Emerging Enterprise Storage Systems

This chapter along with the additional resources given in the references will support the usage of SAN technologies in enterprises. The first half of this chapter develops the new framework needed. The second half of this chapter details the capabilities of fabric topology. To lay the groundwork for a networked storage system, it is important to understand these concepts in order to best plan the first steps of building a new secure and open enterprise storage infrastructure.

Voiceover Internet Protocal (VoIP)

Traditionally, real-time voice communications–both within and outside of corporations (enterprises)—are achieved using public domain circuit-switched telephone networks (PSTNs). These networks use technologies that have been maturing over the last 150 years. However, the recent advances in and proliferation of packet-based switching technologies, World Wide Web (WWW) and PC-based user interfaces, and innovative digital signal processing (DSP) techniques are making real-time voice transmission using packet switching–particularly IP-based techniques—more feasible, at least within the logical boundaries of enterprise networks. Although the IP-based Internet is only about 25 years old, its compatibility with Ethernet2 , and its flexibility, openness and low-cost availability have enabled it to gain more than 260 million users worldwide3. In addition, proliferation of the WWW, multimedia PCs, and innovations in DSP during the last five years has made voice transmission over packet networks, particularly over IP, very attractive economically. In this chapter, we briefly review the technologies and standards—as recommended by IETF and ITU-T—that are making voice over IP (VoIP) a reality in both public and enterprise networks. Our focus is on low bit rate speech compression and silence suppression, voice packetization and encapsulation, sources of packet-voice impairments and methods to mitigate them, and packet-voice transmission engineering.

Multilayered Quality of Service

Today’s networks support applications that deliver text, audio, images and video, often in real time and with a high degree of interactivity, using a common infrastructure. More often than not, traffic is carried over packet-switched networks that treat all data the same, under what is known as best-effort service. Packet switching can achieve very high efficiency through statistical multiplexing of data from numerous sources; however, due to the very nature of packet switching, one should expect fluctuations in throughput, delay, reliability, etc., for any given flow. The greater the statistical multiplexing capabilities, the greater the efficiency and also the greater the variability of achieved performance; in this sense, best-effort service provides maximum efficiency with highly unpredictable service quality. Clearly, not all traffic flows are created equal. Interactive web-based applications tend to be very sensitive to throughput, while real-time voice and video are sensitive to delay and jitter, and traditional data applications such as e-mail and file transfers are fairly insensitive to fluctuations in performance. The concept of quality of service (QoS) has evolved from the realization that in networks that carry heterogeneous traffic it makes sense to treat specific classes of traffic according to their specific needs.

Network Service Availability and Performance

As computer networks, specifically the Internet, become more and more integral to business and society, the performance and availability of services on the Internet become more critical. It is now a common need to provide a reliable network service to millions of Internet users and customers. The performance of these services is commonly a key factor in their success. Web portals and popular sites build relationships with customers based in part on their speed and availability. Even services internal to an enterprise frequently have serious consequences if there is a loss of availability. This chapter discusses how advanced, multilayer switches can be used to increase the performance of network services. For this discussion, the term “performance” refers to availability, latency, and throughput, since all of these factors affect a user’s impression of a site’s performance. This chapter is intended for network service providers who must scale their services, network administrators who need to apply policies to their networks, and developers of switches who need to understand what the utility and requirements for these switches are. It is assumed that the reader has a working familiarity with networking principles, but substantial background information is also provided.

Web Caching

World Wide Web traffic increases at exponential rates saturating network links and web servers. By replicating popular web pages in strategic places on the Internet, web caching reduces core network traffic, reduces web server load, and improves the end-users’ perceived quality of service. In this paper we survey the area of web caching. We identify major research challenges and their solutions, as well as several commercial products that are being widely used.

Web Switching

Web switching may be viewed as an optimized combination of networking functions, such as load balancing, bandwidth and traffic management, cache switching, and site-level security, that are implemented on a single device and are specifically designed to address the unique requirements of World Wide Web (or simply, Web) traffic; for example, efficient management of Web traffic, simplified website management, and fast, reliable, and error-free website operation. More precisely, “Web switches are network devices that can be used to construct a ‘user- and content-aware’ network infrastructure, which has the explicit objective of seamless and high-performance routing of specific user requests for specific Web content to the best server containing that content, irrespective of its physical location (Johnson, 1999a).” A web switch, therefore, is an extremely fast and “intelligent” LAN switch that switches traffic based on content, rather than just addresses (Passmore, 1999), and integrates the traffic management and control functions that have traditionally run on a number of separate devices. These include sophisticated URL load balancing capabilities via local and global server load balancing, bandwidth control, network address translation (NAT), packet filtering, cache redirection, and policies to manage and speed the flow of web traffic.

The OSI Model and Switching

In this chapter we give the motivation and basic concepts of the OSI reference model, discuss its seven-layer architecture, the communication between systems using the OSI model, and finally the relationship between the OSI model and multilayer switching.

Linux Systems as Network Infrastructure Components

LinuxTM has made a lot of noise in the media recently, but wide-scale corporate adoption has been cautious. This chapter introduces the reader to some of the reasons that Linux is going to play an important role as an Internet/network device in the coming years and why corporate technology strategists should consider it for their own environment. First, the term “Linux” is defined via a brief history lesson, and then examples of Linux deployment at each level of the OSI model are given. The reader will recognize the impetus for its rapid development and the explosive growth in its usage.

Interactive Video on Enterprise Networks

Historically, interactive video has been reserved for circuit-switched networks (e.g., ISDN) using the H.320 standard protocol for video signaling, encoding, decoding and media synchronization. Due to the high costs and complexity of bringing ISDN to individual users or facilities in certain regions of the world, the desire to leverage an expanding IP infrastructure, and to take advantage of the new management features in the latest interactive video servers, many network managers are planning to deploy multimedia over IP. Network architects recognize that multimedia over IP implementation details will vary from site to site, depending on a combination of internal business requirements and the unique conditions in a network at the time multimedia communications support goes in. This chapter will assist those who seek to introduce interactive video to their corporate IP network users as a first step towards network convergence. It will give the reader the benefit of lessons learned in past tests and trials, on howto deploy a network with state of the art technologies, capabilities that match user needs and the ability to evolve over time as user needs change.

Virtual Local Area Networks

With the availability of so many high-density, wire-speed Layer 3 switches, why would a network administrator choose to implement Virtual LANs (VLANs) today? The first (and most obvious) answer is cost. Layer 3 switches cost more than Layer 2 switches, and usually have less density, making them a natural fit at the very core of the network, leaving Layer 2 switches to handle Distribution Layer aggregation of wiring closet switches or Data Center switching. Layer 2 switches are often much simpler to implement, and can be implemented with less technical difficulty than routing. VLANs have also recently been reborn in Metropolitan Area Networks (MANs) based upon Ethernet technology as a Virtual Private Networking (VPN) solution. VLANs are now a required feature in any switched LAN solution. The increasing capacity and performance of switches has enabled users to dedicate switch ports to every user on the network, increasing the need for control over broadcast and multicasts throughout the network. To best understand VLANs, it is useful to study how networks evolved into needing VLANs.