Unit 8

Lesson 1 - Building a Small Peer-to-Peer Network

   Overview of the Process

In general, you will build your network by working your way up the Open Systems Interconnection (OSI) model. The Data Link Layer is already established because you (or someone else) installed the NIC and its driver. You will begin this lesson at the Physical Layer, by using cable to make the physical connections between computers. Then you will move up to higher layers by installing peer-to-peer networking software and the Transmission Control Protocol/Internet Protocol (TCP/IP) protocol stack.

Connect the Cables

If you only need to network two computers, you can use a single Ethernet crossover cable to connect one NIC directly to another (this is different than a standard Category 5 patch cable). However, your class will probably use a hub so that more computers can participate in the network.

Use one UTP cable to attach each computer's NIC to one port of the hub. This is demonstrated on the Peer-to-Peer Network Diagram.

Peer-to-Peer Network

Peer-to-Peer Network

If you have network-capable peripherals, such as printers, do not attach them to the hub. For now, only connect peer computers to the hub.

Now supply power to the hub. The hub is a repeater, thus it will not function unless it is plugged in.

Set Up Client for Microsoft Networks

Client for Microsoft Networks is an application that allows a computer to communicate with its peers over a network. All of your computer's network settings will be configured within this application, thus you must install and set it up first.

1.

From the Start menu, select Settings, then Control Panel.

2.

In the Control Panel, select Network. In the Network dialog box, shown on the Network Dialog Box Screen Diagram, the list of components should include your computer's NIC. If it does not appear in this list, see your instructor before continuing.

Network Dialog Box Screen

Network Dialog Box Screen

3.

In the Network dialog box Configuration tab, click Add.

4.

In the Select Network Component Type dialog box, highlight Client, then click Add.

5.

In the Select Network Client dialog box, shown on the Select Network Client Dialog Box Screen Diagram, highlight Microsoft, then highlight Client for Microsoft Networks. Click OK.

Select Network Client Dialog Box Screen

Select Network Client Dialog Box Screen

NOTE:

You may be prompted to insert a disk or point to the location of an installation file. Your instructor will provide these.

Client for Microsoft Networks now appears in the network components list of the Network dialog box.

Network and Transport Layers:
Bind Protocols to Each NIC

When you installed the Ethernet network driver for your NIC, the TCP/IP, Network Basic Input/Output System (NetBIOS) Extended User Interface (NetBEUI), and Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) protocols were installed by default. Now you must tell Client for Microsoft Networks which of these protocols you want to use. This process is called "binding" a protocol to the NIC.

1.

In the Network dialog box Configuration tab, click Add.

2.

In the Select Network Component Type dialog box, highlight Protocol, then click Add.

3.

In the Select Network Protocol dialog box, shown on the Select Network Protocol Dialog Box Screen Diagram, highlight Microsoft, then highlight TCP/IP. Click OK.

Select Network Protocol Dialog Box Screen

Select Network Protocol Dialog Box Screen

TCP/IP now appears in the network components list of the Network dialog box. It is also bound to the NIC installed in your computer. To verify this:

1.

In the Network dialog box Configuration tab, highlight your NIC and click Properties.

2.

In the dialog box for your NIC, click the Bindings tab. It should show that TCP/IP is now associated with the installed NIC. An example of this is shown on the NIC Properties Bindings Tab Screen Diagram.

NIC Properties Bindings Tab Screen

NIC Properties Bindings Tab Screen

NOTE:

Each peer computer in your network must run the same protocol stack. Bind all NICs to TCP/IP.
Network and Transport Layers: Configure TCP/IP

1.

In the Network dialog box Configuration tab, highlight TCP/IP (bound to your NIC) and click Properties.

2.

In the TCP/IP Properties dialog box, click the IP Address tab.

3.

In the IP Address tab, select Specify an IP address. The fields for IP Address and Subnet Mask are activated.

The details of IP addressing and subnet masking are beyond the scope of this course; however, the basics are presented next so you will understand what you need to enter into this dialog box.

   IP Addresses

Each computing device or "host" on a TCP/IP network is assigned a unique IP address. Each IP address is a binary number 32 bits long.

To make it easier for people to read and understand IP addresses, the addresses are often written as four decimal numbers, each separated by a dot. This format is called "dotted decimal notation." Each of the decimal numbers is the equivalent of the 8-bit binary number in one field.

For example, the following binary IP address:

    10000001 00001111 00010001 00000011

the dotted decimal version of the same address is:

    129.15.17.3

An IP address is divided into two parts: the right part identifies an individual host, and the left part identifies the network on which the host resides. Some addresses use 8 bits for the network portion of the address, and use the other 24 bits for the host portion. Other addresses use 16 bits for the network and 16 bits for the host, or 24 bits for the network and 8 bits for the host.

In this exercise, we will use an IP network address portion that is reserved for testing, or for local networks not connected to the Internet: 192.168.xxx.xxx. The "xxx" identifies the host portion of this address. You can insert any numbers there, as long as the number is between 000.001 and 255.254, and each computer uses a unique host address.

NOTE:

For simplicity, we are not dividing this network into subnets.
   Subnet Mask

The subnet mask is a separate 32-bit pattern that marks the network portion and host portions of an IP address. As you can see on the Subnet Mask Diagram, each bit of the subnet mask corresponds to 1 bit of the IP address. A "1" in the subnet mask means that the corresponding bit in the IP address is part of the network portion. A "0" in the subnet mask means that the corresponding IP address bit is part of the host portion. Subnet masks use dotted decimal notation just as IP addresses do.

 

Network Portion

Host Portion

IP Address

129

15

17

3

1

0

0

0

0

0

0

1

0

0

0

0

1

1

1

1

0

0

0

1

0

0

0

1

0

0

0

0

0

0

1

1

Subnet Mask

255

255

0

0

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0
Subnet Mask
Assign IP Addresses and Subnet Masks

Now that you understand the basics of IP addresses and subnet masks, you can continue configuring TCP/IP.

1.

In the IP address tab shown on the IP Address Tab Screen, enter the following address into the first three fields of the IP Address:

    192.168.0

In the last field of the IP Address, enter a unique number between 1 and 254.

NOTE:

Each computer in your network must have a different number in the IP Address field.

 

IP Address Tab Screen

IP Address Tab Screen

2.

In the Subnet Mask, enter the following address:

    255.255.0.0

NOTE:

Each computer in your network must have the same number in the Subnet Mask field.

3.

Click OK to return to the Network dialog box.


LAB
Click the icon to link to the Basic Internet Addressing Exercises lab.

Upper Layers: Configure Workgroup and Resource Sharing

Thus far in this process, you have set up the first four OSI layers of your network:

Physical Layer--Use UTP cable to connect each NIC to a hub port.

Data Link Layer--Install the Ethernet NIC and its driver.

Network and Transport Layers--Bind the TCP/IP protocol stack to each NIC, and assign each node a unique IP address.

Now that you have established the communication foundation of your network, it is time to configure the following two settings that allow Client for Microsoft Networks to interact with your applications and other network nodes:

Assign each node a computer name and workgroup name

Define access to your files or printer
   Assign Each Node a Computer Name and Workgroup Name

Your computer's IP address uniquely identifies it to other machines. However, to help human users recognize your computer, you should assign it a common name.

1.

In the Network dialog box, click the Identification tab. The Identification tab screen will appear as shown on the Identification Tab Screen Diagram.

Identification Tab Screen

Identification Tab Screen

2.

In the Computer Name field, enter a unique, easy-to-remember name that does not include spaces.

3.

In the Workgroup field, give your peer-to-peer network a name. In a business environment, you might set up separate workgroups for Accounting, Sales, or other departments. For your class project, all computers must belong to the same workgroup.

NOTE:

All computers in your peer-to-peer network must have the same name in the Workgroup field.

4.

The Computer Description field is optional. It captures additional information that helps identify each computer.

   Define Access to Your Files or Printer

In a Windows peer-to-peer network, you can decide whether to allow other users to access your hard drive or attached printer. However, you cannot assign different access rights to particular users or groups of users. This default level of control is called "share-level access."

1.

In the Network dialog box, click File and Print Sharing.

2.

In the File and Print Sharing dialog box, select both options, then click OK, as shown on the File and Print Sharing Dialog Box Screen Diagram.

File and Print Sharing Dialog Box Screen

File and Print Sharing Dialog Box Screen

In the Network dialog box, the components list now includes a new entry called "File and printer sharing for Microsoft networks." With this component installed, you can define different types of access for each of your drives, folders, or printers. You can also set a password for any of these resources.

Virus Prevention and Detection

Viruses are destructive and self-replicating applications that are often disguised within an innocent-looking application, such as a game. When a user runs the application, the virus copies itself to the user's system, then performs the job it was designed to do. Some viruses only display a political message. Others erase entire hard drives. A single virus can infect an entire network within minutes, thus virus prevention software is essential for every node on a network.

Excellent applications are available to detect and eliminate viruses; however, all virus prevention programs are blind to new viruses that use new and unknown techniques. When a new virus is discovered anywhere in the world, the developers of virus control software quickly create a software plug-in that allows their application to recognize and eradicate the new threat.

A user can usually prevent problems by promptly downloading and installing each new "signature" file. However, some unfortunate victim must always be the first to discover a new virus. If you do not want that dubious honor, a few simple procedures will reduce the chance that you will get a virus:

Install virus detection software and keep it up to date. As we just explained, software cannot protect against a radically new threat it cannot recognize. However, most viruses, even new ones, use the same well-known basic techniques.

Once your software is installed, use it. It takes a little extra time to scan all incoming floppy disks; however, it is time well spent.

Be wary of electronic mail (e-mail) attachments. Many of the most famous viruses of the past few years have been spread through e-mail systems. Once in a computer, a virus simply mails copies of itself to every entry in a user's e-mail address book. Thus, if you receive an e-mail with an attached executable file, even from a friend, do not launch that program until you verify what it is. If you are not totally sure of an attachment, simply delete the entire message. A virus is an application, thus it does not become active until a user runs it.

Be wary of downloadable software. Reputable World Wide Web (Web) sites that provide free downloadable applications do everything they can to ensure that their content is virus-free. However, for all the reasons we have discussed, it is impossible to be totally sure. Some users who enjoy downloading programs and games set up a non-networked computer as a quarantine area. All new programs are tested on that platform before being used on the "real" system.

Most businesses are willing to install and maintain antivirus software; however, they do not want to spend the extra time and effort necessary to quarantine downloadable applications. Thus, many companies have rules that prohibit employees from downloading applications to the company network, or even bringing in floppy disks. Some companies, especially those who have had virus problems in the past, may even dismiss employees who violate those rules. At first, this seems overly harsh. However, when you consider that a single virus outbreak can cost a company thousands or millions of dollars, it is easier to understand that releasing a virus can be as costly as setting off a bomb.

   Activities

See the Activities and Extended Activities section in Unit 8 Lesson 1 in your textbook Introduction to Networking to test what you have learned so far.

[ Previous Section ] [ Unit Contents ] [ Next Lesson ]