Index:

General Communications Terms

AIP

Application Infrastructure Provider

ASP

Application Service Provider

ATM

Asynchronous Transfer Mode - Sends cells of 53 bytes through a switched network.

CSP

Communications Service Provider

CSU/DSU

Channel Service Unit/Data Service Unit

Spoofing

Changing packets to make them appear to be from a trusted host rather than the actual host.

DOS

Denial-of-Service - an attach that attempts to flood a host or router to prevent legitimate access.

Firewall

Generally protects a trusted network from an un-trusted network.

Bandwidth

Originally the difference between the lowest and highest frequencies available. Normally used as a measure of throughput in bits per second (bps) or bytes per second (Bps)

WAN

Wide Area Network - Usually made up of LANs at different physical locations. Protocols include SDLC, HDLC, X.25, Frame-Relay, ISDN, PPP, HSSI.

LAN

Local Area Network - Usually made up of servers and workstations in one physical location such as a building or campus. Protocols include 802.2, 802.3, FDDI.

SNAP

Subnetwork Access Protocol

CPE

Customer Premise Equipment

PDN

Public Data Network

ISP

Internet Service Provider - Provides the final connection between a customer and an Internet backbone. Often use dial-up.

MTU

Maximum Transmission Unit - The largest number of bytes that can be transmitted over a medium. 1500 bytes for Ethernet and most serial interfaces, 4464 for Token-Ring, and 4470 for ATM, FDDI, and HSSI

VPN

Virtual Private Networking - Provides a secure channel over an insecure network like the Internet. Generally accomplished by tunneling a protocol encrypted inside another. PPTP, IPSEC.

PPPoe

Point to Point Protocol over Ethernet - Used by ADSL providers often with custom software. Also provided by Linksys Cable/DSL routers.

PPTP

Point to Point Tunneling Protocol. Used to carry protocol traffic inside of another protocol's packets.

IPSec

Internet Protocol Security protocol. Offers encryption as an extension to the TCP/IP protocol suite. Offers two modes Tunnel (used by VPN through routers) and Transport (used by hosts).

CO

Central Office - Refers to the telephone company's switching office.

TDP

Tag Distribution Protocol - Tag switching devices use the TDP to distribute, request, and release tag binding information for multiple Network-layer protocols.

TIB

Tag Information Base - Maps tag values to specific destinations, the ports through which they can be reached, and appropriate Data-Link layer information.

DLSw

Appear as source-route bridges in a Token-Ring environment.

NAUN

Nearest Active Upstream Neighbor - Token-Ring

Standards Organizations

ANSI

American National Standards Institute www.ansi.org

IEEE

Institute of Electrical and Electronics Engineers, Inc. www.ieee.org
"The IEEE ("eye-triple-E"), The Institute of Electrical and Electronics Engineers, Inc., helps advance global prosperity by promoting the engineering process of creating, developing, integrating, sharing, and applying knowledge about electrical and information technologies and sciences for the benefit of humanity and the profession."

ITU-T

International Telecommunication Union-Telecommunication Standardization Sector (Formerly CCITT

CCITT

Consultative Committee for International Telegraph and Telephone (Replaced by ITU-T

ISO

International Standards Organization

IETF

Internet Engineering Task Force - Responsible for RFCs (Request for Comments), the Internet standards www.ietf.org

EIA

Electronic Industries Association - Standards for serial communications interfaces

TIA

Telecommunications Industry Association

OSI

Open Systems Interconnect - Layers: Application, Presentation, Session, Transport, Network, Data-link, Physical.

DSL

DSL

Digital Subscriber Line

SDSL

Symmetrical DSL - Upload and download speeds are identical. Maximum of 1.544 Mbps

IDSL

ISDN DSL - Maximum speed 144 Kbps

ADSL

Asymmetric DSL - Upload and download speeds are different. Can be used on an existing analog phone line without disrupting voice calls. Great for home use where most of the traffic is downloads to the customer; not appropriate for business use for servers.

RADSL

Rate Adaptive DSL - Speeds vary depending on line conditions. Often used when the distance between a customer and the CO is more than 18,000 feet.

ISDN

ISDN

Integrated Services Digital Network - Carries voice and data calls over standard digital telephone lines

BRI

Basic Rate Interface - Provides two 64Kbps bearer (B) channels for voice and data and one 16Kbps control (D) channel for call setup and signaling. ITU I-430

MBRI

Multiple Basic Rate Interface

PRI

Primary Rate Interface - Provides 23 64Kbps bearer (B) channels for voice and data on one 64Kbps control (D) channel for call setup and signaling. Speeds of all channels combined approaches T1 (DS1). ITU I-431.

LAPD

Link Access Procedure on the D Channel. Also known as Q.921.

TDM

Time-Division Multiplexing

Bonding

Combining multiple bearer channels into one data channel for increased bandwidth.

TA

Terminal Adapter

NT1, NT2

Network Terminating devices

TE1, TE2

Terminal Equipment

Frame Relay

Frame Relay

Designed for ISDN. Faster than X.25. Discards frames in the event of congestion or frame errors.

FRAD

Frame Relay Access Device - optional devices that frame outgoing data with header and trailer control information before sending it to the Frame Relay switch. They also strip away the header and trailer information at the receiving end. They may or not be present, and they may be standalone devices, or part of another device, such as a router, switch or multiplexor.

LMI

Local Management Interface - LMI is the signaling standard between a CPE device and a FR (Frame Relay) switch. LMI is responsible for managing the connection and maintaining status between the devices. Created by Cisco, Digital Equipment, Northern Telecom, and StrataCom. Classifications: ANSI, Cisco, Q933a.

DLCI

Data Link Connection Identifier

FCS

Frame Check Sequence - Checks the integrity of the frame.

FECN

Forward Explicit Congestion Notification - Travels to the destination.

BECN

Backward Explicit Congestion Notification - Travels back to the source.

Tc

The minimum interval of time for committed rate measurement.

Bc

Committed Burst - the maximum amount of data that the network commits to transfer in the time interval Tc. Measured in bits.

Be

Excess Burst - the maximum amount of uncommitted data, i.e., the amount of data above the Bc, that a Frame Relay network can deliver during the time interval Tc. Measured in bits.

CIR

Committed Information Rate - The agreed-upon (or committed) rate at which frames travel from the FRAD through the Frame Relay network and to the destination device. The rate is measured in bits per second under normal conditions.

X.25

X.25

X.25 defines the connections between a DTE and DCE with respect to remote terminal access and computer communications in a PDN. An X.25 DCE serves as a boundary between the PDN's switch or concentrator.

X.21bis

Physical-layer protocol used in X.25

PLP

Packet Layer Protocol

Default Packet Size

128 Bytes

DNIC

Data Network Identification Code - First 4 digits of X.25 addresses

NTN

Network Terminal Number - 8 to 11 digits of X.25 addresses after the DNIC

X.25 and Frame-Relay Shared Terms

PVC

Permanent Virtual Circuit - Applies to X.25 and Frame-Relay.

SVC

Switched Virtual Circuit - Applies to X.25 and Frame-Relay.

TCP/IP

TCP

Transmission Control Protocol - Connection oriented.

IP

Internet Protocol

UDP

Connectionless.

IGMP

Internet Group Management Protocol

ICMP

ARP

Address Resolution Protocol - Used to resolve IP addresses to physical (MAC) addresses.

RARP

Reverse ARP - Used to resolve physical (MAC) addresses to IP addresses.

DNS

Domain Name Service - Resolves domain names to IP addresses and assists with email.

FTP

File Transfer Protocol - Used to transfer files between hosts.

TFTP

Trivial File Transfer Protocol - Used when security is not an issue, e.g. to configure routers.

Telnet

Terminal sessions over IP

NFS

Network File System - Enables mounting of remote file systems.

SMTP

Simple Mail Transfer Protocol - allows email to be sent.

SNMP

Simple Network Management Protocol

MIB

Management Information Base - part of SNMP

NNTP

Network News Transfer Protocol - used to transfer newsgroups and news messages

POP, POP3

Post Office Protocol - used by mail clients to retrieve email from a mail server.

Novell

SAP

Service Advertising Protocol

IPX

Internetwork Packet Exchange

SPX

Sequenced Internet Packet Exchange

GNS

Get Nearest Server

NLSP

Novell Link-State Routing Protocol

Routing

CDP

Cisco Discovery Protocol

STP

Spanning Tree Protocol - Maintains redundancy without looping. Part of IEEE 802.1d standard. Imposes a seven hop limit.

BPDU

Bridge Protocol Data Units

Root Bridge

(STP) The Bridge with the lowest MAC address.

Root Cost

The number of hops to the Root Bridge

Bridge Port States

Initialization, Blocking, Listening, Learning, Forwarding

GRE

Generic Routing Encapsulation

OSPF

Open Shortest Path First - Routing protocol. Used LSAs to maintain a consistent view of the network.

RIP

Routing Information Protocol - Based on distance vectors. Maximum of 15 hops. The routing table can contain only one path to the destination.

IRDP (IDRP?)

ICMP Router Discovery Protocol - Used to discover nearby routers.

IGRP

Interior Gateway Routing Protocol - Based on distance vectors. Maximum of 255 hops. The routing table can contain multiple paths to the destination.

EGRP

Exterior Gateway Routing Protocol

EIGRP

Exterior-Interior Gateway Routing Protocol

EIGRP

Enhanced Interior Gateway Routing Protocol

BGP

Border Gateway Protocol

ASN

Autonomous System Number

DDR

Dial on Demand Router - Opens and closes connections when there is demand for the services.

Serial Communication Standards

DTE

Data Terminal Equipment - e.g routers, bridges, terminals or PCs

DCE

Data Communications Equipment - e.g. Modems, packet switches, T1 multiplexors. The carrier equipment that supply clocking and switching functions to transfer data through the network.

SLIP

Serial Line Internet Protocol - Caries IP traffic over serial connections. No error-checking.

SDLC

Synchronous Data Link Control. Full-Duplex Serial. Point-to-point and multi-point

HDLC

High-Level Data Link Control. Derived from SDLC.

LAPB

Link Access Protocol Balanced. Derived from SDLC.

HSSI

High-Speed Serial Interface - Used for high-speed, point-to-point serial connections. HSSI defines both the electrical and physical aspects of DTE/DCE interfaces. HSSI supports a maximum signaling rate of 52 Mbps. The cable is shielded twisted pair (STP). HSSI communication is considered peer-to-peer because HSSI assumes intelligence in both DCE and DTE devices. HSSI uses one control signal to indicate that the DTE is available and a second control signal to indicate that the DCE is available.

EIA/TIA-232 (Formerly RS-232)

Unbalanced serial interface for speeds up to 64Kbps

EIA/TIA-449

Balanced serial interface for speeds up to 2Mbps

EIA/TIA-530

A DTE and DCE interface that transmits serial binary data and exchanges control information on separate control circuits. Specific aspects defined include signals, the mechanical interface, and the functioning of interchange circuits.

V.35

ITU-T standard. V.35 is a standard for high-speed synchronous data exchange. It is commonly used for routers and CSU/DSUs (Channel Service Unit/Data Service Units) that interface to T-1 lines. It specifies a bit rate of 48 kbps.

V.24

ITU-T Standard. V.24 applies to the interface at the computer cable (DTE) and its attachment to the back of the modem (DCE). This standard specifies a maximum bit rate of 20 kbps per second over a maximum cable length of 15 meters.

PPP

PPP

Point to Point Protocol - Caries multiple network protocols over serial connections. Uses NCP and LCP.

NCP (PPP)

Network Control Protocol - A family of protocols for establishing and configuring different Network-layer protocols.

LCP (PPP)

Link Control Protocol - establishes, configures and maintains the connection

CHAP

Challenge Handshake Authentication Protocol - Uses a three-way handshake. Challenges are issued at establishment and randomly thereafter.

PAP

Password Authentication Protocol

SMDS

SMDS

Switched Multi-megabit Data Service

SIP

SMDS Interface Protocol - Provides connectionless service over SNI. SIP-1 Physical, SIP-2 and SIP-3 MAC.

SNI

Subscriber Network Interface - Interface between CPE and carrier equipment. Related to SMDS

DQDB

Distributed Queue Dual Bus - Used for cell relay. Related to SMDS

General Computer Terms

PCI

Peripheral Connect Interface - The new (usually white) slots in Pentium-class PCs and Macintoshes.

ISA

Industry Standard Architecture - The old (usually black) card slots in older PCs.

USB

Universal Serial Bus - 12Mbps peripheral connection for PCs and Macintoshes

Legacy Free

PCs that do not have the "legacy" ports: 9- and 25-pin serial, 25-pin parallel and PS/2 mouse and keyboard ports.

CD-ROM/DVD-ROM

Compact Disc or DVD Read Only Memory - a standard for storing data on CDs and DVDs similar to audio/video CDs

CD-R/DVD-R/DVD+R

Compact Disc/DVD Recordable - A CD/DVD that can be written only once

CD-RW/DVD-RW/DVD+RW

Compact Disc/DVD Rewritable - A CD/DVD that can be written and erased

NIC

Network Interface Card - Connects a host to a network cabling system.