Chapter 1

Storage Area Network

A network infrastructure designed to support file servers and provide data storage, retrieval, and replication.

Wide Area Network

A network infrastructure that provides access to other networks over a wide geographical area, which is typically owned and managed by a telecommunications service provider.

Local Area Network

A network infrastructure that provides access to users and end devices in a small geographical area, which is typically an enterprise, home, or small business network owned and managed by an individual or IT department.

Metropolitan Area Network

A network infrastructure that spans a physical area larger than a LAN but smaller than a WAN (e.g., a city). MANs are typically operated by a single entity such as a large organization.

Dial-up Telephone

An inexpensive option that uses any phone line and a modem. The low bandwidth provided by a dial-up modem connection is usually not sufficient for large data transfer, although it is useful for mobile access while traveling.

Business DSL

Business DSL is available in various formats. A popular choice is Symmetric Digital Subscriber Lines (SDSL) which is similar to the consumer version of DSL, but provides uploads and downloads at the same speeds.

Ethernet WAN

Ethernet WANs extend LAN access technology into the WAN. Ethernet is a LAN technology you will learn about in a later chapter. The benefits of Ethernet are now being extended into the WAN.

Reliable Networks

Fault Tolerance Scalability Quality of Service (QoS) Security

Cellular

Internet access uses a cell phone network to connect. Wherever you can get a cellular signal, you can get cellular Internet access. Performance will be limited by the capabilities of the phone and the cell tower to which it is connected.

Dedicated Leased Line

Leased lines are actually reserved circuits within the service provider's network that connect geographically separated offices for private voice and/or data networking. The circuits are typically rented at a monthly or yearly rate. They can be expensive.

DSL

Provide a high bandwidth, always on, connection to the Internet. Runs over a telephone line. In general, small office and home office users connect using Asymmetrical DSL (ADSL), which means that the download speed is faster than the upload speed.

Satellite

The availability of satellite Internet access is a real benefit in those areas that would otherwise have no Internet connectivity at all. Satellite dishes require a clear line of sight to the satellite.

Wireless LAN

Similar to a LAN but wirelessly interconnects users and end points in a small geographical area.

Business Satelite

Similar to small office and home office users, satellite service can provide a connection when a wired solution is not available.

Intrusion prevention systems

These are used to identify fast-spreading threats, such as zero-day or zero-hour attacks.

Cable

Typically offered by cable television service providers, the Internet data signal is carried on the same cable that delivers cable television. It provides a high bandwidth, always on, connection to the Internet.

circuit-switched networks

establishes a dedicated circuit between the source and destination before the users may communicate.

packet-switched network

splits traffic into packets that are routed over a shared network