Meloria • Ever Better
Search Tools Main Menu

Glossary of Networking Terms

Note that the internet offers many searches on terminology that are always up-to-date. Any search engine can be used to search a term. There are also consolidated resources for terminology such as "webopedia".

Anonymous FTP A common use of the File Transfer Protocol (see also), wherein the user does not supply a password, but is only allowed access to a particular set of files. Used extensively on the Internet to distribute software and documentation.

ANSI X3T9.5 the standard for a 100mbit token-passing fiber optic ring network. see FDDI.

ARP (TCP/IP) Address Resolution Protocol, the protocol by which IP hosts find the Local Area Network (e.g. Ethernet) address associated with the IP address to which communication is desired.

ARPANET Advanced Research Projects Administration Network, the Department of Defense's research network.

AUI Attachment Unit Interface. Transceiver cable interface (Ethernet).

Authentication The process of a user proving her or his identity to a host.

Backbone The main University backbone network, known as URNet.

Backbone The specific hardware and software protocols and standards recognized and services used at the point of demarcation to exchange data and control information between a departmental network and the backbone network.

BARRNet Bay-Area Regional Network (TCP/IP).

Broadcast A packet sent to all systems on the local network.

Bus topology A network topology in which all stations are attached at different points along a single wire.

Campus The centrally-operated network that connects departmental backbone networks to each other and provides routing to wide-area networks.

Client-server A model of computing in which a large number of relatively small, single-user machines (the clients) receive data, programs, and possibly CPU time from a much larger, more powerful central machine (the server).

CPU Central processing unit, the core of every modern computer. The CPU executes the programs, manages input and output, and communicates with storage devices.

Datagram A separately-addressed unit of information sent from one host to another.

Denial of service A network security term used to refer to attacks where the intruder does not actually gain access to a network service, but denies access to that service to legitimate users.

Department A University group served by a network that is connected to the backbone network. Examples include the College of Engineering, the Administration Building, the Medical Center, the Computer Science Department, and the Laboratory for Laser Energetics.

Departmental A network which is operated by a department and connects network departmental computing resources to each other.

DNS Domain Name Service is a specification used on the Internet to allow each host the ability to know the numeric address of any other host on the Internet without having to keep its own table of the millions of Internet hosts changing hourly. Using this specification, host names are translated into numeric identifications so that people can use names instead of memorizing numbers.The core of DNS is a distributed database of host names, addresses, mail drops, and other administrative data, used by programs communicating via TCP/IP.

E-mail Electronic mail, messages exchanged between users on networked computers.

Ethernet A networking system developed by Xerox, now adopted by most vendors and the IEEE as standard 802.3

FDDI Fiber Distributed Data Interface, an ANSI standard specifying a 100Mbit/second token-passing network using fiber-optic cable. Work is currently being done to standardize FDDI over twisted pair copper wire. In the future, FFOL (FDDI follow-on LAN) will achieve throughput of upto 2.4 Gbps.

Finger A TCP/IP protocol which retrieves information about users from remote machines.

Firewall A specialized router sometimes with a firewall service module that is installed as a blade, which allows only selected traffic to pass through. Used for highly secure networks, often at the point where the network connects to the Internet.

FTP File Transfer Protocol (TCP/IP), a protocol for moving data between computers.

Fiber Optics A type of cabling which transmits signals using light instead of electricity. It can transmit signals at a higher rate and over longer distances than metallic cable and is less susceptible to electromagnetic interference. Most modern, high-speed networks use fiber optics, often exclusively.

Gateway Often used as a synonym for router, this term may also refer to a device which converts between network media types, such as a Gatorbox, which translates from AppleTalk over PhoneNet to AppleTalk over Ethernet.

Gbps Gigabits per second as multiples of 1024 times Mbps (See Mbps)

Gopher A network information retrieval protocol which provides a transparent menued interface to networked information such as files, images, sounds, etc.

GUI Graphical User Interface, a method of presenting files, programs, and other objects within a computer to the user as icons and windows, and allowing the user to manipulate them in a more intuitive way. Microsoft Windows, MacOS, and the X Window System are common GUI's.

HTTP HyperText Transfer Protocol. HTTP is the actual protocol used by the Web Server and the Browser to communicate.

HTML HyperText Markup Language.

Host A computer system that provides time-shared computing to one or more users simultaneously. Sometimes used to refer to any computer on the network.

Hub Usually used to refer to a multiport Ethernet repeater, which provides connections for several hosts to the Ethernet network. May also be used to refer to a physical site where multiple networks connect.

Icon A small graphic or picture used by a GUI to represent an object such as a file or program. Also used in network management programs to represent devices such as hosts, bridges and routers.

IETF Internet Engineering Task Force, An IAB task force consisting of over 40 groups responsible for addressing short-term Internet engineering issues.

IEEE Institute of Electrical and Electronic Engineers, Developers of a standard set of protocols developed for local area networks.

IEEE 802.2 specifies a standard packet frame for the other sections.

IEEE 802.3 Ethernet,

IEEE 802.4 Token Bus (MAP),

IEEE 802.5 Token Ring,

IEEE 802.6 metropolitan area network.

IEEE 802.11 wireless.

Infrastructure The cabling, support equipment, physical space, conduit, etc. required to support a network.

Interface A connection from a host or router to the network. Each networked host must have one interface, and each router two or more.

Interface card The adapter card installed in a host computer to allow it to attach to the network. Also referred to as a NIC (Network Interface Card).

Internet A network of networks.

Internet As in "the Internet." The world-wide interconnected collection of TCP/IP networks.

IP Internet Protocol, the network layer of TCP/IP.

ISDN Integrated Services Digital Network, a network developed by the phone companies to carry voice and data over the wide area. It is still being standardized but is available in the Rochester area.

ISO International Standards Organization.

IPX Internet Packet Exchange, the network layer for Novell.

ITS The University's Information Technology Services organization.

kbps Kilobits per second, a unit of network speed representing multiples of 1024 bits transmitted per second.

Kerberos A network security system developed at MIT which provides distributed authentication services.

LIU Light Interconnect Unit; a patch panel for fiber optics.

MAC layer Media Access layer, the lower half of ISO Level 2 (Data Link layer); responsible for putting frames (packets) on the physical transmission medium at appropriate times.

Mail Relay A computer that forwards mail from one network to another.

Mbps Megabits per second, a unit of network speed representing multiples of 1048576 bits transmitted per second.

Mesh topology A network topology in which every host is connected to every other host.

Multimode fiber Fiber optic cable which has large fibers, so that the light passing through the fiber can do so in more than one mode. This means that the fiber has less bandwidth but is more easily handled and end devices are less expensive.

NetWare A set of network protocols developed by Novell for file and printer sharing between computers on a local network.

Network A facility used for data communications among computers.

Network I/O Network input and output, measures of the data transmitted and received on a network.

Network protocol A set of data structures, transmission sequences, etc. used to transfer information between computers. such as TCP/IP, IPX.

NIC Network Information Center

NISC Network Information and Support Center or Network Information Services Center

NOC Network Operations Center

Node A station or device on the network that receives input and/or output, such as a computer, a terminal server, a printer, etc.

NSFNet National Science Foundation Network

NYSERNet New York State Education and Research Network. A regional network providing Internet connectivity to the University of Rochester and several other local organizations.

OSI Open Systems Interconnect: the international standard layered model for networking protocols. Consists of seven layers, as follows:

Layer 1 Physical - the cables and electronics.

Layer 2 Data-link - the base network, such as Ethernet, Token Ring
or FDDI.

Layer 3 Network - the protocol which moves data between hosts, such as IP or IPX.

Layer 4 Transport - the protocol which moves data between programs, such as TCP or NCP (NetWare Core Protocol).

Layer 5 - Session - provides coordination between applications on each host.

Layer 6 Presentation - ensures communication between applications by translating data structures, formats and codes.

Layer 7 Application - provides the interface by which the user interacts with the network.

Note that layers 5-7 are somewhat unclear in most network designs, which concentrate on layers 1-4.

OTDR Optical Time-Domain Reflectometer, used to find flaws in fiber optic cable.

Packet switch A device that moves packets from one network to another.

Ping A program which requests a reply from a host running the TCP/IP protocols, used for network testing.

Point of Presence The physical point of interface between two networks, in this realm typically the demarcation connectors between a departmental cable and a backbone device.

Printer sharing A service provided by most network protocols which allows one printer to be used by several hosts.

Ring topology A network topology in which each host connects to two others, and data flows from one host to the next around the ring.

Router A packet switch that operates at OSI Level 3, the "network" layer. The terms gateway and router are used synonymously in this document.

Routing Packet forwarding based on network address.

Secure gateway Another term for firewall.

Server A host that provides some service to other hosts. Examples are terminal servers, disk servers, file servers, mail servers, domain servers, name servers, CPU servers.

Singlemode fiber Fiber optic cable which has small fibers, so that the light passing through the fiber can only do so in one mode. This means that the fiber has more bandwidth but is mode difficult to handle and end devices are more expensive.

Sniffer A device which attaches to a network and displays the data packets as they are sent, used for network troubleshooting.

Snooping The process of capturing packets from a network. This is done routinely for troubleshooting, but may also be done by network intruders to capture passwords and data.

Spoofing The process of transmitting packets on a network while pretending to be some other host. Used by network intruders to subvert security measures.

SQE Signal Quality Error, also known as "heartbeat;" a signal sent by an Ethernet transceiver to a host which tests the integrity of the collision detection system.

SMTP Simple Mail Transfer Protocol, a TCP/IP protocol used for e-mail.

SURANet Southern University Research Network (TCP/IP)

Subnet A term used in TCP/IP to describe a local area network within an organization's internetwork.

Switching The process of taking a receiving a packet from one network and transmitting it on another, with the choice of the network made using information contained in the packet.

T1 A standard for wide area data transmission at 1.544 Mbps.

TCP Transmission Control Protocol

TCP/IP A network system developed for the Department of Defense, which now forms the basis for the worldwide Internet.

TDR Time-Domain Reflectometer, used to find flaws in metallic cable.

TELNET A terminal-to-host protocol (TCP/IP).

10BaseT An IEEE standard (802.3i) which provides for Ethernet over twisted-pair copper cable.

Terminal Server A device that allows terminals to access hosts over the network.

Topology The underlying structure of a network; how the network hosts are connected to each other.

Transceiver A device used to attach a single node to an Ethernet.

University The set of all networks connected to the campus backbone network, internetwork including the backbone itself.

UPS Uninterruptible power supply, a device which provides power to a host or router during a power failure.

WAN Wide area Networks that span a large geographic area. Examples include NSFNET networks and the URNet WAN.

Workstation A computer system that provides dedicated computing to one user at a time.

WWW WorldWide Web, a distributed hypermedia system on the Internet.