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GLOSSARY

MAC ADDRESS
MACRO VIRUS
MAE - METROPOLITAN AREA EXCHANGE
MAIL BOMB
MAJORDOMO
MAN - METROPOLITAN AREA NETWORK
MAPI - MESSAGING APPLICATION PROGRAM INTERFACE
MASQUERADE
MBR - MASTER BOOT RECORD
MASTER/SLAVE
Mbps
MEDIA ACCESS CONTROL LAYER
MIB - MANAGEMENT INFORMATION BLOCK
MIM or MME
MIME - MULTI-PURPOSE INTERNET MAIL EXCHANGE
MIRROR SITE
MODEM
MODEM DOUBLING
MOSAIC
MOTIF
MOZILLA
MPEG - MOVING PICTURE EXPERT GROUP
MPLS - MULTIPROTOCOL LAYER SWITCHING
MUX - MULTIPLEXING


• MAC ADDRESS On a local area network (LAN) or other network, the MAC (Media Access Control) address is your computer's unique hardware number. (On an Ethernet LAN, it's the same as your Ethernet address.) When you're connected to the Internet from your computer (or host as the Internet protocol thinks of it), a correspondence table relates your IP address to your computer's physical (MAC) address on the LAN.
  The MAC address is used by the Media Access Control sublayer of the Data-Link Layer (DLC) layer of telecommunication protocol. There is a different MAC sublayer for each physical device type. The other sublayer level in the DLC layer is the Logical Link Control sublayer.
  

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• MACRO VIRUS is a computer virus that "infects" a Microsoft Word or similar application and causes a sequence of actions to be performed automatically when the application is started or something else triggers it. Macro viruses tend to be surprising but relatively harmless. A typical effect is the undesired insertion of some comic text at certain points when writing a line. A macro virus is often spread as an e-mail virus. A well-known example in March, 1999 was the Melissa virus.
  

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• MAE (pronounced MAY), originally an abbreviation for Metropolitan Area Exchange and now a service mark of MCI WorldCom, is a major center in the United States for switch traffic between Internet service providers (ISP). There are two major MAEs, MAE-East in the Washington, D.C. area and MAE-West in the San Jose, California area. MAE-East interconnects all of the major ISPs and also those from Europe. MAE-West interconnects ISPs in the Silicon Valley area. These two points along with several interconnection points previously identified by the National Science Foundation as network access points (network access point) form what is sometimes considered the national commercial Internet backbone. In addition to MAE-East and MAE-West, there are five regional "Tier-2" MAEs: in Chicago, Dallas, Houston, Los Angeles, and New York. Additional MAEs appear to be in the planning stages. The MAEs and their services, originally developed by MFS Communications, are now owned and operated by MCI WorldCom.
  A MAE can be viewed as a giant local area network (LAN) switch. (In fact, the two major MAEs use an Fiber Distributed-Data Interface switch.) The only ISP device that can interconnect to a MAE switch is a router or a computer host acting as a router. The ISPs work out their own peering agreements and manage their own routing tables. Routers at the two major MAEs need very large routing tables. Cisco's 7xxx series routers are examples of such routers. The regional MAEs consist of an Ethernet switch and an FDDI concentrator. Smaller routers (such as Cisco's 4500-M) are required.
  

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• MAIL BOMB is the sending of a massive amount of e-mail to a specific person or system. A huge amount of mail may simply fill up the recipient's disk space on the server or, in some cases, may be too much for a server to handle and may cause the server to stop functioning. In the past, mail bombs have been used to "punish" Internet users who have been egregious violators of netiquette (for example, people using e-mail for undesired advertising, or spam).
  Mail bombs not only inconvenience the intended target but they are also likely to inconvenience everybody using the server. Senders of mail bombs should be wary of exposing themselves to reciprocal mail bombs or to legal actions.
  

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• MAJORDOMO Like listserv Majordomo (from Latin: "master of the house") is a small program that automatically redistributes e-mail to names on a mailing list. Users can subscribe to a mailing list by sending an e-mail note to a mailing list they learn about; Majordomo will automatically add the name and distribute future e-mail postings to every subscriber. (Requests to subscribe and unsubscribe are sent to a special address so that other subscribers do not see these requests.)
  

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• MAN Metropolitan Area Network, is a network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network (LAN) but smaller than the area covered by a wide area network (WAN). The term is applied to the interconnection of networks in a city into a single larger network (which may then also offer efficient connection to a wide area network). It is also used to mean the interconnection of several local area networks by bridging them with backbone lines. The latter usage is also sometimes referred to as a campus network.
  

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• MAPI Messaging Application Program Interface, is a Microsoft Windows program interface that enables you to send e-mail from within a Windows application and attach the document you are working on to the e-mail note. Applications that take advantage of MAPI include word processors, spreadsheets, and graphics applications. MAPI-compatible applications typically include a Send Mail or Send in the File pulldown menu of the application. Selecting one of these sends a request to a MAPI server.
  

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• MASQUERADE in general is a disguise. In terms of communications security issues, a masquerade is a type of attack where the attacker pretends to be an authorized user of a system in order to gain access to it or to gain greater privileges than they are authorized for. A masquerade may be attempted through the use of stolen logon IDs and passwords, through finding security gaps in programs, or through bypassing the authentication mechanism. The attempt may come from within an organization, for example, from an employee; or from an outside user through some connection to the public network. Weak authentication provides one of the easiest points of entry for a masquerade, since it makes it much easier for an attacker to gain access. Once the attacker has been authorized for entry, they may have full access to the organization's critical data, and (depending on the privilege level they pretend to have) may be able to modify and delete software and data, and make changes to network configuration and routing information.
  

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• MBR Master Boot Record is the information in the first sector of any hard disk or diskette that identifies how and where an operating system is located so that it can be boot (loaded) into the computer's main storage or random access memory. The Master Boot Record is also sometimes called the "partition sector" or the "master partition table" because it includes a table that locates each partition that the hard disk has been formatted into. In addition to this table, the MBR also includes a program that reads the boot sector record of the partition containing the operating system to be booted into RAM. In turn, that record contains a program that loads the rest of the operating system into RAM.
  

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• MASTER/SLAVE is a model for a communication protocol in which one device or process (known as the master) controls one or more other devices or processes (known as slaves). Once the master/slave relationship is established, the direction of control is always from the master to the slave(s).
  Other communication protocol models include the client/server model, in which a server program responds to requests from a client program, and the peer-to-peer model, in which either of the two devices involved can initiate a communication session.
  

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• Mbps stands for millions of bits per second or megabits per second and is a measure of bandwidth (the total information flow over a given time) on a telecommunications medium. Depending on the medium and the transmission method, bandwidth is sometimes measured in the Kbps (thousands of bits or kilobits per second) range or the Gbps (billions of bits or gigabits per second) range.
  A megabit is a million binary pulses, or 1,000,000 (that is, 106) pulses (or "bits"). For example, a U.S. phone company T-carrier system line is said to sustain a data rate of 1.544 megabits per second. Megabits per second is usually shortened to Mbps.
  Some sources define a megabit to mean 1,048,576 (that is, 220) bits. Although the bit is a unit of the binary number system, bits in data communications are discrete signal pulses and have historically been counted using the decimal number system. For example, 28.8 kilobits per second (Kbps) is 28,800 bits per second. Because of computer architecture and memory address boundaries, bytes are always some multiple or exponent of two.
  

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• MEDIA ACCESS CONTROL LAYER In the Open Systems Interconnection (OSI) model of communication, the Media Access Control layer is one of two sublayers of the Data Link Control layer and is concerned with sharing the physical connection to the network among several computers. Each computer has its own unique MAC address. Ethernet is an example of a protocol that works at the Media Access Control layer level.
  

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• MIB Management Information Base is a formal description of a set of network objects that can be managed using the Simple Network Management Protocol (SNMP). The format of the MIB is defined as part of the SNMP. (All other MIBs are extensions of this basic management information base.) MIB-I refers to the initial MIB definition; MIB-II refers to the current definition. SNMPv2 includes MIB-II and adds some new objects.
  

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• MIM or MME file is a file in the Multi-Purpose Internet Mail Extensions (MIME) format that is created by some e-mail programs, including that of America Online (AOL), to encapsulate e-mail that contains image or program attachments. The MIM or MME refers to the three-letter extension or suffix (".mim" or ".mme") at the end of the file name. AOL creates a MIM or MME file when a user sends a note with attachments to other users. Such notes sent to other than AOL users tend to be restored to their original form by the receiver's e-mail software. However, AOL recipients receive a MIM or MME file that they need to "open" so that they can get the individual files inside. AOL users with Windows can use WinZip (using the "Classic Winzip" mode of operation). Mac users can use a similar utility.
  

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• MIME, Multi-Purpose Internet Mail Extensions, is an extension of the original Internet e-mail protocol that lets people use the protocol to exchange different kinds of data files on the Internet: audio, video, images, application programs, and other kinds, as well as the ASCII handled in the original protocol, the Simple Mail Transport Protocol (SMTP). In 1991, Nathan Borenstein of Bellcore proposed to the IETF that SMTP be extended so that Internet (but mainly Web) client and server could recognize and handle other kinds of data than ASCII text. As a result, new file types were added to "mail" as a supported Internet Protocol file type.
  Servers insert the MIME header at the beginning of any Web transmission. Clients use this header to select an appropriate "player" application for the type of data the header indicates. Some of these players are built into the Web client or browser (for example, all browser come with GIF and JPEG image players as well as the ability to handle HTML files); other players may need to be downloaded.
  New MIME data types are registered with the Internet Assigned Numbers Authority (IANA).
  MIME is specified in detail in Internet Request for Comments 1521 and 1522, which amend the original mail protocol specification, RFC 821 (the Simple Mail Transport Protocol) and the ASCII messaging header, RFC 822.
  

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• MIRROR SITE is a Web site or set of file on a computer server that has been copied to another computer server in order to reduce network traffic, ensure better availability of the Web site or files, or make the site or downloaded files arrive more quickly for users close to the mirror site. Mirroring is the practice of creating and maintaining mirror sites.
  A mirror site is an exact replica of the original site and is usually updated frequently to ensure that it reflects the content of the original site. Mirror sites are used to make access faster when the original site may be geographically distant (for example, a much-used Web site in Germany may arrange to have a mirror site in the United States). In some cases, the original site (for example, on a small university server) may not have a high-speed connection to the Internet and may arrange for a mirror site at a larger site with higher-speed connection and perhaps closer proximity to a large audience.
  

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• MODEMs modulates outgoing digital signals from a computer or other digital device to analog signals for a conventional copper twisted pair telephone line and demodulates the incoming analog signal and converts it to a digital signal for the digital device.
  In recent years, the 2400 bits per second modem that could carry e-mail has become obsolete. 14.4 Kbps and 28.8 Kbps modems were temporary landing places on the way to the much higher bandwidth devices and carriers of tomorrow. From early 1998, most new personal computers came with 56 Kbps modems. By comparison, using a digital Integrated Services Digital Network adapter instead of a conventional modem, the same telephone wire can now carry up to 128 Kbps. With Digital Subscriber Line (DSL) systems, now being deployed in a number of communities, bandwidth on twisted-pair can be in the megabit range.
  

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• MODEM DOUBLING is an inexpensive way for a user who wants a fast Internet connection, but can only connect with an analog telephone line, to use two 56kbps modems to double their bandwidth. modem doubling makes it possible for the user to use one of two methods, modem bonding or modem teaming, to achieve a connection speed close to 112kbps.
  

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• MOSAIC was the first widely-distributed graphical browser or viewer for the World Wide Web. It is usually considered to have been the software that introduced the World Wide Web (and the Internet) to a wide general audience. Once Mosaic was available, the Web virtually exploded in numbers of users and content sites. (Of course, the software depended on the recent invention of the Hypertext Transport Protocol, or Hypertext Transfer Protocol , by Dr. Tim Berners-Lee.)
  Mosaic arrived in 1993. Marc Andreessen, then in his early 20's, is credited with inventing or leading the development of Mosaic. He developed it at the National Center for Supercomputing Applications (NCSA) at the University of Illinois in Urbana, Illinois. Andreessen and others went on to become part of Netscape Communications, originally called Mosaic Communications, that developed today's most popular browser, Netscape (it's full name is Netscape Navigator).
  

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• MOTIF is a graphical user interface (GUI) guideline and development toolkit for the X Window System. As such, it defines the rules and tools for the "look-and-feel" in the graphical user interface of most UNIX-based operating systems and their applications. Developed in 1989 by the Open Software Foundation (now part of The Open Group), Motif corresponds to IBM's Common User Access (CUA) guideline for its OS/2 Presentation Manager and to the guidelines built into the Microsoft Windows application programming interfaces, including the Microsoft Foundation Classes (Microsoft Foundation Class Library) for user interface objects (often called widget).
  

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• MOZILLA was Netscape Communication's nickname for Navigator, its Web browser, and, more recently, the name of an open source public collaboration aimed at making improvements to Navigator. This public collaboration was essentially launched and is still substantially supported by Netscape (now owned by AOL); however, the Mozilla project is independent. Netscape can use its code but so can anyone else.
  

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• MPEG standards are an evolving set of standards for video and audio compression and for multimedia delivery developed by the Moving Picture Experts Group (MPEG.
  MPEG-1 was designed for coding progressive video at a transmission rate of about 1.5 million bits per second. It was designed specifically for Video-CD and CD-i media. MPEG-1 audio layer-3 (MP3) has also evolved from early MPEG work.
  MPEG-2 was designed for coding interlaced images at transmission rates above 4 million bits per second. MPEG-2 is used for digital TV broadcast and DVD. An MPEG-2 player can handle MPEG-1 data as well.
  MPEG-1 and -2 define techniques for compressing digital video by factors varying from 25:1 to 50:1.
  A proposed MPEG-3 standard, intended for High Definition TV (HDTV), was merged with the MPEG-2 standard when it became apparent that the MPEG-2 standard met the HDTV requirements.
  MPEG-4 is a much more ambitious standard and addresses speech and video synthesis, fractal geometry, computer visualization, and an artificial intelligence (AI) approach to reconstructing images. MPEG-4 addresses a standard way for authors to create and define the media objects in a multimedia presentation, how these can be synchronized and related to each other in transmission, and how users are to be able to interact with the media objects.
  MPEG-21 provides a larger, architectural framework for the creation and delivery of multimedia.
  

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• MPLS Multiprotocol Label Switching, is a standards-approved technology for speeding up network traffic flow and making it easier to manage. MPLS involves setting up a specific path for a given sequence of packets, identified by a label put in each packet, thus saving the time needed for a router to look up the address to the next node to forward the packet to. MPLS is called multiprotocol because it works with the Internet Protocol (IP), Asynchronous Transport Mode (ATM), and frame relay network protocols. With reference to the standard model for a network (the Open Systems Interconnection, or OSI model), MPLS allows most packets to be forwarded at the layer 2 (switching) level rather than at the layer 3 (routing) level. In addition to moving traffic faster overall, MPLS makes it easy to manage a network for quality of service (QoS). For these reasons, the technique is expected to be readily adopted as networks begin to carry more and different mixtures of traffic.
  

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• MUX (pronounce muks) is an abbreviation for multiplexing, a device that sends multiple signals on a carrier channel at the same time in the form of a single, complex signal to another device that recovers the separate signals at the receiving end. The receiver is sometimes called a demux (or "DEMUX").
  

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