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NOTE:  Items highlighted in RED are defined elsewhere in this Glossary, while items highlighted in BLUE are site links for further information.

Whether you are using a Mac, PC, Linux, Unix or some other type of computer or operating system, in order to connect to the computers on the Internet or in your local LAN, you have to fulfill the same conditions:  Cable or Wireless hardware, ethernet capability and the protocols necessary to send and receive the transmissions with whatever level of security you desire.  There is more than one hardware configuration, more than one protocol and more than one level of security, and not all work with each other.  But the discussion below at least provides a basic explanation about the various terms and abbreviations you will see while setting up the connection:


ETHERNET:  This is a computer networking technology developed in the 1970s at Xerox PARC and now commonly used for local area networks (“LANs”) (see LAN diagram) and broadband since the early 1980s.  It is based upon the Carrier Sense Multiple Access/Collision Detection (“CSMA/CD”).  Ethernet standards for cabling and signaling are part of the OSI (“Open Systems Interconnection Reference Model”) physical layer up to and including the data link layer.  Since its introduction and standardization in 1983 as IEEE 802 and 3, Ethernet has replaced the older LAN technologies like token ring, Arcnet and FDDI (see topology).  Likewise, the old 10Base coaxial cables and connectors have been updated with twisted pair and fiber optic cable (see ethernet and CAT) with the associated higher speed hubs, switches and routers.  Ethernet communications divide the data stream into shorter segments called “frames” (not to be confused with HTML “frames,” which are displays of multiple sections on the same web page).  Each frame contains source and destination addresses as well as error checking data to verify that the transmission is completely received. So-called “jumbo frames” are ethernet frames with more than 1500 bytes of payload. [Also, don’t confuse this with EtherNet/IP:  Stands for Ethernet Industrial Protocol, a communications protocol designed for use in automation networks.]


TCP/IP: The most basic, most common and least secure transmission protocolTCP stands for Transmission Control Protocol.  This is what is responsible for managing the connection between a server (including an Internet ISP) and a client computer.  It makes sure that the data which has to be transferred is split into multiple packets which will then be transmitted to their destination.  If for some reason they don’t, TCP also defines how the missing data will be retransmitted.  IP means Internet Protocol, which assigns the unique addresses to computers on the network as Version 4 (IPv4 - 32 bits long) and later Version 6 (IPv6 - 128 bits).

PPP:  Stands for Point-to-Point Protocol.  It is an extension to TCP/IP that adds the ability to transmit TCP/IP over a serial links and also has login security.  This is a big deal, because plain old TCP/IP can’t be transmitted over a serial link, meaning it is unsuitable for a WAN (Wide Area Network).  This protocol, which was developed prior to PPPoE provides secure login and traffic metering.  It can use authentication, encryption and compression for establishing a connection between two networking nodes, over a large variety of networks, but because of its capabilities it is most often used by ISPs to allow their dial-up and cable users to connect to the Internet.  But not DSL users, because they use ethernet, not serial, connectivity.  Making the jump from serial to ethernet connections, PPPoE, below, followed.

PPPoE:  A derivative of PPP (above), this stands for Point-to-Point Protocol over Ethernet, originally developed by UUNET, Redback Networks and RouterWare and was specifically designed to bring the security and other benefits of PPP to always-on (i.e. permanently connected) ethernet connections such as DSL.  (As discussed above, most cable providers don’t use this protocol, so they stick with PPP.)   It is used to  connect multiple computer users on a local area network (“LAN”) to a remote site through common customer premises equipment like a DSL modem. PPPoE can be used to have an office, hotel or residential building with multiple users share a common Digital Subscriber Line (DSL), cable modem, or wireless connection to the Internet. The PPP protocol information is encapsulated within an Ethernet frame. PPPoE has the advantage that neither the telephone/cable company nor the Internet service provider (ISP) needs to provide any special support.  Moreover, through the network “discovery” stage, it can keep track of which user traffic should go to and which user should be billed.  It is also commonly used with PPTP to create VPNs (see below). Usually, it leverages PPP facilities for authenticating the user with a username and password.  This is normally done through either the PAP or CHAP protocols (see below).

    PAP:  Stands for Password Authentication Protocol.  It is a networking protocol supported by almost every operating system because of its simplicity.  However, because it transmits ASCII passwords in an unencrypted manner, it therefore not secure and not useful for many businesses, which usually use the CHAP protocol.  PAP is a protocol where both ends of the transmission share a password in advance, which can be either weak or strong, depending upon the difficulty of their computational overhead.

    CHAP:  Stands for Challenge-Handshake Authentication Protocol.  Because this provides better security than PAP (above), it is a more secure protocol.  CHAP periodically and randomly verifies the identity of the client by using a three-way handshake requiring the identification of a shared secret.  A variant of CHAP, MS-CHAP, is considered less secure, as it doesn’t require both the client and server to know the plaintext of the encrypted secret.



Computer Coach, 2013


PPTP: Point-to-Point Tunneling Protocol.  This is a method primarily used for implementing VPNs (Virtual Private Networks). It does this by using TCP (Port 1723) and a GRE tunnel to encapsulate PPP packets, which can use a number of protocols, including IP, IPX and NetBEUI.  When used with most recent versions of Microsoft Windows, PPTP implements various levels of authentication and encryption for secure transmissions, although it has some known vulnerabilities.

    GRE: Generic Routing Encapsulation.  This is a tunneling protocol developed by Cisco Systems that can encapsulate a wide variety of network layer protocols inside virtual point-to-point links over an IP Network.

    IPSEC:  IP Security.  An end-to-end security scheme which operates in the Internet layer of the Internet Protocol Suite (vs. other more widespread security systems like Transport Layer Security (“TLS”) which operate in the upper layers like the Application layer.  Because of this, it’s much less used, especially for VPNs, which use GRE, above.



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