Considerations in Planning a Network Infrastructure

Defining Network Infrastructure

A network can be defined as the grouping of hardware devices and software components which are necessary to connect devices within the organization, and to connect the organization to other organizations and the Internet.

Only after the hardware is installed and configured, can operating systems and software be installed into the network infrastructure. The operating systems which you install on your computers are considered the main software components within the network infrastructure. This is due to the operating system containing network communication protocols that enable network communication to occur. The operating system also typically includes applications and services that implement security for network communication.

Another concept, namely network infrastructure, is also commonly used to refer to the grouping of physical hardware and logical components which are needed to provide a number of features for the network, including these common features:

The network or network infrastructure has to exist before a number of servers needed to support applications which are needed by your users can be deployed into your networking environment:

When you plan your network infrastructure, a number of key elements need to be clarified or determined:

When you implement a network infrastructure, you need to perform a number of activities that can be broadly grouped as follows:

The physical infrastructure of the network refers to the physical design of the network together with the hardware components. The physical design of the network is also called the network's topology. When you plan the physical infrastructure of the network, you are usually limited in your hardware component selection by the logical infrastructure of the network

The logical infrastructure of the network is made up of all the software components required to enable connectivity between devices, and to provide network security. The network's logical infrastructure consists of the following:

It is therefore the network's logical infrastructure that makes it possible for computers to communicate using the routes defined in the physical network topology.

The logical components of the network topology define a number of important elements:

Understanding the OSI Reference Model and TCP/IP Protocol Suite

The International Organization for Standardization (ISO) developed the Open Systems Interconnection (OSI) reference model for computing. The OSI model defines how hardware and software function to enable communication between computers. The OSI model is a conceptual framework which can be referenced to better comprehend how devices operate on the network. It is the most widely used guide for a networking infrastructure. When manufacturers design new products, they reference the OSI model's concepts on the manner in which hardware and software components should function.

The OSI model defines standards for:

The OSI model is made up of seven layers which are presented as a stack. Data which is passed over the network moves through each layer. Each layer of the OSI model has its own unique functions and protocols. Different protocols operate at the different layers of the OSI model. The layer of the OSI reference model at which the protocol operates defines its function. Different protocols can operate together at different layers within a protocol stack. When protocols operate together, they are referred to as a protocol suite or protocol stack. When protocols support multiple path LAN-to-LAN communications, they are called routable protocols. The binding order determines the order in which the operating system runs the protocols.

The seven layers of the OSI reference model, and each layers' associated function are listed here:

Transmission Control Protocol/Internet Protocol (TCP/IP) is a network communication protocol suite that can be utilized as the communications protocol on private networks. TCP/IP is also the default protocol utilized on the Internet. The majority of network infrastructures are based on TCP/IP.

As an engineer designing the network infrastructure, you have to provide a TCP/IP design which can provide the following:

The TCP/IP protocol suite is a four layer model which corresponds to seven layers of the OSI reference model:

Understanding Networking Services

Running on the physical hardware in the network infrastructure are networking services. Networking services basically extend the physical network by providing a number of key capabilities, including the following:

There are a number of tools and features included with Windows 2000 and Windows Server 2003 that can be used to manage and monitor the networking services which you deploy within your networking infrastructure.

Network Infrastructure Planning Overview

Planning network infrastructure is a complex task that needs to be performed so that the network infrastructure needed by the organization can be designed and created. Proper planning is crucial to ensure a highly available network and high performance network that result in reduced costs and enhances business procedures for the organization.

To properly plan your network infrastructure, you have to be knowledgeable on a number of factors, including the following:

A typical network infrastructure planning strategy should include the following:

After planning, the following step would be to implement the technologies which you have identified. Implementation of the network infrastructure involves the following tasks:

Windows Server 2003 includes a number of features, and user and computer management tools that can be utilized to plan the network configuration:

Determining Network Layer and Transport Layer Protocols

Windows Server 2003 supports the following network layer and transport layer protocol combinations:

TCP/IP Design Requirements

Before deciding to use a TCP/IP based network design, you first have to determine whether you actually need to utilize TCP/IP. Whether a TCP/IP based network design is required or not is dictated by the networking services and applications required within your network infrastructure:

In order to implement a TCP/IP network infrastructure, you have to gather a number of design requirements, including the following:

There are a number of additional factors which need to be determined before you can create a routing solution for your network:

Determining the IP Addressing Scheme

The IP addressing scheme which you use can be based on:

If you are only using a public IP addressing scheme in your network design, then you need to perform the following activities:

If you are implementing a private IP addressing scheme, then the network design would consist of the following:

The selection of the IP address range needed for the organization should be based on the following factors:

  • Maximum number of IP devices on each subnet
  • Maximum number of network subnets needed in the network design.

    • If you are using a private IP addressing scheme in your network design, consider the following important points:

    IP version 6 (IPv6) was designed to deal with the current shortage of IP addresses with IP version 4 (IPv4). IP version 6 also includes some modifications to TCP/IP.

    The primary differences between IPv6 and IPv4 are listed here

    The advantages of IPv6 are listed below:

    If you want an IP address to provide all services to the network, then each particular service must have a unique TCP port or UDP port from that specific IP address. There are a number of well-known ports which are used by the different services running on your computers.

    The main port numbers used by protocols/services running on your computers are listed here:

    Determining Locations of Network Components

    When planning locations for your hardware and software components, the factors that you need to consider are primarily determined by how your users need to access your devices to carry out their daily tasks.

    When determining locations for cables, a few important factors to consider are listed here:

    • To maintain the network infrastructure, you need to be knowledgeable on where cables are located.
    • You also need to know how cables are arranged when needing to both maintain and troubleshoot network infrastructure issues.
    • When determining locations for cables and the routing strategy of your cables, you need know what the locations are of any obstacles which could affect the performance of your cables. These obstacles should be bypassed.
    • When routing cables, there are a number of components which cables have to either pass around or through, that have to be determined:
      • Air conditioning ducts.
      • Firewalls
      • Plenums
    • You would need to determine the manner in which the cables should be installed.
    • In cases where the cables have to run down into the center of the room from the ceiling, it important to determine the precise location of the utility pole that will hold the cables.
    • You need to determine the location of each cable terminus.
    • You should cater for additional cable runs for any future network expansion plans.

    When determining locations for connectivity devices, a few important factors to consider are listed here:

    • You need to determine the locations of hubs and patch panels.
    • The network's size and the installation site determines the following:
      • Locations of hubs and patch panels.
      • Number of hubs and patch panels needed.
    • You should always include ceiling heights in your planning - remember that cable runs are typically longer than what they seem because they run around obstacles.
    • The size of the network and the protocols which you plan to utilize determines how connectivity is established. For instance, hubs and switches can be used to connect building floors. Routers can be used to create an internetwork.

    When determining locations for servers, a few important factors to consider are listed here:

    • Servers need to be physically secured and protected from power strikes and interruptions.
    • With internetworks, the locations of your users that need to access servers is a determining factor for server placement.
    • If you are planning to use departmental servers for your network, place these servers in locked closets.
    • A better option to using a departmental server strategy is to place all servers in a central data center. It is easier to physically secure servers when they reside in a single data center.
    • For servers that need to be accessed by all users within the organization, you need to place these servers where they can directly be connected to the backbone network.

    When determining locations for workstations, a few important factors to consider are listed here:

    • Before placing any workstation, you need to determine which computer type is needed.
    • You also need to determine how workstations should be placed relative to the actual desk.

    When determining locations for printers and other shared components, a few important factors to consider are listed here:

    • Printers should be placed where users can easily access them.
    • Be careful when placing printers that release gases when they operate as it can cause a discomfort to users.
    • When determining the location of printers, include factors such as maintenance access to the printer, and the locations of the printer's supplies (toner, paper).


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