Transcript Introduction - cse services

CSE 5346 – Networks II:
High Performance Networks
and Quality of Service
Spring 2016
Mike O’Dell
Senior Lecturer
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Introduction
Performance and
Quality of Service
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CSE 5346 – Computer Networks II
Course Objective:
Understand the concepts critical to quality
of service and understand how the Internet
supports advanced classes of service. Focus
on topics such as QoS architectures, queue
management, traffic modeling, and relevant
quality of service protocols deployed in IP
networks. Understand current QoS
practices such as Flow Aware Networking.
Introduction
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CSE 5346 – Computer Networks II
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Instructor: Mike O’Dell ([email protected])
GTA: Sharad Velmajala
([email protected])
Class Web Site: http://ranger.uta.edu/~odell/
Required Textbook (general topics/lectures):
High-Speed Networks and Internets Performance and Quality of Service, Second
Edition, William Stallings, Prentice Hall, 2002
(ISBN: 0-13-032221-0)
Introduction
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CSE 5346 – Computer Networks II
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Secondary Textbooks/References:
1) Guide to Flow-Aware Networking: Quality of
Service Architectures and Techniques for
TrafficManagement, Domżał, Wójcik,
Jajszczyk, Springer Internatiional, 2015
(ISBN: 978-3-319-24973-5, and 978-3-31924975-9 for eBook)
2) End-to-End QoS Network Design, Second
Edition, Szigeti, Hattingh, Barton, Briley, Cisco
Press, 2014(ISBN-13: 978-1-58714-369-4)
3) Internet RFCs
Introduction
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Course Foundation Assumptions
(pre-requisites)
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Good understanding of packet-switched
networking concepts and principles of
operation
Good understanding of Internet protocols
and architectures (e.g., IP protocol stack)
Solid foundation in computer operating
systems fundamentals
Ability to perform independent research,
analyze findings and document results
Introduction
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Class Administration & Policy
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Web Site: http://ranger.uta.edu/~odell/
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Email - will be used for time-critical info
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Schedule
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– Schedule, Syllabus, Class Materials/Information
– I will use ONLY UTA email (mavmail) account for
correspondence
– Ambitious... may be modified... check web site
frequently
Attendance… expected, not measured
Late Submission and Make-Up Policy
– Late Homework, Programs/Projects: 10%/day,
max of 40%, then zero
– Quizzes and Exams: NO make-ups. NO early
exams/quizzes. Absence = zero grade.
Introduction
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Class Administration & Policy
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Grading Policy
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Final Grade Assignment (typical-guideline
only)
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Projects (4 x 8%)
Project 5 & Presentations
Quizzes (5 x 5%)
Exam 1
Exam 2
32%
13%
25%
15%
15%
– Based on final numerical score out of 100%
possible:
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A
B
C
D
F
> 85%
85% – 75%
75% - 65%
65% - 55%
55% & below
– Generally final grades will not be “curved”.
Introduction
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Class Administration & Policy
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Honesty… expected, dishonesty will not be
tolerated
– Discussions, brainstorming are encouraged,
HOWEVER
– Homework, Final Paper & Programming
Assignments, Quizzes, Exams, etc. are to be YOUR
individual work
– See the syllabus and UTA references for
definitions of
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Cheating
Collusion
Plagiarism
Any suspected violation of this policy will be
referred to the UTA Office of Student
Conduct for disposition.
Introduction
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Class Administration & Policy
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Office Hours
– Individual grades or questions on grading of
individual quizzes, exams, etc. are discussed only
during office hours (i.e. NOT at the end of class
period)
– Mr. O’Dell’s Office Hours (in ERB 647)
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MWF: 12:30 PM – 1:30 PM
– Mr. Velmajala’s Office Hours (in TBD)
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Introduction
TBD
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What will we cover?
Some Review
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New Content
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Networking Introduction/Review
– This week… setting the stage
Performance Modeling and Estimation
Congestion, Network Traffic
Analysis/Management and Routing
Quality of Service Models in the Internet
– Queuing models, traffic and flow management
– QoS Foundation: Intserv and Diffserv
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Flow Aware Networking
– Architectures, Techniques, Considerations
Introduction
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How will we cover it?
Classroom lectures
 Quizzes(5) and exams (2)
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– NO final exam
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Incremental, 5-phase, network
simulation project
– “DIY Simulator”
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Self-study research, and simulation
analysis by students
Introduction
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Introduction
An Overview of Internetworking –
Traffic Management and Quality
of Service
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What is (an) the (i)Internet?
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connected computing
devices - hosts, endsystems:
– PC’s, workstations,
servers
– PDA’s, phones, toasters,
cars
– running network
applications
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communication links:
– fiber, copper, radio,
satellite (physical
connections)
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router
server
local ISP
workstation
mobile
regional ISP
company
network
routers/switches:
– forward packets (chunks)
of data thru network
Introduction
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The Need for Speed!
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Scale
– growing number of
hosts -> growing
demands on
bandwidth
– new technologies
result in new
paradigms for
device and
connection types
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e.g. ??
User Expectations!
Introduction
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Application
– demand for large
to huge file
transfers
– increasing critical
nature of Internet
use
– demand for “realtime” performance
characteristics
– demand for
guarantees of
service levels
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e.g. ??
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The Need for Improved
(better) Levels of Service
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Applications
– often create
inelastic traffic
– often sensitive to
delay
– often sensitive to
jitter
– often critical in
nature
– generate elastic
traffic as well
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User Requirements!
Introduction
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Delay Sensitivity & Criticality
Introduction
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The Need for Improved
(better) Levels of Service
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Applications
– often create
inelastic traffic
– often sensitive to
delay
– often sensitive to
jitter
– often critical in
nature
– generate elastic
traffic as well
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User Requirements!
Introduction
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Basic Internet
Service is “BestEffort”
– all packets treated
equally
– designed for
elastic traffic
– no guarantees of
bandwidth or
throughput
– no guarantees of
delay
– no guarantee of
jitter (delay
variation)
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IP-based Internets (aka
TCP/IP networks)
Internetworking: the dominant paradigm
of computer networking
Evolution of key internetworking technologies:
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packet switching: best effort, or specified, preconfigured type of service
critical functions of Internet protocol stack
– TCP: reliable end-to-end transport
– UDP: best effort datagram transport
– IP: internet routing and delivery (v4…v6)
Important Trends: dynamic routing, load balancing,
traffic/flow management, congestion avoidance,
reliable transfer
Introduction
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Advancements in Internet
Standards and Architecture
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Many recent advancements are driven by the
need to support streaming and “live”
multimedia and other real-time applications
Evolution of the Internet’s Integrated
Services Architecture (ISA, or IntServ) and
Differentiated Services (DS, or DiffServ)
QoS Architectures/Frameworks are driving
protocol changes:
– IPv6 – includes specific features for QoS
– Realization of enhancements to IntServ/DiffServ
architectures
– Flow Aware Networking models
Introduction
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Delays in Packet Switched
(e.g. IP) Networks
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End-to-end delay (simplified) =
(dprop + dtrans + dqueue + dproc) x Q
A
B
Where:
 Propagation delay (dprop)
 Transmission delay (dtrans)
 Queuing delay (dqueue)
 Processing delay (dproc)
 Number of links (Q)
Introduction
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So what’s the problem?
What makes this so hard?
(I.e., what are we going to focus on
in this course.)
Introduction
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Delays in Packet Switched
(e.g. IP) Networks
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A
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End-to-end delay (simplified) =
– (dprop + dtrans + dqueue + dproc) … on each link
Where:
B
 Propagation delay (dprop) = d/s
 Transmission delay (dtrans) = L/R
 Queuing delay (dqueue) = ?
 Processing delay (dproc) = ?
Much more later
 Number of links (Q) = ?
Introduction
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The Router in IP Networks
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An Internet router has two functions:
– Establish routes: routing protocols
– Forward packets: move from input to
appropriate output
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Routers play THE KEY ROLE in end-toend performance (throughput) of
network applications
– Routing: establishing paths consistent with
requirements
– Forwarding: queue management at each hop
on the path
Introduction
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Basic IP router architecture
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Two key router functions:
1. run routing algorithms/protocol (RIP, OSPF, BGP)
2. forward datagrams from incoming link (queue) to outgoing link
(queue)
routing
processor
routing, management
control plane (software –
multi-millisecond speed)
Output links
Input links
forwarding tables computed,
pushed to input ports
high-speed
switching
fabric
router input ports
Introduction
forwarding data
plane (hardware –
nanosecond
speed)
router output ports
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Input port functions
link
layer
protocol
(receive)
line
termination
lookup,
forwarding
queueing
switch fabric
(bus, memory, etc.)
physical layer:
bit-level reception
data link layer:
e.g., Ethernet
decentralized switching:
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Introduction
given datagram destination, lookup
output port using the forwarding table
in input port memory (“match plus
action”)
goal: complete input port processing at
‘line speed’
queuing: if datagrams arrive faster
than forwarding rate into switch fabric
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Input port queuing
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fabric slower than input ports combined -> queueing may occur
at input queues
 queueing delay and loss due to input buffer overflow!
Head-of-the-Line (HOL) blocking: queued datagram at front
of queue prevents others in queue from moving forward
switch
fabric
output port contention:
only one red datagram can be
transferred.
lower red packet is blocked
Introduction
switch
fabric
one packet time
later: green packet
experiences HOL
blocking
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Output port functions
switch
fabric
datagram
buffer(s)
queueing
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link
layer
protocol
(send)
line
termination
buffering required when datagrams arrive from
fabric faster than the transmission rate
scheduling discipline chooses among queued
datagrams for transmission
Introduction
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Output port queueing
switch
fabric
at packet time t, multiple
packets arrive for same
output port
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switch
fabric
at packet time t+1,
output queue grows
buffering when arrival rate via switching fabric
exceeds output line speed
queueing (delay) and loss due to output port
buffer overflow!
Introduction
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Hence, our focus…
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We will study, primarily, the Internet’s
network layer:
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Traffic management
Queuing disciplines, queue management
Flow aware traffic policies
IP protocol and relevant standards (rfc’s)
Demonstrated via a multi-phase, “buildyour-own” network QoS routing
simulator
Introduction
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