our argument in favor of the Fog as the natural component puter Network Distributed Systems of the platform required for the support for the Internet of Things .

3 In the fourth section we examine analytics and big Keywords data in the context of applications of interest. The recogni- tion that some of these applications demand real-time ana- Fog Computing , Cloud Computing , IoT, WSAN, Software lytics as well as long-term global data mining illustrates the Defined Networks, Real Time Systems, Analytics interplay and complementary roles of Fog and Cloud. We conclude with comments about the state of the Fog Com- 1. INTRODUCTION puting and discussion of future work. The pay-as-you-go Cloud Computing model is an effi- cient alternative to owning and managing private data cen- 2. THE FOG Computing PLATFORM. ters (DCs) for customers facing Web applications and batch processing. Several factors contribute to the economy of Characterization of Fog Computing scale of mega DCs: higher predictability of massive aggre- Fog Computing is a highly virtualized platform that pro- gation, which allows higher utilization without degrading vides compute, storage, and networking services between performance; convenient location that takes advantage of end devices and traditional Cloud Computing Data Centers, inexpensive power; and lower OPEX achieved through the typically, but not exclusively located at the edge of network.

4 Deployment of homogeneous compute, storage, and network- Figure 1 presents the idealized information and Computing ing components. architecture supporting the future IoT applications, and il- Cloud Computing frees the enterprise and the end user lustrates the role of Fog Computing . from the specification of many details. This bliss becomes Compute, storage, and networking resources are the build- a problem for latency-sensitive applications, which require ing blocks of both the Cloud and the Fog . Edge of the Network , however, implies a number of characteristics that make the Fog a non-trivial extension of the Cloud. Let us list them with pointers to motivating examples. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are Edge location, location awareness, and low latency.

5 Not made or distributed for profit or commercial advantage and that The origins of the Fog can be traced to early pro- copies bear this notice and the full citation on the first page. To copy posals to support endpoints with rich services at the otherwise, or republish, to post on servers or to redistribute to lists, edge of the network, including applications with low requires prior specific permission and/or a fee. latency requirements ( gaming, video streaming, MCC'12, August 17, 2012, Helsinki, Finland. augmented reality). Copyright 2012 ACM 978-1-4503-1519-7/12 $ 13. the source. We elaborate in section 4 on the interplay between Fog and Cloud regarding Big Data. Fog Players: Providers and Users It is not easy to determine at this early stage how the different Fog Computing players will align. Based on the nature of the major services and applications, however, we anticipate that: Subscriber models will play a major role in the Fog (In- fotainment in Connected Vehicle, Smart Grid, Smart Cities, Health Care, etc.)

6 The Fog will give rise to new forms of competition and cooperation between providers angling to provide global services. New incumbents will enter the arena as users and providers, including utilities, car man- ufacturers, public administrations and transportation agencies. Figure 1: The Internet of Things and Fog Comput- ing 3. FOG Computing AND THE Internet . Geographical distribution. In sharp contrast to the OF Things . more centralized Cloud, the services and applications targeted by the Fog demand widely distributed de- In this section we demonstrate the role the Fog plays in ployments. The Fog, for instance, will play an active three scenarios of interest: Connected Vehicle, Smart Grid, role in delivering high quality streaming to moving ve- and Wireless Sensor and Actuator Networks. hicles, through proxies and access points positioned Connected Vehicle (CV).

7 Along highways and tracks. The Connected Vehicle deployment displays a rich sce- Large-scale sensor networks to monitor the environ- nario of connectivity and interactions: cars to cars, cars to ment, and the Smart Grid are other examples of inher- access points (Wi-Fi, 3G, LTE, roadside units [RSUs], smart ently distributed systems, requiring distributed com- traffic lights), and access points to access points. The Fog puting and storage resources. has a number of attributes that make it the ideal platform to deliver a rich menu of SCV services in infotainment, safety, Very large number of nodes, as a consequence of the traffic support, and analytics: geo-distribution (throughout wide geo-distribution, as evidenced in sensor networks cities and along roads), mobility and location awareness, in general, and the Smart Grid in particular. low latency, heterogeneity, and support for real-time inter- actions.

8 Support for mobility. It is essential for many Fog appli- A smart traffic light system illustrates the latter. The cations to communicate directly with mobile devices, smart traffic light node interacts locally with a number of and therefore support mobility techniques, such as the sensors, which detect the presence of pedestrians and bikers, LISP protocol 1 , that decouple host identity from loca- and measures the distance and speed of approaching vehi- tion identity, and require a distributed directory sys- cles. It also interacts with neighboring lights to coordinate tem. the green traffic wave. Based on this information the smart Real-time interactions. Important Fog applications in- light sends warning signals to approaching vehicles, and even volve real-time interactions rather than batch process- modifies its own cycle to prevent accidents. ing. Re-coordinating with neighboring STLs through the or- chestration layer of the Fog follows any modification of the Predominance of wireless access.

9 Cycle. The data collected by the STLs is processed to do real-time analytics (changing, for instance, the timing of the Heterogeneity. Fog nodes come in different form fac- cycles in response to the traffic conditions). The data from tors, and will be deployed in a wide variety of environ- clusters of smart traffic lights is sent to the Cloud for global, ments. long-term analytics. Interoperability and federation. Seamless support of Smart Grid certain services (streaming is a good example) requires Smart Grid is another rich Fog use case. We defer sec- the cooperation of different providers. Hence, Fog com- tion 4 a discussion of the interplay of Fog and Cloud in the ponents must be able to interoperate, and services context of Smart Grid. must be federated across domains. Wireless Sensors and Actuators Networks Support for on-line analytic and interplay with the The original Wireless Sensor Nodes (WSNs), nicknamed Cloud.

10 The Fog is positioned to play a significant role motes [2], were designed to operate at extremely low power in the ingestion and processing of the data close to to extend battery life or even to make energy harvesting 1. feasible. Most of these WSNs involve a large number of low 14. bandwidth, low energy, low processing power, small memory third tier deal with visualization and reporting (human-to- motes, operating as sources of a sink (collector), in a unidi- machine [HMI] interactions), as well as systems and pro- rectional fashion. Sensing the environment, simple process- cesses (M2M). The time scales of these interactions, all part ing, and forwarding data to the static sink are the duties of the Fog, range from seconds to minutes (real-time ana- of this class of sensor networks, for which the open source lytics), and even days (transactional analytics). As a result TinyOS2 is the de-facto standard operating system.