Local Area Networks (LANs) have 3 basic topologies, these are:Introduction
Transmission Media
Physical
Topologies
Medium Access Protocol
Operating System
Video Conferencing
Network software
Network Proposal
Network Proposal 2
Recommended System
Bibliography
Glossary
This is a feasibility study into the benefits, and cost of installing an local area network for a local IT company. The network must offer state of the art hardware and technology. The proposed network will have 100 nodes connected to it. The network must have sufficient bandwidth to allow video conferencing.
To help the reader understand some of the concepts of computer networking I have included short descriptions about transmission media, network topologies and network access control. Where appropriate some abbreviations and phrases have been included in a glossary at the end of this report.
Unless stated otherwise all prices include VAT, and are in sterling (where prices are in a foreign currency the sterling equivalent is also shown). When quoting a price I will also included the name of the supplier. Supplies will be listed in the bibliography.
There are some common features of both network proposals. These are separate from the network proposals. The total price quoted at the end of each network proposal only includes:
The cost of the hardware needed to build the network (PC’s, cabling)
Software to run the network (e.g. WindowsNT and Novell NetWare)
The price does not include:
Software users of the network will run (word processors, etc..)
Video conferencing hardware and software
The cost of employing people to build the network.
When specifying computer and server specifications I have set out the minimum specification that the computer much meet. However, I have not listed some features because they are common to all new computers. These include, USB, floppy disk, cache, mouse, graphics card.
There are various different types of transmission media, each with their own advantages and disadvantages. They can be divided into two types, physical and non-physical.
This involves some kind of cabling. There are three main types is common use, Coaxial, Twisted pair, and fibre optic.
Coaxial. This type of cable has two conductors. One is a single solid wire. This is surrounded by an insulator, this in turn is then surrounded by a wire mesh (like the aerial lead for your TV). Because it is well insulated and can accommodate large bandwidths it is well suited to high speed networking. This is a relatively insecure medium, because it is possible to listen to the signal without the signal being affected.
Coaxial cable is reasonably cheap and reliable. If there is a problem with the cable it can be replaced easily.
Twisted Pair. This is usually two wires loosely spun around each other. One wire is used to transmit data. The other is used to receive. Because of this two cables need to be connected to the node (if the network topology is a bus, or ring). This is a relatively insecure medium, because it is possible to listen to the signal without the signal being affected.
The are two variations of twisted pair, shielded twisted pair (STS) and unshielded twisted pair (UTS). UTS is much slower than STS because the two wires are not shielded from each other.
Fibre Optic. This allows very high bandwidth transmission by modulating the data into a beam of light. This is sent along either a special glass or plastic fibre. Fibre optic is not affected by interference, unless someone cuts the cable. If this does happen the re-connecting the cable is expensive. Because unlike coaxial and twisted pair, which can be easily repaired, this needs to either have the whole cable replaced or for the cable to be rejoined using a special connector. If the cable is interfered with, the transmitting and receiving nodes can detect this (because the signal has to be cut). Because of this fibre optic is the most secure type of transmission media.
This is the most expensive type of cabling, because of the special equipment that is needed.
Non-physical transmission media includes, microwave link and radio. These are not required for the proposed system. They are useful for network links that are within the line of sight and where cabling is not suitable.
Local Area Networks (LANs) have 3 basic topologies, these are:
Star. With a star network each node is directly connected to a central hub. The server is also connected to this hub. Because each node has a direct connection to a hub this type of topology uses a lot of cable. To reduce the amount of cabling it is possible to use more that on hub, as shown in the diagram to the right.
The amount of cabling needed for this type of network topology means that this is an expensive solution.
If a node on the network goes down, then the rest of the network is not affected. However with the amount of cabling involved it could be difficult to find a damaged cable. Adding a new node is difficult because if needs to be connected directly to the server, which could be on the other side of the building, which is why hubs are used.
Bus. A bus network has all the nodes connected to the server with one cable. Each node "drops off" from this cable. When a node is transmitting it is the only device using the cable, and all other nodes can receive the transmission (even if the node is not the intended recipient). When the signal reaches the end of the cable the signal is absorbed by the terminators. Because the signal degrades over distance a repeater is needed about every 200 metres. Because this type of topology does not allow real-time transmission it is not suitable for large scale video conferencing.
This type of topology is relatively cheap because it has very little cabling. If either the cable is disconnected or cut then all the nodes after the break in the cable are disconnected from the network. Maintaining this type of network is relatively easy, because there is only one cable that can be broken, and if a node goes down it does not effect the rest of the network.
Adding a new node is easy because the cable is taken from the nearest machines and connected to the new node, this does, however, require that the network be show.
Ring. A simple ring network has all the nodes connected to each other with one connection. Unlike with a bus network the cable does not pass the node, in enters the node, with a new cable connecting to another node. This allows for the signal to be boosted by each node, allowing for larger networks.
If any node on this type of network goes down, then the whole network also goes down. Adding a new node to this type of network is similar to adding a node to a bus network.
There are many different types of controlling how and when a node has access to the network. Some are dependant upon the type and size of the network topologies.
Carrier sense multiple access with collision detection (CSMA/CD). This protocol allows nodes to transmit using the same cable. If two nodes try to transmit at the same time they both stop transmitting, jam the cable (to stop another node from transmitting), and wait a random time before trying to re-transmit.
Because this can cause the network to slow down it is important to reduce the chances of a collision happening. This is achieved by listening for a transmission, and, if the line is clear begin transmitting.
Token Bus. All the nodes are arranged into a logical ring, and a token is passed from node to node (following the ring). When a node that is waiting to transmit receives the token it sends the frame. Once the node has finished sending the frame it passes the token onto the next node. Because only one frame is transmitting at anyone time data frames cannot collide.
The larger the network is with this type of control protocol the longer it will be before a node has a change to send more data. This can be overcome by splitting the network into several sub networks. However for a network of 100 nodes this should not be necessary. This is the best choice if real-time communication is important.
Token Ring. This type of access control specifically applies to ring networks. Like token bus a token is passed around the network, when a node receives the token and wants to transmit it is allowed to do so. The data is then passed from node to node until the data reaches the destination node. The destination node copies the data and continues to pass it along the ring. Once the data is received by the transmitting node the data is removed from the network. The token is then passed to the next node.
The problem is that with a large network, passing the data from node to node is time consuming, and unnecessary if the destination node has been found.
Polling. This is similar to control token passing. The difference is that the server asks, in turn, each node if it is waiting to transmit. If it is the node is allowed to transmit it does so. There are a couple of disadvantages with this system. First the network can be busy for long periods as the server polls each node to ask if it wants to transmit. Secondly, if a node wants to send data to another node it must be transmitted via the server, putting an unnecessary demand on the server's resources. This protocol is not suitable to real-time communication.
The latest version of this operating system is v5. It allows the use of many different types of network protocol to be used, this includes IP (Internet Protocol) and IPX (Internetwork Packet Exchange). NetWare offers a full migration path between IPX and IP, so that any existing computer networks can be upgraded to use IP.
NetWare comes packaged with Netscape's FastTrack web server. This will allow the company to offer, an internal web service to the employees. The advantage of this is that it will allow greater communication between management and the employees.
Novell Directory Services (NDS) offers many benefits to the network manager, and the users of the network. It allows centralised access of all the network resources, and allows the users, and network managers to access the network services through a single login.
Novell NetWare v5 Server costs £653.30. This allows for 5 users. To add an additional 100 users costs £3,863.40 (NovaTech)
WindowsNT is available to two separate versions, WindowsNT Server, and WindowsNT workstation.
WindowsNT workstation is the OS used on each workstation. It looks and operates (as far as the user knows) like Windows95. Unlike Windows95, however, NT has memory protection. WindowsNT Server is the OS run on the computer(s) that are the network servers.
WindowsNT offers a number of security features, including user authentication, access control, and Point-to-Point Tunnelling Protocol (PPTP) for secure Internet connections.
Like NetWare, WindowsNT can use its own file system called NTFS (NT File System). This offers a high level of security and reliability.
Because the WindowsNT GUI is similar the Windows95/98 GUI many users will already be familiar with the system, and will need little training.
WindowsNT Server costs £636.85. This allows for a maximum 5 users. To add an additional 100 users costs £3,173.00 (£31.73 per user).
Both of the proposed networks will use this video conferencing solution.
The Intel ProShare Video System 500 comes supplied with the following:
Intel ProShare conferencing software with integrated Microsoft NetMeeting and PhotoExchange
Single PCI ISDN/audio/video capture card
Headset with microphone
Composite colour video camera
(Intel)
The cost for this system is $799 (exc. VAT), total price for 100 users is $93,882.50 (approx. £58,207.15. Based on a exchange rate of 1.62).
As not every PC on the network will require video conferencing hardware, the cost has not been included in the total cost of either network proposal.
An office usually requires 4 different types of software, word processor, spreadsheet, database and a presentation package. Because of this many software publishers package all these types of software together. Examples of this are MS Office, and Lotus SmartSuite. MSOffice includes, Word, Excel, Access, PowerPoint (and other software). Lotus SmartSuite includes Word Pro, 1-2-3, Approach and Freelance (and other software)
Because MS Office includes software titles that are generally considered to be the industry standard this will be used. The advantage of this is that most computer users will have used it before. MSOffice is available in several versions (each with different software) the relevant version is MSOffice Pro 97, this includes Word, Excel, Access, PowerPoint, Outlook and Internet Explorer.
Although it is possible to purchase a single copy of MSOffice and install it onto every workstation, it is illegal (software piracy). To be able to do this the software must be licensed.
The total price to licence 101 copies (1 for the server) of MSOffice 97 Pro is £18,555.72 (Technomatic).
For teams work software MS Project 98 is the best choice as it offers full integration with MSOffice programs.
The total price to licence 101 copies (1 for the server) of MSProject 98 is £23,268.38 (Technomatic).
The total price for both of these packages is £41,824.10.
This network will use the bus topology, with token bus passing access control. Coaxial cable, with BNC connectors will be used to connect the nodes.
A combination of WindowsNT and NetWare. With this configuration NetWare will be used to provide the networking facilities (such as access control, and network protocol), and WindowsNT is used to provide the user interface.
Each workstation should conform to this minimum specification:
CPU: Pentium2 333Mhz
RAM: 64Mb
HD Space: 4Gb
HD Interface: IDE (or SCSI)
Installed OS: WindowsNT Workstation
Monitor: 15"
Quantex advertise the following system (PC Direct Nov'98, page 148)
CPU: Pentium2 450Mhz
RAM: 64Mb
HD Space: 4.3Gb
HD Interface: IDE
Monitor: 17"
Other features: 32 speed CDROM, ZIP drive
Installed OS: WindowsNT 4 workstation
Note: Does not include network card
Price: £1173.83
Total cost for 100 workstations = £117,383.
dan technology can supply the following system. dan have a facility on their web site to choose the specification that you require.
CPU: 333MHZ Pentium II INTEL Processor
HD Space: 4Gb
HD Interface: EIDE
Memory: 64Mb
Monitor: 15"
Installed OS: WindowsNT 4 workstation
Note: Does not include video camera or network card
Other features: 32 speed CDROM
Price: £1089.22
Total cost for 100 workstations = £108,922.00
Because the dan machine has a lower price it will be used for the workstations. As the dan system does not come with network cards they need to be purchased separately. NovaTech can supply 100 network cards for £4064.33.
The server should have the following minimum specification:
CPU: Two PII 450Mhz
RAM: 128Mb
HD Space: 15Gb
HD Interface: SCSI 2
Installed OS: NetWare 5
Time Computers advertise this system (PC Direct Nov'98, page 152)
CPU: PII 450Mhz (can support dual processors)
RAM: 128Mb
HD Space: 9.1Gb
HD Interface: SCSI 2
Installed OS: WindowsNT Server
Other features: 8Gb tape streamer, 100Mbps network card, 56k modem, 24 speed CDROM.
Note: Hard drive is smaller than required, and additional 9.1Gb can be added for £388.92.
Price: £3523.83
Total price (with added HD): £3912.75
dan technology advertise the following system:
CPU: Dual PII 450Mhz
RAM: 128Mb
HD Space: 18Gb
HD Interface: SCSI 2
Installed OS: WindowsNT Server
Other features: 32 speed CDROM, network card.
Price: £6112.35
As the Time system is significantly cheaper this will be used as the server. The file server should be powered though a UPS (uniteruptable power supply). Insight sell a APC brand UPS for £273.78.
Assuming that the average distance between two PC's on the network is approximately 3 metres, 300 metres of cabling is required. Another 30 metres (minimum) is needed to connect the server (the server should be kept is a secure room). 101 BNC T-pieces are needed, 201 BNC crimp plugs, and 2 BNC terminators. Insight can provide all this for £457.44. The size of the network dictates that a repeater is needed. A suitable repeater is available from Dabs Direct for £175.07.
The total price for the hardware (PC's, cables, etc...) is: £117,805.37.
This network configuration will be running Novell NetWare on the server, with WindowsNT Workstation providing the operating system for the users PCs. The total cost for the NetWare server, with licences is £4516.70. WindowsNT Workstation is pre-installed on all the workstations.
There should be 1 printer shared between 20 workstations on this network. To accomplish this a printer server is needed. This allows the printer to be accessed by anyone on the network, but the workstations should be configured to print to the nearest printer.
The printer to be used on this network will be the HP LaserJet 4000. There reasons for this are:
Prints 16 pages per minute. As the printers are used in an office environment the speed at which the printer operates is important.
WindowsNT driver. Often hardware is not supplied with drivers for WindowsNT, and it is important to be sure that the hardware is supplied with them.
The total price is £5,416.52 (from Nike Data Centre - referred by the HP website).
As Hewlett Packard printers are to be used, Hewlett Packard printer servers should also be used (to ensure compatibility) the HP JetDirect 300X is most suitable. It is possible to buy these from the Hewlett Packard website, the price for 5 is £1,195.25.
The total cost for this network is £128,933.84.
The star topology is to be used for this network. It will use the twisted pair type cabling, with RJ45 connectors. The access control method will be token bus to ensure that each workstation has a fair chance of sending is data over the network. The server software will be WindowsNT server, and all the workstations will be running WindowsNT Workstation.
Each workstation should conform to this minimum specification
CPU: Pentium2 400Mhz
RAM: 128Mb
HD Space: 4Gb
HD Interface: IDE (or SCSI)
Installed OS: WindowsNT Workstation
Monitor: 17"
dan technology can provide the following system:
CPU: 400MHZ Pentium II INTEL Processor
RAM: 128Mb
Monitor: 17"
Hard Disk: 4.0GB Ultra DMA EIDE
Other: 32 speed CDROM
Operating System: WindowsNT workstation
Network: 3COM 900 PCI COMBO Card
Price: £1395.90
Price x 100: £139,590.00
Quantex can provide this system:
CPU: Pentium2 450Mhz
RAM: 64Mb (additional 64Mb from NovaTech is £75.20)
HD Space: 4.3Gb
HD Interface: EIDE
Installed OS: WindowsNT Workstation
Monitor: 17"
Other: Zip drive, 32 speed CDROM, network card.
Total Price: £1,249.03
Price x 100: £124,903.00
Because the Quantex system has a better specification and a lower price this is the system that will be used for the workstations.
As the network is to use a star topology, the network will be divided up into a number of sub networks. Each sub net will have a maximum of 20 workstations. This will require 5 network hubs with at least 20 connectors, and 1 with a minimum of 6 (1 for each hub and 1 for the server). If the hubs have spare connections, this will allow for future upgrades to the network. All the hubs need to be capable of 100Mbps.
Simply advertise 3com's SuperStack II Hub (24 RJ45 connectors) for £856.58. Total price £4,282.90. 1 more additional hub is required, 3com's OfficeConnect TP800 (8 RJ45 connectors) costs £247.93. As each workstation is supplied with a network card no more need to be purchased.
As each workstation only needs to connect to the local hub (and not the server) the cabling requirements are lower (than if they were connected to 1 central hub). I have made the assumption that each workstation is about 3 metres away from each other. The total length of cable needed to connect 20 nodes to 1 hub is 630 metres. To connect all 100 nodes to their local hub will need 3,150 metres. Assuming that each node is 60 metres away from each other then 900 metres of cabling is needed to connect each hub to the central hub. A total of 4,050 metres is needed. Simply sell this type of cable in reels of 20 metres for £19.98, a total of 203 of these reels will needed at a total cost of £4,055.94. 212 RJ45 connectors are needed at a cost of £250.16 (from Simply). The total cost of cabling is £8,836.93.
The server should meet/be upgradable to this set of specifications:
CPU: Dual PentiumII 400Mhz
RAM: 128Mb
HD Space: 15Gb
HD Interface: SCSI 2
Installer OS: Windows NT Server
dan technology can provide the following system:
CPU: Dual 400MHZ Pentium II
RAM: 128Mb
Monitor: 17"
Hard Disk: 18Gb
Other: 32 speed CDROM, PCI RAID controller, network card
Operating System: WindowsNT Server (5 user)
Price: £5,242.85
Time can supply the following system:
CPU: PentiumII 450Mhz (additional PII 450 can be purchased from NovaTech for £457.08)
RAM: 128Mb
HD Space: 9.1Gb (an extra 9.1Gb from NovaTech is £366.60)
HD Interface: SCSI 2
Installed OS: WindowsNT Server (5 user)
Other features: 8Gb tape streamer, 100Mbps network card, 56k modem, 24 speed CDROM.
Note: Hard drive is smaller than required, and additional 9.1Gb can be added for £388.92.
Price: £3523.83
Total price (with added HD and CPU): £4347.51
Because the Time server has better specification, and is much cheaper than the dan system the Time machine will be the system used for the server.
As all the workstations are supplies with WindowsNT Workstation pre-installed, and the server has WindowsNT server installed no additional networking software needs to be purchased. But the server needs to have its licence increased to 100 users. NovaTech sell additional licences at £31.73, total price for the additional 95 licences is £3,014.35.
There should be 1 printer shared between 20 workstations on this network. To accomplish this a printer server is needed. This allows the printer to be accessed by anyone on the network, but the workstations should be configured to print to the nearest printer.
The printer to be used on this network will be the HP LaserJet 4000. There reasons for this are:
Prints 16 pages per minute. As the printers are used in an office environment the speed at which the printer operates is important.
WindowsNT driver. Often hardware is not supplied with drivers for WindowsNT, and it is important to be sure that the hardware is supplied with them.
The total price is £5,416.52 (from Nike Data Centre - referred by the HP website).
With a star topology network the printer server is connected to the local network hub. As Hewlett Packard printers are to be used, Hewlett Packard printer servers should also be used (to ensure compatibility). Technomatic can supply 5 Hewlett Packard printer servers (JetD rj45) for £1,086.88.
The total price for this network is £147,605.19
Each of the network systems have their own benefits and weaknesses.
Advantages
Cost.
Reliability (NetWare is more stable than WindowsNT)
Scalability. Adding more workstations involves inserting it onto the bus.
Disadvantages
Speed. This could limit the number of people using video conferencing.
Reliability. If the cable is cut the network will go down.
Total price is: £128,932.84.
Advantages
Speed
Reliability. If a cable is cut only the workstation (or workstations connected to the hub) are effected.
Scalability. Adding new nodes will not effect the network speed for the other nodes.
Workstation specification is better.
Server specification is better.
Disadvantages
Cost
WindowsNT Server is not as stable as Novell
Scalability. Each network hub only has 2 spare connections. Adding more workstations will eventually require more hubs.
Total price is: £147,605.19.
I would recommend that the second network proposal should be adopted, because it will offer high performance, and reliability.
Dabs Direct. PC Direct. November 1998 issue, page 432.
Insight. PC Direct. November 1998 issue, page 306
Quantex. PC Direct. November 1998 issue, page 142. Web site: www.qtx.co.uk
dan technology. PC Direct. November 1998 issue, page 37. Web site: www.dan.co.uk
Simply. PC Direct. November 1998 issue, page 233. Web site: www.simply.co.uk
Technomatic. PC Direct. November 1998 issue, page 485. Web site: www.technomatic.co.uk
PC Direct is published by Ziff-Davis.
This is a list of websites that I visited, and used for background information in writing this report.
3com
Cisco
Hewlett Packard
IBM
Intel
NovaTech
Novell
Specifically:
www.novell.com/catalog/primer/primer.html
www.novell.com/catalog/glossary.html
www.novell.com/netware5/index.html
Microsoft
Specifically:
www.microsoft.com/ntworkstation/
www.microsoft.com/ntserver/nts/exec/overview/retailprice.asp
Frame Data sent on the network. This contains details about the destination node, and other details that may depend upon the network protocol being used.
GUI. Graphical User Interface
IP Internet Protocol.
IPX Internetwork Packet Exchange (IPX) A protocol that allows the exchange of message packets on an internetwork.
Hub A network hub is used to connect many nodes to 1 central point. This can then connect to the a network server, or another hub.
IT Information Technology.
LAN Local Area Network.
Mbps. (megabits per second) Unit of measure for data transfer rates; two to the 20th power (1,048,576) bits per second. (Novell)
Memory Protection. Protects memory from being written to or read by tasks that do not own the memory. This is essential for a secure network operating system.
MS Microsoft.
NDS Novell Directory services.
NTFS NT File system.
PPTP Point-to-point Tunnelling Protocol.
Repeaters. Repeaters are used to increase the distance over which a network signal can be propagated. As a signal travels through a transmission medium, it encounters resistance and gradually becomes weak and distorted. The technical term for this signal weakening is "attenuation." All signals attenuate, and at some point they become too weak and distorted to be reliably received. Repeaters are used to overcome this problem. (Novell)
Node Equipment connected to the network that can communicate with other devices on the network (usually a workstation).
RAID. Redundant arrays of inexpensive disks.
SCSI. Small Computer Systems Interface.
SCSI2. This is also known as SCSI wide.
USB. Universal Serial Bus. This can be used to connect various types of low speed devices to a computer. For example, mice, keyboards and digital cameras.