Ch1

Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain
Chapter 1
Introduction

Objectives
 Understand the significance of TCP/IP in the
modern era of pervasive computing and
communication
 Appreciate the need for designing and building
high-performance TCP/IP networks
 Gain a clear understanding of the metrics used for
performance evaluation of TCP/IP networks

Contents
 TCP History
 TCPApplications
 Significance of TCP Performance
 Performance Metrics

TCP History

Birth of TCP/IP
 1973: First note by Dr. Vinton G. Cerf
Only the concept of TCP (no separate IP)
 1974: Cerf & Kahn published detailed discussion
of TCP design in Transcom
Still no separate IP
 1974: First official spec. of TCP in RFC 675
Still no separate IP
 1978: Split into two protocol stacks
TCP: RFC 760
IP: RFC 761

Adoption of TCP/IP
 1980: DoD adopts TCP/IP as preferred
protocol for ARPAnet
 1983: All sites connected to ARPANet
switch to TCP/IP

TCP
Applications

Basic TCPApplications
 Email (SMTP)
 Web browsing (HTTP)
 File transfer (FTP)
 Remote login (RLOGIN)
These are the most popular, standard TCP applications. Other
customized applications can be built on top of these basic
applications.

Significance of
TCP Performance

Why Study TCP Performance
 Dependence on TCP/IP networks
 The critical role of TCP protocol engine
 Emergence of new networking technologies
and environments
 IP convergence

Dependence on TCP/IP Networks
 More people rely on TCP/IP networks than
ever before
 Some use TCP/IP consciously
E.g. file download
 Some use it without knowing
For example withdrawing money from ATM
machine

Dependence on TCP/IP (cont.)
 We depend on TCP at office, home, and
while on the move
 We depend on TCP not only for research,
but also for critical business transactions
and entertainment
 Internet (powered by TCP/IP) is now a key
tool used by our kids to prepare their
projects at schools

Critical Role of TCP
 Many believe that network performance can be
boosted by simply upgrading hardware
Not correct in many occasions
 TCP sits between application and network
 TCP has total control of how application data
should be released to the network
 TCP is a complex protocol which interacts with
many network elements in the end to end path
 Unless TCP is optimized, hardware alone cannot
boost network performance

Emergence of New Networking
Technologies
 We are witnessing proliferation of different
networking technologies
Wireless, satellite, optical etc.
 TCP algorithms suitable for one environment, do
not always work best in another
 Need for research into new algorithms
Evidence: large number of articles on TCP are
published every year in top journals and conferences

IP Convergence
 Many traditional non-TCP/IP industries are
converging to TCP/IP
E.g. cellular communication, video and other
entertainments, etc.
 Understanding TCP/IP performance
fundamentals thus becomes important to
scientists and engineers working in all these
industries

Performance
Metrics

Performance Metrics
 Round trip delay:The time needed to travel
from source to destination, plus the time to travel
from destination back to the source.
 One way delay: The time needed to travel from
source to destination, or from destination to
source.
 Maximum delay: Maximum tolerable delay

Performance Metrics (Cont.)
 Delay variation (or jitter): Variation in
delay for individual packets.
 Packet loss rate: Ratio of the number of
packets lost (or corrupted) to the total
number of packets transmitted.
 Bandwidth: Application bytes transferred
in seconds.

Performance Metrics (Cont.)
 Throughput variation: Variability in the
received bandwidth over a given time scale.
 File transfer time: Time takes to transfer a
file/object on the WWW.
 Fairness: Long-term/short-term fairness among
all TCP/UDP flows.
 Resource consumption: Amount of resource
consumed, e.g. CPU cycles, memory usage,
battery, etc.

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