Roll No:
EXPERIMENT NO.1
Data Compression and its effects on network
DATA COMPRESSION
Data compression or source coding is the process of encoding information using fewer bits (or other information-bearing units) than an uuencoded representation would use through use of specific encoding schemes. For example, this article could be encoded with fewer bits if we accept the convention that the word "compression" be encoded as "comp". One popular instance of compression that many computer users are familiar with is the ZIP file format, which, as well as providing compression, acts as an archive, storing many files in a single output file.
As is the case with any form of communication, compressed data communication only works when both the sender and receiver of the information understand the encoding scheme. Compressed data can only be understood if the receiver knows the decoding method.
Compression is important because it helps reduce the consumption of expensive resources, such as disk space or connection bandwidth. However, compression requires information processing power, which can also be expensive. The design of data compression schemes therefore involves trade-offs between various factors including compression capability, any amount of introduced distortion, computational resource requirements, and often other considerations as well.
Data compression is widely used in backup utilities, spreadsheet applications, and database management systems. Certain types of data, such as bit-mapped graphics, can be compressed to a small fraction of their normal size.
LOSSLESS AND LOSSY COMPRESSION
There are two compression methods.
1. Lossless compression.
2. Lossy compression.
Lossless Compression
1. Lossless compression is possible because most real world data has stastical redundancy.
2. Always fails to compress some files.
Lossy Compression
1. Lossy scheme accept some loss of data in order to achieve higher compression.
2. Lossy data compression will also come to a point where compressing again does not work.
COMPRESSION TECHNIQUES
Various types of compression algorithms are in use in the world today. For compression, a scope needs to be set ahead of time. There are compression methods for data (entire files), links (data that travels between routers), hard drives (data stored on a hard drive), and so on. This section of the chapter focuses on compression across WAN links (links).
COMPRESSION TYPES
· Link
· Payload
· TCP Header
Figure illustrates where various types of compression make transmission more efficient.
Link Compression
Both the header and the data are compressed. Because the entire frame is compressed, it must be uncompressed immediately upon receipt at the other end of the link so that the header information can be used to further forward the frame. Thus, a link-compressed frame is only compressed for the trip across one link.
Link compression is not dependent on any particular protocol function. Every frame that leaves the interface that is configured for compression is reduced in size-no questions asked, no exceptions to the rule.
Because the header and data are unusable after being compressed, link compression should be used only for data transmission over point-to-point dedicated connections.
It is also important to remember that if compression is used on one side of a link, compression must also be enabled on the other side, and the same compression algorithm must be used at both ends. Compression can be compared to a language. If English is spoken on one end, then English must be present on the other end to decipher the communication.
Payload Compression
Payload compression is needed if the WAN switches must examine the data sent from a customer location. WAN technologies such as Frame Relay require that the L2 header information be untouched so that the provider's switches can read it and make forwarding decisions based on it. Any implementation of VCs disallows link compression. In these cases, payload compression is appropriate.
TCP Header Compression
This type of compression is most beneficial when used with implementations that transmit small packets, such as Voice over IP, Telnet, and so forth. This type of compression can be done on just about any WAN implementation (X.25, Frame Relay, ISDN, and so on).
COMPRESSION ISSUES
Compression is not a feature that is simply turned on or off. When selecting the algorithm that is to be utilized for a particular deployment, you should consider the following:
Modem compression - Some modems implement compression. Modems that use MNP5 and V.42bis are not compatible. Although each offers 2 and 4 times compression, they cannot communicate with each other. If you use modem compression, make sure that the modems at both ends of the connection are using a common protocol. If compression is being performed by the modem, do not attempt to configure compression at the router level. If modem compression is successfully enabled, then data compression (from the router for example) should not be enabled. Remember that compressing a compressed string might increase the size. Conversely, if compression is performed on the router, then the modem should not attempt any further compression.
Data encryption - Encryption occurs at the network layer where compression is an L2 function. The main purpose of encryption is security. Encryption removes common patterns in data streams. In other words, when Stack tries to find redundant strings, there are none. When Predictor looks into the dictionary for common patterns, there are none. Therefore, the compression is unsuccessful and can actually expand the traffic it was attempting to compress. In such a case, the traffic is sent uncompressed.
CPU and memory - Some algorithms are memory intensive and some are CPU intensive. Thus, before you plan or implement compression, you must know the physical configuration of your router (that is, its RAM and CPU) before ordering additional hardware.
Conclusion:-
· Lossless data compression method is more efficient than Lossy data compression method because it could compress any type of data without any data loss.
· Out 3 types of compression link compression is more appropriate as in this both header and payload are compressed which ensures lesser data loss.
· The main issue with compression is that the method used for compression at sender and receiver must be common.
EXPERIMENT NO.2
Installation of Windows NT & Novell Netware
WINDOWS NT:
· Put the Windows NT boot floppy in the disk drive and turn your computer on.
· Your computer will now boot up into Windows NT Setup. Follow the directions on the screen and insert the disks in the floppy drive when prompted.
The next screen will say Welcome to Setup. Here it gives you three choices. To setup Windows NT, hit the Enter key. This is the option that you want choose.
· You will now be brought to a screen that will detect Mass Storage Devices which are your hard drives and CD-ROM drives. Hit the Enter key to detect these devices and follow the directions on the screen. After it finishes detecting your mass storage devices hit Enter to continue. Here, you may be asked to insert the Windows NT CD. If the setup program asks for it, insert it in the drive and hit Enter to continue.
· The next screen that appears is the Licensing Agreement. Scroll to the bottom of this document using the Page Down key and then press the F8 key to continue.
· The next screen that is brought up shows you what hardware has been detected in your computer. If everything looks all right, hit Enter to continue.
· Now, a screen will come up that asks you where you would like to install Windows NT. If you have only one Hard Disk, install to C:. If you have more than one Hard Drive, install Windows NT on the one that does not have Windows 95 or Windows 3.1 on it if there is enough space on it (more than 200 megabytes free) and hit Enter to continue.
· Also on this screen, you may be presented with the option to convert your file system to NTFS. We suggest that you keep the hard drive's file system as FAT16 at this point because it is easy to convert it NTFS later, but it is very difficult, if not impossible, to convert it back to FAT16 at a later date.
· Now, you will be asked what directory to install Windows NT to. Select the default of \WINNT.
· Finally, the setup program will check your hard drive to make sure that it is free of errors and then it will proceed to copy the files needed to start the graphical portion of Windows NT Setup. Hit Enter to start checking your hard drive and copying files.
· After it finishes copying files, remove the floppy disk and CD-ROM from the appropriate drives and reboot your computer by pressing Enter when prompted.
· When the computer reboots, it will automatically boot into the Windows NT setup wizard. Click Next to continue.
· When prompted, insert the Windows NT 4.0 CD in the CD-ROM drive and click on OK to continue.
· You will be asked to select how you would like to install Windows NT. Select Typical.
· Now, enter your name and organization in the appropriate fields and click Next to continue.
· Next, you will be asked to register your copy of Windows NT. Enter the CD Key in the field. This number can be found on the back of the CD jacket.
· Enter the name of your computer and the workgroup you want to be part of. The name of your computer and workgroup can be anything you want, but you may want to ask others in your department what their workgroup is so that file sharing with them is easier.
· You will now be shown a screen asking you to enter a password for the account "Administrator". Enter the password of your choice and then click Next to continue. It is very important that you do not forget this password because if you do, the only way to reset it is to reinstall Windows NT!
· In this next window, select Create Recovery Disk.
· A screen now comes up that informs you that the program will start to set up the network. Click on Next again to begin setting up the network.
· You will now be shown a screen that asks you how your computer will be connected to a network. For this, you want to check the box next to the selection Wired to the Network.
· A screen will then appear asking you what network card you have installed. To have Windows NT auto detect your card, click on the button Start Search. After it finds the card, click on Next.
· The next screen that comes up asks you which network protocols you would like to install. Check the boxes next to the protocols TCP/IP and NW Link IPX/SPX and then click Next to continue.
Depending on what type of network card you have in your computer, you may be presented with a box labeled Connection Type. Select the option Auto detect and hit Enter to continue.
· Windows NT will then ask what Network Services to install. Leave these settings as is.
· After this, a screen labeled TCP/IP Setup will appear. There will be a setting concerning DHCP. For this, select: Obtain an IP address from a DHCP server
· The next window you see will be labeled Microsoft TCP/IP Properties. At the top of the window, there will be a row of tabs that you can click on to bring up a different page. The left-most column of the following table corresponds to each tab. Make the changes to each tab listed in this table and then click OK to continue.
· A box informing you that Windows NT will now start networking services appears next. Click the button Next to continue.
The next box will ask you to enter the name of your workgroup. Enter the workgroup that you wish to be in (Since we are a part of CAE, we use the workgroup CAE but you will want to enter the workgroup that is used in your area).
· Click Finish to finalize your settings.
The next window is labeled Display Properties. The setup program will automatically detect your video card. After it completes this, you can adjust the video settings to your liking and then click on the button Test to make sure the new settings work. Once you have confirmed that they do work correctly, click on OK.
· Windows NT setup will first copy some files to the hard drive and then it will create the emergency disk. After this is completed, Windows NT will proceed to finish installing itself.
· Once the computer has rebooted, Windows NT is installed and ready to go.
NOVELL NETWARE:
Insert the CD in the CD-ROM.
Select the language in which to install the server.
Press Enter to continue.
Now select the COUNTRY, CODE PAGE, and KEYBOARD. If you selected to install in English and are in the US, then the defaults should suffice. If not then select the proper setting before continuing.
The screen below is the NetWare 6.5 software license agreement. After reading the license agreement press F10 to accept it and continue.
Here you are prompted to create a boot partition if one has not already been created. If you have already installed a previous version of NetWare (or other OS) then you will see that partition in this list. For a fresh install it is suggested that you highlight those partitions and then hit the delete key if that space is going to be used for the NetWare 6.5 Operating System. Once you have the desired free space you can create a boot partition by hitting the ENTER key.