Chapter 8 - Network Architecture

Network architecture describes how a network is arranged and how resources are coordinated and shared. 

Network topology describes the physical arrangement of the network.

Bus network

each device is connected to a common cable called a bus or  backbone, and all communications travel along this bus.

Ring network

each device is connected to two other devices, forming a ring. When a message is sent, it is passed around the ring until it reaches the intended destination.

Star network

Star network—each device is connected directly to a central network switch. Whenever a node sends a message, it is routed to the switch, which then passes the message along to the intended recipient. The star network is the most widely used network topology today. It is applied to a broad range of applications from small networks in the home to very large networks in major corporations

Tree network

Tree network—also known as a hierarchical network and often used to share corporate wide data. Each device is connected to a central node, either directly or through one or more other devices. The central node is connected to two or more subordinate nodes that in turn are connected to other subordinate nodes, and so forth, forming a treelike structure. 

Mesh network

Mesh network—this topology is the newest type and does not use a specific physical layout (such as a star or a tree). Rather, the mesh network requires that each node have more than one connection to the other nodes. The resulting pattern forms the appearance of a mesh. If a path between two nodes is somehow disrupted, data can be automatically rerouted around the failure using another path. Wireless technologies are frequently used to build mesh networks.

Network strategies define how information and resources are shared.

Client Server network - widely used on the Internet

Commonly used server operating systems :

• Windows Server
• Mac OS X Server
• Linux
• Solaris

Advantages :

• handle large networks efficiently
• availability of powerful network management software to monitor and control network activities

Disadvantages :

• Cost of installation and maintenance

Peer-to-Peer (P2P) network

• Nodes have equal authority and can act as both clients and servers
• File sharing software such as eDonkey and BitTorrent used to share files with other microcomputer

Advantage :

• Easy and inexpensive to set up

Disadvantage :

• Lack of security controls - few businesses use this type of network to communicate sensitive information

An intranet is a private network within an organization that resembles the Internet. Like the public Internet, intranets use browsers, websites, and web pages. Typical applications include electronic telephone directories, e-mail addresses, employee benefit information and internal job openings.

An extranet is a private network that connects more than one organization. Many organizations use Internet technologies to allow suppliers and others limited access to their networks. The purpose is to increase efficiency and reduce costs.

A firewall consists of hardware and software that control access to a company’s intranet and other internal networks. Most use software or a special computer called a proxy server to decides whether it is safe to let a particular message or file pass into or out of the organization’s network. All communications between the company’s internal networks and the outside world pass through this server.

Intrusion detection systems (IDS) work with firewalls to protect an organization’s network. These systems analyze all incoming and outgoing network traffic. Using advanced pattern matching and heuristics, an IDS can recognize signs of a network attack and disable access before an intruder can do damage.

Virtual private networks (VPN) create a secure private connection between a remote user and an organization’s internal network. Special VPN protocols create the equivalent of a dedicated line between a user’s home or laptop computer and a company server.