Transcript INFS 361 Chapter 1 Notes

INFS 361
Chapter 1 Notes
UTM
Bob Bradley
Fall 2005
Network Types
• LANs – Local Area Networks
• WANs – Wide Area Networks
• internets – Connections of networks
• The Internet
Four Elements of a Network
• Hardware Devices
– Server Stations (Hosts)
• PCs and Appliances
– Clients Stations (Hosts)
• PCs, Set-top boxes, PDAs
– Switches (Hubs)
– Routers
• Software Application Programs
– E-Mail, Web, IM, DB
– Clients, Servers, P2P
• Media
– Wires, Fiber, Wireless
– Transmission Lines
• Access lines and Trunk Lines
• Messages
– Frames and packets
Stations and Applications
• The computers that communicate over
networks are called stations
– On the Internet we call them hosts
– Client stations and server stations
• Servers provide service to clients
• Clients and servers run application
programs
A Network
• A network is a transmission system that
allows an application on any station in the
network to communication with an
application on any other station in the
network.
Server Station / Hardware
Client Stations / Hardware
Stations: the computers that communicate over a network
are called stations.
Server Station / Hardware
Client Stations / Hardware
Client Application
Web Browser
IE or Firefox
Server Software
Web Server
Apache
Server Software
Mail Server
SMTPd
or MS Exchange
Apache
SMTPd
Client Application
E-Mail Client
Outlook or Eudora
Software: Client and server stations on a network run
application programs that communicate with each other
Server Station / Hardware
Client Stations / Hardware
Client Application
Web Browser
IE or Firefox
Server Software
Web Server
Apache
Server Software
Mail Server
SMTPd
or MS Exchange
Apache
SMTPd
Client Application
E-Mail Client
Outlook or Eudora
Messages: The applications communicate by sending
messages. In a single network, the messages are called frames.
Switch
Switch
Switch
Switches: Stations (and other devices) on a Local Area
Network are connected by switches (hubs).
Frame
Frame
Switch
Frame
Switch
Switch
Frame
Frame
Frames: Switches forward messages between stations
called frames. Frames stay within a single network (LAN)
Frame
Switch
Frame
Frame
Router
Internet
or
another
network
Router: Routers forward messages outside of a single
network, to another network.
In order for a device to communicate with a device on a
different network, it sends the message to a router.
Media
• All of these stations and devices are connected
together with media:
– Wires
• Copper, Cat 5, UTP, Coax
– Fiber
• Single Mode & Multi-Mode
– Wireless
• Microwave
• Radio – 802.11b
• Satellite
– Media Converters
Packets
• When messages are transmitted over a
network, they are broken down into shorter
messages called packets.
– typically a few hundred bytes long
Parts of a Packet
• Each packet contains:
– Header
• To, from, sequence, flags, checksum
– Payload / Data
Header
Dest-Addr Source-Addr
Payload / Data
GET /index.htm HTTP/1.0….
• Packet Switching
– The breaking of transmissions into short selfcontained messages
• Multiplexing
– Messages of many conversations can be sent
over the same transmission lines
• Reduces the number of lines that have to be run
• Reduces the costs
• WANs – Wide Area Networks
– Networks that link sites together
– Trunk Lines
• 56 k, T1, T3, Frame Relay
• LANs – Local Area Networks
– Networks within sites
– Switches
• Workgroup Switches
• Central Core Switches
• Ethernet
• Picture in book on page 8
Internets
• A collection of networks connected by
routers so that any application on any host
computer on any network can send
messages called packets to any other
application on any host computer on any
other network in the internet.
• Use the TCP/IP protocol
Internet Terms
• Hosts
– A computer connected to an internet
• IP Address
– Each host on an internet has an Internet
Protocol address or IP Address
– 32 bit number
– Dotted decimal notation
• 10.1.2.3
Switches Versus Routers
• Switches
– Provide connection within
networks
– Operate at layer 2 (Data
Link Layer)
• Routers
– Provide connection
between networks
– Operate at layer 3
(Network Layer)
Packets and Frames
• Within single networks, messages are called
frames.
– Frames only travel in a single network.
• Within internets, messages from the source host
to the destination host are called packets.
– A packet is carried in a frame
• Packets are encapsulated in frames
– A packet goes all the way from the source to the
destination host
The Internet
• The global collection of connected networks.
– Hundreds of millions of host computers
• ISPs – Internet Service Providers
– Connect organizations to “The Internet”
• NAP – Network Access Points
– Connect up ISPs.
– Internet Backbone
• TCP/IP
– All the ISPs can work together because all ISPs and
all hosts transmit according to the TCP/IP standard.
• internets versus the Internet
– internets: any internet that connects multiple
networks
– The Internet: the worldwide Internet
• Intranet
– Internal internet for use within an organization
– Based on the TCP/IP tandards
• Extranet
– To connect multiple firms