Technical Info New Network User Orientation Here is where you'll find out all that critical stuff about networking that computer types always assume you already know. It is recommended that you start your first tour of this area with the Network Architecture Section. If you have an item of information that you feel should be included anywhere in this area, (or if you find any gross inaccuracies) please notify a CaTS member. In this section we'll explain the concept of a network, what it is composed of, your place in it and how to move around on it. Take a look at the graphic below. It provides a general overview of how the network you are connected to is arranged.
Local Area Network (LAN) Let's start with the blue computers on the right labeled "College of Veterinary Medicine". These machines make up what is called a Local Area Network or LAN. A LAN is usually defined as being a collection of computers and related hardware linked together within a building or campus. This linkage allows sharing of resources between all of the devices connected to the network. The computers with a monitor and keyboard represent the personal computers in the offices throughout the college and the tall blue boxes represent File Server computers. The red lines represent the cabling and hardware that is used to interconnect all of the computing resources comprising the LAN. File servers provide a place to store software and data that is accessible to anyone connected to the LAN. They also store information about all of the users connected to the LAN in a user account. This information includes things such as what areas within the file servers a user has access to, whether or not the user is currently logged into the network, etc. In fact, when you "log into" the network all you are doing is contacting the file servers and letting them know you are connected. Your account, or userID, on a file server provides you with a point of presence on the network. For example when someone sends you electronic mail, the message goes to your account on the file server where it waits until you log in. Wide Area Network (WAN) When you begin linking LAN's together to allow sharing of services between them you form what is known as a Wide Area Network or WAN. WAN's can be anywhere from campus wide to world wide in scope depending on who you talk to and what mood they are in that day. In the diagram above, you will find that the college of Veterinary Medicine is connected to the main KSU campus. This forms a WAN and gives you access to services available on the red KSU mainframe computers. Global Networks When a large number of WAN's world wide are connected together you form Global Networks. The Internet is an example of this type of network. If you look at the diagram above you'll see that the Internet is represented by a cloud of blue dots. If you imagine that each dot in the cloud represents a computer or a LAN or even a WAN you begin to get an idea of how large the Internet really is and the amount of information that can be accessed on it. One of the most confusing issues for the beginning network user is the concept of a network address. It's no wonder that there is such confusion since there are so many ways of being connected to a net. To ease the pain let's look at your network address from the point of view of just our LAN here at the college. Remember, your point of presence on the LAN is basically your userID or account on the file servers. Every network user has an account on the file server called "VETMAIL". The naming convention we use for userID's is usually just your first initial and last name. For example, Richard Nixon would have the userID "RNIXON". As a result, your network address is the combination of your userID and the name of the file server that the account resides on. Therefore, Nixon's address would be VETMAIL/RNIXON. If two users are logged into the same file server then they don't even need to include the name of the file server as part of the address. Now let's look at how addressing works when you consider being connected to the Internet. The Internet uses a communications protocol called TCP/IP (Transmission Control Protocol/Internet Protocol). This protocol requires that each machine connected to the network be assigned an IP (Internet Protocol) number to be used as an address. This number is always a group of four numbers like this: 129.130.130.200. There is an organization that is responsible for allocating the addresses and insuring that no two users are given the same address. To begin with, look at how someone out on the Internet would set up an address to send an Email message to a user account on our file server VETMAIL. The address would be the userID and VETMAIL's IP address connected by the @ symbol. The file server VETMAIL has been assigned the address 129.130.129.12. To send an Email message to userID "RNIXON" then, the address would be rnixon@129.130.129.12. The designers of the TCP/IP protocol recognized that humans would have a difficult time remembering these long strings of digits so they developed a mechanism that allows text based names to be used in place of the numeric addresses. This system relies on the concept of domains in order to connect a name with an IP number. Here's an example address - rnixon@vet.k-state.edu. If we parse this address from right to left we'll see that the user is in the .edu domain. EDU is the domain name reserved just for educational institutions. Other domains you'll see include .com for commercial, .mil for military, etc. The .ksu part of the address further defines the user as being located at Kansas State University and the .vet identifies the specific file server VETMAIL as the machine on which user "rnixon" is located. Hardware connected to the network maintains tables that computers can use to link text based addresses with the proper numeric address. Since the TCP/IP protocol doesn't require you to be logged into a file server to use it's features our network is set up to issue your computer it's own IP address for use when using those features. Network TerminologyYou've heard these lines hundreds of times before: "Wow! You need to FTP a copy of this new program from balvits.narl.edu!" or "Oh, yeah, I found this cool Web page at Trendy State University!" or even worse, "You mean you don't know the difference between TELNET and TELEPHONE?". What in the world are people talking about? Most of the new terms you are hearing come from activities or services available on the Internet. This area will bring you up to speed on the above mentioned and several other terms that you'll frequently hear so glibly bandied about by your colleagues.
ETHERNETEthernet is a network protocol that computers use to pass data back and forth over a network. It is used in Local Area Networks where distances between computers are limited to a few hundred feet. This term is frequently used (erroneously) to describe an entire network as in the phrase, "I would like my computer to be attached to the Ethernet." The ethernet protocol can accommodate a theoretical bandwidth of 10 million bits of data per second (10 MB/S). Hence, this protocol is sometimes referred to as 10BaseT when connected using UTP wiring. New technologies have increased the potential bandwidth to 100MB/S or 100BaseT, referred to as Fast Ethernet; and 1000MB/S, or 1000BaseT, referred to as Gigabit Ethernet. We also have the capability of both listening and sending data at the same time on a set of wires, called full-duplexing, which doubles the theoretical bandwidth. The wiring that connects our three buildings, VMS, VMT, and VCS together, is a fiber-optic cable that is using Fast Ethernet, or 100MB/S at full-duplex. The convention for running ethernet over fiber cable is "FX", so you can say our network backbone is "100BaseFX at full-duplex." FTPFile Transfer Protocol. This is a means by which you can connect your computer to another computer at a remote location for the purpose of transferring files back and forth. The remote machine must be running software called an FTP Host that will respond to your computers requests. Your machine must run a program called an FTP Client that will coordinate transfers with the FTP Host software. HOMEPAGEThis is a file on a World Wide Web server that is set up to welcome users to the site and provide information about what's available, what the site is set up for, and who to contact for problems or further information. The content of the homepage is entirely up to the individual or organization that sets up the site. INTERNETThe Internet is a global network of networks. It is not centrally managed by any individual or organization. Information on computers attached to the Internet can be accessed using a variety of software tools including but not limited to: FTP, Telnet, WWW. The Intranet is a local version of the Internet, where local resources (normally within a company or, in this case, a college) are accessed using Internet type software tools. Access to Intranet resources are usually restricted to users within the company (college). NETSCAPE, INTERNET EXPLORERThese are the most popular Internet/WWW Browsers that use a bookmark metaphor to keep track of locations on the Web, and URL information to find files on the Web. Other enhancements such as the ability to download and display text while graphics are still being retrieved make these browsers a favorite. TELNETTelnet provides a way of logging into a remote computer and using your keyboard and monitor as a terminal on that machine. This gives you the ability to run programs or manipulate files on the remote machine just as if you were sitting at a terminal attached directly to it. In order to use TELNET you need to have an account set up on the remote computer. URLUniform Resource Locator. This is an identifier used by WWW Browsers to locate and retrieve data from remote Web sites. The keywords and addresses included in the URL tell a browser what type of resource you are trying to locate and where that resource can be found. Typical URL's might look like: http://www.vet.k-state.edu or file:///h|apps/share/html/onlnhlp.htm. The first one points to a Web site's homepage at vet.k-state.edu while the second points to a file called onlnhlp.htm in the apps\share\html directory on drive H of a local fileserver. UTPUnshielded Twisted Pair. Sometimes referred to as 10BaseT wiring. Cabling commonly used in the connection of telephone networks within a building. It consists of multiple pairs of conductors that are twisted around each other for the purpose of limiting electrical interference. It has no shield (foil wrapper or copper braid) around the conductor pairs since it is not intended to carry high frequency signals or data. Since the installed cables usually have extra pairs of conductors intended for telephone expansion, they provide an attractive means for connecting computers together without having to string new cabling throughout a building. UTP is rated by categories that indicate how fast data can be passed through the cable. Most installed cable is CAT 3 suitable for data rates of 10 Megabits per second or less. Newer cable installations use CAT 5 which is rated for 100Megabits per second (100BaseT) or less. WWWWorld Wide Web. The World Wide Web was established in an effort to make accessing information on the Internet as user friendly as possible. This goal has been largely realized by the creation of a world wide network of Web sites and a user interface that ties together a variety of Internet access tools in one application. This interface is called a Browser. The first widely distributed Browser was known as Mosaic, but the most popular browsers today are Netscape and Internet Explorer. |
