The cloud is migrating to the edge of the network, where routers themselves may become the virtualisation infrastructure, in an evolution labelled as "the fog". However, many other complementary technologies are reaching a high level of maturity. Their interplay may dramatically shift the information and communication technology landscape in the following years, bringing separate technologies into a common ground. This paper offers a comprehensive definition of the fog, comprehending technologies as diverse as cloud, sensor networks, peer-to-peer networks, network virtualisation functions or configuration management techniques. We highlight the main challenges faced by this potentially breakthrough technology amalgamation.

/pdf/finding-your-way-in-the-fog-towards-a-comprehensive-4mcy1vvqbd.pdf

Finding your Way in the Fog: Towards a Comprehensive Definition of Fog Computing

The U-Net communication architecture provides processes with a virtual view of a network interface to enable userlevel access to high-speed communication devices. The architecture, implemented on standard workstations using offthe-shelf ATM communication hardware, removes the kernel from the communication path, while still providing full protection. The model presented by U-Net allows for the construction of protocols at user level whose performance is only limited by the capabilities of network. The architecture is extremely flexible in the sense that traditional protocols like TCP and UDP, as well as novel abstractions like Active Messages can be implemented efficiently. A U-Net prototype on an 8node ATM cluster of standard workstations offers 65 microseconds round-trip latency and 15 Mbytes/sec bandwidth. It achieves TCP performance at maximum network bandwidth and demonstrates performance equivalent to Meiko CS-2 and TMC CM-5 supercomputers on a set of Split-C benchmarks.

/pdf/u-net-a-user-level-network-interface-for-parallel-and-buva1gimsh.pdf

U-Net: a user-level network interface for parallel and distributed computing

With the growth of data volumes and variety of Internet applications, data centers (DCs) have become an efficient and promising infrastructure for supporting data storage, and providing the platform for the deployment of diversified network services and applications (e.g., video streaming, cloud computing). These applications and services often impose multifarious resource demands (storage, compute power, bandwidth, latency) on the underlying infrastructure. Existing data center architectures lack the flexibility to effectively support these applications, which results in poor support of QoS, deployability, manageability, and defence against security attacks. Data center network virtualization is a promising solution to address these problems. Virtualized data centers are envisioned to provide better management flexibility, lower cost, scalability, better resources utilization, and energy efficiency. In this paper, we present a survey of the current state-of-the-art in data center networks virtualization, and provide a detailed comparison of the surveyed proposals. We discuss the key research challenges for future research and point out some potential directions for tackling the problems related to data center design.

Data Center Network Virtualization: A Survey

We have designed and implemented a new operating system facility for I/O buffer management and data transferacross protection domain boundaries on shared memory machines. This facility, called fast buffers (fbufs), combines virtual page remapping with shared virtual memory, and exploits locality in I/O traffic to achieve high throughput without compromising protection, security, or modularity. goal is to help deliver the high bandwidth afforded by emerging high-speed networks to user-level processes, both in monolithic and microkernel-based operating systems.This paper outlines the requirements for a cross-domain transfer facility, describes the design of the fbuf mechanism that meets these requirements, and experimentally quantifies the impact of fbufs on network performance.

Fbufs: a high-bandwidth cross-domain transfer facility

https://www.cs.uic.edu/~ygu/paper/udt-comnet-v3.pdf

UDT: UDP-based data transfer for high-speed wide area networks

A data center can share processing resources using virtual networks. A virtual machine manager (10) hosts one or more virtual machines (11, 411), the virtual machines forming part of a segmented virtual network (34). Outgoing messages from the virtual machines have an intermediate destination address of an intermediate node in a local segment of the segmented virtual network, and the virtual machine manager has a router (18) for determining a new intermediate destination address outside the local segment, for routing the given outgoing message. By having the router as part of the virtual machine manager rather than having only a switch in the virtual machine manager, the need for virtual machines for implementing gateways is avoided. This can reduce the number of “hops” for the message between virtual entities hosted, and thus improve performance. This can help a service provider to share physical processing resources of a data center between different clients having their own virtual networks.

Routing across a virtual network

Example embodiments disclosed herein relate to a persistent volume at an offset of a virtual block device of a storage server. Example embodiments include requesting that a persistent volume be dissociated from a virtual block device in response to the termination of a virtual machine.

Persistent volume at an offset of a virtual block device of a storage server

The advantages of user-space protocols are well-known, but implementations often exhibit poor performance. This paper describes a user-space TCP implementation that outperforms a 'normal' kernel TCP and that achieves 80% of the performance of a 'single-copy' TCP. Throughput of 160 Mbit/s has been measured. We describe some of the techniques we used and some of the problems we encountered.

http://www.hpl.hp.com/techreports/95/HPL-95-110.pdf

Experiences implementing a high performance TCP in user-space

Two important questions in high-speed networking are firstly, how to provide Gbit/s networking at low cost and secondly, how to provide a flexible low-level network interface so that applications can control their data from the instant it arrives.We describe some work that addresses both of these questions. The Jetstream Gbit/s LAN is an experimental, low-cost network interface that provides the services required by delay-sensitive traffic as well as meeting the performance needs of current applications. Jetstream is a combination of traditional shared-medium LAN technology and more recent ATM cell- and switch-based technology.Jetstream frames contain a channel identifier so that the network driver can immediately associate an incoming frame with its application. We have developed such a driver that enables applications to control how their data should be managed without the need to first move the data into the application's address space. Consequently, applications can elect to read just a part of a frame and then instruct the driver to move the remainder directly to its destination. Individual channels can elect to receive frames that have failed their CRC, while applications can specify frame-drop policies on a per-channel basis.Measured results show that both kernel- and user-space protocols can achieve very good throughput: applications using both TCP and our own reliable byte-stream protocol have demonstrated throughputs in excess of 200 Mbit/s. The benefits of running protocols in user-space are well known- the drawback has often been a severe penalty in the performance achieved. In this paper we show that it is possible to have the best of both worlds.

/pdf/user-space-protocols-deliver-high-performance-to-1i8j1wvh1a.pdf

User-space protocols deliver high performance to applications on a low-cost Gb/s LAN

Many current implementations of protocols such as the Transmission Control Protocol/Internet Protocol (TCP/IP) are inefficient because data are often accessed more frequently than necessary. Three techniques that reduce the need for memory bandwidth are proposed. The techniques are copy-on-write, page remapping, and single-copy. Afterburner, a network-independent card that provides the services that are necessary for a single-copy protocol stack, is described. The card has 1 MByte of local buffers and provides a simple interface to a variety of network link adapters, including HIPPI and asynchronous transfer mode (ATM). Afterburner can support transfers to and from the link adapter card at rates up to 1 Gbit/s. An implementation of TCP/IP that uses the features provided by Afterburner to reduce the movement of data to a single copy is discussed. Measurements of the end-to-end performance of Afterburner and the single-copy implementation of TCP/IP are presented. >

Aled Justin Edwards

Papers

Routing across a virtual network

Persistent volume at an offset of a virtual block device of a storage server

Experiences implementing a high performance TCP in user-space

User-space protocols deliver high performance to applications on a low-cost Gb/s LAN

Afterburner (network-independent card for protocols)