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Protocols and the TCP/IP Suite
Lecture 12
Overview
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Requirement of Protocol
Why Layered Approach is Adopted
Key Features of a Protocol
Simple Protocol Architecture
Addressing
TCP/IP and OSI model
General Networking Terminology
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The Need For Protocol Architecture
1.) the source must activate
communications path or
inform network of
destination
2.) the source must make
sure that destination is
prepared to receive data
To transfer data
several tasks
must be
performed:
3.) the file transfer
application on source must
confirm file management
program at destination is
prepared to accept and store
file
4.) a format translation
function may need to be
performed if the formats on
systems are different
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Functions of Protocol Architecture
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breaks logic into subtask modules which are
implemented separately
modules are arranged in a vertical stack
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each layer in the stack performs a subset of functions
relies on next lower layer for primitive functions
changes in one layer should not require changes in other layers
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Key Features of a Protocol
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A protocol is a set of rules or conventions that
allow peer layers to communicate.
The key features of a protocol are:
Syntax
• format of data
blocks
Semantics
• control information
for coordination and
error handling
Timing
• speed matching and
sequencing
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A Simple Protocol
agents involved:
• applications
• computers
• networks
examples of
applications
include file
transfer and
electronic mail
these execute on
computers that
support multiple
simultaneous
applications
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Communication Layers
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communication tasks are organized into three
relatively independent layers:
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Network access layer
 concerned with the exchange of data
Transport layer
 provides reliable data transfer
Application layer
 Contains logic to support applications
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Network Access Layer
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covers the exchange of data between an end
system and the network that it is attached to
concerned with issues like :
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destination address provision
invoking specific services like priority
access to & routing data across a network for two
end systems attached to the same network
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Transport Layer
concerned with
providing
reliable delivery
of data
essentially
independent of
the nature of
the applications
common layer
shared by all
applications
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Application Layer
contains the logic
needed to support
user applications
separate module
is needed for each
type of application
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Protocol Architecture and Networks
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Protocols in a Simplified Architecture
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Addressing
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Two levels of addressing are needed:
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Protocol Data Unit (PDU)
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the combination of data and control information
is a protocol data unit (PDU)
typically control information is contained in a PDU
header
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control information is used by the peer transport
protocol at computer B
headers may include:
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source port, destination port, sequence number,
and error-detection code
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Network Access Protocol
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after receiving segment from transport layer, the
network access protocol must request
transmission over the network
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the network access protocol creates a network
access PDU (packet) with control information
header includes:
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source computer address
destination computer address
facilities requests
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TCP/IP Protocol Architecture
Result of
protocol
research and
development
conducted on
ARPANET
Referred to as
TCP/IP
protocol suite
TCP/IP
comprises a
large collection
of protocols
that are
Internet
standards
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TCP/IP Layers and Example Protocols
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Physical Layer
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covers the physical interface between computer
and network
concerned with issues like:
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characteristics of transmission medium
nature of the signals
data rates
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Network Access Layer
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covers the exchange of data between an end
system and the network that it is attached to
concerned with issues like :
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destination address provision
invoking specific services like priority
access to & routing data across a network for two
end systems attached to the same network
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Internet Layer
implements procedures
needed to allow data to
travel across multiple
interconnected networks
uses the Internet
Protocol (IP) to provide
routing function
implemented in end
systems and routers
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Host-to-Host (Transport) Layer
• concerned with
providing reliable
delivery of data
• common layer
shared by all
applications
• most commonly
used protocol is
the Transmission
Control Protocol
(TCP)
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Operation of TCP/IP
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TCP/IP Address Requirements
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Two levels of addressing are needed:
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TCP/IP Addressing
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Operation of TCP/IP
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Transmission Control Protocol (TCP)
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TCP is the transport layer protocol for most
applications
TCP provides a reliable connection for transfer of
data between applications
A TCP segment is the basic protocol unit
TCP tracks segments between entities for duration of
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each connection
TCP Header
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User Datagram Protocol(UDP)
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alternative to TCP
does not guarantee delivery, preservation of
sequence, or protection against duplication
adds port addressing capability to IP
used with Simple Network Management Protocol
(SNMP)
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UDP Header
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IPv6
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Provides enhancements over existing IP
Designed to accommodate higher speeds and the
mix of graphic and video data
Driving force was the need for more addresses
due to growth of the Internet
IPv6 includes 128-bit source and destination
address fields
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IPv6 Header
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TCP/IP Protocols
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Standardized Protocol Architectures
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Layer Specific Standards
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OSI Standardization
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framework for standardization was motivator
lower layers are concerned with greater levels of
details
each layer provides services to the next higher
layer
three key elements:
Protocol
specification
Service
definition
Addressing
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Primitive Types
REQUEST
A primitive issued by a service user to invoke some
service and to pass the parameters needed to specify
fully the requested service
INDICATION
A primitive issued by a service provider either to:
indicate that a procedure has been invoked by the peer
service user on the connection and to provide the
associated parameters, or
notify the service user of a provider-initiated action
RESPONSE
A primitive issued by a service user to acknowledge or
complete some procedure previously invoked by an
indication to that user
CONFIRM
A primitive issued by a service provider to acknowledge
or complete some procedure previously invoked by a
request by the service user
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Service Primitives and Parameters
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define services between adjacent layers using:
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primitives to specify function performed
parameters to pass data and control information
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Internet Applications
Applications that operate on top of TCP include:
FTP
SMT
P
SSH
TCP
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Multimedia Terminology
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Multimedia Terminology
audio generally encompasses sounds that are
produced by a human, telephony and related
voice communications technology
image supports the communication of individual
pictures, charts, or drawings
video service carries sequences of pictures in
time
text is information that can be entered via a
keyboard and is directly readable and printable
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Multimedia Applications
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Domains of Multimedia Systems
and Example Applications
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Elastic and Inelastic Traffic
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Multimedia Technologies
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Internetworking Terms
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End System (ES) – device used to support end-user
applications or services
Intermediate System (IS) – device used to connect
two networks
Bridge – an IS used to connect two LANs that use
similar LAN protocols
Router - an IS used to connect two networks that
may or may not be similar
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Functions of a Router
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Provide a link between networks
Provide for the routing and delivery of data
between processes on end systems attached to
different networks
Provide these functions in such a way as not to
require modifications of the networking
architecture of any of the attached subnetworks
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Network Differences Routers Must Accommodate
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Addressing schemes
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Maximum packet sizes
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Different maximum packet sizes requires segmentation
Interfaces
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Different schemes for assigning addresses
Differing hardware and software interfaces
Reliability
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Network may provide unreliable service
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Summary
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Why we need protocols for communication
Benefits of adopting layered approach
From simple to featured protocol example
Addressing schemes
Standards Comparison (TCP/IP Vs. OSI)
Functionality of and important device on the basis
of studied protocol
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