IV. Basic Glossary on Campus Networks Another glossary is RFC1208. See "Online Papers" above. ANSI "American National Standards Institute" - A definer of standards of all kinds, including FDDI. AppleTalk - A protocol family developed by Apple Computer to implement LANs serving Macintoshes. ATM "Asynchronous Transfer Mode" - a method for switching little fixed-size packets (cells) around. Like T1 and DS3, digitized voice was a major consideration in its design, but it can be used for data. It is designed around fixed speeds too, roughly 150 Mbps and 600 Mbps. The fixed cell size is 53 bytes. Though ATM is really designed for voice and WANs, there are schemes to use it in LANs. ATM is a big buzzword these days but it is still very new. AUI "Attachment Unit Interface" - the Ethernet/IEEE 802.3 term for the interface between a MAU and a station. A special kind of cable known as an "AUI Cable" can attach a MAU to a station at a distance (up to 50 meters). BNC Connector "Bayonet Neill-Concelman connector" - a type of connector used for attaching coax cable to electronic equipment which can be attached or detached quicker than connectors that screw. ThinWire Ethernet (IEEE 802.3 10BASE2) uses BNC connectors. Bridge - A network "relay" which reads, buffers, and sends data to relay it from one data link to another, but makes the two data links appear as one to levels higher than the data link layer. CDDI "Copper Data Distribution Interface" - essentially a way to use electrical communications cables in an FDDI network. Several companies have worked out ways to do this but ANSI has yet to standardize one. I think CDDI was coined by Crescendo corporation for their scheme, but it may well be adopted by ANSI as the name. So far there are schemes that work on Coax, on STP and UTP, but the front runners look like they will be able to run on UTP for about 100 meters. CMIP "Common Management Information Protocol" - An OSI protocol for management of network equipment. Not widely implemented. See SNMP. CMOT "CMIP over TCP/IP" - A protocol consisting of CMIP running under TCP/IP. An alternative to SNMP. Coaxial Cable - Any of a number of kinds of electrical communications cable designed so one conductor is in the center and the second conductor forms a ring around it. Depending upon who you talk to, someone might have a specific kind of coaxial cable in mind. Some well known kinds are various Cable TV cables, cables used by IBM 327x terminals and ARCnet, and cables used by Ethernet & IEEE 802.3. DECnet - Trade name of Digital Equipment Corporation for some of their networking products. It is a kind of network built out of Digital Equipment Corporations own networking protocols (with some standard protocols also used). Dialup Modem - Modem used over ordinary dial-up telephone lines as opposed to private or leased lines. Ethernet - LAN data-link protocol developed by a consortium of vendors; later standardized as IEEE 802.3 with a few modifications. For many applications, users have not adopted all the IEEE 802.3 differences. Ethernet/802.3 now can be run on two types of coaxial cable as well as multi-mode fiber and unshielded twisted-pair. "Raw" rate of data transmission is 10 megabits/second. FDDI "Fiber Data Distribution Interface" - LAN data-link protocol. Designed to run on multi-mode fiber. "Raw" rate of data transmission is 100 megabits/second. Developed by the American National Standards Institute. FDDI-2 - Same speed, same fiber, same basic protocol as FDDI. FDDI-2 adds a layer which allows you to allocate fixed bandwidth to applications of your choice, making it more like broadband. FDDI-2 is still rather new. Fiber - optical fiber: a very long, narrow, flexible piece of glass. Used for high-speed communications. FOIRL "Fiber Optic Inter-Repeater Link" - a standard for running IEEE 802.3 over fiber. It was originally designed to link two repeaters, and only supports two attachments. Many users use it to attach a station to a repeater. See 10BASE-F. FTP - Protocol in the "TCP/IP" family for copying files from one computer to another. Stands for "File Transfer Protocol". Gateway - A type of "network relay" that attaches two networks to build a larger network. Modern "narrow" usage is that it is one that translates an entire stack of protocols, e.g., translates TCP/IP-style mail to ISO-style mail. Older usage used it for other types of relays--in particular, in the "TCP/IP" world, it has been used to refer to what many now insist is a "router". GOSIP "Government Open Systems Interconnect Profile" - A subset of OSI standards specific to US Government procurements, designed to maximize interoperability in areas where plain OSI standards are ambiguous or allow options. Theoretically, required of all US Government networking procurements since mid-1990. Heartbeat - In Ethernet (Version 2), a test of the collision functionality of the transceiver. The term "Heartbeat" is often (wrongly) used interchangeably with "SQE" which is a similar function of IEEE 802.3. See Question on SQE/Heartbeat below. IPX - Novell's protocol used by Netware. Utilizes part of XNS. A router with "IPX routing" purports to interconnect LANs so that Novell Netware clients & servers can talk through the router. MAU "Media Adaptor Unit" - an IEEE 802.3 or Ethernet device which attaches a station to the cable. Popularly called a "transceiver". Can be attached by cable to the station or built into the station. MIB "Management Information Base" - the set of parameters an SNMP management station can query or set in an SNMP agent (e.g. router). Standard, minimal MIBs have been defined (MIB I, MIB II), and vendors often have custom entries. In theory, any SNMP manager can talk to any SNMP agent with a properly defined MIB. Multimode fiber - A type of fiber mostly used for shorter, e.g. campus distances. It can carry 100 megabits/second for typical campus distances, the actual maximum speed (given the right electronics) depending upon the actual distance. It is easier to connect to than Single Mode Fiber, but its limit on speed x distance is lower. NFS "Network File System" - an IP-based protocol originally developed by Sun Microsystems which provides file services. OSI "Open System Interconnect" - A standard put forth by the ISO for communication between computer equipment and networks. OSI Reference Model - A model put forth by the ISO for communication between computer equipment and networks, which maps out 7 protocol layers. Top layer: layer number 7: application layer layer number 6: presentation layer layer number 5: session layer layer number 4: transport layer layer number 3: network layer layer number 2: data-link layer (e.g. IEEE 802.x) Bottom layer: layer number 1: physical layer (wire & electricity) This model explains what each layer does. The model is often used to explain anyone's protocols (not just OSI) to the point where many people seem to believe that true data-communications requires these 7 layers. POP "Post Office Protocol" - A TCP/IP-based protocol designed to allow client-stations (e.g. micros) to read mail from a server. There are three versions under the name "POP": POP, POP2, and POP3. Latter versions are NOT compatible with earlier versions. Protocol - The "rules" by which two network elements trade information in order to communicate. Must include rules about a lot of mundane detail as well as rules about how to recover from a lot of unusual communication problems. Thus they can be quite complicated. Relay - One terminology uses the term "relay" as a device that interconnects LANs, different kinds of relays being repeaters, bridges, routers, and gateways. Repeater - In the "Ethernet" world, a "relay" that regenerates and cleans up signals, but does no buffering of data packets. It can extend an Ethernet by strengthening signals, but timing limitations on Ethernets still limit their size. RFC "Request For Comments" - The name is a real red herring when it comes to Internet RFCs. Some really are "Requests For Comments" but all Internet protocol documents are stamped with an RFC number that they never shake, so the acronym RFC generally refers to documents that describe protocols in the TCP/IP family. RG numbers (E.g. RG62; sometimes there are qualifiers, e.g. RG 58 A/U) a shorthand designation for military cable. RG58 & RG62 designate two different types of cable used by the military. Some data-communications equipment was designed to work with a particular military standard, e.g. IBM 3270-type terminals use RG62. In other cases, people use an RG-numbered cable that is close to what they need: for example Thinwire Ethernet & IEEE 802.3 10BASE2 define the type of cable they need and people sometimes substitute flavors of RG58, which are "close". One can't recommend this practice because you can get yourself in trouble. I think "RG" originally stood for "Radio Guide", presumably reflecting the fact that the series of cables was designed to handle radio frequencies. The IEEE 802.3 10BASE2 specifications define two RG numbered cables (RG58 A/U and RG58 C/U) as meeting the cable requirements for thin Ethernet. However, cable vendors may list a range of cables under these same RG numbers, and some of the cables listed may not meet the 802.3 specs. You need to check the cable specifications closely, and beware of relying on the RG number alone when ordering network cables. Router - A network "relay" that uses a protocol beyond the data-link protocol to route traffic between LANs and other network links. Routing Protocol - a protocol sent between routers by which routers exchange information own how to route to various parts of the network. The TCP/IP family of protocols has a bunch, such as RIP, EGP, BGP, OSPF, and dual IS-IS. Shielded Twisted Pair - a type of twisted-pair cable with a metallic shield around the twisted conductors. The shield reduces the noise from the cable and reduces the effects of noise on the communications in the cable, but changes the electrical characteristics of the cable so some equipment optimized to non-shielded cable runs worse on shielded cable. Single Mode fiber - a type of fiber optic cable used for longer distances and higher speeds, e.g. for long-distance telephone lines. See also "Multimode Fiber". SMTP "Simple Mail Transfer Protocol" - the protocol in the TCP/IP family used to transfer electronic mail between computers. It is not oriented towards a client/server system so other protocols (see "POP") are often used in that context. However, servers will use SMTP if they need to transfer a message to another server. SNMP "Simple Network Management Protocol" - Originally developed to manage IP based network equipment like routers and bridges, now extended to wiring hubs, workstations, toasters, jukeboxes, etc. SNMP for IPX and AppleTalk under development. Widely implemented. See CMIP. SQE Test "Signal Quality Error Test" - an IEEE 802.3 function that tests the transceiver. The term "SQE" is often (wrongly) used interchangeably with "Heartbeat" which is a similar function of Ethernet Version 2. See Question on SQE/Heartbeat below. TCP/IP "Transmission Control Protocol/Internet Protocol" - literally, two protocols developed for the Defense Data Network to allow their ARPANET to attach to other networks relatively transparently. The name also designates the entire family of protocols built out of IP and TCP. The Internet is based upon TCP/IP. TELNET - a protocol in the TCP/IP family that is used for "remote login". The name is also often used as the name of the client program that utilizes the TELNET protocol. Terminal Server - a network device that allows a number of terminals to attach to a LAN, and do remote logins across the LAN. TN3270 - A variant of the TELNET program that allows one to attach to IBM mainframes and use the mainframe as if you had a 3270 or similar terminal. Token Ring - People often mean 802.5 when they say "Token Ring" (see below). In the more general sense of the word, a type of LAN that has stations wired in a ring, where each station constantly passes a special message (a "token") on to the next. Whoever has the token can send a message. Tunneling - An important concept in the design of many kinds of networks: taking some protocol-family's ability to move packets from user to user, or to open virtual-circuits between users, and use this as if it were a data-link protocol to run another protocol family's upper layers (or even the same protocol family's upper layers). Examples: running TCP/IP over AppleTalk instead of something like Ethernet; running AppleTalk over DECnet instead of something like LocalTalk or Ethernet. Twisted Pair - The type of wire used by the phone company to wire telephones -- at least over distances like between your house and the central office. It has two conductors, which are twisted. The twists are important: they give it electrical characteristics which allow some kinds of communications otherwise not possible. Ordinary telephone cables are not shielded (see "Shielded twisted Pair"). T1 - A phone-company standard for running 24 digitized voice circuits through one 1.5megabit/second digital channel. Since phone companies run lots of T1, and will run T1 between customer sites, the standard is often used for data communications, either to provide 24 low-speed circuits, or to provide 1 high-speed circuit, or to be divided other ways. UTP (Unshielded Twisted-Pair) - See "Twisted-Pair" and "Shielded Twisted-Pair". X.400, X.500 - OSI protocols for mail and directory services. 10BASE-T - A variant of IEEE 802.3 which allows stations to be attached via twisted-pair cable. 10BASE-F - A variant of IEEE 802. 3 under development which allows stations to be attached via multimode fiber. It will offer a variety of methods of using fiber in an IEEE 802.3 network that go beyond what is currently offered in FOIRL. The current 10BASE-F draft is likely to be confirmed. draft is likely to be confirmed. Sections of the draft include "Fiber Optic Medium and Common Elements of Medium Attachment Units and Star, Type 10BASE-F (Section 15)", "Fiber Optic Passive Star and Medium Attachment Unit, Type 10BASE-FP (Section 16)", "Fiber Optic Medium Attachment Unit, Type 10BASE-FB (Section 17)", and "Fiber Optic Medium Attachment Unit, Type 10BASE-FL (Section 18)". 802 - The set of IEEE standards for the definition of LAN protocols. A story goes that a long time ago, IEEE and ANSI decided that IEEE would get the slow protocols and ANSI would get the fast ones, thus IEEE defined the 802 protocols and ANSI defined FDDI. Presumably IEEE saw limited application for FDDI at the time. Also, the IEEE standards-making committees associated with these standards. 802.1 - The IEEE 802 standard for Network Management and Network Bridging of IEEE 802 networks. 802.2 - An IEEE standard for the portion of LAN data-link protocols that is the same for all flavors of IEEE LAN protocols, e.g. 802.3 and 802.5. Sometimes not used. 802.3 - An IEEE standard for LANs--their "improved" version of Ethernet. See Ethernet. 802.4 - An IEEE standard for LANs: Token Bus networks. Basically, standardizes MAP, a protocol that operates a Token Bus protocol on broadband. 802.5 - An IEEE standard for Token-Ring-based LANs. See Token Ring. 802.6 - An IEEE standard for Metropolitan Area Networks. Also known as DQDB. 802.7 - IEEE 802 technical advisory group on Broadband. 802.8 - IEEE 802 technical advisory group on FDDI & fiber optics. 802.9 - IEEE 802 group on integrated data & voice networks. 802.11 - Proposed IEEE 802 group for wireless Ethernet.