Network/Connectivity at MIT

MITnet Glossary

This is a list of terms and concepts that might be helpful to someone trying to understand something about connecting to MITnet.

*Definition from the CNET: glossary

**Definition from Webopedia

5ESS (5th-release Electronic Switching System)

This is the type of phone switch in use at MIT. The phone switch is the equipment that makes the connection between your phone and the number you dial. In networking, we use 5ESS phone jacks to run MITnet service to workstations and printers.

AAUI (Apple's Auxilary Unit Interface)

This is an interface unique to Macintosh computers. To use a computer with this interface on MITnet, you need a transceiver that changes the interface from AAUI to either AUI or UTP.

**Access Point, AP, Wireless Access Point, Base Station

A hardware device or a computer's software that acts as a communication hub for users of a wireless device to connect to a wired LAN. APs are important for providing heightened wireless security and for extending the physical range of service to which a wireless user has access.

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**Certificate Authority, Certificate, Site Certificate, Personal Certificate

A trusted third-party organization or company that issues digital certificates used to create digital signatures and public-private key pairs. The role of the CA in this process is to guarantee that the individual granted the unique certificate is, in fact, who he or she claims to be. Usually, this means that the CA has an arrangement with a financial institution, such as a credit card company, which provides it with information to confirm an individual's claimed identity. CAs are a critical component in data security and electronic commerce because they guarantee that the two parties exchanging information are really who they claim to be.

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*DHCP (Dynamic Host Configuration Protocol)

An Internet protocol for automating the configuration of computers that use TCP/IP. DHCP can be used to automatically assign IP addresses, to deliver TCP/IP stack configuration parameters such as the subnet mask and default router, and to provide other configuration information such as the addresses for printer, time and news servers.

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**DNS (Domain Name Server)

An Internet service that translates domain names into IP addresses. Because domain names are alphabetic, they're easier to remember. The Internet, however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. For example, the domain name www.example.com might translate to 198.105.232.4.

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*Ethernet

Ethernet is a standard for connecting computers into a local area network (LAN). The most common form of Ethernet is called 10BaseT, which denotes a peak transmission speed of 10 mbps using copper twisted-pair cable.

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Ethernet Adapter Card (Network Interface Card, pcmcia Card)

A network interface card, sometimes built in to a computer, or inserted into a PCMCIA slot. An Ethernet card can enable both a physical connection to the network (using a cable) or a wireless network connection.

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Ethernet Drop, Network Drop

A wall or floor outlet, often associated with a telephone jack, into which you can plug a network cable and thus physically connect a computer to the network. At MIT, this requires registering for DHCP.

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**Gateway

A node on a network that serves as an entrance to another network. For example, when a user connects to the Internet, that person essentially connects to a server that issues the Web pages to the user. These two devices are host nodes, not gateways. In enterprises, the gateway is the computer that routes the traffic from a workstation to the outside network that is serving the Web pages. In homes, the gateway is the ISP that connects the user to the internet.
In enterprises, the gateway node often acts as a proxy server and a firewall. The gateway is also associated with both a router, which use headers and forwarding tables to determine where packets are sent, and a switch, which provides the actual path for the packet in and out of the gateway.

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Interfaces (Cables and Connectors)

The cable that comes out of the wall jack is a UTP (Unshielded Twisted Pair) Ethernet cable. It is most often black and has a plastic modular end that snaps into a matching port on your computer. To see what the connectors on a UTP cable look like, examine the wires on your digital desktop phone. If you have a single drop coming from a single jack, you will use a UTP cable.

Sometimes in dorm rooms where not enough ports are available, students are given transceivers to which several computers can be connected. The cables that come off transceivers are AUI (Auxilary Unit Interface). These cables have a metal housing and either pins or holes at the end, depending on which end you look at. They look something like a serial or VGA cable you would find on a PC. Ask your RCC about transceivers.

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*IP (Internet Protocol)

The Internet protocol defines how information gets passed between systems across the Internet.

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*IP Address, Static IP Address

This address is a unique string of numbers that identifies a computer on the Internet. These numbers are usually shown in groups separated by periods, like this: 123.123.23.2. All resources on the Internet must have an IP address.

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Jacks

Computers are connected to the network via 5ESS jacks, the same kind used to connect the ISDN (digital) phones. If you look at a jack, you will see that it has two ports (places to plug in a wire). You need an open port on a 5ESS jack to have a connection to MITnet.

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MAC (Media Access Control) Address

A unique identifier on a network interface card; on most wireless cards, this is the 12 character (hexadecimal) string printed on the card.

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*NIC (Network Interface Card)

An adapter card that physically connects a computer to a network cable. E.g., an Ethernet card.

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**PCMCIA

Short for Personal Computer Memory Card International Association, and pronounced as separate letters, PCMCIA is an organization consisting of some 500 companies that has developed a standard for small, credit card-sized devices, called PC Cards. Originally designed for adding memory to portable computers , the PCMCIA standard has been expanded several times and is now suitable for many types of devices. There are in fact three types of PCMCIA cards. All three have the same rectangular size (85.6 by 54 millimeters), but different widths.
* Type I cards can be up to 3.3 mm thick, and are used primarily for adding additional ROM or RAM to a computer.
* Type II cards can be up to 5.5 mm thick. These cards are often used for modem and fax modem cards.
* Type III cards can be up to 10.5 mm thick, which is sufficiently large for portable disk drives.

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*TCP/IP (Transmission Control Protocol/Internet Protocol)

These two protocols were developed by the U.S. military to allow computers to talk to each other over long distance networks. IP is responsible for moving packets of data between nodes. TCP is responsible for verifying delivery from client to server. TCP/IP forms the basis of the Internet, and is built into every common modern operating system (including all kinds of Unix, the Mac OS, and the latest versions of Windows).

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Transceiver

A piece of networking hardware usually used to moderate interfaces. For instance, you would need a transceiver if the MITnet wire coming from the phone jack has a UTP interface and your workstation has an AAUI interface. Transceivers are also used to "share" an MITnet wire: a UTP interface coming from a wall can be connected to a transceiver that allows two or four computers with AUI interfaces to connect to the network.

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UTP (Unshielded Twisted Pair)

A type of interface used to connect workstations or printers to 5ESS (digital phone) jacks, and then to MITnet. This is a modular interface with little plastic connectors on the ends that snap into place. The connectors are also known as RJ-45 connectors. The MIT ISDN phone system uses this type of wiring. The name comes from the fact that the wiring is unshielded and pairs of wires are twisted together to eliminate crosstalk on them.

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