1 kommunikatsiooniteenuste arendus irt0080 loeng 2 avo ots telekommunikatsiooni õppetool, ttÜ...
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Kommunikatsiooniteenuste arendusIRT0080Loeng 2
Avo Otstelekommunikatsiooni õppetool,
TTÜ raadio- ja sidetehnika [email protected]
The Internet
Every machine transparently connected to
every other
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Implementation
Applications
OS
Applications
OS
Multi layer implementation-Breaking down into smaller components-Easier to implement
Single layer implemen-tation
Applications
OS
Co
mm
un
icat ion
Applications
OS
Co
mm
un
icat ion
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Message Transmission Example
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TCP
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The Problem• only nodes on the same physical/link layer
network could communicate
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Solution
Gateways
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Multiple Access Protocols
Multiple access protocols
Contention-based Conflict-free
Random access Collision resolution
FDMA,
TDMA,
CDMA,
DQDB, etc
ALOHA,
CSMA
WINDOW, etc
DQDB: Distributed Queue Dual Bus
BTMA: Busy Tone Multiple AccessISMA: Internet Streaming Media Alliance
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Channel Sharing Techniques
Channel Sharing Techniques
Static Channelization
Dynamic Medium Access Control
Scheduling
Random Access
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Throughput
G86420
0.5
0.4
0.3
0.2
0.1
0
Slotted Aloha
Aloha
0.368
0.184
G
S
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Vastastikused häired
Interference Margin (dB) and Load Factor
0
5
10
15
20
25
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Load Factor
Inte
rfer
ence
Mar
gin
(d
B)
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E-Mail Standards (1)
SMTPTo Send
SMTPTo Send
SendingE-MailClient
ReceivingE-MailClient
Sender’s MailServer
Receiver’s MailServer
Simple Mail Transfer Protocol (SMTP) to transmit mail in real time to a user’s mail server or between mail servers
Sender-initiated
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E-Mail Standards (2)
Sending E-MailClient
ReceivingE-MailClient
Sender’s MailServer
Receiver’s MailServer
POP orIMAP
To Receive
POP or IMAP to download mail to receiver when the receiver is next capable of downloading mail.
Receiver-initiated
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E-Mail Standards (3)
SendingE-MailClient
ReceivingE-MailClient
Sender’s MailServer
Receiver’s MailServer
MessageRFC 822 or 2822HTML bodyUNICODE
Message Body Format Standard
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Lingidhttp://en.wikipedia.org/wiki/Client_server
http://en.wikipedia.org/wiki/Application_server
ftp://ftp.prenhall.com/pub/esm/sample_chapters/cs/stallings/index.html
http://www.williamstallings.com