the workings of the internet cecs 5030 with cathie norris, jennifer smolka & gerald knezek cecs...
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The Workings of the InternetThe Workings of the Internet
CECS 5030
with Cathie Norris,
Jennifer Smolka & Gerald Knezek
CECS 5030
with Cathie Norris,
Jennifer Smolka & Gerald Knezek
OverviewOverview
Layered Organization Topologies Network Transports Access Methods Routing
Layered Organization Topologies Network Transports Access Methods Routing
ISO/OSI Model ISO/OSI Model
Developed by International Organization for Standardization in 1974
Consists of seven layers Each with unique function Each hands off functions to adjacent layer Modules (layers) may be replaced with
another of equal functionality (Xerox vs. Novell, for example)
Developed by International Organization for Standardization in 1974
Consists of seven layers Each with unique function Each hands off functions to adjacent layer Modules (layers) may be replaced with
another of equal functionality (Xerox vs. Novell, for example)
OSI Model LayersOSI Model Layers
Physical
Data Link
Network
Transport
Session
Presentation
Application
Transmission of binary signal
Transfer of units of information, framing, and error checking
Delivery of packets of information, which includes routing
Provision for end-to-end reliable and unreliable delivery
Establishment and maintenance of sessions
Data formatting and encryption
Network applications such as file transfer and terminal emulation
OSI Layer Function Provided
Network TopologiesNetwork Topologies
Architectural “drawings” that show the overall physical configuration for a given communications system
Determine access methods and rules used to design and implement a communication system
Represent the drawing of your network cable plant
Three main types: star, ring, and bus
Architectural “drawings” that show the overall physical configuration for a given communications system
Determine access methods and rules used to design and implement a communication system
Represent the drawing of your network cable plant
Three main types: star, ring, and bus
Network TopologiesNetwork Topologies
Linear Bus - Ethernet/IEEE 802.3 10Base2 and 10Base5
Star Wired Bus - Ethernet/IEEE 802.3i 10BaseT
Star Wired Ring - Token Ring/IEEE 802.5
Dual Counter Rotating Ring - FDDI/ANSI X3T9.5
Wireless - Product Specific
Linear Bus - Ethernet/IEEE 802.3 10Base2 and 10Base5
Star Wired Bus - Ethernet/IEEE 802.3i 10BaseT
Star Wired Ring - Token Ring/IEEE 802.5
Dual Counter Rotating Ring - FDDI/ANSI X3T9.5
Wireless - Product Specific
Star TopologyStar Topology
First used with the telephone switches Centralized hub with all stations connected No single point of failure effects the whole
network, except the hub Oldest and most popular topology Better network management
First used with the telephone switches Centralized hub with all stations connected No single point of failure effects the whole
network, except the hub Oldest and most popular topology Better network management
Central Hub
Node Node
Node Node
Ring TopologyRing Topology
All stations (repeaters) are enclosed in a loop
Each receives the signal and repeats it on the other side to its “downstream” neighbor
Data is transmitted in one direction only Single point of failure when one station
quits repeating Management processes invoked that
dynamically remove a station allowing the ring to return to an operational state
All stations (repeaters) are enclosed in a loop
Each receives the signal and repeats it on the other side to its “downstream” neighbor
Data is transmitted in one direction only Single point of failure when one station
quits repeating Management processes invoked that
dynamically remove a station allowing the ring to return to an operational state
Ring TopologyRing Topology
Node
NodeNode
Node
Data Direction
ReceiverTransmitter
Repeater
Bus TopologyBus Topology
Also known as linear bus Uses a single length of cable with all
stations attached to it The network is terminated at its endpoints
(not a closed loop) A break on the single cable will bring
down all attachments on the network The bus topology is most commonly used
for Ethernet networks
Also known as linear bus Uses a single length of cable with all
stations attached to it The network is terminated at its endpoints
(not a closed loop) A break on the single cable will bring
down all attachments on the network The bus topology is most commonly used
for Ethernet networks
Bus TopologyBus Topology
NodeNode NodeNode
NodeNode
Star-Wired Bus TopologyStar-Wired Bus Topology
Each node is attached to hub
When one node fails, it doesn’t affect the other nodes
The hub is a single point of failure for all nodes
Hub failure causes all nodes to lose connectivity
Each node is attached to hub
When one node fails, it doesn’t affect the other nodes
The hub is a single point of failure for all nodes
Hub failure causes all nodes to lose connectivity
NodeNode
NodeNode
NodeNodeNodeNode
NodeNode
NodeNode
Concentrator Hub
Concentrator Hub
Physical MediaPhysical Media
Physical media provide the connections between network devices that make networking possible
There are four main types of physical media in widespread use today:
Coaxial Cable Twisted Pair Fiber Optic Cable Wireless Media
Physical media provide the connections between network devices that make networking possible
There are four main types of physical media in widespread use today:
Coaxial Cable Twisted Pair Fiber Optic Cable Wireless Media
Thick Coaxial CableThick Coaxial Cable
Used in the first Ethernet networks Type RG-11 / 10Base5 Usually orange/black Thickness of a small garden hose Very expensive and heavy cable Two strands along the axis Conductor down the center Insulator surrounds conductor Shielded mesh serves as outside
Used in the first Ethernet networks Type RG-11 / 10Base5 Usually orange/black Thickness of a small garden hose Very expensive and heavy cable Two strands along the axis Conductor down the center Insulator surrounds conductor Shielded mesh serves as outside
Thin Coaxial CableThin Coaxial Cable
Alternative to Thick Ethernet Cable Type RG-58 / 10Base2 / “Cheapnet” Usually black Thickness of a pencil More flexible than thick Ethernet Reduced the cost of the cabling Flexible
Alternative to Thick Ethernet Cable Type RG-58 / 10Base2 / “Cheapnet” Usually black Thickness of a pencil More flexible than thick Ethernet Reduced the cost of the cabling Flexible
Twisted Pair CableTwisted Pair Cable
Phone Systems
Twisted Pair Cable consists of two copper wires, usually twisted around each other to cancel out any noise in the circuit
Two main type of Twisted Pair Cabling Shielded Twisted Pair (STP) Unshielded Twisted Pair (UTP)
Phone Systems
Twisted Pair Cable consists of two copper wires, usually twisted around each other to cancel out any noise in the circuit
Two main type of Twisted Pair Cabling Shielded Twisted Pair (STP) Unshielded Twisted Pair (UTP)
Shielded Twisted Pair (STP)Shielded Twisted Pair (STP)
Shielded twisted pair is the original media used for token ring networks
STP can be used for high-speed networks, such as FDDI or ATM, where shielding is important
Shielded twisted pair is the original media used for token ring networks
STP can be used for high-speed networks, such as FDDI or ATM, where shielding is important
Unshielded Twisted Pair (UTP)
Unshielded Twisted Pair (UTP)
Most commonly used twisted pair cable Uses common telephone wire UTP was standardized by the IEEE 802.3
committee in October of 1990 UTP for LANs is now classified as:
Category 3 - used for LANs up to 10 Mbps Category 4 - used for LANs up to 16 Mbps Category 5 - used for LANs up to 100 Mbps
Most commonly used twisted pair cable Uses common telephone wire UTP was standardized by the IEEE 802.3
committee in October of 1990 UTP for LANs is now classified as:
Category 3 - used for LANs up to 10 Mbps Category 4 - used for LANs up to 16 Mbps Category 5 - used for LANs up to 100 Mbps
Fiber Optic CableFiber Optic Cable
Uses light signals transmitted over a very thin filament, usually made of glass
Advantage over other types of media security against eavesdropping immunity to interference maximum length of a single
segment
Most expensive of all media
Uses light signals transmitted over a very thin filament, usually made of glass
Advantage over other types of media security against eavesdropping immunity to interference maximum length of a single
segment
Most expensive of all media
Wireless MediaWireless Media
Connect your computer to your cell phone?
Problems with stability of connection
Have wireless for a long time
Commercial Satellite Geostationary Orbit Microwave Wavelength Expensive
Connect your computer to your cell phone?
Problems with stability of connection
Have wireless for a long time
Commercial Satellite Geostationary Orbit Microwave Wavelength Expensive
Wireless MediaWireless Media
A number of wireless media are used in internetworking, e.g.:
Microwave
Commercial Radio wave
Infrared signaling (Palm Synching)
A number of wireless media are used in internetworking, e.g.:
Microwave
Commercial Radio wave
Infrared signaling (Palm Synching)
Concentrators/HubsConcentrators/Hubs
Hubs allow multiple users to be connected to a single network as a shared device
The more users on a hub the slower the response time
Hubs allow multiple users to be connected to a single network as a shared device
The more users on a hub the slower the response time
Network TransportsNetwork Transports
Ethernet / Fast Ethernet / IEEE 802.3
Token Ring / IEEE 802.5
FDDI / FDDI/ANSI X3T9.5
Wireless/IEEE 802.11
Ethernet / Fast Ethernet / IEEE 802.3
Token Ring / IEEE 802.5
FDDI / FDDI/ANSI X3T9.5
Wireless/IEEE 802.11
Ethernet Cable NamesEthernet Cable Names
Name Thick Coaxial Thin Coaxial
UnshieldedTwisted
Pair FiberWire Type RG-8 RG-58 22 - 26 AWG 62.5/125 micronIEEE Name 10BASE5 10BASE2 10BASET 10BASEF
Standard Number IEEE 802.3 IEEE 802.3a IEEE 802.3i NAOther Names Thick net Thin net UTP
How Ethernet WorksHow Ethernet Works
Sent the message and listens for a response
An access method based on the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) algorithm
Cooperative effort between Digital, Intel, and Xerox produced Ethernet version 1.0 in 1980
Sent the message and listens for a response
An access method based on the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) algorithm
Cooperative effort between Digital, Intel, and Xerox produced Ethernet version 1.0 in 1980
How Ethernet WorksHow Ethernet Works
Ethernet was adopted with modifications by the standards committees IEEE 802.3 and ANSI 8802/3
Most widely used network system today
Ethernet was adopted with modifications by the standards committees IEEE 802.3 and ANSI 8802/3
Most widely used network system today
Normal Ethernet OperationNormal Ethernet Operation
DataData
Address mismatchpacket discarded
Address mismatchpacket discarded
Address matchpacket processed
Send datato node D
Transmitted packet seenby all stations on the LAN
(broadcast medium)AA
CCBB
DD
Final Ethernet IssuesFinal Ethernet Issues
Ethernet is an access method that strictly adheres to the CSMA/CD algorithm
Ethernet is a multiprotocol solution
Ethernet is usually hardware (firmware), not software
Ethernet is an access method that strictly adheres to the CSMA/CD algorithm
Ethernet is a multiprotocol solution
Ethernet is usually hardware (firmware), not software
How Token Ring WorksHow Token Ring Works
Token Ring controls which PC can send messages by passing a token from station to station around the ring
When a PC wants to transmit it will replace the token with a “frame” (message)
The frame is passed from PC to PC until it reaches its destination
Token Ring controls which PC can send messages by passing a token from station to station around the ring
When a PC wants to transmit it will replace the token with a “frame” (message)
The frame is passed from PC to PC until it reaches its destination
How Token Ring WorksHow Token Ring Works
The destination PC makes a copy of the “frame” (message) and marks the frame to indicate that it got the message
The frame circulates around the network until it gets back to the sender
The sender, seeing that the message has been received, replaces it with a new token
The destination PC makes a copy of the “frame” (message) and marks the frame to indicate that it got the message
The frame circulates around the network until it gets back to the sender
The sender, seeing that the message has been received, replaces it with a new token
Wide Area Network (WAN) Topologies
Wide Area Network (WAN) Topologies
Dedicated Circuits 56Kb T-1 DS-3
Frame-Relay 56Kb to T-1 speeds
Integrated Services Digital Network (ISDN)
Dedicated Circuits 56Kb T-1 DS-3
Frame-Relay 56Kb to T-1 speeds
Integrated Services Digital Network (ISDN)
Inter-networkingInter-networking
Networks have their restrictions
Thick coaxial cable maximum length is 500 meters
LANs are broadcast-oriented
Proper network design is impossible using repeaters
Networks have their restrictions
Thick coaxial cable maximum length is 500 meters
LANs are broadcast-oriented
Proper network design is impossible using repeaters
Inter-networkingInter-networking
Properly extending the LAN requires special devices known as bridges and routers
A LAN that uses bridges is called an extended LAN
A LAN that uses routers is called an internet or inter-network
A gateway between dissimilar networks
Properly extending the LAN requires special devices known as bridges and routers
A LAN that uses bridges is called an extended LAN
A LAN that uses routers is called an internet or inter-network
A gateway between dissimilar networks
Inter-networkingInter-networking
Bridges and routers are data-forwarding devices that forward packets to one or more LANs
They allow for more efficient networks to be designed
Bridges and routers are data-forwarding devices that forward packets to one or more LANs
They allow for more efficient networks to be designed
Inter-networking CategoriesInter-networking Categories
Physical
Data Link
Network
Transport
Session
Presentation
Application
Repeaters
Bridges
Routers
Gateways
RepeatersRepeaters
Extend the network by interconnecting multiple segments
Have transformed into wiring concentrators (hubs)
Low cost Can be used to interconnect different
wiring types but not different access methods
e.g. Coax to twisted pair
Extend the network by interconnecting multiple segments
Have transformed into wiring concentrators (hubs)
Low cost Can be used to interconnect different
wiring types but not different access methods
e.g. Coax to twisted pair
Bridge DesignsBridge Designs
Cascaded Locates on bridge next to another in a
pillar fashion Backbone
For networks with many LANs Backbone cable is run vertically in
building’s riser LAN “ribs” run on each floor
Star Used in wide area networks or remote
bridged networks
Cascaded Locates on bridge next to another in a
pillar fashion Backbone
For networks with many LANs Backbone cable is run vertically in
building’s riser LAN “ribs” run on each floor
Star Used in wide area networks or remote
bridged networks
CascadedCascaded
Cable segment 1
Cable segment 2
Cable segment 3
Terminal Server
Terminal
Workstation
File Server
Host
BackboneBackbone
Fiberbackbone Fiberbackbone
Floor 1
Floor 20
Terminal
Workstation
Host
Workstation
StarStar
California
Virginia
North CarolinaTexas
Serial line
Serial line
Serial line
Introduction to RoutersIntroduction to Routers
Routers are data forwarding devices but operate differently than a bridge
Routers separate networks into regions. Each region is assigned a unique network number
These network numbers are unique for each network they are assigned to
Packet forwarding is based on these network Ids Routers route packets based on a protocol as well as
a network ID Most routers today are multiprotocol in that one box
can forward different protocol packets Routers, like bridges, can be used locally or remotely
Routers are data forwarding devices but operate differently than a bridge
Routers separate networks into regions. Each region is assigned a unique network number
These network numbers are unique for each network they are assigned to
Packet forwarding is based on these network Ids Routers route packets based on a protocol as well as
a network ID Most routers today are multiprotocol in that one box
can forward different protocol packets Routers, like bridges, can be used locally or remotely
RoutingRouting
Most network protocols were designed with network-layer routing
Routers base forwarding decisions on an embedded network number in the network layer header of the packet
Network numbers can be thought of as area codes in the phone system
Must use the area code to call different areas Any number of end stations may be assigned to one
network number Most routers do not keep track of individual end
stations’ addresses Network numbers group network stations into one or more
network numbers Taken as a whole, routers combine networks and form
internets
Most network protocols were designed with network-layer routing
Routers base forwarding decisions on an embedded network number in the network layer header of the packet
Network numbers can be thought of as area codes in the phone system
Must use the area code to call different areas Any number of end stations may be assigned to one
network number Most routers do not keep track of individual end
stations’ addresses Network numbers group network stations into one or more
network numbers Taken as a whole, routers combine networks and form
internets
Routers - OperationRouters - Operation
Network 1
Network 2
B
C
Destination network address is localtransmit packet directly to the end station
Destinationnetwork number
is differentFind router
and give packetto the router
Router sendspacket directly
to the end station
MAC address for the router
Router Z
Node PNode A
Node D
Routing DiagramRouting Diagram
Network 1
Network 2
Network 3
Network 4
A
B
C
D
E
F
G
H
MAC Addresses Router Z
Router Y
Router X
Multiprotocol RoutersMultiprotocol Routers
LANs currently operate with many different types of protocols
Apple Computers can use AppleTalk UNIX workstations use TCP/IP Client/Server applications could use Novell
NetWare To require one router for each protocol on the LAN is
not efficient Multiprotocol routers were invented to handle this
Arrived around 1986 Routes not only based on the network IDs but are
able to pass the packet to the correct protocol processor by examining the Type of packet
LANs currently operate with many different types of protocols
Apple Computers can use AppleTalk UNIX workstations use TCP/IP Client/Server applications could use Novell
NetWare To require one router for each protocol on the LAN is
not efficient Multiprotocol routers were invented to handle this
Arrived around 1986 Routes not only based on the network IDs but are
able to pass the packet to the correct protocol processor by examining the Type of packet
GatewaysGateways
Complex devices that provide for a protocol translation during data forwarding
Examples are: TCP/IP to SNA asynchronous to synchronous serial
stream Gateways differ from bridges and routers
Perform protocol translation of the incoming packet to match the outgoing stream
Complex devices that provide for a protocol translation during data forwarding
Examples are: TCP/IP to SNA asynchronous to synchronous serial
stream Gateways differ from bridges and routers
Perform protocol translation of the incoming packet to match the outgoing stream
ReferencesReferences
From Networking 101Jim Cabral, Puget Technology Group, Inc. &
Tammy Ruth, Children’s Hospital and Medical Center
From Networking 101Jim Cabral, Puget Technology Group, Inc. &
Tammy Ruth, Children’s Hospital and Medical Center
www.pugettech.com