Burke's theorem and networks of queues - FRONT!

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23 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

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Weiqiang Sun

INTRODUCTION

Weiqiang Sun

About the course


Lecturer: Weiqiang Sun (
孙卫强
)


TA: Kai Kang(
康凯
)



Requirements and grading:


One problem set each week (20%)


Class participation (15%)


Final exam (65%)



Textbook


Bertsakas

&
Gallager
, Data Networks, 2
nd

Edition



Course website (lecture notes, problem set & solutions etc.)


http://front.sjtu.edu.cn/datacomm/

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Content coverage


This course will cover fundamental aspects of data network analysis
and design



Architecture


Network layering


Protocols


Point
-
to
-
point


End to end


Multi
-
access


Algorithms


Error recovery


Routing


Flow control


Analysis tools


Queueing theory


Probabilistic modeling

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Course syllabus

4

#

TOPICS

WEEK #

1

Introduction to Data Networks

1

2

The data link layer: framing and error correction

2

3

The data link layer: ARQ
protocols

3

4

The Little's Theorem

4

5

M/M/x Queue

5

6

Burke's Theorem and network of queues

6

7

M/G/1 queue

7

8

Reservation and priority queues

8

9

Aloha protocol

9

10

Local Area Networks: CSMA and CSMA/CD

10

11

Broadcasting routing and routing in data networks

11

12

Flow and Congestion Control

12

13

Higher Layer Protocols: TCP/IP and ATM

13

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Guest lectures (tentative)

5

#

TOPICS

Guest speaker

Week #

1

The future of data networks

Monique J. Morrow (Cisco
SP AP CTO)

TBD

2

Trends and challenges in
China Mobile communications

A
-
Qiang

Shen
, Assistant
Prof. of BUPT, China

TBD

3

Broadband Access
in

Shanghai

Telecom

Chengbing

Shen

TBD

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The history of Internet


1946, first appearance in science fiction:
A logic named Joe


1969, interconnection of two nodes, later became ARPANET


1974, TCP Protocol became an RFC and the first use of term “Internet”


1976, X.25 became a CCITT (later ITU
-
T) standard


1978, International packet switched service in US and Europe


1981, X.25 based network grew from Europe and US to Canada, HK
and Australia


1983, first TCP/IP base wide
-
area network started to operate, NSFNET
started construction in 1985


1989, commercial mail services were available on NSFNET


1991, WWW was publicized at CERN: European Organization for
Nuclear Research


1996, the use of internet had become commonplace

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Weiqiang Sun

The history of Internet


1946, first appearance in science fiction:
A logic named Joe


1969, interconnection of two nodes, later became ARPANET


1974, TCP Protocol became an RFC and the first use of term “Internet”


1976, X.25 became a CCITT (later ITU
-
T) standard


1978, International packet switched service in US and Europe


1981, X.25 based network grew from Europe and US to Canada, HK
and Australia


1983, first TCP/IP base wide
-
area network started to operate, NSFNET
started construction in 1985


1989, commercial mail services were available on NSFNET


1991, WWW was publicized at CERN: European Organization for
Nuclear Research


1996, the use of internet had become commonplace

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Weiqiang Sun

Network applications


E
-
mail


The World Wide Web


Remote access


Collaboration


File sharing (FTP, BT etc)


Streaming (
PPLive
, IPTV etc)


Voice telephony (VoIP)


And much more….

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Network coverage areas


Wide Area Networks (WAN)


Large footprint, usually country scale, or inter
-
country scale, 1000KM and more


Use leased line/circuit switching


Metro Area Networks (MAN)


Medium footprint, in a city (metropolitan), 50
-
100KM


Provides connectivity for LAN in a city


Local Area Networks (LAN)


Small span, in a building or office, ~100M


Direct high speed connection


Home Area Networks (HAN)


Personal Area Networks (PAN)


Storage Area Networks (SAN)




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Switching techniques


Circuit switching


Dedicated resources


Low efficiency


Higher Quality of Service



Packet switching


Shared resources


Can be used to implement virtual circuits


High efficiency


Prone to congestion and packet loss

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Weiqiang Sun

Network footprints and switching
techniques


Wide Area Networks (WAN)



Metro Area Networks (MAN)



Local Area Networks (LAN)



Home Area Networks (HAN)



Personal Area Networks (PAN)



Storage Area Networks (SAN)




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Circuit switching

Packet switching

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The layered network model


OSI
reference model

12

Application

Presentation

Session

Transport

Network

Data Link
Control

Physical
Interface

Application

Presentation

Session

Transport

Network

Data Link
Control

Physical
Interface

Network

DLC

PHY

DLC

PHY

Network

DLC

PHY

DLC

PHY

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Your friend’s PC

Your PC

….

DSL Modem

W
-
less router

The OSI reference model in the context of
broadband access


an example

13

Application

Presentation

Session

Transport

Network

Data Link
Control

Physical
Interface

Application

Presentation

Session

Transport

Network

Data Link
Control

Physical
Interface

Network

DLC

PHY

DLC

PHY

DLC

PHY

PHY

Network

DLC

PHY

DLC

PHY

Weiqiang Sun

The layered network model


OSI
reference model

14

Application

Presentation

Session

Transport

Network

Data Link
Control

Physical
Interface

Application

Presentation

Session

Transport

Network

Data Link
Control

Physical
Interface

Network

DLC

PHY

DLC

PHY

Network

DLC

PHY

DLC

PHY

Peer communications

Inter
-
layer
communications

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The physical layer


Responsible for transmission of bits over a link


Wireline

link, such as twisted pair, fiber optics, serial lines etc


Wireless link, such as satellite link, free space optics, microwave etc


Modulation and de
-
modulation (MODEM)


Mapping the bits from high layer to signals and the reverse


Modes of operation


Synchronous, intermittent synchronous, and asynchronous


Can incur transmission errors


Noise, power loss etc


Can induce transmission delay


The speed of light (EM wave)

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The data link control layer


Responsible for error
-
free transmission of bits across a
point
-
to
-
point

link


Realizes a reliable “virtual” link


Re
-
transmit, or drop packet if some error occurs


Framing, error detection and correction



Sometimes in a shared media, is also responsible for
contention resolution/access control


e.g. in a wireless radio network


The MAC
sublayer

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The Network layer


Routing and flow control in the network (network wide)


One network layer process on each node


Route the packets to the proper outgoing DLC, or to up layer
(at destination)



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Network layer

DLC Layer

Link 1

DLC Layer

Link 1

DLC Layer

Link 1

A node

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The transport layer


Break messages into packets and reassemble


Packet of size suitable for network layer


Multiplex sessions with same source/destination nodes


Re
-
sequence packets at destination


Recover from packet loss or failures


Provide end
-
to
-
end flow control




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Other layers


Presentation layer


Provides character code conversion, data encryption, data
compression,
etc.


Session layer


Obtains virtual end to end message service from transport layer


Provides directory assistance, access rights, billing functions, etc.



Standardization has not proceeded well here, since transport
to application are all in the operating system and don't really
need standard interfaces

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The Internet model

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application

transport

IP

Data link and
lower layer

application

transport

IP

Data link and
lower layer

IP

Ethernet

Token
ring

Token ring

Ethernet

Ethernet

IP

protocol

IP

protocol

TCP/UDP protocol

FTP, HTTP, SMTP…

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Encapsulation

21

application

transport

IP

Data link and
lower layer

Ethernet

“hi”

“hi”

“hi”

“hi”

“hi”

User data

TCP data

IP packet

Ethernet Frame

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The “Hi” example

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Hi

TCP header

IP header

Frame header / trailer