See also Glossary (Black Box), and Glossary (Communication News), and a web-related glossary (Netcraft), and even the communications entry in the foldoc.
Communication Speeds and Distances

Communication Speeds and Distances

[IMAGE: A Chart of communication speeds]
10base-F
Fiber Ethernet. Fiber optics that mimic Ethernet, but much greater distances (up to 2km).
10base-T
Ethernet running over unshielded twisted-pair at 10Mbs, effective network diameter 250m.
AIN
(Advanced Intelligent Network).
ALTS
(Alternative Local Transport Service).
AnyLAN
[IEEE 802.12 100VG-AnyLAN] 100Mbps using the new DPMA technology, connects to Ethernet, Token Ring, and others, being developed by HP & IBM.
ARCnet
Ardis
A wireless carrier started in 1984 by IBM. 19,200bps (since 1993, still 4,800bps in some areas), 256 byte packets. 800 Mhz, uses 2 watts to transmit. Has 35,000 customers in over 400 metropolitan areas in the US (1993) 90% of US business locations.
ATM
(Asynchronous Transfer Mode) 45Mbps - 622Mbps (45Mbps & 155Mbps are specified in the draft ATM standard). ATM networks are proposed to run at over 2Gbps. Some switches up to 140Mbps are now (4/93) available. They comprise DS3 (T3) WAN, FDDI LAN, Fiber Channel LAN, and SONET LAN linked using SNMP. Data converted into fixed length 53 byte cells (48 byte cell + 5 byte header) facilitating high speed switching. (AAL 3/4 (ATM Adaptive Layer) supports 44 byte cells and AAL 5 supports 48 byte cells.)
baud
Literally, changes in state per second, and since this is usually only two states (high and low voltage) it is the same as bps. If one or two parity bits are used per 8 bit character transmission the 8 bit byte throughput will be slower than bps/8.
Bell
103 Standard for 300bps modems in the United States, originally developed at AT&T Bell Laboratories.
Bell 212A
Standard for 1200bps modems in the United States.
bps
bits per second.
CDDI
(Copper Distributed Data Interface) is FDDI running on unshielded twisted pair.
CDMA
(Code Division Multiple Access) Still in the trial stages (5/1996) Developed by Motorola and Qualcom. A digital data network in the US for use by cellular phones. This and TDMA are likely to become the dominant digital cellular system in the US (2/1996). In Europe and Asia it is GSM.
CDPD
(Cellular Digital Packet Data) A wireless carrier, an inernet protocol based network, who's specs have just been finalized (1993). 19,200bps, 114 byte packets. 800 Mhz, uses 0.6 3 watts to transmit. Operates in the 9000 cell sites.
Sends digital data over idle analog voice channels, such as CSC. (see PCWeek 13 13, 4,3/34,34 29 Jan 1996 for CDPD distribution)
CLASS
(Custom Area Signalling Service).
CO
(Common Office) telephony term for switch house.
CPE
CSC
(Circuit switched cellular) 2,400bps - 14,400bps analog system designed for voice communication, but with cellular phone and cellular modem gets improved data transmission.
CSMA/CD
(Carrier-Sense Multiple Access/Collision Detection) Fast ethernet, similar to `old' ethernet technology.
DCS
DECT
(Digital European Cordless Telecommunications) Standard for radio telecommunications.
DISA
(Direct Invaded System Access).
DPAM
(Demand Priority Access Method)
DQDB
(Distributed Queue Dual Bus) fibre optic based.
DS0
(Digital Signal level 0). International term for 64Kbps digital data service.
E1
CCITT E1 multiplexes 32 64Kbps digitized voices circuits onto a 2Mbs link, and is the European equivalent of the US T1. (The Japanese have such a protocol similar to the US T1, but they are all different standards.)
Ethernet
[IEEE 802.3] 10Mbps (14,800 64 byte packets per second theoretical limit). MTU is 1500 bytes. (Minimum packet size is 72 bits.) Only goes 0.5km. Runs on (originally) 1/2 inch diameter shielded cable, a lighter coaxial (thinnet), or even shielded twisted pair cable.
Currently (1993) connects 25 million computers.

The efficiency of Ethernet is roughly a function (a), computed as five times the length of the line in kilometers times the capacity of the system in megabits per second, divided by the packet size in bits. When a exceeds a certain level (Leonard Kleinrock of UCLA sets it at 0.05), Ethernet's efficiency plummets. (reference)

See also gigabit ethernet, below.

Fast Ethernet
100Mbps, effective network diameter of 250m, runs on unshielded twisted pair cable.
FCS
(Fibre Channel Standard) 155Mbps.
FDDI
(Fiber Distributed Data Interface) 100Mbps (170,000 64 byte packets per second theoretical limit) using 1300nm light wavelengths. Fiber optic, orange cable. Dual-attached counter-rotating token ring topology. Goes 2km, with networks limited to approximately 200km (using repeaters).
FDDI II
Faster FDDI. Gbps.
FDMA
(Frequency Division Multiple Access)
fiber optic
Fiber is much more expensive than copper but goes longer distances more accurately because it fades much less with distance, and has a very low error rate (1 in 1012 ), being unaffected by RFI (RF interference). Speed of electrons in copper wire is about the same as light in fibre (.6 speed of light in a vacuum, or 180,000 km s-1) but light can be turned on faster than signals can be generated, and so light signals can be packed much more closely together, resulting in faster switching and faster network.
Gbps
The five Gigabit per second testbeds have completed their systems: AURORA, BLANCA, CASA, NECTAR, VISTANet. The sixth is MAGIC.
Gigabit Ethernet (from the 802.3z Task Force)
1Gbps, effective network diameter: 500m over multinode fiber, 2Km over singlemode fiber, 25m over copper, (and 100m over Category 5 unshielded twisted pair). Due to appear in mid-1997.
GSM
(Global System for Mobile communication) The cellular network (900MHz range) used throughout Europe and Asia. See CDMA and TDMA. Being used on the 1900MHz for PCS by American Personal Communications in the Washington/Baltimore are (5/1996).
HIPPI
Up to 1.6Gbps (32 bit - 800Mbps, double wide (64 bit) 1600Mbps). (Developed at Los Alamos National Labs, MN) 10km with fibre optic cable, but only 36m with coaxial cable.
HP-IL
(Hewlett-Packard Interface Loop) An obsolete HP protocol from the 80s. A low power, low cost proprietary network running at 5Kbps with a range of over 100m, for connecting low power, smart peripherals and controllers.
internet
(10/92) 7500 networks, 1 million computers, 4 million users, 100 countries. [(1991) The Internet is a federally funded computer network, with one million users, 118,000 hosts at colleges, DARPA, NSF, NASA, DoE, DoH&HS, &c.]
Isochronous Ethernet
[IEEE 802.9] ISOEnet, by National Semiconductor.
ISOEnet
Isochronous Ethernet.
ITU-T
standards committee, formerly CCITT.
IXC
LAN
(Local Area Network).
LATA
Legacy LANs
Ethernet, Token Ring, FDDI.
LocalTalk Apple's network.
256Kbps, range 1000 feet.
MTU
(Maximum Transmission Unit) Largest amount of data that can be transported in a single internet packet.
OC-1
(Optical Carrier level 1) (STS-1) 51.84Mbps SONET.
OC-3
(Optical Carrier level 3) (STS-3 or STM-1) 155.52Mbps SONET.
OC-12
(Optical Carrier level 12) (STS-12 or STM-4) 622.08Mbps SONET.
OC-24
(Optical Carrier level 24) (STS-24 or STM-8) 1244.16Mbps SONET.
OC-48
(Optical Carrier level 48) (STS-48 or STM-16) 2488.32Mbps SONET.
Omnipoint
(IS-661) Falls between TDMA and CDMA
PCS
(Personal Communication Service) There are four PCS systems (May 1996) - TDMA, CDMA, GSM, and Omnipoint. Narrow band PCS will offer two-way paging service in 1995. Broad-band PCS will offer voice and data communication at around 9,600bps in 1996.
PTM
(Packet Transfer Mode) variable-sized packet technology, with enhanced performance over ATM, originally developed by IBM.
RAM Mobile Data
A wireless carrier started in 1991. 8000bps (19,200bps - 1995), 512 byte packets. 900 Mhz, uses 2 watts to transmit.
Uses mobitex standard. Works with RadioMail. Has 10,000 customers in over 100 metropolitan areas in the US (1993).
SDDI
(Shielded twisted-pair Distributed Data Interface) Same as FDDI but over shielded twisted pair.
SDH
(Synchronous Digital Hierarchy) The SONET STS-n (or OC-n) specifications.
SMDS
(Switched Multimegabit Data Service). RBOC's version of ATM/SONET.
SNMP
(Simple Network Management Protocol).
SONET
(Synchronous Optical Network) There are specifications for 51.84Mbps to 2488.32Mbps (See STS-n (OC-n) and STM-n).
SS7
STM-1
(Synchronous Transport Module level 1) (OC-3 or STS-3) CCITT specification for SONET at 155.52Mbps.
STM-4
(Synchronous Transport Module level 4) (OC-12 or STS-12) CCITT specification for SONET at 622.08Mbps.
STM-8
(Synchronous Transport Module level 8) (OC-24 or STS-24) CCITT specification for SONET at 1244.16Mbps.
STM-16
(Synchronous Transport Module level 16) (OC-48 or STS-48) CCITT specification for SONET at 2488.32Mbps.
STS-1
(Synchronous Transport Signal 1) (OC-1) 51.84Mbps SONET.
STS-3
(Synchronous Transport Signal 3) (OC-3 or STM-1) 155.52Mbps SONET.
STS-12
(Synchronous Transport Signal 12) (OC-12 or STM-4) 622.08Mbps SONET.
STS-24
(Synchronous Transport Signal 24) (OC-24 or STM-8) 1244.16Mbps SONET.
STS-48
(Synchronous Transport Signal 48) (OC-48 or STM-16) 2488.32Mbps SONET.
T1
A digital carrier facility used to transmit a DS1 formatted digital signal at 1.544Mbps. Equivalent to 24 voice channels (DS0) digitized at 64Kbps.
T1C
3.153Mbps, equivalent to 2 T1s or 48 voice channels.
T2
6.312Mbps, equivalent to almost 4 T1s or 94 voice channels.
T3
A digital carrier facility used to transmit a DS3 formatted digital signal at 44.746Mbps. Equivalent to 672 voice channels or 28 T1s.
T4
273Mbps, equivalent to 6 T3s or 4032 voice channels.
TCNS
(Thomas-Conrad Networking System) 100Mbps proprietary networking system based on ARCnet. Runs on fiber, coax and shielded twisted pair.
TCP/IP
IP datagrams have an IP header followed by a TCP segment header followed by data.
TDMA
(Time Division Multiple Access). A digital data network in the US for use by cellular phones. This and CDMA are likely to become the dominant digital cellular system in the US (2/1996). In Europe and Asia it is GSM.
Token-ring
[IEEE 802.5) 4 or 16Mbps (30,000 64 byte packets per second theoretical limit). Ring type of LAN, currently (1993) connecting 10 million computers.
V.fast
V.34, 28.8Kbps standard, the last gasp of analog data communications.
WAN
(Wide Area Network).
wireless technologies
see Ardis, CSC, CDPD, RAM Mobile Data, and PCS.

Other random references:
WirelessWorld 3 3 page 58, May 1996