IT Essentials v6.0 – Chapter 7: Networking Concepts

Sections & Objectives

7.1 Principles of Networking

  • Explain components and types of computer networks.

7.2 Networking Standards

  • Explain the purpose and characteristics of networking standards.

7.3 Physical Components of a Network

  • Explain the purpose of physical components of a network.

7.4 Basic Networking Concepts and Technologies

  • Configure network connectivity between PCs.

7.5 Chapter Summary

7.1 Principles of Networking

7.1.1 Computer Networks

Computer Network Devices and Components

  • Host Devices – any device that sends and receives information on the network (computer, printer, etc.)
  • Intermediary Devices – exist in between host devices
  • Media – component over which the message travels from source to destination

Can you name each device or component shown here? 

7.1.2 Types of Networks

Major types of networks include:

  • Local Area Networks (LANs)
  • Wireless Local Area Networks (WLANs)
  • Personal Area Networks (PANs)
  • Metropolitan Area Networks (MANs)
  • Wide Area Networks (WANs)

Peer-to-Peer Networks

  • No dedicated servers
  • Each computer decides which resources to share
  • No central administration or security

Client-Server Networks

  • Server with software installed for client access
  • Resources controlled by centralized administrator

7.2 Networking Standards

7.2.1 Reference Models

Organizations, such as lEEE, IETF, and ISO, develop open standards for networks so that any client running any operating system can access network resources.

The OSI model and the TCP/IP model are both reference models used to describe the data communication process.

As application data is passed down through the layers, protocol information is added at each level. This is known as the encapsulation process.

7.2.2 Wired and Wireless Standards

When Ethernet operates in half-duplex, the IEEE 802.3 standard specifies that a network implement the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) access control method.

The 802.3 standard also specifies cable types for Ethernet including:

  • 10Base-T
  • 100Base-TX
  • 1000Base-T
  • 10GBase-T

The IEEE 802.11 standard specifies that wireless LANs use Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA).

WLAN standards include 802.11a, 802.11b, 802.11g, 802.11n, and 802.11ac

When configuring an 802.11 WLAN, use the strongest encryption available.

Since 2006, the strongest encryption has been WPA2.

7.3 Physical Components of a Network

7.3.1 Network Devices

  • Modems convert a computer’s digital data into a format that can be transmitted on the ISP’s network.
  • Switches microsegment LANs by sending data only to the computer that needs it.
  • Wireless access points (APs) connect wireless devices. Routers use IP addresses to forward traffic to other networks.
  • In a home or small office, a route often includes a switch, a firewall, and an AP.

7.3.2 Cables and Connectors

  • Coaxial and twisted-pair cables use electrical signals over copper to transmit data. Fiber-optic cables use light signals to transmit data. These cables differ in bandwidth, size, and cost.
  • There are several types of coaxial cable: 10Base5 (thicknet), 10Base2 (thinnet), RG-59 (cable TV), RG-6 (better than RG-59)
  • Twisted-pair cables are terminated with an RJ-45 connector. Twisted-pair comes in two types:
    • Unshielded Twisted-Pair (UTP)
    • Shielded Twisted-Pair (STP)
  • Fiber-optic cables are broadly classified into two types:
    • Single-mode fiber (SMF) – Uses lasers to send a single ray of light that can travel hundreds of kilometers.
    • Multimode fiber (MMF) – Uses LEDs to send multiple light signals that can travel up to 550 meters.

  • Twisted-pair is the most popular type of cabling used in LANs today.
  • There are two different twisted-pair wiring schemes: called T568A and T568B.
  • Each wiring scheme defines the pinout, or order of wire connections, on the end of the cable.
  • Two types of cables can be created: a straight-through cable and a crossover cable.
  • A straight-through cable is the most common cable type. The wiring scheme is the same on both sides.
  • A crossover cable uses both wiring schemes. T568A on one end of the cable and T568B on the other end of the same cable.

7.4 Basic Networking Concepts and Technologies

7.4.1 Networked Equipment Addressing

The MAC address is hard coded onto the network interface card (NIC) by the manufacturer.

  • The MAC address is 48 bits represented in hexadecimal

The Internet Protocol (IP) address is assigned by network administrators based on the location within the network.

Two versions of Internet Protocol (IP) Addressing:

  • IPv4: 32-bit represented in dotted-decimal
  • IPv6: 128-bit represented in hexadecimal

Host devices need both addresses to communicate on the network.

  • MAC addresses do not change when devices move from one network to another.
  • IP addresses change because they are based on where the device is in the network.

An IPv4 address is composed of two parts. The first part identifies the network. The second part identifies a host on that network.

Computers and routers use the subnet mask to calculate the network portion of the destination IPv4 address.

A one bit in the subnet mask means that bit is part of the network portion. So the first 24 bits of the address are network bits. The last 8 bits are host bits.

Two rules help reduce the number of digits needed to represent an IPv6 address.

  • Rule 1 – Omit Leading 0s
  • Rule 2 – Omit All 0 Segments

7.4.2 Transport Layer Protocols

The two protocols that operate at the transport layer are Transport Control Protocol (TCP) and User Datagram Protocol (UDP)

  • TCP is considered reliable, because it ensures that all of the data arrives at the destination.
  • UDP does not provide for any reliability.

TCP and UDP use a source and destination port number to keep track of application conversations.

The destination port number is associated with the destination application on the remote device.

The source port number is dynamically generated by the sending device.

7.5 Chapter Summary

This chapter introduced the operation of computer networks. The following concepts from this chapter are important to remember:

  • Computer devices and components include host devices, intermediary devices, and media.
  • Major network types include LANs, WLANs, PANs, MANs, WANs, Peer-to-Peer, and Client-Server
  • Networking standards are conceptually organized into two reference models: the OSI model and the TCP/IP model
  • Wired networks use CSMA/CD when operating in half-duplex. Wireless networks use CSMA/CA.
  • Network devices include modems, switches, wireless APs, routers, and firewalls.
  • Network media includes coaxial cables, twisted-pair cables, and fiber-optic cables. Wireless signals are also considered media.
  • The two twisted-pair wiring schemes are T568A and T568B.
  • Devices need a physical address (MAC) and a logical address (IP) to communicate on the network.
  • The transport layer includes the two protocols, TCP and UDP. TCP is reliable but introduces overhead that is not used with UDP.
  • The transport layer tracks conversations between applications using source and destination port numbers.

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