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Troubleshooting Techniques

Data flow over a mobile cellular network, details on structured cabling, connecting Macs to your network using AppleTalk and the usual solutions to vexing network problems

How does data flow between the mobile service provider and the user? What are the advantages of the different protocols available and what are the limitations? Which are the most widely used protocols? Specify the different bandwidths that are used in mobile technologies.

All cell phones have special codes associated to them. These codes are used to identify the phone, the phone's owner and the service provider. When you first power up the phone, it listens for a SID on the control channel. The control channel is a special frequency that the phone and base station use, to talk to one another about things such as call set-up and channel changing. If the phone cannot find any control channels to listen to, it knows it is out of range, and displays a "no service" message.

When it receives the SID, the phone compares it to the SID programmed into the phone. If the SIDs match, the phone knows that the cell it is communicating with is part of its home system. Along with the SID, the phone also transmits a registration request, and the MTSO (Mobile Telephone Switching Office) keeps track of your phone's location in a database. Hence, the MTSO knows which cell you are in when it wants to ring your phone.

The MTSO gets the call, and it tries to find you. It looks in its database to see which cell you are in. The MTSO picks a frequency pair that your phone will use in that cell to take the call. The MTSO communicates with your phone over the control channel to tell it what frequencies to use, and once your phone and the tower switch on those frequencies, the call is connected.

You are talking by two-way radio to a friend! As you move toward the edge of your cell, your cell's base station will note that your signal strength is diminishing. Meanwhile, the base station in the cell you are moving toward (which is listening and measuring signal strength on all frequencies, not just its own one-seventh) will be able to see your phone's signal strength increasing. The two base stations coordinate themselves through the MTSO, and at some point, your phone gets a signal on a control channel telling it to change frequencies. This hand off switches your phone to the new cell.

For more information on how cell phones work and how data signals transfer from one mobile phone to another, visit http://www.howstuffworks.com/cell-phone2.htm

I wish to connect two computers via cable to transfer data and to use a single Internet connection on both. Please let me know how I can do this and what accessories I need for the setup?

When you set up Internet Connection Sharing (ICS) on the host computer, two network adapters are required for ICS to function properly. To determine the number of adapters that are installed, double-click Network, in Control Panel. Look in the Network Properties dialog box for the information that is appropriate to your connection type.

For computers that are using a standard modem connection, the following adapters are used:

TCP/IP (Shared)—Dialup Adapter

TCP/IP (Home)— Network Adapter

For more information on Internet Connection Sharing visit http://support.microsoft.com/support/kb/articles/q234/8/15.asp
http://www.duxcw.com/digest/Howto/network/net2pc/ is a link with information on "How to Network Two Windows 95/98 Computers"

For more information on Internet connection sharing in Windows visit http://www.infinisource.com/techfiles/ics-troubleshooting.html


Could you explain in detail structured cabling? How is it done and what devices are required?
Structured Cabling is a system of wiring wherein the main components, once installed, do not change. In its most basic form, a structured wiring system consists of horizontal wiring and appropriate connecting hardware. Structured Cabling is a technique of cabling buildings for the purpose of electronic communications. It is a standard method of engineering and installing a data and voice cabling system in a business environment.

It provides the flexibility of application independence, multiple logical topologies, and easy moves, adds and changes. Structured Cabling System (SCS) wiring is defined as all required equipment and cabling, including hardware, termination blocks, cross connect wire or cordage, patch panels, patch cords, telecommunication outlets, and fiber light guide, cable installed and configured to provide computer data and voice connectivity from each data or voice device to the network file server or voice network/switch designated as the service point of the local area network.

The SCS serves as a vehicle for transport of data, video and voice telephony signals throughout the network from designated demarcation points to outlets located at various desks, workstation and other locations as indicated by the customer. In addition, these links/channels are capable of supporting high-end applications such as 100 Base-T.

For more information on Structured cabling visit:


Can you please give me information on the following?

  • Class A, B, C and D
  • Subnet Mask and how I can change my subnet ID? When does it become necessary to change my subnet ID?

Generally speaking, each computer that accesses the Internet has to have a unique IP address. In most cases, when you connect to the Internet from home, your Internet service provider assigns a unique IP address to your computer. But, if you want to connect all the computers in your office to the Internet at the same time using a single Internet connection, you'd usually ask your Internet service provider for a range of IP addresses— one IP address per computer. This is where different IP classes come into play— depending on the number of computers you want to connect you'd need a different class of IP address range.

Class C
This is the most widely used class by small businesses. When you look at the IP address, you'll notice that class C networks start with a first number that's between 192 and 223 (205.161.74.x for example). This can range up to 2,097,151 class C networks and each network can handle close to 254 computers.

Class B
IP addresses of this type range between 128 and 191. It's possible to have 16,384 of these networks and each class B network can handle up to 65,534 IP addresses or computers.

Class A
Ranges between 1 and 126. Only 126 of these networks are available. However, each class A network can handle 16,777,214 IP addresses or computers.

For more information on TCP/IP, please visit http://www.hill.com/library/publications/tcpip.shtml
For information on subnet masking visit http://www.cisco.com/univercd/cc/td/doc/product/iaabu/pix/pix_v42/pix42cfg/pix42ape.htm and

I am new to networking and am very interested in it. Could you please suggest some good sites where I can read articles on networking concepts, beginning from the basic through advanced?

The following links contain tutorials on networking: http://elara.hypermart.net/webdirectory/PERL/Tutorials/Networking/ http://www.rad.com/networks/tutorial.htm

Please give me information on the following:

  • I want to network four MACs with 10 IBM PCs, through structured CAT 5 cables. Do you suggest a 24/32 port 100 mbps hub or a LAN Switch for faster speed and bandwidth?
  • Which protocol/ software should be used for the four MACs to be part of the IBM PCs' network, so that all can communicate amongst each other, be it PC to PC, PC to MAC and vice-versa? How do I do it under Windows 2000.

Hubs and switches basically perform the same function. They connect multiple computers and equipment, though how they do this varies.

While a switch is faster, a hub is economical. You can go for a switch if your priority is high bandwidth in a multiple user and heavy application environment. You can go for a Hub if you have less users or light applications. Meanwhile, a switch is always a good investment.

You can use the AppleTalk protocol to communicate MAC with other computers.

Networking on an Apple Macintosh computer is implemented through the AppleTalk protocol. Applications and processes can communicate across a single AppleTalk network or an AppleTalk Internet, which is a number of interconnected AppleTalk networks. By using AppleTalk, applications and processes can be transferred, data can be exchanged and resources such as printers and file servers can be shared. AppleTalk remote access is supported by the AppleTalk Control Protocol (ATCP).

With ATCP, Macintosh clients can run the AppleTalk network protocol over Point-to-Point Protocol (PPP). With ATCP support, a remote user can access a Web server over TCP/IP, print a document to an AppleTalk printer, and connect to a Macintosh file server (over TCP/IP or AppleTalk), all with the same dial-up connection over PPP.

The following configuration steps are related to Windows 2000 Operating System.

  • Open Network and Dial-up Connections.
  • Right-click the connection you want to configure, and then click Properties.

Do one or more of the following:

  • To configure dialing devices, phone numbers, host address, country/region codes, or dialing rules, click the General tab.
  • To configure dialing and redialing options, multilink configuration, or X.25 parameters, click the Options tab.
  • To configure identity authentication, data encryption, or terminal window and scripting options, click the Security tab.
  • To configure the remote access server and protocols used for this connection, click the Networking tab.
  • To enable or disable Internet connection sharing and on-demand dialing, click the Sharing tab.

Note: To open Network and Dial-up Connections, click Start, point to Settings, and then click Network and Dial-up Connections.

Depending on the type of connection you are configuring, different options appear. For example, a local area connection only displays the General tab.

I am using a laptop and a desktop. My hard disk of my laptop has crashed. I want to restore the data backup (on the desktop) to my laptop computer through a PCMCIA card driver. I propose to do this by booting up the laptop with the bootable floppies and from there I want to get the data on to my desktop with a network card. Is there any way of recognizing the PCMCIA card in DOS? That is, is it possible to assign some drive letter to the PCMCIA card while the system boots from a bootable floppy drive?

Please let me know the make and model of the PCMCIA card and the laptop that you are using. Most of the PCMCIA card manufacturers provide DOS drivers/software that enables the PCMCIA card to work under DOS. However, you can try the following, which might help you find a solution for the problem you are facing.

  • Networking the Laptop and the Desktop.
  • Using an External Zip Drive/CD Writer.

How can a Wireless LAN be implemented? What is the methodology used? What are the advantages and disadvantages?
A wireless LAN is a flexible data communications system implemented as an extension to, or as an alternative for, a wired LAN. Using radio frequency (RF) technology, wireless LANs transmit and receive data over the air, minimizing the need for wired connections. Thus, wireless LANs combine data connectivity with user mobility.

For more information on setting up a wireless LAN visit http://www.proxim.com/wireless/whiteppr/whatwlan.shtml and for benefits of wireless LANs visit http://www.wirelesslan.com/benefits/.

How do I connect a cable to a connector? Can you please give details about the cable, how many wires should be there and the value of each wire?
A connector is part of a cable that plugs into a port or interface to connect one device to another. Most connectors are either male (containing one or more exposed pins) or female (containing holes in which the male connector can be inserted).

For more information on connecting a cable to a connector visit:

How can two computers communicate using IR rays?
In order to connect two Windows 95 computers using IrDA, you need to have the IrDA driver, which is compatible with Windows 95.

Here is the link which provides information about the drivers used to connect two Windows 95 system using IrDA and to download the same:

http://www.microsoft.com/windows95/downloads/ contents/WURecommended/S_WUCommunications/ W95IrDA/Default.asp

To connect your Desktop to the Notebook using Infrared port.

Infrared is a communication port generally used in hand-held devices such as Palmtop, which are equipped with an Infrared port. Infrared port is usually in-built with the Laptops and Palmtops.

For more information on IRDA visit http://www.pcquest.com/jul97/irda.html

IRDA supports only a distance of up to seven meters.

Can you please tell me how to network three computers using a LAN card step-by- step?
Check the links below for a step-by-step explanation for connecting three computers using a LAN card.

http://www.webdevelopersjournal.com/ columns/greg1.html

I have two computers with Windows 98 installed on both. How do I connect them using an Ethernet card?

For connecting computers, you should have the following important components installed in the Configuration tab of Network dialog boxes that you can get by double-clicking on the Network icon in Control panel window displayed by clicking Start-Settings- Control Panel in both the computers:

  • Client for Microsoft Networks.
  • File and printer sharing for Microsoft Networks

(If printers need to be shared)

  • TCP/IP
  • Ethernet card.

Here are some links, which give information regarding configuring a network in Windows 98/ 98 SE and Windows 95:


I have a Windows 2000 Professional system with D-link 56kbps external modem while my friend also has a Windows 2000 Professional system with 56kbps HSP micro internal modem. We have tried to connect the two computers through my phone line and modem. We made one connection for incoming calls and have also made a new connection with the other PC's phone number. When I dial to my friend's PC, I only get the fax tone i.e. the tone one gets when one connects to the ISP. After that nothing happens. Can you explain how I can complete this connection?

You can use HyperTerminal in order to connect two computers. Please follow the steps given below to start the HyperTerminal:

1. You can start HyperTerminal by clicking Start-Programs-Accessories- Communications.
2. Click HyperTerminal-Click Hypertrm.exe.

NOTE: For information about how to use HyperTerminal, click the Help menu in HyperTerminal. NM

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