PTU ATM practical

NORTH WEST INSTITUTE OF ENGINEERING & TECHNOLOGY

DHUDIKE (MOGA)PAGE-1

Semester-6th HARDWARE LAB-V (ATM) CS-314

S.No INDEX Pg.No T.Sign.

1 Installing Windows 2000 Server.

2 Creating User Accounts.

3 Implementation of Ethernet Between two PC’s.

4 Installing and Configuring DHCP Server

5 Memory Management Techniques in Network.

6 Various Network Utility.

7 How To Share File and Folder in Network.

8 Configure NTFS Permissions(IIS 6.0).

9 IP Addressing.

10 Process Utilization.

PRACTICAL - 1

Submitted By: Roll No: Submitted to:

DHEERAJ BRAR 80407107036 ER. LAKHBIR SINGH




AIM: - Installing Windows 2000 Server.

With proper planning, installing Windows 2000 Server is incredibly easy. Before starting, it is important to check our hardware and software against the hardware and software compatibility lists. In particular, if our hardware is not supported, we may not be able to complete the installation.

Below are the steps to a successful installation:

1) The first step is to get our computer to boot from the CDROM. If we are performing a clean install and our CDROM drive is bootable, then we should be able to simply insert the Windows 2000 CDROM and boot our computer. Make sure that we do not have a floppy disk in the drive. If we are installing over an existing operating system and our CDROM is bootable, then we will want to enter our BIOS and change the boot order to boot from our CDROM first. If our CDROM is not bootable, then we will need to make boot disks in order to begin the installation, which can be done using the Makeboot.exe utility on the CDROM.

2) When setup starts, we will see the message Set-up is loading files. This will take some time to complete. If it seems to be taking more time than we expected, look at bottom of the screen to make sure that it is actively loading files.

3) Once the files are loaded, we will be presented with a screen that will offer 3 options as follows:

To set up Windows 2000 now, press enter

To repair a Windows 2000 installation, press R To quit setup without installing Windows 2000 press F3






Since we are installing Windows 2000, we will press enter.

4) The next screen displays the license agreement. Press F8 to agree. 5) The next screen will show our current partition configuration and offer

the following 3 choices: To set up Windows 2000 on the selected item, press enter - If we

select this option, then Windows will be installed on the highlighted partition.

To create a partition in the un-partitioned space, press C - If we select this option, enter size of partition we wish to create in MB and press enter. We should create a partition that is at least 2GB in size if not larger.

To delete the selected partition, press D - When deleting a partition, we will receive a warning message that all data will be lost from the partition and we must press "L" to continue.

6) If we have selected a partition to be formatted, we will be presented with the option to format it as NTFS or FAT. We will probably want to format it as NTFS, although if we are unsure, we can format it as FAT and convert it to NTFS later.

7) Setup will now format the partition and then copy files to it. Once complete, Windows 2000 will reboot and will begin the GUI-based portion of setup.

8) After the Windows 2000 splash screen appears, we will see Welcome to the Windows 2000 setup Wizard. Press next to continue.

9) Now the plug and play process starts and Windows will attempt to identify our hardware and install drivers for these devices.






10) Next, we have the option to customize our Regional Settings which includes items such as keyboard lawet and locale. These can be changed after setup is complete.

11) Next we will be prompted to enter our name and company name and on the next screen we will enter the computer name and admin password. Do not lose or forget this password.

12) The next section will present Windows 2000 Components. Select the components that we wish to install. If we are unsure, just hit next as these can be added later.

13) Setup will spend some time completing final tasks and then will reboot. Make sure that we remove the CDROM before rebooting. If we changed our boot order in our BIOS, we will most likely want to change it back.

PRACTICAL – 2

AIM: - Creating a User Account for the Server.






In order to run the Server securely as a service, we need to create a user account for it in Windows.

To create a user account in Windows XP Professional or Windows 2000: 1) After we install the Server, open the Computer Management console.

(e.g., on the Desktop, right-click My Computer, then click Manage.)2) Expand the Local users and group’s node, right-click Users, and then

click New User. The New User dialog box appears.3) Create the user account (e.g., GSFTPServer), click Create, and then

click Close.4) Close the Computer Management console.5) In Administrative Tools, click Local Security Policy. The Local

Security Settings dialog box appears.6) Expand the Local Policies node, and then click User Rights

Assignment.7) In the right pane, in the Policy column, double-click Act as part of the

operating system. The Properties dialog box appears. 8) Click Add user or Group. The Select Users or Groups dialog box

appears. 9) Select the new user we just added (GSFTPServer), click Add, and then

click OK.10) If necessary, assign permissions for this user account in Windows.11) Assign the server to the new user account and log the server on as a

service.

To create a user account in Windows NT:

1) After we install the server, open the User Manager (Control Panel > Administrative Tools > User Manager).






2) On the main menu, click File, then click New User to create a new user account for "GSFTPServer". The User Properties dialog box.

3) Provide the Server's information, as shown below, and then click OK.

4) On the main menu bar, click Policies, and then click User Rights. The User Rights Policy dialog box appears.

5) Select the Show Advanced User Rights check box.

6) In the Right list, click Act as part of the operating system.






7) Click Add. The Add Users and Groups dialog box appears.

8) Make sure that the drop-down list at the top of this dialog has our own computer selected. Click the Show Users button and select GSFTPServer from the list.

9) Click Add.

10)Click OK in both dialogs.

11)Assign permissions for this user account in Windows.

12)After assigning permissions, we should assign the server to the new user account we have created and then log the server on as a service.

PRACTICAL – 3

AIM: - Implementation of Ethernet between two PC’s.

HARDWARE REQUIRED:-






1) LAN CARD: - A LAN card or NIC (Network Interface Card) is a piece of hardware which allows computers to communicate over a network. Most LAN cards are connected to a computer via PCI slots. Normally, LAN cards have a RJ-45 connector jack for connecting Ethernet cables. LAN cards have LED’s, which show whether the connection is active or not.

2) ETHERNET CABLES: - Ethernet cables are required to connect PC’s.

As different devices are to be connected, a cross cable is used. In a cross cable, both the connectors have the different colour standard i.e. 568A or 568B.



http://upload.wikimedia.org/wikipedia/commons/9/9e/Network_card.jpg

http://upload.wikimedia.org/wikipedia/commons/2/28/10baseT_cable.jpeg




568A 568B

3) LAN TESTER: - Before connecting an Ethernet cable with a hub, we need to make sure that the wire will work properly or not, this is done with the help of a LAN tester. A LAN tester has 16 LED’s arranged in two parallel lines of 8 each. When the two ends of the Ethernet wire are connected to a LAN tester, then , if the LED of same number glow simultaneously, then the Ethernet wire is properly functional otherwise the wire is discarded.

STEPS: -

1) Check all the wires to be used with a LAN tester.2) Connect the Ethernet cables to the PC’s. Make sure that the connections

are tight.3) Now, on every system, perform the following steps:-

a) Right click on “My Network Places” and select “Properties” from the drop down menu



Pin

Color

1 Orange/White2 Orange3 Green/White4 Blue5 Blue/White6 Green7 Brown/White8 Brown

Pin

Color

1 Green/White2 Green3 Orange/White4 Blue5 Blue/White6 Orange7 Brown/White8 Brown




b) The new screen shows all the network connections.

c) Right click on “Local Area Connection” and select “Properties” from the drop down menu.






d) A new screen showing “Local Area Connection Properties” opens. Select “Internet Protocol (TCP/IP)” click on “properties”.

e) A new opens showing “Internet Protocol (TCP/IP) Properties” opens. This window shows the IP address settings. Click on the second option i.e. “Use the following IP address”.






In this option, mention the IP address of the system. The “Subnet mask” option is filled automatically. Fill in the IP address of our system.

f) Click on “OK”.

4) We can see whether all the systems connected to the hub are correctly configured and working properly or not by:-






a) Click on start menu and select “Run”.

b) In “Run”, write “ping [IP address]” to see whether the system is connected properly or not.

In case, the system is not configured properly, it will show:-






Otherwise, if everything is fine, then, it will show:-

5) Now, after the connection is established, the following steps are carried for sharing of data:-

a) If we want to share a folder, we will right click on the folder and select “Sharing and Security”.






b) A new window opens. In the new window, check the option “Share the folder on the network”. If we want to allow the users to make changes in our file, and then check the option “Allow network users to change my files”, otherwise, do not check it.

6) We can see the data shared by other PC’s by opening “My Network Places”, in this; we will be able to see all the shared folders.






If we want to see the folders shared by one of the PC’s on the network, we can do it by typing “\\ IP address” in the “Run” window.

PRACTICAL – 4






AIM: - Installation of DHCP Server.

The Dynamic Host Configuration Protocol (DHCP) automates the assignment of IP addresses, subnetup or regains connectivity to the network. The DHCP client sends out a query requesting a response from a DHCP server on the locally attached network. The query is typically initiated immediately after booting up and before the client initiates any IP based communication with other hosts. The DHCP server then replies to the client with its assigned IP address, subnet mask, DNS server and default gateway information.

The assignment of the IP address usually expires after a predetermined period of time, at which point the DHCP client and server renegotiate a new IP address from the server's predefined pool of addresses. Configuring firewall rules to accommodate access from machines who receive their IP addresses via DHCP is therefore more difficult because the remote IP address will vary from time to time. Administrators must usually allow access to the entire remote DHCP subnet for a particular TCP/UDP port.

IP address allocation

Depending on implementation, the DHCP server has three methods of allocating IP-addresses:

Manual allocation, where the DHCP server performs the allocation based on a table with MAC address - IP address pairs manually filled by the server administrator. Only requesting clients with a MAC address listed in this table get the IP address according to the table.

Automatic allocation, where the DHCP server permanently assigns to a requesting client a free IP-address from a range given by the administrator.



http://en.wikipedia.org/wiki/Server_administrator

http://en.wikipedia.org/wiki/MAC_address

http://en.wikipedia.org/wiki/Firewall_(networking)

http://en.wikipedia.org/wiki/Internet_Protocol

http://en.wikipedia.org/wiki/Booting




Dynamic allocation, the only method which provides dynamic re-use of IP addresses. A network administrator assigns a range of IP addresses to DHCP, and each client computer on the LAN has its TCP/IP software configured to request an IP address from the DHCP server when that client computer's network interface card starts up. The request-and-grant process uses a lease concept with a controllable time period. This eases the network installation procedure on the client computer side considerably.

On the system, where the DHCP-server is getting installed, we must use a static (= manually assigned) IP-address

Like with all other Server related components, we can start the setup of the DHCP-server from "Configure our Server", which is part of the "Administrative Tools"



http://en.wikipedia.org/wiki/Network_interface_card

http://en.wikipedia.org/wiki/Server_(computing)

http://en.wikipedia.org/wiki/TCP/IP

http://en.wikipedia.org/wiki/Network_administrator




On the left side, expand on "Networking”, select "DHCP" and thenstart the "Windows Component Wizard”:






To start the "Windows Component Wizard", we could also have used in the Control-Panel. The applet for "Add / Remove Programs" and selected to "Add / Remove Windows Components”:

Select (click on) the line "Networking Services" and then click on the button "Details" :






Locate and select the line by placing the checkmark on:"Dynamic Host Configuration Protocol (DHCP)",(other items may already be selected),continue with "OK Back in the window of "Windows Component Wizard”, continue now with "Next"

Back in the window of "Windows Component Wizard", continue now with “Next".






CONFIGURE DHCP SERVER:-






After installing the DHCP-server, we need to configure it before we can use it:

Select "DHCP”, which is part of the Windows menu "Administrative Tools". In the left plane, we will see the name and IP-address of the DHCP-server.

After installation, a DHCP server is not authorized. Do not forget this later!We need to define the range of IP-addresses to be assigned (=distributed) by the DHCP-server. A definition of a range of IP-addresses (with or without additional options) is called a "Scope": select our DHCP-server and then either with a right-click or from the menu "Actions" selects to define a "New Scope":






Up comes the Wizard select "Next"

Define a name for our scope continue with "Next"






Define the range of IP-address and the subnet-mask. Select a range, which does not include the IP-address of the server itself or any other device with a manually assigned IP-address (like: network printers). Although we could exclude them in the next step, usually a range is reserved for such manually assigned addresses and then the rest (in this case: 100 - 199) is given to the DHCP-server for automatic distribution.






If we could not define separate ranges for manually assigned and DHCP-assigned IP-addresses, then we could here define IP-addresses or ranges of IP-addresses to be excluded: not to be used by the DHCP-server.






Typically, an IP-address is assigned (= "leased" ) for a limited time. This avoid running out of addresses, when visitors to we office connect to the network and get an IP-address assigned. Without a time-limit, such an IP-address could not be reused. Usually, 8 days is a good choice and will ensure that people every day in the office will continue to use the same IP-address once assigned to them, since their systems will in time extend the "lease". And if they come back from a 2 week vacation and the "lease" has expired, then the DHCP-server will assign a new IP-address to them.

In addition to the IP-address and Sub-Netmask, a DHCP-server can also be use to define other TCP/IP configuration items on the Client systems.

.






We can also configure the WINS server address






We need to activate the scope, (which we can do later with a right-click on the scope and selecting: "Activate"/"Deactivate" :)






We still have to "Authorize" the DHCP-server: select the server and either right-click or from the menu "Action" select "Authorize”:

Note: on my system, I had to close now the DHCP-windows and open it up again to see, that the DHCP-server is now "Running”:






a quick check on the "Scope Options", which we have configured already:






If required, we can change or add the options of the scope.We can configure in the "Properties" of the scope, tab: DNS, that once the DHCP-server has assigned an IP-address the address will be updated in the DNS-server, allowing now other systems on the network to locate our system:

Once the DHCP-server is configured and authorized and the scope is activated, IP-addresses will be distributed.






PRACTICAL - 5

AIM: - Memory Management Techniques in Network.

SET QUOTAS ON NTFS VOLUME:-

Disk quotas are based on file ownership and are independent of the folder location of the user's files within the volume. For example, if users move their files from one folder to another on the same volume, their volume space usage does not change. However, if users copy their files to a different folder on the same volume, their volume space usage doubles. If one user creates a 200 kilobyte (KB) file, and another user takes ownership of that file, the first user's disk use increases by 200 KB.

We can set disk quotas to limit the amount of disk space users can access on a partition, that uses the NTFS. To do so, follow these steps:

1) Double-click My Computer.

2) Right-click the partition on which we want to set disk quotas, and then click Properties.

3) On the Quota tab, click the Enable Quota Management check box.






4) If we want all new users to have access to an unlimited amount of disk space, click Do Not Limit Disk Space.

If we want all new users to have access to a limited amount of disk space, click Limit Disk Space To, and then type the amount of disk space (in megabytes [MB] or KBs). If we want a warning message to be displayed when a user is close to reaching his or her quota limit, click

Set Warning Level To, and then type the amount of disk space (in MB or KB) that can be used before the warning message is displayed.

5) If we want to set a custom disk quota for a user, click Quota Entries.

6) On the Quota menu, click New Quota Entry.

7) In the Domain\Name box, type "<domain>\<username>" (without quotation marks), where <domain> is the Windows domain on which the user has an account, and <username> is the user for whom we are setting a disk quota.

8) If we want the user to have access to an unlimited amount of disk space, click does not limit disk space.

If we want the user to have access to a limited amount of disk space, click Limit Disk Space To, and then type the amount of disk space (in MB or KB). If we want a warning message to be displayed when the user is close to reaching his or her quota limit, click Set Warning Level To, and then type the amount of disk space (in MB or KB) that can be used before the warning message is displayed.

9) Click OK.

10)On the Quota menu, click Close.






11)Click OK, and then click OK again when we are prompted to enable disk quotas.

ADDITIONAL OPTIONS UNDER DISK QUOTAS

Deny Disk Space to Users Exceeding Quota Limit - Users who exceed their quota limit receive an "insufficient disk space" error from Windows and cannot write additional data to the volume without first deleting or moving some existing files from it.

Individual programs determine their own error handling for this condition. To the program, it appears that the volume is full. If we clear this check box, users can exceed their quota limit.

Enabling quotas and not limiting disk space use are useful when we do not want to deny users access to a volume but want to track disk space use on a per-user basis. We can also specify whether or not to log an event when users exceed either their quota warning level or their quota limit.

Limit Disk Space To - Enter the amount of disk space that new users of the volume are allowed to use and the amount of disk space that has to be used before an event is written to the system log.

Administrators can view these events in Event Viewer. We can use decimal values (for example, 20.5) For the disk space and warning levels, select the appropriate units from the drop-down list (for example, KB, MB, GB, etc.).






Log Event When a User Exceeds the Quota Limit - If quotas are enabled, an event is written to the system log on the local computer whenever users exceed their quota limit. Administrators can view these events in Event Viewer, filtering for disk event types.

Log Event When a User Exceeds the Warning Level - If quotas are enabled, an event is written to the system log on the local computer whenever users exceed their quota warning level. Administrators can view these events in Event Viewer, filtering for disk event types.

After we enable disk quotas on a volume, any users with write access to the volume who have not exceeded their quota limit can store data on the volume. The first time a user writes data to a quota-enabled volume, default values for disk space limit and warning level are automatically assigned by the quota system. The Administrator account is not included in the quota system.






PROGRAM-7

AIM: - Write a program to share file and folders on network.

To share a drive or folder on the network

1. Open Windows Explorer, and then locate the drive or folder you want to share.

2. Right-click the drive or folder, and then click Sharing and Security. o If you are sharing a drive, on the Sharing tab, click if you

understand the risk but still want to share the root of the drive, click here.

o If you are sharing a folder, go to the next step. 3. Do one of the following:

o If the Share this folder on the network check box is available, select the check box.

o If the Share this folder on the network check box is not available, this computer is not on a network. If you would like to set up a home or small office network, click the Network Setup Wizard link and follow the instructions to turn on file sharing. Once file sharing is enabled, begin this procedure again.



ms-its:C:%5CWINDOWS%5CHelp%5Cfilefold.chm::/windows_share_your_folders.htmHELP=glossary.hlp%20TOPIC=gls_drive

ms-its:C:%5CWINDOWS%5CHelp%5Cfilefold.chm::/windows_share_your_folders.htmEXEC=ExploreWClass,explorer.exe,%20CHM=ntshared.chm%20FILE=alt_url_windows_component.htm




To open a shared folder on another computer

1. Open My Computer. 2. Under Other Places, click My Network Places. The shared folders

on your network are displayed. If they are not listed, do the 3. following: 4. Double-click the computer where the shared folder is located. 5. Double-click the folder you want to open.



ms-its:C:%5CWINDOWS%5CHelp%5Cnetwork.chm::/net_open_net_folder.htmHELP=network.hlp%20TOPIC=gls_net_shared_folder

ms-its:C:%5CWINDOWS%5CHelp%5Cnetwork.chm::/net_open_net_folder.htmEXEC=,EXPLORER.EXE,%20::%7B20D04FE0-3AEA-1069-A2D8-08002B30309D%7D%20CHM=ntshared.chm%20FILE=alt_url_windows_component.htm




PRACTICAL - 8

AIM: - Configure NTFS Permissions (IIS 6.0).

WHY WE USE NTFS PERMISSIONS?

Use NTFS permissions to define the level of access to our directories and files that we want to grant to specific users and groups of users. Proper configuration of file and directory permissions is crucial for preventing unauthorized access to our resources.

REQUIREMENT

Credentials: Membership in the Administrators group on the local computer.

Tools: Iis.msc

RECOMMENDATION

As a security best practice, log on to our computer using an account that is not in the Administrators group, and then use the Run as command to run IIS Manager as an administrator. At the command prompt, type runas Procedures

TO SECURE A WEB SITE BY USING NTFS PERMISSIONS

1) In IIS Manager, expand the local computer, right-click the Web site or file we want to configure, and click Permissions.






To add a group or user that does not appear in the Group or user names list box, click Add, and in the Enter the object names to select text box, type the name of the user or group. Click OK.

-OR-

To change or remove permissions from an existing group or user, click the name of the group or user in the Group or user names list box.

2) To allow or deny permission such as Read & Execute, List Folder Contents, Read, or Write, in the Permissions for group or user name list box, select the Allow or Deny check box next to the appropriate permission, and then click OK.

With NTFS permissions, we also have the choice of assigning special permissions to groups or users. Special permissions are permissions on a more detailed level. For better management, we should assign broad-level permissions to users or groups, where it is applicable. For descriptions of permissions, see "Permissions for files and folders" in Help and Support Center for Windows Server 2003.

TO SECURE A WEB SITE USING NTFS SPECIAL PERMISSIONS

1) In IIS Manager, expand the local computer, right-click a Web site or file we want to configure, and click Permissions.

2) Click Advanced, and then do one of the following on the Permissions tab:

To set special permissions for an additional group or user, click Add, and in the Enter the object name to select text box, type the name of the user or group. Click OK.






To view or change special permissions for an existing group or user, click the name of the group or user, and then click Edit.

To remove an existing group or user and its special permissions, click the name of the group or user and then click Remove. If the Remove button is unavailable, clear the Allow inheritable permissions from the parent to propagate to this object and all child objects. Include these with entries exclusively defined here. Check box, and then click Remove. Click OK and skip steps 3-6 below.

3) To allow or deny permission such as Read & Execute, List Folder Contents, Read, or Write, in the Permissions list box, select the Allow or Deny check box next to the appropriate permission.

4) In the Apply onto list box, click the folders or subfolders we want these permissions to be applied to.

5) To prevent the subfolders and files from inheriting these permissions, clear the Apply these permissions to objects and/or containers within this container only check box, and then click OK three times.

PRACTICAL - 9

AIM: - IP Addressing.






INTRODUCTION:-

This document will give us the basic information to configure router for routing IP, such as how addresses are broken down and how sub netting works, how to assign each interface on the router an IP address with a unique subnet.

ADDITIONAL INFORMATION :-

Address—the unique number ID assigned to one host or interface in a network.

Subnet—portions of a network sharing a particular subnet address. Subnet mask—A 32-bit combination used to describe which portion of

an address refers to the subnet and which part refers to the host. Interface—A network connection.

UNDERSTANDING IP ADDRESSES :-

An IP address is an address used to uniquely identify a device on an IP network. The address is made up of 32 binary bits which can be divisible into a network portion and host portion with the help of a subnet mask. The 32 binary bits are broken into four octets (1 octet = 8 bits). Each octet is converted to decimal and separated by a period (dot). For this reason, an IP address is said to be expressed in dotted decimal format (for example, 172.16.81.100). The value in each octet ranges from 0 to 255 decimal, or 00000000 - 11111111 binary.

Here is how binary octets convert to decimal: The right most bit, or least significant bit, of an octet will hold a value of 20. The bit just to the left of that will hold a value of 21. This continues until the left-most bit, or most significant bit, which will hold a value of 27. So if all binary bits are a one, the decimal equivalent would be 255 as shown here:






1 1 1 1 1 1 1 1 128 64 32 16 8 4 2 1 (128+64+32+16+8+4+2+1=255)

Here is a sample octet conversion when not all of the bits are set to 1. 0 1 0 0 0 0 0 1 0 64 0 0 0 0 0 1 (0+64+0+0+0+0+0+1=65)

And this is sample shows an IP address represented in both binary and decimal. 10. 1. 23. 19 (decimal) 00001010.00000001.00010111.00010011 (binary)

These octets are broken down to provide an addressing scheme that can accommodate large and small networks. There are five different classes of networks, A to E. This document focuses on addressing classes A to C, since classes D and E are reserved and discussion of them is beyond the scope of this document.

Note: Also note that the terms "Class A, Class B" and so on are used in this document to help facilitate the understanding of IP addressing and subnetting. These terms are rarely used in the industry anymore because of the introduction of classless interdomain routing (CIDR).

Given an IP address, its class can be determined from the three high-order bits. Figure 1 shows the significance in the three high order bits and the range of addresses that fall into each class. For informational purposes, Class D and Class E addresses are also shown.






Figure 1

In a Class A address, the first octet is the network portion, so the Class A example in Figure 1 has a major network address of 10. Octets 2, 3, and 4 (the next 24 bits) are for the network manager to divide into subnets and hosts as he/she sees fit. Class A addresses are used for networks that have more than 65,536 hosts (actually, up to 16777214 hosts!).

In a Class B address, the first two octets are the network portion, so the Class B example in Figure 1 has a major network address of 172.16. Octets 3 and 4 (16 bits) are for local subnets and hosts. Class B addresses is used for networks that have between 256 and 65534 hosts. In a Class C address, the first three octets are the network portion. The Class C example in Figure 1 has a major network address of 193.18.9. Octet 4 (8 bits) is for local subnets and hosts - perfect for networks with less than 254 hosts.






NETWORK MASKS: - A network mask helps we know which portion of the address identifies the network and which portion of the address identifies the node. Class A, B, and C networks have default masks, also known as natural masks, as shown here:

Class A: 255.0.0.0Class B: 255.255.0.0Class C: 255.255.255.0

An IP address on a Class A network that has not been sub netted would have an address/mask pair similar to: 8.20.15.1 255.0.0.0. To see how the mask helps we identify the network and node parts of the address, convert the address and mask to binary numbers.

8.20.15.1 = 00001000.00010100.00001111.00000001255.0.0.0 = 11111111.00000000.00000000.00000000

Once we have the address and the mask represented in binary, then identifying the network and host ID is easier. Any address bits which have corresponding mask bits set to 1 represent the network ID. Any address bits that have corresponding mask bits set to 0 represent the node ID.

8.20.15.1 = 00001000.00010100.00001111.00000001255.0.0.0 = 11111111.00000000.00000000.00000000 ----------------------------------- net id | host id

netid = 00001000 = 8hostid = 00010100.00001111.00000001 = 20.15.1

UNDERSTANDING SUBNETTING :-






Subnetting allows we to create multiple logical networks that exist within a single Class A, B, or C network. If we do not subnet, we will only be able to use one network from our Class A, B, or C network, which is unrealistic. Each data link on a network must have a unique network ID, with every node on that link being a member of the same network. If we break a major network (Class A, B, or C) into smaller subnetworks, it allows we to create a network of interconnecting subnetworks. Each data link on this network would then have a unique network/subnetwork ID. Any device, or gateway, connecting n networks/subnetworks has n distinct IP addresses, one for each network / subnetwork that it interconnects.

To subnet a network, extend the natural mask using some of the bits from the host ID portion of the address to create a subnetwork ID. For example, given a Class C network of 204.15.5.0 which has a natural mask of 255.255.255.0, we can create subnets in this manner:

204.15.5.0 - 11001100.00001111.00000101.00000000255.255.255.224 - 11111111.11111111.11111111.11100000 --------------------------|sub|----

By extending the mask to be 255.255.255.224, we have taken three bits (indicated by "sub") from the original host portion of the address and used them to make subnets. With these three bits, it is possible to create eight subnets. With the remaining five host ID bits, each subnet can have up to 32 host addresses, 30 of which can actually be assigned to a device since host ids of all zeros or all ones are not allowed (it is very important to remember this). So, with this in mind, these subnets have been created.

204.15.5.0 255.255.255.224 host address range 1 to 30204.15.5.32 255.255.255.224 host address range 33 to 62204.15.5.64 255.255.255.224 host address range 65 to 94204.15.5.96 255.255.255.224 host address range 97 to 126204.15.5.128 255.255.255.224 host address range 129 to 158






204.15.5.160 255.255.255.224 host address range 161 to 190204.15.5.192 255.255.255.224 host address range 193 to 222204.15.5.224 255.255.255.224 host address range 225 to 254

NOTE: - There are two ways to denote these masks. First, since we are using three bits more than the "natural" Class C mask, we can denote these addresses as having a 3-bit subnet mask. Or, secondly, the mask of 255.255.255.224 can also be denoted as /27 as there are 27 bits that are set in the mask. This second method is used with CIDR. Using this method, one of these networks can be described with the notation prefix/length. For example, 204.15.5.32/27 denotes the network 204.15.5.32 255.255.255.224. When appropriate the prefix/length notation is used to denote the mask throughout the rest of this document.

The network subnetting scheme in this section allows for eight subnets, and the network might appear as:

Notice that each of the routers in Figure 2 is attached to four subnetworks, one subnetwork is common to both routers. Also, each router has an IP address for each subnetwork to which it is attached. Each subnetwork could potentially support up to 30 host addresses.

This brings up an interesting point. The more host bits we use for a subnet mask, the more subnets we have available. However, the more subnets available, the less host addresses available per subnet. For example, a Class






C network of 204.17.5.0 and a mask of 255.255.255.224 (/27) allows we to have eight subnets, each with 32 host addresses (30 of which could be assigned to devices). If we use a mask of 255.255.255.240 (/28), the break down is:204.15.5.0 - 11001100.00001111.00000101.00000000255.255.255.240 - 11111111.11111111.11111111.11110000 --------------------------|sub |---

Since we now have four bits to make subnets with, we only have four bits left for host addresses. So in this case we can have up to 16 subnets, each of which can have up to 16 host addresses (14 of which can be assigned to devices).

Take a look at how a Class B network might be subnetted. If we have network 172.16.0.0, then we know that its natural mask is 255.255.0.0 or 172.16.0.0/16. Extending the mask to anything beyond 255.255.0.0 means we are subnetting. We can quickly see that we have the ability to create a lot more subnets than with the Class C network. If we use a mask of 255.255.248.0 (/21), how many subnets and hosts per subnet does this allow for?

172.16.0.0 - 10101100.00010000.00000000.00000000255.255.248.0 - 11111111.11111111.11111000.00000000 -----------------| sub |-----------

We are using five bits from the original host bits for subnets. This will allow us to have 32 subnets (25). After using the five bits for subnetting, we are left with 11 bits for host addresses. This will allow each subnet so have 2048 host addresses (211), 2046 of which could be assigned to devices.

Note: In the past, there we limitations to the use of a subnet 0 (all subnet bits are set to zero) and all ones subnet (all subnet bits set to one). Some






devices would not allow the use of these subnets. Cisco Systems devices will allow the use of these subnets when the subnet zero command is configured.

EXAMPLE :-

We are given two addresses / mask combinations, written with the prefix/length notation, which have been assigned to two devices. Our task is to determine if these devices are on the same subnet or different subnets. We can do this by using the address and mask of each device to determine to which subnet each address belongs.

Device A: 172.16.17.30/20Device B: 172.16.28.15/20

Determining the Subnet for Device A: 172.16.17.30 - 10101100.00010000.00010001.00011110255.255.240.0 - 11111111.11111111.11110000.00000000 -----------------| sub|------------Subnet = 10101100.00010000.00010000.00000000 = 172.16.16.0

Looking at the address bits that have a corresponding mask bit set to one, and setting all the other address bits to zero (this is equivalent to performing a logical "AND" between the mask and address), shows we to which subnet this address belongs. In this case, Device A belongs to subnet 172.16.16.0.

Determining the Subnet for Device B: 172.16.28.15 - 10101100.00010000.00011100.00001111255.255.240.0 - 11111111.11111111.11110000.00000000






-----------------| sub|------------Subnet = 10101100.00010000.00010000.00000000 = 172.16.16.0

From these determinations, Device A and Device B have addresses that are part of the same subnet.

PRACTICAL - 10

AIM: - Processor Utilization.

We can use the resource-utilization formula from the previous section to estimate the response time for a heavily loaded CPU. However, high utilization for the CPU does not always indicate a performance problem. The CPU performs all calculations that are needed to process transactions. The more transaction-related calculations that it performs within a given period, the higher the throughput will be for that period. As long as transaction throughput is high and seems to remain proportional to CPU






utilization, a high CPU utilization indicates that the computer is being used to the fullest advantage.

On the other hand, when CPU utilization is high but transaction throughput does not keep pace, the CPU is either processing transactions inefficiently or it is engaged in activity not directly related to transaction processing. CPU cycles are being diverted to internal housekeeping tasks such as memory management. We can easily eliminate the following activities:

Large queries that might be better scheduled at an off-peak time Unrelated application programs that might be better performed on

another computer

If the response time for transactions increases to such an extent that delays become unacceptable, the processor might be swamped; the transaction load might be too high for the computer to manage. Slow response time can also indicate that the CPU is processing transactions inefficiently or that CPU cycles are being diverted.When CPU utilization is high, a detailed analysis of the activities that the database server performs can reveal any sources of inefficiency that might be present due to improper configuration.

ABOUT PROCESSOR UTILIZATION

This topic discusses performance problems related to the processor, or central processing unit (CPU). The following sections are included:

IDENTIFYING PROCESSOR BOTTLENECKS :-

The CPU does the actual processing of instructions received by the computer. Information moves between the various components of the computer, such as the CPU, hard disk, and RAM, depending on the clock






speed of the CPU and the size of the data bus the CPU uses to move the information. Faster clock speeds mean that more trips are made back and forth by the data bus during the same time interval. Clock speeds are usually expressed as megahertz (MHz). The data bus can carry 16, 32, or 64 bits of data on each trip, depending on the bus size. (How much data is carried is also a function of the operating system used and what transfer rate the application is based on.)

Processor bottlenecks are characterized by very high CPU % Utilization numbers while the network adapter card remains well below capacity. If CPU % Utilization is high, we can:

o Upgrade the CPU. o Add additional CPUs to the same computer. o Replicate the site on another computer and distribute traffic across

both computers. o Move processor-intensive applications such as database applications

to another computer.

THROTTLING USE OF THE PROCESSOR :-

We can limit the percentage of time the CPU spends processing out-of-process WAM, ISAPI, and CGI applications for individual Web sites by enabling process throttling. Limiting access to the CPU is useful if we host multiple sites on one computer and we are concerned about out-of-process applications on one site using all of the CPU capacity, thereby preventing other sites from using it.

If a restricted site’s out-of-process applications use more than the assigned percentage of processor time during a specified time interval, the event is logged and consequences occur based on the amount of overrun of the assigned percentage. The consequences are:






o Level 1: An event is written to the Windows 2000 Event Log when the total processor use over the specified time period exceeds the limit.

o Level 2: If the processor use exceeds 150 percent of the limit, an event is written to the Event Log, and all the out-of-process applications on that Web site have their CPU priority set to Idle.

o Level 3: If the processor use exceeds 200 percent of the limit, an event is written to the Event Log, and all the out-of-process applications on that Web site are stopped.

Once a site has reached a Level 2 or Level 3 consequence, the consequence remains in effect until the next time interval. For example, if a site’s out-of-process applications are restricted to 10 percent of the CPU processing time during a 24-hour interval, the site’s applications should be using the CPU for only 2.4 hours out of 24. If the site uses the CPU longer than 2.4 hours, but less than 3.6 hours, the only consequence is that an event is written to the Event Log. Once the site uses the CPU for more than 3.6 hours, all out-of-process applications on the site are set to Idle. If the server is not very busy and the applications continue to use processor time, eventually reaching 4.8 hours of use during the 24-hour interval, the out-of-process applications are stopped on the Web site.

Process accounting is reset at the end of the 24-hour period and the site returns to normal functioning. Administrators can return a site to normal functioning sooner by changing the percentage set for a Web site, or by stopping and restarting the site. Web site Operators do not have permission to change this setting. For information on setting process restrictions, see Throttling Processes. If we enable process throttling, then we should probably lower the CGI timeout interval. By default, the interval is set to 5 minutes. If the CGI applications fail, the thread is not released until the timeout value is reached. The time between failure and when the thread is finally released is counted as time that the application is using the






processor. The CGI timeout in IIS 5.0 is the total amount of time a CGI application is given to complete, not the time until I/O must occur.

SIZING A PROJECT:-

Selecting a processor is one of the most critical decisions we make when designing an embedded system. Our selection is based on the features required to satisfy the control functionality of the final product and the raw computing power needed to fulfill those system requirements

In any case, once the system development has progressed, it's in the team's best interest to examine the CPU utilization so we can make changes if the system is likely to run out of capacity. If a system is undersized, several options are available: upgrade the processor (if possible), reduce available functionality, or optimize, optimize, optimize.

For example, if we're measuring the CPU utilization of a engine management system under different systems loads, we might plot engine speed (revolutions per minute or RPM) versus CPU utilization

Figure 2: CPU utilization vs. system load (RPM)

Figure 2 shows the salient data in graphical form. Of course we'll want to reduce the amount of manual work to be done in this process. With a little up-front work instrument the code, we can significantly reduce the labor






necessary to derive CPU utilization.

Table 2: System load data and calculated utilization

RPM T (μs) % Idle %CPU

500 249 72.3 27.7

1,000 272 66.2 33.8

1,500 310 58.1 41.9

2,000 350 51.4 48.6

2,500 372 48.4 51.6

3,000 451 39.9 60.1

3,500 703 25.6 74.4

4,000 854 21.1 78.9

4,500 1008 17.9 82.1

5,000 1206 14.9 85.1

5,500 1359 13.2 86.8

6,000 1501 12.0 88.0

MEMORY UTILIZATION:-

Although the principle for estimating the service time for memory is the same as that described in Resource Utilization and Performance,, we use a different formula to estimate the performance impact of memory utilization than we do for other system components. Memory is not managed as a single component such as a CPU or disk, but as a collection of small components called pages.






When the operating system needs to allocate memory for use by a process, it scavenges any unused pages within memory that it can find. If no free pages exist, the memory-management system has to choose pages that other processes are still using and that seem least likely to be needed in the short run. CPU cycles are required to select those pages. The process of locating such pages is called a page scan. CPU utilization increases when a page scan is required.

Memory-management systems typically use a least recently used algorithm to select pages that can be copied out to disk and then freed for use by other processes. When the CPU has identified pages that it can appropriate, it pages out the old page images by copying the old data from those pages to a dedicated disk. The disk or disk partition that stores the page images is called the swap disk, swap space, or swap area. This paging activity requires CPU cycles as well as I/O operations.

Eventually, page images that have been copied to the swap disk must be brought back in for use by the processes that require them. If there are still too few free pages, more must be paged out to make room. As memory comes under increasing demand and paging activity increases, this activity can reach a point at which the CPU is almost fully occupied with paging activity. A system in this condition is said to be thrashing. When a computer is thrashing, all useful work comes to a halt.

Swapping frees up more memory with each operation. However, as swapping continues, every process that is swapped out must be read in again, dramatically increasing disk I/O to the swap device and the time required to switch between processes. Performance is then limited to the speed at which data can be transferred from the swap disk back into memory. Swapping is a symptom of a system that is severely overloaded, and throughput is impaired.






Many systems provide information about paging activity that includes the number of page scans performed, the number of pages sent out of memory (paged out), and the number of pages brought in from memory (paged in):

Paging out is the critical factor because the operating system pages out only when it cannot find pages that are free already.

A high rate of page scans provides an early indicator that memory utilization is becoming a bottleneck.

A high rate of paging in can result from a high rate of process turnover with no significant performance impact.

STATIC ALLOCATION:-

If all memory is allocated statically, then exactly how each byte of RAM will be used during the running of the program can be established at compile time. The advantage of this in embedded systems is that the whole issue of memory-related bugs-due to leaks, failures, and dangling pointers-simply does not exist. Many compilers for 8-bit processors such as the 8051 or PIC are designed to perform static allocation. All data is either global, file static or function static, or local to a function. The global and static data is allocated in a fixed location, since it must remain valid for the life of the program.

The local data is stored in a block set aside for each function. This means that if a function has a local variable x, then x is stored in the same place for every invocation of that function. When the function is not running, that location is usually not used. This approach is used in C compilers when the hardware is not capable of providing suitable support for a stack. Figure 1 shows the memory organization with no heap and no stack, just global and one static block per function.






This approach prohibits the use of recursion or any other mechanism that requires re-entrant code. For example, an interrupt routine can't call a function that may also be called by the main flow of execution. In return for this loss of flexibility, the programmer is guaranteed no run-time memory allocation issues. It might be useful if all compilers gave the programmer the option of not using the stack. By statically defining all of the space, the programmer sacrifices some flexibility and efficiency, in exchange for extra robustness.

To benefit from the inherent memory safety of a completely static environment, it's important that the programmer avoid introducing dangers by trying to implement dynamic memory (such as reusing global data for different purposes) on top of the static environment.

For large systems, completely static allocation is not feasible since an enormous amount of RAM would eventually be required to satisfy every possible execution path of the program.

STACK-BASED MANAGEMENT






The next step up in complexity is to add a stack. Now a block of memory is required for every call of a function, and not just a single block for each function in existence. The blocks are stored on a stack, and are usually called stack frames.

The stack grows and shrinks as the program executes, and for many programs, it isn't possible to predict, at compile time, what the worst case stack size will be. A multitasking system will have one stack per task (plus possibly an extra one for interrupts). Some judgment must be exercised to make sure that each stack is big enough for all of its activities. It's an awful shame to suffer from an untimely stack overflow especially if one of the other stacks has a reserve of space that it never uses. Unfortunately, most embedded systems do not support any kind of virtual memory management that would allow the tasks to draw from a common pool as the need arises.

Figure 2: The life of a simple stack






One rule of thumb is to make each stack 50% bigger than the worst case seen during testing. In order to apply this rule, the programmer must know how big the stack, or stacks, became during testing. One simple technique is to "paint" the stack space with a simple pattern. As the stack grows and shrinks this will overwrite the area with its data. At a later time, a simple loop can run through the stack's predefined area to detect the furthest extent of the stack. Figure 2 shows an example of the life of a simple stack. The simple pattern written to the stack should be non-zero, since it is quite common to have data on the stack which has been assigned to zero. It would be difficult to distinguish this data from unused stack space.

HEAP-BASED MANAGEMENT:-

Many objects, structures, or buffers require a lifetime that does not match the invocation of any one function. This is particularly true in event-driven programs, which is typical of many embedded systems. One event may cause an item to be created, and that item will remain in use until some other event leads to its demise. In C programs heap management is carried out by the malloc() and free() functions. The malloc() function allows the programmer to acquire a pointer to an available block of memory of a specified size. The free() function allows the programmer to return a piece of memory to the heap when the application has finished with it.






Figure 4: The heap after a number of allocations Figure 4 shows the heap after a number of allocations. On the left-hand side, the free list still only contains a single element. Next, one of the blocks is freed and the right-hand side shows a free list with a second element. The available bock is of size 15 bytes. If an allocation of 10 bytes took place, the block of 15 may be broken down into a block of 10 and a block containing the remainder. The remainder block may be so small that no request is ever made that it can satisfy. While free blocks such as this may be merged later with adjacent free blocks, there is a danger that some will be lost forever.

MULTITASKING:-

While each task must have its own stack, it may or may not have its own heap, and regardless of whether the heap is based on the static allocation scheme, pools, or a general purpose allocation scheme. Having more than one heap means that we have to tune the size of a number of heaps, which is a disadvantage. However one heap for many tasks must be reentrant, which means adding lock that’s, will slow down each allocation and de- allocation.

It may be necessary to allow one task to allocate a piece of memory which may be freed by another task. This is useful for passing inter-task messages. When memory is passed between tasks in this way, make sure that it is always well defined who owns the memory at each point. It is obviously important that two tasks do not both believe that they own a piece of memory simultaneously. If this happened, it could lead to two calls to free the same memory block.

DISK UTILIZATION:-






Because each disk acts as a single resource, we can use the following basic formula to estimate the service time, which is described in detail in Resource Utilization:

S= P/(1-U)However, because transfer rates vary among disks, most operating systems do not report disk utilization directly. Instead, they report the number of data transfers per second (in operating-system memory-page-size units.) To compare the load on disks with similar access times, simply compare the average number of transfers per second.

If we know the access time for a given disk, we can use the number of transfers per second that the operating system reports to calculate utilization for the disk. To do so, multiply the average number of transfers per second by the access time for the disk as listed by the disk manufacturer. Depending on how our data is laid out on the disk, our access times can vary from the rating of the manufacturer. To account for this variability, it is recommended that we add 20 percent to the access-time specification of the manufacturer.

The following example shows how to calculate the utilization for a disk with a 30-millisecond access time and an average of 10 transfer requests per second:

U = (A * 1.2) * X = (.03 * 1.2) * 10 = .36

U:-is the resource utilization (this time of a disk). A:-is the access time (in seconds) that the manufacturer lists. X:-is the number of transfers per second that wer operating system

reports.






We can use the utilization to estimate the processing time at the disk for a transaction that requires a given number of disk transfers. To calculate the processing time at the disk, multiply the number of disk transfers by the average access time. Include an extra 20 percent to account for access-time variability:

P = D (A * 1.2)

P:-is the processing time at the disk. D:-is the number of disk transfers. A:-is the access time (in seconds) that the manufacturer lists.

For example, we can calculate the processing time for a transaction that requires 20 disk transfers from a 30-millisecond disk as follows: P = 20 (.03 * 1.2) = 20 * .036 = .72

Use the processing time and utilization values that we calculated to estimate the expected service time for I/O at the particular disk, as the following example shows:

S = P/(1-U) = .72 / (1 - .36) = .72 / .64 = 1.13



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