ITM 301 Chapter Notes - Chapter 1: Simple Mail Transfer Protocol, Remote Desktop Protocol, Internet Message Access Protocol

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ITM 301 - Friday, September 9, 2016
Chapter 1 Introduction to Networking
A network is a group of computers and other devices that are connected by some type of
transmission media.
It can be as small as 2 computers connected by a cable or as large as the Internet
They might communicate through copper wires, fiber-optic cable, or radio waves
HOW NETWORKS ARE USED
The resources a network makes available to its users include apps and the data provided by
these apps. These resources are referred to as network services.
Client-Server Apps
It involves 2 computes
The 1st, a client computer, requests data or a service from the 2nd computer, called the
server. i.e. Using a web browser to request a Web page.
These networked devices use methods and rules for communication know as
protocols.
The following are several popular client-server apps used on networks and the Internet:
1. Web service It serves up webpages to clients. The primary protocol used by web
servers and browsers (clients) is HTTP (Hypertext Transfer Protocol). When HTTP is
layered on top of an encrypted protocol, such as SSL (Secure Sockets Layer) or TLS
(Transport Layer Security), the result is HTTPS (HTTP Secure).
2. Email ServicesIt involves 2 servers. The client uses SMTP (Simple Mail Transfer
Protocol) to send an email to the first server. The first server sends the message on to the
receiver’s mail server. The recipient’s mail server delivers the message to the receiveing client
using either protocol: POP3 (Post Office Protocol, v.3) or IMAP4 (Internet Message Access
Protocol, v.4). Using POP3, email is downloaded; using IMAP4, the client app manages the email
stored on the server.
3. FTP service – It transfers files between 2 computers and primarily uses FTP (File
Transfer Protocol). It doesn’t provide encryption. An encrypted one is SFTP (Secure
FTP)
4. Telnet service – It’s to allow an administrator or other user to “remote in” or control a
computer remotely. It’s also not encrypted.
5. Remote Desktop – It uses RDP (Remote Desktop Protocol) to provide more secure,
encrypted transmissions that allow a technician to remote in.
6. Remote apps – It’s an app that’s installed and executed on a server and is presented to
a user working at a client computer.
File and Print Services
File services refers to a server’s ability to share data files and disk storage space.
A computer that provides file services is called a file server.
Using print services to share printers across a network saves time and money.
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Communication Services
Using the same network to deliver multiple types of communications services, such as video,
voice, and fax, is known as convergence.
Unified communication (UC) refers to the centralized management of multiple network-based
communication.
The following are 3 types of communication services your network might support and the
protocols and models they use:
1. Conversation voice – VoIP (Voice over IP) allows 2 or more people to have voice
conversation over a network. VoIP apps use a point-to-point model rather than a
client-server model, which means that each computer involved is independent of the
other computers.
2. Streaming live audio/video – A video teleconference (VTC) app allows people to
communicate in video and voice, using point-to-point model. When you watch sports
on your computer, the app is using a client-server model with one server and many
clients, called a multicast distribution. The session layer protocol for these is RTP
(Real-time Transport Protocol).
3. Streaming stored audio/video – You’re using a client-server model, as the movie stored
on something like Youtube.com is streamed to your client computer.
Bandwidth means the amount of traffic, or data transmission activity, on the network.
CONTROLLING NETWORK ACCESS
A topology describes how the parts of a whole work together.
Physical topology applies to hardware and describes how computer, other devices,
and cables fit together to form the physical network.
Logical topology has to do with software and describes how access to the network is
controlled.
Controlling how users and programs get access to resources on a network is a job for the
operating systems used on the network.
Peer-to-Peer Network Model
Using this, the OS of each computer on the network is responsible for controlling access to its
resources without centralized control.
The computers (called nodes or hosts) on the network form a logical group of computer and
users that share resources.
Advantages are that they are simple to configure and are less expensive to set up and
maintain than other types of networks.
Disadvantages are that they’re not scalable, they’re not necessarily secure and they’re not
practical for connecting more than a few computers because it becomes too time consuming
to manage the resources on the network.
Client-Server Network Model
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