Network fundamentals

Topic 3. Network

Network fundamentals


Identify different types of networks.

-Local Area Network (LAN)

A computer that connects computer systems that are within a limited geographical area.Data and peripherals can be shared. Usually client-server, connected with hub/ switch and Ethernet cabling.

-Virtual Local Area Network (VLAN)

Devices or LANs from different segments in a LAN connected logically.Usually via software, not hardware.

-Wide Area Network (WAN)

Connects different computer systems or LANs from different geographical areas, can span over a city, country or the world,

-Storage Area Network (SAN)

Type of LAN designed to handle large data transfers. Each client is connected to a server that provides access to storage devices

-Wireless Local Area Network (WLAN)

Connects nodes in limited geographical area but with no wires. Allows for mobile devices and easier connection/ removal, although less secure.

-Internet

The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. 

-Extranet

External extension to a LAN- Part of a network that uses internet protocols to allow controlled access by specific users to LAN or WAN.
-Virtual Private Network (VPN)
A VPN allows the creation of a LAN that is managed through a server software application, to which clients can also connect from a remote location, even though a different network.

-Personal Area Network (PAN)

Network covering individual's working area, in a very small space.

-Peer-to-peer (P2P)

Different to client-server, no centralized server. All nodes have equal privileges and responsibility for processing and sending data. All are client and server at same time, consuming and supplying resources from and to other peers

Outline the importance of standards in the construction of networks.

（Standards enable compatibility through a common “language” internationally. ）
We need common rules/ standards when forming a network, otherwise some computer systems may not be able to connect due to incompatibilities, especially when trying to connect internationally.
Primary reason for standards:
Ensuring that hardware and software produced by different vendors can work together.

Describe how communication over networks is broken down into different layers.

（Awareness of the OSI seven layer model is required, but an understanding of the functioning of each layer is not.）

Open Systems Interconnection (OSI) model:

Application (The end-receiver application e.g. email)

Specific inter and supports services to the end users for network access.

Presentation (Encryption and decryption of message for security)

Ensure that message are presented to the upper layer in a presented to the upper layer in a standard format.

Session (Retransmission of data if not received by device)

Responsible for establishing , managing, synchronizing, and terminating sessions between end-user applications.

Transport (transmission, error detection)

Responsible for delivery of an entire message.

Network (routing)

Controls the source to destination delivery of data packets across multiple hops.

Data link (Network Interface Card (NIC) )

Converts raw transmission facility provided by physical layer into a reliable and error-free link.
Physical (cabling system components )
Deals with transmission of individual bits from one node to another over physical medium.

Identify the technologies required to provide a VPN.

A. hardware and software requirements:

  1. internet access
  2. VPN software
  3. VPN routers
  4. VPN appliances
  5. VPN concentrators

B. Secure VPN

1. Internet protocol security protocol (IPSec)(p146
2. Secure Sockets Layer (SSL) 3.0 or Transport Layer Security (TLS) with encryption.

C. Trusted VPN

1. layer 2 VPN:
Asynchronous Transfer Mode (ATM) circuits
Frame relay circuits
Transport of layer 2 frames over MultiProtocol Label Switching (MPLS)
2. Layer 3 VPN:
MultiProtocol Label Switching (MPLS) with constrained distribution of routing information through Border Gateway Protocol (BGP)
3. Hybrid VPN
A combination of both secure and trusted  technologies or a combination of two VPN technologies.

Evaluate the use of a VPN.

（The use of a VPN has led to changes in working patterns.）

1. Employees work as if they were directly connected to the company’s network

Improves productivity of remote employees.
Communication is easier.

2. Improve overall productivity

Decrease operational costs versus traditional Wide Area Networks.
Extends connections across numerous geographic sites without the use of a leased line.

3. Improve security

Companies take advantage of the internet to provide secure connections

4. Offer flexibility to remote offices

Offers the flexibility to employees to take advantage of the company’s Intranet over an existing Internet connection