Networking

WINDOWS NT

(Windows New Technology) A 32-bit operating system from Microsoft for Intel x86 CPUs. NT is the core technology in Windows 2000 and Windows XP (see Windows). Available in separate client and server versions, it includes built-in networking and preemptive multitasking. Windows NT was introduced in 1993 as Version 3.1 with the same user interface as Windows 3.1. In 1996, Version 4.0 switched to the Windows 95 desktop and changed some of the dialogs

TCP/IP

(Transmission Control Protocol/Internet Protocol) A communications protocol developed under contract from the U.S. Department of Defense to internetwork dissimilar systems. Invented by Vinton Cerf and Bob Kahn, this de facto Unix standard is the protocol of the Internet and the global standard for communications.

SPX

(Sequenced Packet EXchange) The transport layer protocol in the NetWare operating system. Similar to the TCP layer in TCP/IP, it ensures that the entire message arrives intact. SPX uses NetWare's IPX as its delivery mechanism. Application programs use SPX to provide client/server and peer-to-peer interaction between network nodes

SNMP

(Simple Network Management Protocol) A widely used network monitoring and control protocol. Data are passed from SNMP agents, which are hardware and/or software processes reporting activity in each network device (hub, router, bridge, etc.) to the workstation console used to oversee the network. The agents return information contained in a MIB (Management Information Base), which is a data structure that defines what is obtainable from the device and what can be controlled (turned off, on, etc.). Originating in the Unix community, SNMP has become widely used on all major platforms.

CMIP

(Common Management Information Protocol) Pronounced "c-mip." A network monitoring and control standard from ISO. CMOT (CMIP over TCP) is a version that runs on TCP/IP networks, and CMOL (CMIP over LLC) runs on IEEE 802 LANs (Ethernet, Token Ring, etc.).

NMS

Also known as NMS, it is an SNMP-based network management software from Novell for monitoring and controlling NetWare networks. NMS was superseded by ManageWise.

LAN

(Local Area Network) A communications network that serves users within a confined geographical area. The "clients" are the user's workstations typically running Windows, although Mac and Linux clients are also used. The "servers" hold programs and data that are shared by the clients. Servers come in a wide range of sizes from Intel-based servers to mainframes. Printers can also be connected to the network and shared

WAN

(Wide Area Network) A long-distance communications network that covers a wide geographic area, such as a state or country. The telephone companies deploy WANs to service large regional areas or the entire nation. Large enterprises have their own private WANs to link remote offices, or they use the Internet for connectivity. The Internet, of course, is the world's largest WAN.

ATM

Asynchronous Transfer Mode) A network technology for both local and wide area networks (LANs and WANs) that supports realtime voice and video as well as data. The topology uses switches that establish a logical circuit from end to end, which guarantees quality of service (QoS). However, unlike telephone switches that dedicate circuits end to end, unused bandwidth in ATM's logical circuits can be appropriated when needed. For example, idle bandwidth in a videoconference circuit can be used to transfer data.

ATM is widely used as a backbone technology in carrier networks and large enterprises, but never became popular as a local network (LAN) topology (see below). ATM is highly scalable and supports transmission speeds of 1.5, 25, 100, 155, 622, 2488 and 9953 Mbps. ATM is also running as slow as 9.6 Kbps between ships at sea. An ATM switch can be added into the middle of a switch fabric to enhance total capacity, and the new switch is automatically updated using ATM's PNNI routing protocol.

MPLS

(MultiProtocol Label Switching) A standard from the IETF for including routing information in the packets of an IP network. MPLS is used to ensure that all packets in a particular flow take the same route over a backbone. Deployed by many telcos and service providers, MPLS can deliver the quality of service (QoS) required to support realtime voice and video as well as service level agreements (SLAs) that guarantee bandwidth. Large enterprises may also use MPLS in their national networks.

Similar to Cisco's tag switching, an MPLS router attaches labels (tags) containing forwarding information to outgoing IP packets. These "label edge routers" (LERs) sit at the edge of the network and perform the complex packet analysis and classification before the packet enters the core of the network. The routers within the core, known as "label switch routers" (LSRs), quickly examine the label and forward the packet per its directions without having to look up data in tables and compute the forwarding path each time. The edge routers at the receiving end remove the labels.

ISDN

(Integrated Services Digital Network) An international standard for switched, digital dial-up telephone service for voice and data. Analog telephones and fax machines are used over ISDN lines, but their signals are converted into digital by the ISDN terminal adapter (see below).

Although announced in the early 1980s, it took more than a decade before ISDN became widely available. It enjoyed a surge of growth in the early days of the Internet, because it provided the only higher-speed alternative to analog modems in many areas. Still working in many behind-the-scenes applications, ISDN is rarely used for Internet access.

BGP

Border Gateway Protocol) A routing protocol that is used to span autonomous systems on the Internet. It is a robust, sophisticated and scalable protocol that was developed by the Internet Engineering Task Force (IETF). BGP4 supports the CIDR addressing scheme, which has increased the number of available IP addresses on the Internet. BGP was designed to supersede EGP, the original exterior gateway protocol. It is also known as a path vector protocol

RTP

(Rapid Transport Protocol) The protocol used in IBM's High Performance Routing (HPR) system.

 (Realtime Transport Protocol) An IP protocol that supports realtime transmission of voice and video. It is widely used for IP telephony and audio and video streaming. An RTP packet rides on top of UDP, the non-reliable counterpart of TCP, and includes timestamping and synchronization information in its header for proper reassembly at the receiving end. Secure RTP (SRTP) is a version of RTP that provides confidentiality and message authentication.

RTCP

(Realtime Control Protocol)
RTCP is a companion protocol to RTP that is used to maintain QoS. RTP nodes analyze network conditions and periodically send each other RTCP packets that report on network congestion.

RTSP

Realtime Streaming Protocol)
RTSP is used to control an RTP session at the application layer. It enables functions such as pause, rewind and fast forward to be provided in the user's client software.

RIP

(Raster Image Processor) The hardware and/or software that rasterizes an image for display or printing. RIPs are designed to rasterize a specific type of data, such as PostScript. As desktop computers became more powerful, software RIPs became more appealing than specialized hardware RIPs. Software can be upgraded more easily, and the operation is always speeded up by installing a faster CPU.

 (Routing Information Protocol) A simple routing protocol that is part of the TCP/IP protocol suite. It determines a route based on the smallest hop count between source and destination. RIP is a distance vector protocol that routinely broadcasts routing information to its neighboring routers and is known to waste bandwidth. It also has a limit of 15 hops. If a route is advertised as having 16 hops, it is flagged as unreachable. AppleTalk, DECnet, TCP/IP, NetWare and VINES all use incompatible versions of RIP.

(Remote Imaging Protocol) An earlier graphics format from TeleGrafix Communications, designed for transmitting graphics over low-speed lines. Using a communications program that supported RIP enabled graphical interfaces to be used on a BBS with respectable performance via modem.

IPv6

(Internet Protocol Version 6) The next generation IP protocol. Started in 1991, the specification was completed in 1997 by the Internet Engineering Task Force (IETF). IPv6 is backward compatible with and is designed to fix the shortcomings of IPv4, such as data security and maximum number of user addresses.

IPv6 increases the address space from 32 to 128 bits, providing for an unlimited (for all intents and purposes) number of networks and systems. It also supports quality of service (QoS) parameters for realtime audio and video. Originally called "IP Next Generation" (IPng), IPv6 is expected to slowly replace IPv4, with the two existing side by side for many years.

IPv6 was officially deployed in July 2004 when ICANN added IPv6 records to its DNS root server for the .jp (Japan) and .kr (Korea) country codes.

SONET

(Synchronous Optical NETwork) A fiber-optic transmission system for high-speed digital traffic. Employed by telephone companies and common carriers, speeds range from 51 Mbps to 40 Gbps.

SONET is an intelligent system that provides advanced network management and a standard optical interface. Specified in the Broadband ISDN (B-ISDN) standard, SONET backbones are widely used to aggregate T1 and T3 lines. The European counterpart to SONET is the Synchronous Digital Hierarchy, and the term "SONET/SDH" is widely used when referring to SONE