Media Access Control (MAC)

MAC technology provides unique identification and access control for computers on an Internet Protocol (IP) network. In wireless networking, MAC is the radio control protocol on the wireless network adapter. MAC works at the lower sublayer of the data link layer (Layer 2) of the OSI model.

MAC assigns a unique number to each IP network adapter called the MAC address. A MAC address is 48 bits long. The MAC address is commonly written as a sequence of 12 hexadecimal digits such as 48-3F-0A-91-00-BC.

Multiple-Input Multiple-Output (MIMO)

MIMO is the method of utilizing multiple antennas for wireless communications. For wireless networking, MIMO technology appears in some WiFi routers, greatly enhancing their capability over single-antenna routers.

MIMO WiFi routers utilize the same network protocols and signal ranges that non-MIMO routers do. The MIMO products achieve higher performance by more aggressively transmitting and receiving data over WiFi channels. MIMO signaling technology can increase network bandwidth, range and reliability at the potential cost of interfering with other wirless equipment.

The exact number of antennas utilized in a MIMO WiFi router can vary. Typical MIMO routers contain three or four antennas instead of the single antenna that is standard in all earlier forms of consumer WiFi routers. MIMO is a key element of the 802.11n WiFi networking standard.

Modem

Traditional modems used in dial-up networking convert data between the analog form used on telephone lines and the digital form used on computers. Standard dial-up network modems transmit data at a maximum rate of 56,000 bits per second (56 Kbps). However, inherent limitations of the public telephone network limit modem speeds to 33.6 Kbps or lower in practice.

Broadband modems that are part of cable and DSL Internet service use more advanced signaling techniques to achieve dramatically higher network speeds than traditional modems. Broadband modems are sometimes called "digital modems" and those used for traditional dial-up networking, "analog modems." Cellular modems that establish Internet connectivity through a digital cell phone also exist.

Maximum Transmission Unit (MTU)

The MTU is the maximum size of a single data unit (e.g., a frame) of digital communications. MTU sizes are inherent properties of physical network interfaces, normally measured in bytes. The MTU for Ethernet, for instance, is 1500 bytes. Some types of networks (like Token Ring) have larger MTUs, and some types have smaller MTUs, but the values are fixed for each physical technology.

Higher-level network protocols like TCP/IP can be configured with a maximum packet size, a parameter independent of the physical layer MTU over which TCP/IP runs. Unfortunately, many network devices use the terms interchangeably. On both home broadband routers and Xbox Live enabled game consoles, for example, the parameter called MTU is in fact the maximum TCP packet size and not the physical MTU.

Nagle Algorithm

The Nagle algorithm, named after engineer John Nagle, was designed to reduce LAN and other network congestion from TCP applications. TCP implementations on UNIX began using the Nagle algorithm in the 1980s, and the algorithm remains a standard feature of TCP implementations today.

The Nagle algorithm works by aggregating data on the sending side of TCP applications. It accumulates sequences of small messages into larger TCP packets before data reaches the wire, thereby preventing the generation of unnecessarily large numbers of small packets. When the Nagle algorithm works as designed, TCP applications utilize network resources more efficiently.

Applications can enable or disable the Nagle algorithm with the TCP_NODELAY socket option. Windows, Linux, and Java systems all normally enable the Nagle algorithm by default. However, in some cases, the Nagle algorithm has a negative effect on application performance, so network application engineers may prefer to disable it.

Network Attached Storage

NAS allows files to be stored and retrieved across a computer network. A NAS includes a dedicated hardware device often called the head that connects to a local area network (usually via Ethernet). This NAS "server" authenticates clients and manages file operations in much the same manner as traditional file servers, through well-established network protocols like NFS and CIFS/SMB.

NAS systems attempt to reduce the cost associated with traditional file servers. Rather than utilize general-purpose computer hardware and a full-featured network operating system (NOS) like NetWare, NAS devices generally run an embedded operating system on simplified hardware. NAS boxes support hard drives, and sometimes tape drives, but lack peripherals like a monitor or keyboard. Designed specifically for network storage, a NAS tends to be easier to manage than a file server.

Network Address Translation (NAT)

NAT allows an Internet Protocol (IP) network to maintain public IP addresses separately from private IP addresses. NAT is a popular technology for Internet connection sharing. It is also sometimes used in server load balancing applications on corporate networks.

In it's most common configuration, NAT maps all of the private IP addresses on a home network to the single IP address supplied by an Internet Service Provider (ISP). This allows computers on the home LAN to share a single Internet connection. Additionally, it enhances home network security by limiting the access of external computers into the home IP network space.

NetBIOS

NetBIOS is a software protocol for providing computer communication services on local networks. Microsoft Windows uses NetBIOS on Ethernet or Token Ring networks.

NetWare

The NetWare operating system was one of the first software products built for the networking of personal computers (PCs). NetWare emphasizes file and print serving capabilities, and the predominant use of NetWare is as a LAN server. Early version of NetWare appeared in the late 1980s, and today NetWare enjoys an installed base of millions of computers.

Network Interface Card (NIC)

a NIC provides the hardware interface between a computer and a network. A NIC technically is network adapter hardware in the form factor of an add-in card such as a PCI or PCMCIA card.

Some NIC cards work with wired connections while others are wireless. Most NICs support either wired Ethernet or WiFi wireless standards. Ethernet NICs plug into the system bus of the PC and include jacks for network cables, while WiFi NICs contain built-in transmitters / receivers (transceivers).

Node

A node is any device connected to a computer network. Nodes can be computers, personal digital assistants (PDAs), cell phones, or various other network appliances. On an IP network, a node is any device with an IP address.

OSI Model

The OSI model defines internetworking in terms of a vertical stack of seven layers. The upper layers of the OSI model represent software that implements network services like encryption and connection management. The lower layers of the OSI model implement more primitive, hardware-oriented functions like routing, addressing, and flow control.

In the OSI model, data communication starts with the top layer at the sending side, travels down the OSI model stack to the bottom layer, then traveses the network connection to the bottom layer on the receiving side, and up its OSI model stack.

The seven Layers of the OSI Model:

1. Application
2. Presentation
3. Session
4. Transport
5. Network
6. Data Link
7. Physical

Peer-to-peer (P2P)

A peer-to-peer network allows computer hardware and software to function without the need for special server devices. P2P is an alternative to client-server network design.

P2P is a popular technology for file sharing software applications like Kazaa, WinMX and Overnet. P2P technology helps the P2P client applications upload and download files over the P2P network services.

Personal Area Network (PAN)

A personal area network - PAN - is a computer network organized around an individual person. Personal area networks typically involve a mobile computer, a cell phone and/or a handheld computing device such as a PDA. You can use these networks to transfer files including email and calendar appointments, digital photos and music.

Peripheral Component Interconnect (PCI)

PCI (Peripheral Component Interconnect) is an industry specification for connecting hardware devices to a computer's central processor. Both Ethernet and Wi-Fi network adapters for desktop and notebook computers commonly utilize PCI.

PCI defines the electrical characteristics and signal protocol used for two devices to communicate over a computer's central bus. PCI network adapters and other devices exist in several different shapes and sizes called "form factors."

Besides traditional Ethernet PCI cards that manufacturers pre-install inside desktop computers, common PCI form factors for consumer network devices are:

• Card Bus - either Wi-Fi or Ethernet PC Card (also known as PCMCIA or "credit card") network adapters
• Mini PCI - Wi-Fi network cards embedded inside notebook computers

Personal Computer Memory Card International Association (PCMCIA)

PCMCIA is an industry organization best know for developing a standard network adapter using the PC Card form factor. The PC Card form factor was designed for thinness, and PCMCIA is therefore especially well suited for notebook computers. Most notebooks contain two PCMCIA slots that hold one or two of these cards.

PC Cards come in three types. All PC Cards have the same width and length - 54.0 millimeters wide and 85.6 millimeters long - but vary in thickness:

• Type 1 - 3.3 millimeters thick
• Type 2 - 5.0 millimeters thick
• Type 3 - 10.5 millimeters thick

Port Number

A port number represents an endpoint or "channel" for network communications. Port numbers allow different applications on the same computer to utilize network resources without interfering with each other.

In IP networking, port numbers can theoretically range from 0 to 65535. Most popular network applications, though, use port numbers at the low end of the range (such as 80 for HTTP). The port number is included as a field within the header of each IP packet.

Point-to-point Protocol Over Ethernet

It is a network protocol sometimes used by broadband modems for DSL Internet service.

PPPoE allows Internet Service Providers to manage access through accounts with user names and passwords. Some DSL service providers chose PPPoE as it proved a convenient technical solution for converting subscribers from dial-up Internet.

Point-to-point Tunneling Protocol

PPTP is a network protocol used in the implementation of Virtual Private Networks (VPN). PPTP technology extends the Point to Point Protocol (PPP) standard for traditional dial-up networking. PPTP operates at Layer 2 of the OSI model. As a network protocol, PPTP is best suited for the remote access applications of VPNs, but it also supports LAN internetworking.

Network Protocol

A network protocol defines rules and conventions for communication between network devices. Protocols for computer networking all generally use packet switching techniques to send and receive messages in the form of packets.

Network protocols include mechanisms for devices to identify and make connections with each other, as well as formatting rules that specify how data is packaged into messages sent and received. Some protocols also support message acknowledgement and data compression designed for reliable and/or high-performance network communication. Hundreds of different computer network protocols have been developed each designed for specific purposes and environments.

Proxy Server

Proxy servers act as a "middleman" or broker between the two ends of a client/server network connection. Proxy servers work with Web browsers and servers, or other applications, by supporting underlying network protocols like HTTP.

Proxy servers provide three main functions:

1. firewalling and filtering
2. connection sharing
3. caching

The features of proxy servers are especially important on larger networks like corporate intranets and ISP networks. The more users on LAN and the more critical the need for data privacy, the greater the need for proxy server functionality.

Public Switched Telephone Network (PSTN)

PSTN is the global collection of interconnects originally designed to support circuit-switched voice communication. The PSTN provides the traditional Plain Old Telephone Service (POTS) to residences and many other establishments. Parts of the PSTN are also utilized for DSL, VoIP and other Internet-based network technologies.

The basic PSTN network link supports 64 Kbps bandwidth. In residences, the PSTN phone line carrying this bandwidth is typically a copper cable. Traditional dial-up modems utilize nearly 56 Kbps of this bandwidth when connected to a phone line. The PSTN utilizes the SS7 signaling protocol.