程序代写CS代考 python Java flex distributed system assembly PowerPoint 演示文稿

PowerPoint 演示文稿

Advanced Network Technologies
Introduction
Dr. | Lecturer
School of Computer Science

COMP 5416
› Title: Advanced Network Technologies
› UOS code: COMP5416
› Credit point: 6
Wednesday 18:00-20:00, weeks 1-13
Online
› Lab/Tutorial:
Wednesday 20:00-21:00, weeks 1-13, starting from today
Thursday 17:00-18:00, weeks 1-13
Sydney time by default
Note your time zone, especially ADST/AEST change in October.
Online

People
› , Coordinator and Lecturer
Weeks 1-13
Office: J12-4W-425
– Phone: (02) 8627 4865

https://www.sydney.edu.au/engineering/about/our-people/academic-staff/wei-bao.html
Office hour: By appointment, through Zoom
Clearly note COMP5416 in the email title when you contact me
› Background
Research: Networking, Mobile Computing, Internet of Things, Distributed Systems.
Research Group: Centre for Distributed and High Performance Computing (http://sydney.edu.au/distributed_computing/)
University of Toronto

People
› Zhengjie Yang, Tutor
Weeks 1-13
Office: J12-West Wing
–
Office hour: by appointment, through Zoom
› Background
Research: Networking, mobile computing, distributed machine learning.
4-year experience in tutoring this UoS
› , Tutor
Weeks 1-13
Office: J12-West Wing

Office hour: by appointment, through Zoom

Emergency procedures (on campus)
In the unlikely event of an emergency we may need to evacuate the building.
If we need to evacuate, we will ask you to take your belongings and follow the green exit signs .
We will move a safe distance from the building and maintain physical distancing whilst waiting until the emergency is over.
In some circumstances, we might be asked to remain inside the building for our own safety. We call this a lockdown or shelter-in-place.
Further information is available at www.sydney.edu.au/emergency

Due to physical distancing requirements building occupants are not gathering at the usual assembly area when evacuating. The advice is to disperse rather than assemble but you should keep your class together (with physical distancing) if you intend to return to class once the emergency is over. If you intend to end the class, you can let the students disperse.
5

Keeping our community safe
We can all help reduce the spread of COVID-19 through following good hygiene practices:

Wash hands regularly, for at least 20 seconds with soap and water, or use an alcohol-based hand rub.
Cover your mouth when coughing and sneezing with a tissue or a flexed elbow.
Maintain a distance of at least 1.5m between yourself and others, where possible.
Avoid large gatherings, where possible.
Avoid close contact with anyone with cold or flu symptoms, e.g. fever, cough, runny nose or shortness of breath.

Remind students to follow guidelines for health management when coming to campus, to protect the health of our students and staff.

Following good hygiene practices on or off campus will also help protect the broader community.
6

Keeping our community safe
All students and staff who have cold or flu symptoms should isolate themselves from others.
If you are unwell with cold or flu symptoms please excuse yourself from this class and we will support you to continue the work remotely.
Make sure you read the information on special consideration in the unit outline.

As a precaution, and generally as good practice, we are asking all students and staff who have cold or flu symptoms to isolate themselves from others and get tested for COVID-19.

If you are have these symptoms, please excuse yourself from this class (even if you are wearing a surgical mask) and we will support you to continue the work remotely or bring you up to speed asap.

Make sure you read the information on special consideration in the unit outline.

Keeping our community safe
The University is following advice from the government and related public health authorities.
For the latest information, see the advice on the University website.
In some classes, especially those involving use of shared equipment, please follow additional advice from your coordinators.
Please take care of each other and yourselves and if you need support reach out to your unit coordinator or the health and wellbeing area of the Current Students website.

Provide students with additional details for unit of study as applicable.
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Tips for students joining online
Remember that you are still in a space with other students.
Mute your microphone when not speaking.
Use earphones or headphones – the mic is better and you’ll disturb others less.
If you have a webcam, please switch it on so we can see you!
If you are speaking to the camera, make eye contact with the camera (and therefore your classmates and teacher).
Try not to talk over someone else.
Use the chat function to send messages to the teacher or classmates during class.

For those of you haven’t taken part in online classes before, here are a few tips to help make it a great experience and ways to communicate with each other during the class.
9

Tips for students learning online
For tips and guides on learning online and the tools you will use, refer to Learning while off campus resources in Canvas.

Visit Canvas to access resources to support your online learning experience.
10

Resources
Canvas: https://canvas.sydney.edu.au/
Login using Unikey and password
Link to Units website: https://sydney.edu.au/units/
Official schedule, list of learning outcomes, etc
Copies of slides
Lab instructions
Assignment instructions
Lecture videos
We intend to record the lectures, but the technology is not reliable
Submit official assignment work here;
see your grades; etc

Textbook and material
Computer Networking: A TopDown Approach 6th or 7th edition, and ,
Some of the information on the slides of this course is taken from the companion material of this textbook that is subject to copyright 1996-2012,
J.F Kurose and K.W. Ross, All Rights Reserved.

Expectations
Students attend scheduled classes, and devote an extra 6-9 hrs per week
doing assessments
preparing and reviewing for classes
revising and integrating the ideas
practice and self-assess
Students are responsible learners
Participate in classes, constructively
Respect for one another (criticize ideas, not people)
Humility: none of us knows it all; each of us knows valuable things
Check canvas site at least once a week!
Notify academics whenever there are difficulties

Evaluation
› W6: Assignment 1, 20%
Covers W1—W6
› W12: Assignment 2, 20%
Covers W6—W12
› Exam period: Final exam, 60%
Covers everything

› School of CS policy: you must get at least 40% of the marks available on the exam, in order to pass the unit. (40% barrier on exam, less than 40% in the exam is automatically a FAIL.)

Special Consideration (University policy)
If your performance on assessments is affected by illness or misadventure
Follow proper bureaucratic procedures
Have professional practitioner sign special USyd form
Submit application for special consideration online, upload scans
Note you have only a quite short deadline for applying
http://sydney.edu.au/current_students/special_consideration/
Also, notify coordinator by email as soon as anything begins to go wrong
There is a similar process if you need special arrangements eg for religious observance, military service, representative sports

Late assessments
Suppose you hand in work after the deadline:
Penalty of 5% per day late, e.g.:
A good assignment that would normally get 9/10 and is 2 days late loses 10% of the full 10 marks, i.e. new mark = 8/10
An average assignment that would normally get 5/10 and is 5 days late loses 25% of the full 10 marks, i.e. new mark = 2.5/10
Assignments more than 10 days late get 0.
Warning: submission sites get very slow near deadlines.
You can resubmit if there is time before the deadline. Only the latest version will be marked.

Academic Integrity (University policy)
“The University of Sydney is unequivocally opposed to, and intolerant of, plagiarism and academic dishonesty.
Academic dishonesty means seeking to obtain or obtaining academic advantage for oneself or for others (including in the assessment or publication of work) by dishonest or unfair means.
Plagiarism means presenting another person’s work as one’s own work by presenting, copying or reproducing it without appropriate acknowledgement of the source.” [from site below]
http://sydney.edu.au/elearning/student/EI/index.shtml
Submitted work is compared against other work (from students, the internet etc)
Turnitin
Penalties for academic dishonesty or plagiarism can be severe
Complete self-education AHEM1001

DISABILITY SERVICES
Do you have a disability?
You may not think of yourself as having a ‘disability’ but the definition under the Disability Discrimination Act is broad and includes temporary or chronic medical conditions, physical or sensory disabilities, psychological conditions and learning disabilities.
The types of disabilities we see include:
anxiety, arthritis, asthma, asperger’s disorder, ADHD, bipolar disorder, broken bones, cancer, cerebral palsy, chronic fatigue syndrome, crohn’s disease, cystic fibrosis, depression, diabetes, dyslexia, epilepsy, hearing impairment, learning disability, mobility impairment, multiple sclerosis, post traumatic stress, schizophrenia , vision impairment, and much more.

Students needing assistance must register with Disability Services –
it is advisable to do this as early as possible.

http://sydney.edu.au/study/academic-support/disability-support.html

Other support
Learning support
http://sydney.edu.au/study/academic-support/learning-support.html
International students
http://sydney.edu.au/study/academic-support/support-for-international-students.html
Aboriginal and Islanders
http://sydney.edu.au/study/academic-support/aboriginal-and-torres-strait-islander-support.html
Student organization (can represent you in academic appeals etc)
http://srcusyd.net.au/ or http://www.supra.net.au/
Please make contact, and get help
You are not required to tell anyone else about this
If you are willing to inform the unit coordinator, they may be able to work with other support to reduce the impact on this unit
eg provide advice on which tasks are most significant

Advice
Metacognition
Pay attention to the learning outcomes
Self-check that you are achieving each one
Think how each assessment task relates to these
Time management
Watch the due dates
Start work early, submit early
Networking and community-formation
Make friends and discuss ideas with them
Know your tutor, lecturer, coordinator
Keep them informed, especially if you fall behind
Don’t wait to get help
Enjoy the learning!

https://www.sydney.edu.au/units/COMP5416

Syllabus
Introduction, Network overview
Network performance, Application layer 1
Application 2
Transport 1
Transport 2
Network science: queues
Multimedia network 1
Multimedia network 2
Wireless and Mobile 1
Wireless and Mobile 2
Advance Network Protocols
Network science: Network optimization*
Recent advances in Network*, Review

Basic network performance analysis
Wireshark, HTTP packet sniffing
Python socket programming
Math foundations for network analysis
Transport layer and TCP
Network and queue simulator
Multimedia network
Real-time protocol
Scheduling and Queues
Network programming
Wireless and noise
Internet of Things Experiment
T: Review and Q&A

Goals
Facts/Knowledge
› How is information transported?
› How to make communications efficient?
› Why does it work in this way? (Differentiate this unit from basic-level units.)

Theory
› Tutorials: Use math to solve problems
› Why is math important?
Practice
› Labs: will require programming
› All programming will be done in Python (version 3.X)
You should be fine if you know Java/C
› Wireshark experiment

Layered Network

ISO/OSI model
ISO: International Organization for Standardization
OSI: Open Systems Interconnection

application

presentation

session

transport

network

link

physical

Network Layers

application

presentation

session

transport

network

link

physical

application

transport

network

link

physical

ISO/OSI model
textbook

application

transport

network

link

Other textbooks

process

transport

internetwork
/Internet

network interface

hardware

Other names

Network Layers
Physical
How to organize data transfer among
adjacent network nodes?
How to transfer bits from one device to another?
Link
How to send message to non-adjacent nodes?
Network
How to provide end-to-end connections for programs
running at different devices in the network?
How to provide network applications satisfies users?
Transport
Application

Physical Layer
Role: Transmitting raw bits over a physical link connecting network nodes.

http://www.eetimes.com/document.asp?doc_id=1276305

Link Layer
Role: data transfer between neighboring network elements.

Bit error detection:
Sender 010101, receiver 010100
Medium access control:
Two devices talking at the same time?
Link-layer addressing:
This information is for you.

Network Layer
Role: routing and forwarding packets from (every) source to (every) destination

Transport Layer
Role: manage program-program (process-process) data transfer

Application Layer
Role: support network applications

Video/Audio

Over TCP/UDP

network support for multimedia
Preview: Practice

application

transport

network

link

physical

HTTP, FTP, SMTP, DNS, P2P…
Wireless
network
TCP, UDP, Transport Protocol

Max min fairness

Preview: Theory

application

transport

network

link

physical

Network
Optimization
Queueing Theory
Principles
of
CDMA
Example:
Game Theory

Socket programming
Preview: Programming/Experiment

application

transport

network

link

physical

Wireshark
Queue simulator
Socket

Network analysis example

Two users competing for one channel
User 1
User 2

Two users competing for one channel
User 1
User 2
A collision happens! No one is successful!

Two users competing for one channel
Situations User 1’s benefit User 2’s benefit
1 off, 2 off 0 0
1 on, 2 off 10 0
1 off, 2 on 0 10
1 on, 2 on -5 -5

In cellular network, for example, we can schedule 1 and 2 in a fair way.

In many other situations? Selfish users.

Two users competing for one channel
Situations User 1’s benefit User 2’s benefit
1 off, 2 off 0 0
1 on, 2 off 10 0
1 off, 2 on 0 10
1 on, 2 on -5 -5

Solution: Game Theory!
Mathematical models of conflict and cooperation between intelligent rational decision-makers!

Useful to solve many economical problems!

Also useful to analyse computer networks and the Internet!

Prisoner’s dilemma
Two members of a criminal gang are arrested

Each prisoner has no means of communicating with the other

Each prisoner can:
1 confess
2 keep silent

Prisoner’s dilemma
Result

Both confess: both serve 5 years in prison

Both keep silent: both serve 1 year in prison

A confesses, B keeps silent (vice versa):
A is set free
B serves 10 years in prison

Prisoner’s dilemma
A’s decision
(A, B) utility

B’s decision Confess Keep silent
Confess (-5,-5) (-10,0)
Keep silent (0,-10) (-1,-1)

A’s decision
(A, B) utility

B’s decision Confess Keep silent
Confess (-5,-5) (-10,0)
Keep silent (0,-10) (-1,-1)

The tuple satisfies: no player has anything to gain by changing only his own strategy

A’s decision
(A, B) utility

B’s decision Confess Keep silent
Confess (-5,-5) (-10,0)
Keep silent (0,-10) (-1,-1)

The tuple satisfies: no player has anything to gain by changing only his own strategy
A changes his/decision, loss

A’s decision
(A, B) utility

B’s decision Confess Keep silent
Confess (-5,-5) (-10,0)
Keep silent (0,-10) (-1,-1)

The tuple satisfies: no player has anything to gain by changing only his own strategy
B changes his/decision, loss

A’s decision
(A, B) utility

B’s decision Confess Keep silent
Confess (-5,-5) (-10,0)
Keep silent (0,-10) (-1,-1)

The tuple satisfies: no player has anything to gain by changing only his own strategy

Not a !

Back to our problem
User 1
User 2

Back to our problem
1’s decision
(1, 2) utility

2’s decision Transmit Keep silent
Transmit (-5,-5) (0,10)
Keep silent (10,0) (0,0)

Back to our problem
1’s decision
(1, 2) utility

2’s decision Transmit Keep silent
Transmit (-5,-5) (0,10)
Keep silent (10,0) (0,0)

Two Nash Equilibria

Back to our problem
1’s decision
(1, 2) utility

2’s decision Transmit Keep silent
Transmit (-5,-5) (0,10)
Keep silent (10,0) (0,0)

Two Nash Equilibria

Pure and mix strategy
This is still not ideal.
Solution: mixed strategy.
Each player can make probabilistic decision!
User 1: transmit with probability p1
keep silent with probability (1-p1)
User 2: transmit with probability p2
keep silent with probability (1-p2)

Back to our problem
1’s decision
(1, 2) utility

2’s decision Transmit Keep silent
Transmit (-5,-5) (0,10)
Keep silent (10,0) (0,0)

p1*p2
(1-p1)*p2
p1*(1-p2)
(1-p1)*(1-p2)
-5*p1*p2+10*p1*(1-p2)+0*(1-p1)*p2+0*(1-p1)*(1-p2)
= -5*p1*p2+10*p1*(1-p2)

So what?
Let’s try p2=2/3
User 1’s average utility
-5*p1*p2+10*p1*(1-p2)
=-5*p1*2/3+10*p1*1/3
=0
No matter how to change p1, user 1’s utility is 0

Similarly
If p1=2/3
No matter how to change p2, user 1’s utility is 0

So what?
p1=p2=2/3 is a
Why?
User 1’s average utility
If p2=2/3
No matter how to change p1, user 1’s utility is 0
If p1=2/3
No matter how to change p2, user 1’s utility is 0

What happens if users are cooperative?

If the users are not selfish,

p1=p2=1/3 is the optimal solution
User 1’s average utility is 5/3
User 2’s average utility is 5/3

Network performance in summery
Situations Solution Utility
Selfish users p1=2/3, p2=2/3 (0,0)
Cooperative users p1=1/3
p2=1/3 (5/3,5/3)

Delays

Delay
Four sources of packet delay
dproc: nodal processing
check bit errors
determine output link
typically < msec A B propagation transmission nodal processing queueing dqueue: queueing delay time waiting at output link for transmission depends on congestion level of router dnodal = dproc + dqueue + dtrans + dprop Delay Four sources of packet delay dtrans: transmission delay: L: packet length (bits) R: link bandwidth (bps) dtrans = L/R dprop: propagation delay: d: length of physical link s: propagation speed in medium (~2x108 m/sec) dprop = d/s dtrans and dprop very different propagation nodal processing queueing dnodal = dproc + dqueue + dtrans + dprop A B transmission Transmission Delay and Propagation Delay bit 1 trans t t bit 2 trans bit N trans …… sender receiver bit1 arrives bit2 arrives Bit N arrives Transmission delay Propagation delay Overall delay Yes, this might happen in packet-switch networks as well. 64 Store and Forward Store-and-forward takes L/R seconds to transmit (push out) L-bit packet into link at R bps store and forward: entire packet must arrive at router before it can be transmitted on next link end-end delay: 2 L/R (assuming zero propagation delay) one-hop numerical example: L = 7.5 Mbits R = 1.5 Mbps delay = 5 sec source R bps destination 1 2 3 L bits per packet R bps 2L/R for a single packet of size L to traverse the two links. Answer: M routers implies a delay of (M+1) L/R 65 Queueing delay R: link bandwidth (bps) L: packet length (bits) a: average packet arrival rate traffic intensity = La/R La/R ~ 0: avg. queueing delay small La/R <~ 1: avg. queueing delay large La/R > 1: more “work” arriving
than can be serviced, average delay infinite!

La/R ~ 0
La/R <~ 1 La/R -> 1: La/R tends toward 1

A Brief Discussion on Queueing Theory
Server

Queue