Our Group has designed a NT network for the hypothetical company name "ETC Inc" that is in the business of providing technical support for UNIX, LINUX, and Window NT operating system. The company has approximately 425 employees and in excess of 400 PC networked in four subnets environment. We deliberately stayed away from a simple network design because we wanted a Network that will have a substantial degree or fault tolerance, eliminate significantly single points of failure, reduce traffic on the backbone, isolate traffic to their local subnet, there by enhance network performance and stability. We have also done some math, showing that if we build a simple network with single points of failure and the network goes down for a day, the cost of the downtime at a minimum can be in the range of :

(Number of Employees * Eight-hours * ON-AVERAGE-15-DOLLARS-PER-HOUR). This works out to be (400 * 8 * 15.00 = $48,000).

With a day downtime cost of $48,000.00, we felt it was justified to build some redundancy in the system to mitigate against downtime. With a down time cost of this magnitude we have decided that it makes good business sense to invest in a solid network upfront rather than be faced with costly down time and poor performance at the back end. Network traffic and data collision and bottleneck problems were minimize by the decision to have a mixture of distributed and enterprise servers strategically placed. The networking hardware is duplicated at almost every level in the network in pursuit of a design that will have a dual path to a resource. The only networking devices that are not redundant are the 24 port hubs in the subnet and the first 12 line port switch in the subnet. Here the risk of down time can be minimizing by having a spare 12 port switch and a 24 port hub in-house. In the event of failure of a 24 port hub, at most 24 people will be affected for a very short period of time. As soon as the deviant hub is isolated it can be replace in minutes. The same logic goes for the first line of 12 port switch as well. . In short the network is design with link redundancy, providing at a minimum dual links from each component to the rest of the network, there by enhancing reliability and resiliency.

The Group decided to allocate on average ten (10) square meters per employee. The requisit space for personnel is (425 * 10) = 4250 square meters. For hallways and other support closets and room we will add another 1000 square meters for a total space requirement of 5250 square meters. ETC Inc. will be housed in a two-story building, evenly dividing the space to 2625 square feet per floor. The dimension of each floor will be 20 meters by 144 meters.

Wire Closet Layout.

There will be four wire closets, two on each floor of the building. Theses closets are subnet centric, meaning that one closet will be dedicated to a particular subnet. The Closets are close to the centers of the building on each floor, so hosts PC are less that 100 meters from the Wire closet. The furthest a host PC can be from the nearest wire closet is the distance of (20 + 72) = 92 meters, which in the range of CAT5 100 meters limit. The wire closet are connected by switches and routers which facilities communicate of host across the entire LAN irrespective of subnets, and not exceeding the limits of CAT5 length limitation boundary.

Wire Closet Contents:

Three of the four closets will have identical equipment to connect its subnet. Each closet will have the following equipment:

Five 24 Port Hubs

One twelve port Hub

One NT Server for Subnet's Office Support application and Default gateway.

In one wire closet on each floor, an eight port fiber ready switch and a six port fiber ready router are deployed in addition to the above list of networking gear. The eight port switch is connect to the 12 port switch in each subnet to facilitate inter subnet connectivity. Since switches cannot send traffic directly to a host on a different subnet, it must send the traffic up to a router. The router then send the traffic to the switch in the appropriate closet, and in turn to the switch in the subnet, which is then sent to the particular hub and then to the designated host.

Router Justification Between Subnets: Because switches cannot send traffic to different subnets the eight port switch must be connected to a router which will route the communication to the appropriate subnet. The eight port switch on each floor in addition to be connected to the router on the same floor is also connected to the router on the ajoining floor. This design is adopted to mitigate against failure or a router on a particular floor. In the event of a router failure, the router on the other floor picks up the routing tasks. This cross connection of router to switch also protect the network in the event of an eight port switch failure on the floors

Main Wire Closet / Enterprise Server Room:

The Enterprise servers will share a room with the main Wire Closet. In addition to having all the equipment that the other three closets have the Main closet will have all the Enterprise servers and other networking gears as listed:

The PDC Server, Windows NT OS, also running DHCP services

The BDC Server, Windows NT OS, also serving as the WINS services,

Firewall Server Linux

WWW Server Linux

Mail Server with Linux OS also servings as the DNS Server.

Three additional 4 Port Routers

Two four port fast Ethernet Switch.

One of the routers will connect the internal network to the WEB and provide a secondary protection service. It will also provide a path to the Enterprise Servers via the fast Ethernet Switch. There is a redundant router in the main closet that will also facilitate a path to the Enterprise servers. The last router in the closet is in front of the Firewall server as interfaces with the WWW.

Wire Closet Connection:

All connection in the wire closet from the first inter subnet router going up the tree are fiber optic connection. See Network Diagram.

The Network will require at minimum 9 servers.

PBC 1

BDC 1

Mail Server 1

WWW Server 1

FireWall Server 1

One (1) Server in each Subnet to take care of

Local subnet Office Support Operation, for a total of 4

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Total Servers 9

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DHCP: Since TCP/IP configuration on each of the 400+ host machine is tedious, time consuming, error prone and is relatively difficult to configure, we have decided to install DHCP service on the Network to allocate dynamically to the host PC their IP Address. This will relieve the Network Administrator from the task of manually configuring the host table of each host, thereby eliminating the possibility of misconfiguration, which will leave the computer unable to communicate. Additionally this will reduce workload if the need arise to change the computer name or moving the computer to a different subnet. The installation of DHCP service will make TCP/IP administration easier and more flexible both for the user and the network administrator since TCP/IP configuration information is done automatically.

WINS: Since WINS is the complementary service to DHCP for name resolution to IP numbers in the dynamic environment, we have also decided to install WINS service. WINS is the service that resolves Windows network machine names (NetBIOS) name to Internet IP address, allowing Windows machine on a network to find and communicate with each other easily.

DNS: DNS, Domain Name System/Server Service is also installed on the network, to translate or resolve the IP Number form its alphanumeric name often refer to as its FQDN (Fully Qualify Domain Name). We have decided that this network will have access to the WWW, therefore in order to resolve FQDN of non-windows host or a host on a remote network as in the World Wide Web, then DNS Services will be required to perform the resolution of IP address resolution for the FQDN on behalf of the local host.

Because the number of users in the organization is relatively small, our network will operate under a single domain modle namely CULC (centralized user login control). All users, users group, and machine account information resides on a single domaim with a single administrative authority. To manage CULC domain we installed one PDC server (PDCALPHA.TEST.ORG) with 1 Gig. RAM memory and 9.1 Gigabyte of harddrive and the BDC server (BDCBETA.TEST.ORG) as an identical machine. The network diagram shows the locations of PDC and BDC servers in our network.

Server Names: Since the server are static and in most cases would not be moved around, we have decided to adopt a naming convention that would easily identify the server to its function and it subnet location. For example, the Server assigned to "subnet A" is named SUB_A_SERV1 while the server assigned to "subnet B" is named SUB_A_SERV1. Similarly we will have PDC_Serv, BDC_Serv, MAIL_SERV … etc. Since the host/workstations are not necessarily static, and are not assign to a particular subnet, we have adopted the naming scheme of appending the company name to a contiguous serial numbering system. This scheme adds to the transparency of naming the host, such that they will not have names that are seemingly dedicated to a particular PC, but rather as part of the company named ETC.

For example, workstation's Host Name will be as follows:

ETC001.test.org

ETC002.test.org

ETC031.test.org

ETC400.test.org

To solve IP address assigning problem, we decided to use only two one bit C class IP address blocks (192.221.221.0, 192.221222.0). Using subnet masks we subdivided IP address blocks in four subnets. The IP addresses to the machines are assigned dynamically through DHCP

For Complete list on names and IP addresses please refer to IP Address.

Name Resolution: As alluded to earlier, Name resolution will be done primarily by WINS service for NT Client Workstations. WINS is a service that resolves Windows network machine name to an IP address. For example if a host wants to communicate to a resource in a different subnet, , it will send a NameQueryRequest to its primary WINS server. It request that the server look in the database to find the entry of the desired resource, locate its IP Address, and send the IP address back to the requesting client, and the client cached the IP address. If however the resource is not a Windows client, or it is not a local resource, then the DNS server is asked to resolved the Name / IP address request.

Network Costing: For Networking costing see NetWork Cost Structure