Transcript Lecture 6 - Aerobic Suspended Growth

EETS 7304
Internet Protocols
by
Dr. Faruk Hadziomerovic
Textbook: Andrew Tanenbaum:
Computer Networks 4-th Ed.
Complementary: Peterson, Davie:
Computer networks, 3-rd Ed.
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Syllabus
The course is to introduce students to the concept of Networking. After
introduction (uses of computer networks, PSTN, PLMN, Internet,
reference models, networks examples, standard bodies) the course goes
into details TCP/IP layers implementation: the physical layer
(theoretical limits, transmission media, multiplexing, switching, GSM,
ADSL vs. cable, fiber vs. satellite), the data link layer (framing, error
detection, sliding window, HDLC, verification), the medium access
protocol (CSMA/CD, Ethernet, 802.xx, data link layer switching), the
network layer (routing algorithms, congestion control, IP addressing
and application on Internet, ICMP, IPv6), the transport layer (UDP,
TCP, performance issues), the application layer (DNS, e-mail,
client/server model, web, multimedia, VoIP), network security (data
encryption, public-key algorithms, firewalls, VPNs, authentication
protocols).
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Admin
Office hours: Thursdays 5 to 6:30 PM
(Adjunct Room at 3-rd floor Junkins)
Verification (open book, no electronic
devices):
Final 3 hours, 40%, SMU scheduled.
Midterm 1.5 hours, 20% mid October.
4 Tests/Assignments, 10% each, every 3
weeks.
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Chapter 1: Introduction
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Uses of Computer networks
Network Hardware
Network Software
Reference Models
Network Examples
Network Standardization
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Business Applications
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common data bases (inventories, payrolls).
company e-mail.
video-conferencing (sharing virtual blackboard).
e-business (suppliers and customers ordering parts in
a real time).
• e-commerce (airlines, bookstores, e-bay shopping).
• e-governement (application forms and submittals).
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Business Applications: client-server
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Client-server communications
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Home Applications
• access to remote information (surfing the web for: business,
government, finance, news, music, digital library like IEEE).
• person-to-person: e-mail, messenger, phone with
video – SKYPE.
• Newsgroups
• Interactive entertainment: playing chess.
• peer-to-peer (swapping music indicating on Napster server,
keeping shared list of available songs on personal computer).
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Home Applications: peer-to-peer
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Mobile Users
• smart phone (Blackberry): PDA (Personal Digital Assistant)
combo with cellular phone.
• mobile office (while on the move: surf the web, send e-mail).
• fleets of (trucks, taxis, delivery vehicles, repairs).
• military.
• telemetry (parking, vending machines, utility meter reading).
• m-commerce use WAP (Wireless Application Protocol).
Locality of the shopping, maps, etc.
• cheap and popular SMS.
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Wireless vs. Mobile examples
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Social Issues
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censoring (moderating?) newsgroups
with sensitive character, politics, religion.
tracking users activities (cookies).
electronic theft.
viruses and security.
Uncle Sam vs. privacy.
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Network Hardware
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Local Area Networks
Metropolitan Area Networks
Wide Area Networks
Wireless Networks
Home Networks
Internetworks
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Classification by types of Physical links
Broadcast links: Everybody listens (promiscuous mode).
Destination address necessary.
•
Unicast: “Watson come here. I want you.”
Although everybody listens only Watson responds.
•
Multicast (stations are subscribed to the group): “all
passengers flight 234 to report to gate 33 for boarding.”
•
Broadcast: everybody receives a message.
Point-to-point links: equivalent (but not equal) to unicast.
•
No node in between. No addressing necessary.
•
Logical point-to-point might have many nodes in between.
Point-to-multipoint: HDLC. One address necessary either sender
or receiver.
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Classification by physical size
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Local Area Networks
a.
b.
Two broadcast LANs: (a) Bus, (b) Ring
LANs with decentralized (vs. centralized channel allocation) control:
IEEE 802.3 = Ethernet (10 Mbps, 100 Mbps, 10 Gbps)
Ring networks: IEEE 802.5 = IBM Token Ring (4 and 16 Mbps), FDDI
(Fiber Distributed Data Interface) Gbps.
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Metropolitan Area Networks
Example of MAN: cable TV.
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WAN (Wide Area Networks) = Internet
•
•
Data Message is split into PDUs (Packet Data
Units have maximum length).
Routers are switching elements for PDUs. They
use store and-forward concept.
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Store-and-forward concept
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•
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Connection-oriented: Virtual Circuits (every packet goes the same route).
Conectionless: routing decisions are made locally at each router ->
missequencing.
Source routing: source specifies path (sequence of routers) in a packet
header.
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History: Network Milestones
1876 Alexander Graham Bell telephone,
1878 exchange
1884 long distance
1901 Marconi ship-to-shore telegraph using Morse code.
Before WWI Strawger Switch
WWI: Teletype (fax) (start/stop bits predecessor of RS232 for modems)
1924 Henry Nyquist from AT&T Sampling Theorem
WWII: Automatic Repeat Request (ARQ) introduced sequence numbering
1948 Claude Shannon from Bell Labs Channel Capacity Theorem
1950s Forward Error Correction (FEC)
1960 Crossbar switch: Ericsson
1960 RS232 physical layer interface standard
1960 Laser enabled fiber optic communication
1960s Digital Electronic Switch with stored program computer (SPC) 1ESS US Bell
1962 T-1 Carrier System (24 DS0s=1.536 Mbps + 8kbps = 1.544 Mbps) developed by
AT&T, DS30 in Europe (32 DS0s = 2.48 Mbps)
1963 Geo-stationary satellite was placed 36,000 miles above equator
1968 FCC decision to let any vendor to attach its equipment to telephony network
1964 First commercial computer network for SABRE built by IBM
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Network Milestones (2)
1970 ALOHA
1971 ARPANET promoted packet switching
1974 Ethernet (Metcalfe at Xerox)
1974 TCP/IP Cerf and Kahn.
1974 SNA (System Network Architecture) was IBM standard: SDLC (Synchronous
Data Link Control) -> ISO HDLC (High Level Data Link Control) -> 1984 CCITT
(ITU) LAPD (Link Access Procedure D-channel)
1976 Western Electric 4ESS fully digital voice switch
1983 ARPANET was split to MILNET (160 nodes, 24 in Europe, 11 Pacific rim) and
ARPANET for Universities (50 nodes) -> NSFNET
1983 ISO OSI (Open System Interconnect) revised 1995 (7 Layer Standard).
1984 AT&T divestiture caused split into 23 BOCs + AT&T services, Lucent systems &
technology.
1984 ISDN (Integrated Services Digital Network) CCITT -> ITU (BRI - Base Rate
ISDN: 2B+D, and PRI - Primary Rate ISDN: 23B+D)
1984 SS7 - out of band signaling CCITT -> Intelligent Networks (IN)
1984 X.25 packet switching networks CCITT
1987 was 3.2 million km fiber in USA
1988 US/Britain transatlantic fiber 40,000 conversations
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Telephone switching
dialer
register
ringer
bell
Strawger step-by-step concept
signaling
marker
register
bell
dialer
voice
crossbar switch
Stage Networks: Benes (recursive approach),
Closs 3 stage networks (recursive)
Interconnection networks: Shuffle (Stone 1971),
Delta (Patel 1976), Omega (Lawrie 1975) etc.
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Hardware switching: Interconnection Network
(3 stages blocking vs. 5 stages non-blocking)
X
N=000
N=000
Y
001
001
010
010
011
011
100
100
101
101
110
110
111
111
non-blocking addition
blocking
Number of switches = (N/2) log2N + (N/2) (log2N - 1) = N log2N - N/2 = 20
vs crossbar 8 * 8 = 64 for N=8 for N=64 => crossbar = 64*64=4096, stage = 32*6 + 32*5 = 352.
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Network topologies
Point-to-point
Point-to-multipoint
Bus: Aloha, wireless (radio),
Ethernet (coax)
Ring: FDDI
Star
Gateway
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General or mesh
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Fully connected
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Wireless Networks
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Categories of wireless networks:
System interconnection – Bluetooth.
Wireless LANs (WiFi) – 802.11: 50 Mbps/30
ft.
Wireless WANs (telephone cellular networks:
GSM, CDMA, UMTS) ~ 2 Mbps.
WiMax (bypassing telephone system) –
802.16: 10 Mbps/10 ml.
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Wireless Networks (2)
(a) Bluetooth configuration: PC master-slave (mouse, keyboard, etc.)
(b) Wireless LAN (WiFi): PC use wireless modems to talk to base
station.
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Wireless Networks (3)
(a) Individual mobile
computers
(b) A flying LAN
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Home Network Categories
• Computers (desktop PC, PDA, shared peripherals
• Entertainment (TV, DVD, VCR, camera, stereo,
MP3)
• Telecomm (telephone, cell phone, intercom, fax)
• Appliances (microwave, fridge, clock, furnace,
a/c)
• Telemetry (utility meter, burglar alarm,
babycam).
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Network Software
• Protocol Hierarchies
• Design Issues for the Layers
• Connection-Oriented and Connectionless
Services
• Service Primitives
• The Relationship of Services to Protocols
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Network Software: Protocol Hierarchies
Layers, protocols, and interfaces. Each layer is a kind of
virtual machine offering services to the layer above it.
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The philosopher-translator-secretary architecture.
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Framing and Encapsulation
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Design Issues for the Layers
• Addressing: network has many computers. An address is
needed to specify a specific destination.
• Error Control: the way to tell if the message is correct.
• Flow Control: fast sender can swamp slow receiver.
• Multiplexing: statistical multiplexing at any level.
• Routing: either political or technical optimization.
• Sequencing: keep the order of received messages.
• Dissasembling/reassembling.
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Connection-Oriented and Connectionless Services
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Services to Protocols Relationship
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Interfaces and Service Access Points
System A
Layer (N+1)
interface
System B
peer protocol
interface
protocol
Layer N
Layer (N+1)
interface
protocol
peer protocol
service
access
Layer N
Interface: boundary between adjacent layers in the same system.
Service Access Point (SAP): is a point where the service is provided
by lower layer to higher layer.
Interface protocol: operating rules between adjacent layers across the
interface.
Primitive: messages of interface protocol.
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Generic OSI service primitives
System A
System b
Service
Service
user
provider
layer (N+1) layer N
Service
provider
layer N
request
Service
user
layer (N+1)
indication
response
confirm
System A
System B
connection request
connection ack
connection phase
data (request)
data (ack)
data transfer phase
disconnect request
disconnect ack
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Five service primitives for implementing a simple
connection-oriented service.
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Packets sent in a simple client-server interaction on
a connection-oriented network.
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Service primitives vs. protocol messages
Idle
Idle
data query
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Connect
listen
send
rece
ive
rece
ive
send
disco
nnect
disco
nnect
client
server
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Reference Models
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•
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The OSI Reference Model
The TCP/IP Reference Model
A Comparison of OSI and TCP/IP
SS7 Reference Model vs. OSI
A Critique of the OSI Model and Protocols
A Critique of the TCP/IP Reference Model
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OSI Reference Model
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ISO OSI reference model (protocol stack)
Application Layer
User interface (task-to-task)
Presentation Layer
Data representation, formatting, code conversion
Session Layer
Transport Layer
Network Layer
Data Link Layer
Physical Layer
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Dialog Control (connection establishment,
message exchange)
Packetizing, end-to-end reliability (error checking,
flow control)
Routing: X.25
Point-to-point error free: HDLC, LAPD
Coding, modulation: AMI, NRZ, Manchester
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OSI layer functions
Physical layer: provides electrical, functional, and procedural means to activate,
maintain, and deactivate physical links that transparently pass the bit stream for
communication; only recognizes individual bits (not characters nor frames) and provides
bit synchronization; peer-to-peer.
Data link layer: provides functional and procedural means to transfer data between
network entities and possibly correct transmission errors; provides activation,
maintenance and deactivation of data link connection; groups bits into characters and
message frames; provides frame synchronization, error control, media access control, and
flow control; peer-to-peer.
Network layer: provides routing, relaying, and switching functions to establish,
maintain, and terminate network layer connections between users.
Transport layer: provides transparent transfer of data between systems for upper layers;
provides end-to-end control and information interchange with required quality of service.
Session layer: provides mechanism for organizing dialogue between application
processes; allows full duplex or half-duplex data exchange (finite state machine message
exchange).
Presentation layer: provides different data presentation (for application layer); provides
syntax selection and conversion (encryption) by allowing user to select presentation
context.
Application layer: provides process parts necessary for communication between
processes.
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Physical Layer: Baseband PCM waveform types
Bits
1
0
1
1
0
0
1
1
0
+V
NRZ - Non Return to Zero
-V
+V
AMI - Alternate Mark Invert
-V
+V
Manchester coding
-V
Requirements:
1. No DC component,
2. Self-clocking,
3. Error detection,
4. Bandwidth compression
5. Noise immunity.
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Fourier Transform: periodic signals
xt  
n 
j 2nf 0t
C
e

 n
n  
n 
jn 0t
C
e
 n
1
Cn 
T0
where
n  
Example: Pulse train
T0
2


X t  e  jn0t dt
T0
2
A
t
T
T0
AT/T0
1
Cn 
T0
T0
2
 Ae

T0
2
 jn0t
 AT  sin Tnf 0 

dt  
 T0  nTf 0 
=>>
T0/T
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
A
A
A
; C  C  0;
for T0/T=2 => C  ; C  C  ; C  C  0; C  C  
1  2
2
3
4
0 2 1
3
3 4
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non-periodic signals


1
 j 2ft
j 2ft


S  f    S t   e
dt S t  
S
f

e
df

2 

Example: unit impulse function d(t)
d
1  j 2ft
e j 2fd  e  j 2fd sin( 2fd )
d t   
e
dt 

2d
2 j  2fd
2fd
d
1.2
1
1/2d
0.8
0.6
f = 1/(2d)
0.4
d
d
t
0.2
0
-12.5
-10
-7.5
-5
-2.5
0
2.5
5
7.5
10
12.5
-0.2
2fd
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Delta impulse

1
 j 2ft
or
d t  
d t    d t   e
dt  1
2



e j 2ft dt

=>> white spectrum.
1/2d
1
d
d
t
f
0
white spectrum
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Handshaking between two modems in RS-232C
PC
DTE
TD
RTS
DTR
RD
CTS
DSR
RI
RLSD
GRND
Modem
Data Set Ready
DSR
DTR
Data Terminal Ready
RI
Ring Indicator
RTS
DCE
Request To Send
CTS
CD
Clear To Send
Carrier Detect
TD
RD
Modem
DCE
RTS – 0011110
RI - 0000111
TD
RTS
DTR
RD
CTS
DSR
R
RLSD
GRND
PC
Transmit Data
Receive Data
DSR
DTR
RI
DTE
RTS
CTS
CD
TD
RD
DB9 bit
connector
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