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Lesson 4 Network architecture
Objective Define network architecture and its use.

Designing Network Architecture

If you wanted to build a house, you wouldn't just go to the lumber store and the hardware store, buy some supplies, and begin construction, without a blueprint of what you wanted to build. Too many things need to be taken into consideration: rooms, doors, windows; water pipes and electric cables; outlets, and so on. These different elements must be visualized and thought through ahead of time, unless you have infinite money and infinite time, and don't really care about what your house ultimately looks and feels like.

Designing the Network Achitecture

You need the network architecture document for the same reasons you need a blueprint to build a house. This document defines the overall integration of the various hardware and software components used by an organization to develop their Intranet, Extranet, and Internet sites. As a visualization tool, the network architecture document is useful in ensuring that the needs of the site and the resources available for it are understood by the team as well as the client.

The Web team

For the Web site development team, the primary concern is the ability of the network to support the business objectives of the Web site. IT staff, or in the case of Webteam, the Technical team, generally make the key decisions regarding the network architecture. However, the Web site development team should ensure that the IT staff is aware of the technological needs that the site will require to function smoothly.

The use of the Requirements Definition

The main source of information when designing the network architecture for a site is the Requirements Definition. As you know, the Requirements Definition lists the hardware and software requirements, as well as the type of connections and other specifications related to the hardware to achieve the site's business objectives. To go back to the house analogy, the Requirements Definition lists the materials needed, while the network architecture illustrates how these materials will be used and integrated into a whole.

The network architecture

The diagram below illustrates how a sample network architecture is put together. It is much easier to understand the configuration needed for a given project when you can see the relationship between the different parts.

Switch
  1. Connects network segments with high usage percentages.
  2. Offers higher performance than a bridge or router
  3. Costs less than a bridge or router
  4. Helps create virtual LANs
  5. Bases forwarding decisions on a packet's media access control (AC) destination address
Gateway
  1. Acts as a translator between networks using incompatible communications protocols.
  2. Connects networks of personal computers to mini-computer- or mainframe-based hosts.
Connectivity Devices The physical connections among network hardware; include cables, phone lines, and other connection lines.
Bridge
  1. Isolates traffic on a segment
  2. Helps control traffic congestion
  3. Bases forwarding decisions on a packet's media access control (MAC) desination address
  4. Less flexible, but faster than a router
Router
  1. Connects two or more networks.
  2. Forwards packets and filters traffic, based on protocol-specific software addresses, source and destination port number, and soon.
  3. More flexible than a bridge, but requires more processing power.
Hub/Concentrator
  1. Interconnects multiple devices in a network.
  2. Enables distribution of information among connected devices.
Repeater
  1. Repeaters are network devices operating at physical layer of the OSI model that amplify or regenerate an incoming signal before retransmitting it. They are incorporated in networks to expand its coverage area. They are also known as signal boosters.

Web Hardware Components

Some key questions

What will happen if various pieces of the network hardware crash? What provisions exist for backing up web files? For backing up customer and transaction data?

Network crashes have various flavors. A router effects a segment, while a server could truly bring the whole network down. It all depends on redundancy and criticality of the hardware's location. Click the sidebar to learn more about keeping your system failsafe.

In the next lesson, you will learn about how bandwidth is measured and how bandwidth needs are evaluated.

Network Architecture Elements


Click the link below to read about network architecture.
Network Architecture Elements

Evaluating Networks - Quiz

Click the Quiz link below to test your knowledge of a design team's responsibilities and the documents used in network architecture.
Evaluating Networks - Quiz