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Introduction to Networking
James R. Coakley, PhD
OEMBA Information Systems
Theoretical Framework: 5-layer network model
Application Layer (Layer-5)
Transport Layer Network Layer
Data Link Layer Physical Layer
(Layer-1)
Application
Transport
Network
Data Link
Application
Transport
Network
Data LinkPhysical
Application
Transport
Network
Data LinkPhysical
Theoretical Framework: 5-layer network model
Application Layer (Layer-5)
Transport Layer Network Layer
Data Link Layer Physical Layer
(Layer-1)
Application
Transport
Network
Data Link
Application
Transport
Network
Data LinkPhysical
Application
Transport
Network
Data LinkPhysical
Five-Layer Network ModelMajor Functions
Application Layer (top) User interface with application software HTTP (Hyper Text Transfer Protocol)
Example of an application layer address: www.bus.oregonstate.edu
FTP (File Transfer Protocol) Telnet
Allows you to log on to remote systems SMTP (Simple Mail Transfer Protocol)
Theoretical Framework: 5-layer network model
Application Layer (Layer-5)
Transport Layer Network Layer
Data Link Layer Physical Layer
(Layer-1)
Application
Transport
Network
Data Link
Application
Transport
Network
Data LinkPhysical
Application
Transport
Network
Data LinkPhysical
Five-Layer Network ModelMajor Functions
Transport Layer Packetizing
Break large messages into smaller packets at source Reassemble packets at final destinationCreates/appends TCP (Transmission Control Protocol)
headerPacket #Source/Destination Port ID
80 (Web) 25 (E-mail)
Data PacketTCP Hdr
What is a “Port”?A channel for passing data in and out of a
computing device
InputDevices
SecondaryStorage
OutputDevices
ControlUnit
PrimaryStorage
ALU
Registers
The CPU
CommunicationDevicesPort
Port
Numbers allow different applications on the same computer to utilize network resources without interfering with each other The IP address is like a telephone number
Identifies the computer on the network The Port is the extension
Identifies the channel within the computer
Theoretical Framework: 5-layer network model
Application Layer (Layer-5)
Transport Layer Network Layer
Data Link Layer Physical Layer
(Layer-1)
Application
Transport
Network
Data Link
Application
Transport
Network
Data LinkPhysical
Application
Transport
Network
Data LinkPhysical
Five-Layer Network ModelMajor Functions – cont’d
Network Layer: Addressing and Routing. Internet Protocol prepares IP header.
Contents of IP header include Source/Destination IP Address and Routing Information
Example of an IP address: 128.192.64.224 Addressing
DHCP Server (Dynamic Host Control Protocol Server) Assigns IP addresses to client machines requesting an IP address
DNS Server (Domain Name Service Server) Similar to directory assistance – used for finding destination IP
addresses. Routing
Routing tables; Routers (Tracert); Routing Protocols
Data PacketTCP HdrIP Hdr
Theoretical Framework: 5-layer network model
Application Layer (Layer-5)
Transport Layer Network Layer
Data Link Layer Physical Layer
(Layer-1)
Application
Transport
Network
Data Link
Application
Transport
Network
Data LinkPhysical
Application
Transport
Network
Data LinkPhysical
Five-Layer Network ModelMajor Functions – cont’d
Data Link Layer Media Access Control (Handling message
collisions) Error Detection/Error Correction Message Delineation (Identifying beginning and
ending of packets – since all computer transmissions go out as 0s and 1s over the physical layer)
DL layer appends a DL header and DL Trailer
Data PacketTCP HdrIP HdrDL Hdr
Data Link LayerData Direction Methods
Methods to direct data between locations Circuit switching Packet switching Frame relay
Faster, less expensiveDoes not perform error correction
ATM, etc.
Data Link LayerProtocols
What: the communication language used by computing devices in a network
Data Link LayerProtocols
Ethernet: Bus with CSMA/CD Carrier Sense Multiple Access/Collision
Detection Fast Ethernet (100 mbps) Gigabit Ethernet
Token RingFDDI
Fiber Distributed Data InterfaceToken Ring on fiber
FDDI
FDDI (Continued)
Local Area Network
Connects PCs together Peer-to-peer Server-based
File server
Distance restrictions Between 1000 and 5000 feet Why?
Wide Area Network
What is it?How connect?
Leased Lines Satellite
Other options VAN
Private, data-only network managed by third party Virtual Private Network
Run WAN over internet (tunneling)
Data Link LayerInternetworking Devices
Gateway: Where one network meets another Routers & Bridges: Gateways that determine the
next network point to which a packet should be forwarded Bridge – same network protocol – works at data link
layer Router – different network protocol – works at network
layer Switch & Hub: Joins computers together within a
LAN Switches can inspect packets and forward only to address Hub forwards to all nodes
Internetworking Devices
Connect Networks together Gateway (NL)
Connect networks with different protocols
Router (NL) Connect networks with
different protocols Bridge (DL)
Connect networks with same protocol
Hubs (PL) Route messages on
network using broadcast Switch (PL)
Route messages on network using Point-to-point
Data Link LayerInternetworking Devices
Broadband router Combines the features of a traditional network
switch, firewall, and DHCP server Dynamic Host Configuration Protocol
DHCP assigns unique IP addresses to devicesReleases and renews these addresses as devices leave
and re-join the networkEliminates need for pre-configured IP address
FirewallRestricts access to network based on IP address of
sender
Theoretical Framework: 5-layer network model
Application Layer (Layer-5)
Transport Layer Network Layer
Data Link Layer Physical Layer
(Layer-1)
Application
Transport
Network
Data Link
Application
Transport
Network
Data LinkPhysical
Application
Transport
Network
Data LinkPhysical
Layer 1 - Physical Layer
Wired Media/Wireless Media: Examples Twisted pair; Coaxial; Fiber Optic Cables Microwave; Satellites and wireless (cell phones)
Physical LayerBackground on Telecommunications
Modem Modulate – demodulate Multiplexing
Physical LayerTelecommunications Media
Criteria that determine ability to transmit data: Frequency: cycles per second (baud). Hertz is
one cycle per second. measure of speed. (assume send one bit per cycle)
Bandwidth: difference between highest and lowest frequencies which can be transmitted. measure of capacity (pulse-code modulation)
Attenuation: signal strength weakens as it travels over distance.
Interference: EMI (electromagnetic) and RFI (radio frequency)
Physical LayerTelecommunications Media (cont’d)
Physical: Twisted Pair: standard telephone lines
High availability, lower speeds, poor securityHigh-speed data lines
T1 (1.54 mbps)T3 (45 mbps)
Cable: coaxial cableLess interference, higher bandwidthHigher cost, low security
OpticalGreater speed, better security
Physical LayerTelecommunications Media (cont’d)
Electronic Microwave
Towers spaced 30 miles apart (line of sight)Easier than trenching wires into dirtSusceptible to interference
SatelliteEliminates line-of-sight issuePropagation delay
HF (high frequency)/RF (radio frequency)Use for short range (within warehouse)
Backbone
Physical Layer Broadband Communications
High-speed connections Distinguish “upstream” and “downstream”
56K modem has upstream of 31.2 and downstream of 56 For Internet use, need higher downstream rates
Three options: DSL (telephone lines) Cable Modem (cable) Satellite (microwave)
Cable Modem
Send and receive data over the coaxial cable used in cable television system
DSL - Digital Subscriber Lines
Brings high bandwidth information to homes or small businesses over ordinary telephone lines Can use telephone and PC on the same line and at
the same time
Satellite Technologies
A device used to transmit and receive signals from a satellite transponder
How does it work?
Ping
Used to test connection to a specific sitePing www.google.com
Sends four, 32-byte packets to the destination
Multiple competing technologiesCDMA - 1xRTT : code-division multiple access
70 kbps data rate Mostly US, Canada, Korea
GSM-GPRS: global system for mobile communication
40 kbps data rateAvailable world-wide
T-Mobile has roaming agreements in Europe
CDPD: Cellular Digital Packet Data Based on IP (packet switched) and conforms to ISO
standardsUp to 19.2 kbps data rate
Physical Layer Wireless Wide Area Network
Closer to having standards for WLANWi-Fi: 802.11 families
(b) – wireless ethernet. 2.5 Ghz band 11 mbps (5 mbps data rate)
(a) – proposed standard. 54 mbps on 5 Gig radio band(g) – works in b band, but delivers 54 mbps speed (20 mbps
data rate)Bluetooth
Connect devices to PC within 30 feet710 kbps
IR devices6 feet, 4 mbps
WiMax
Physical Layer Wireless Local Area Network
Application LayerWireless Application Protocol
WAP Format web pages for display on wireless devices Move to fully synchronized PDAs
Providence Health Care
