network engineering fundamentals

exam notes

Intranet

Private networks in use by just one company enable businesses to communicate and perform transactions among global employee and branch locations.

Extranet

Companies develop extranets to provide suppliers, vendors, and customers with limited access to corporate data to check order status, inventory and parts lists.

Remote access

The ability to connect from one network to one location to another.

Fault tolerance

Fault tolerance ensures that when failure occurs there is limited impact on the hardware and software and internet access can recover quickly.

Scalability

The ability to expand quickly to support new users, applications, equipment and external networks without impacting the performance of the service being delivered to existing users.

Quality of service

Congestion occurs when bandwidth demand exceeds the network capability, and QoS refers to the mechanism that manages a congested work.

Network infrastructure security

Protecting the network devices from outside contact.

Content security

Protecting the network content in various ways, such as availability, confidentiality and integrity.

Security breach

Can lead to various consequences including network outage, loss of personal or business funds, theft of intellectual property such as project bids, patents and strategic plans, and exposure of customer data.

Instant messaging

Real based text communication (windows, live messenger etc).

Blogs

Web pages published by people containing their thoughts and opinions (Facebook, google blogpost).

Podcasting

Audio or video recording converted for use on phones or any smartphones.

Wikis

Web pages created and edited by a group of people sharing information (Wikipedia).

Collaboration tools

Web-based software allowing people to work together on projects over the web.

Data

This protects the information carried in packets and stored on network attached devices.

Protocol

Rules that govern the process of network communication.

Optic fibre

The medium that carries data in the form of light signals in wired connections.

Copper

The medium that carries data in the form of electrical pulses in wired connections.

Packets

Connectionless messages that are broken into small parts.

Infrastructure

A network security concern which protects devices and cabling.

Router

A device that helps direct messages between networks.

Integrity

A security measure in maintaining data so that information is not altered in transmission.

Confidentiality

A certain security measure where only intended and authorised individuals can read data.

Availability

A security measure where timely and reliable access to resources is not disrupted by security breaches.

Network card

A device that connects a workstation or server to the media.

Proprietary

A limited use protocol owned by a company.

Communication

Begins with a message, or information that must be sent from one individual or device to another.

Sender/message source

The originator of the message in the communication process.

Receiver/message destination

The intended recipient of the message in the communication process.

Channel

The media that provides the pathway over which the message can travel from the source to destination.

Segmentation

Dividing data into smaller pieces that can be easily transmitted over the communication pathway.

Devices

Components of a network that can send, receive, or process data.

Media

The physical medium that carries the communication signals.

Protocols

Rules that define how data is transmitted and received over a network.

End devices

Pieces of equipment which are either the source or destination of a network communication, e.g. PC or a laptop.

Intermediary devices

Devices that connect individual hosts to the network and can connect multiple networks to form an internetwork.

Medium

This provides the channel over which the message travels from source to destination.

Copper

A type of media used for network communication.

Fibre optic cable

A type of media that uses light to transmit data.

Wireless

A type of media that transmits data without physical connections.

LAN

Local Area Network; a group of end devices and users under the control of administration.

WAN

Wide Area Network; a network that connects LANs that are located far apart.

MAN

Metropolitan Area Network; a network that covers a larger geographic area than a LAN but smaller than a WAN.

WLAN

Wireless Local Area Network; a LAN that uses wireless communication.

SAN

Storage Area Network; a network designed to provide access to consolidated, block-level data storage.

Internetwork

A collection of two or more LANs connected by WANs.

Protocol suite

A group of interrelated protocols that are necessary to perform a communication function.

Layered model

Used to describe the complex process of network communication.

TCP/IP

An open standard developed by industry members that includes four communication functions.

OSI Model

Provides an abstract description of the network communication process and a framework for building a suite of open systems protocols.

Physical layer

This describes the electrical, mechanical and functions interfaces to the physical medium and carries signals for all the higher layers. Can provide data encoding, physical medium specification and transmission technique.

Data link layer

This can provide error free transfer of data frames from one node to another over the physical layer. This can provide frame delimiting, frame acknowledgement and frame error checking.

Network layer

This controls the operation of the subnet, deciding which physical path the data should take based on network conditions, priority of service and other factors. This provides addressing devices, routing of frames among networks and logical physical address mapping.

Transport layer

This ensures that messages are delivered error free in sequence and with no losses or duplications. This provides message segmentation, message acknowledgement and session multiplexing.

Session layer

This allows session establishment between processes running on different stations. It provides session establishment, maintenance and termination.

Presentation layer

Formats data to be presented to the application layer. This provides character code translation, data compression, data encryption.

Application layer

This serves as a window for users and application processes to access network services. This provides resource sharing and device redirection, remote file access and remote printer access.

TCP/IP model

Describes the functionality of the protocols that make up the TCP/IP protocol suite. These protocols are implemented on both the sending and receiving hosts, they interact to provide end to end delivery of applications over a network.

Creation of data

Occurs at the application layer of the originating source end device.

Segmentation and encapsulation

The process of data as it passes down the protocol stack in the source end device.

Generation of data

Occurs onto the media at the network access layer of the stack.

Transportation of data

Involves moving the data through the internetwork, which consists of media and any intermediary devices.

Reception of data

Occurs at the network access layer of the destination end device.

Decapsulation and reassembly

The process of data as it passes up the stack in the destination device.

Passing data

Involves sending this data to the destination application at the application layer of the destination end device.

Addressing

A device accessible on the public internet has a unique internet protocol (IP) address, which includes source IP address and destination IP address.

Encapsulation

When a packet is created, the header must contain the IP header, which contains the destination and source addresses.

Routing

Provides services to direct packets to their intended destination host. The source and destination hosts are not always connected to the same network.

Router

An intermediary device that connects networks and selects paths for and directs packets towards their destination.

Hop

Each route a packet takes to reach the next device.

Decapsulation

The process of opening encapsulated data that are usually sent in the form of packets over a network.

Common network layer protocols

Include Internet protocol version 4 (IPV4), Internet protocol version 6 (IPv6), Novell internetwork packet exchange (IPX), AppleTalk, Connectionless network service (CLNS/DECNet).

IPV4

The most used version of IP, the sole layer 3 protocol used to transport user data across the internet.

IPV4 basic characteristics

Connectionless: no connection establishes before sending data packets. Best effort: no overhead is used to guarantee packet delivery. Media independent: operates independently of the medium carrying the data.

IP header

Holds the delivery and handling instructions of an IP packet.

IPV4 packet header

Contains fields such as IP source address, IP destination address, Time-to-Live, Type-of-Service, Protocol, Fragment offset, and Flag.

Time-to-Live

An 8-bit binary value that indicates the remaining life of a packet.

Type-of-Service

An 8-bit binary value that is used to determine the priority of each packet.

Protocol

An 8-bit binary value that indicates the data payload type that the packet is carrying.

Fragment offset

Indicates where a fragment belongs in the original packet when a router fragments a packet.

Flag

3-bit control flags, such as 'more fragments' and 'don't fragment' flags.

Version

Contains the IP version number.

Header length

Specifies the size of the packet header.

Packet length

Gives the entire packet size, including header and data in bytes.

Identification

Primarily used for uniquely identifying fragments of an original IP packet.

Header checksum

The checksum field used for error checking the packet header.

Options

Provides other services but is rarely used.

Subnet

Dividing networks into smaller groups to manage broadcast domains and ensure efficient data flow.

Broadcast

Layer 2 broadcasts send messages to all devices in a network.

Security

Dividing networks by ownership enhances security by controlling access between them.

Hierarchical addressing

Addressing that comprises a network and a host portion to uniquely identify each host.

IPV4 address

Composed of 32 bits divided into a network address and a host address.

Dotted decimal notation

The format of an IPV4 address written as four decimal values separated by a dot (e.g., 192.168.18.57).

Routing

The process of choosing a path for the packet when communicating outside a local network.

Routing table

Stores information about connected and remote networks.

Packet forwarding

The steps a router takes to determine the appropriate action upon receiving a frame.

Static routing

Routes to remote networks with the associated next hops can be manually configured on the router.

Dynamic routing

Routers automatically update and share information about the best paths for data to travel through a network.

Static Routing

Cannot produce any network overhead, no processing is required.

Dynamic Routing

Provides routers with up-to-date information even when fault occurs.