Download CCNA 1 Module 11 TCP/IP Transport and Application Layers

TCP/IP Transport and
Application Layers
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1
Objectives
• TCP/IP Transport Layer
• TCP/IP Application Layer
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2
TCP/IP Transport Layer
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3
Introduction to Transport Layer
• Five basic services:
Segmenting upper-layer application data
Establishing end-to-end operations
Transporting segments from one end
host to another end host
Ensuring data reliability
Providing flow control
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Reliability
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Flow Control
• Avoids the problem of a host at one side of
the connection overflowing the buffers in the
host at the other side
• Ensures the integrity of the data
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6
Session Establishment
• One function of the
transport layer is to
establish a connectionoriented session
between similar devices
at the application layer.
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Session Maintenance and Termination
• Congestion can occur
during data transfer
• To terminate, the
sending host sends a
signal that indicates the
end of the
transmission, which is
acknowledged by the
receiver.
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8
Three-Way Handshake
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9
Windowing
• A method of controlling the amount of
information transferred end to end
• Information can be measured in terms of
the number of packets or the number of
bytes
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Window Size
• TCP window sizes are variable during
the lifetime of a connection.
• Larger window sizes increase
communication efficiency.
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11
Acknowledgment
• Positive acknowledgment requires a
recipient to communicate with the
source, sending back an
acknowledgment message when it
receives data.
• Sender keeps a record of each data
packet that it sends and expects an
acknowledgment.
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12
TCP Sequence and Acknowledgment
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13
Transmission Control Protocol (TCP)
• The protocols that use TCP include:
FTP (File Transfer Protocol)
HTTP (Hypertext Transfer Protocol)
SMTP (Simple Mail Transfer Protocol)
Telnet
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14
TCP Segment Format
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UDP
• The protocols that use UDP include:
TFTP (Trivial File Transfer Protocol)
SNMP (Simple Network Management
Protocol)
DHCP (Dynamic Host Control Protocol)
DNS (Domain Name System)
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UDP Segment Format
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TCP and UDP Port Numbers
• Both TCP and UDP use port (socket)
numbers to pass information to the
upper layers.
Numbers below 1024 are considered wellknown ports numbers.
Numbers above 1024 are dynamically
assigned ports numbers.
Registered port numbers are those
registered for vendor-specific
applications. Most of these are above
1024.
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18
TCP and UDP Port Numbers
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19
TCP/IP Application Layer
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Introduction to Application Layer
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Responsibilities of Application Layer
• Identifying and establishing the
availability of intended communication
partners
• Synchronizing cooperating applications
• Establishing agreement on procedures for
error recovery
• Controlling data integrity
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Application Layer Examples
• Domain Name System
• File Transfer Protocol
• Hypertext Transfer Protocol
• Simple Mail Transport Protocol
• Simple Network Management Protocol
• Telnet
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DNS
• The Domain Name System (DNS) is a system
used for translating names of domains into IP
addresses.
• There are more than 200 top-level domains on
the Internet, examples of which include the
following:
.us – United States
.gov – government sites
.uk – United Kingdom
.org – non-profit sites
.edu – educational sites
.net – network service
.com – commercial sites
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FTP and TFTP
• FTP is a reliable, connection-oriented
service that uses TCP to transfer files
between systems that support FTP.
• TFTP is a connectionless service that uses
User Datagram Protocol (UDP).
TFTP is used on routers to transfer
configuration files and Cisco IOS images.
TFTP is designed to be small and easy to
implement.
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25
HTTP
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SMTP
• E-mail servers communicate with each other
using the Simple Mail Transport Protocol
(SMTP) to send and receive mail.
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SNMP
• The Simple Network Management Protocol (SNMP) is
an application layer protocol that facilitates the
exchange of management information between
network devices.
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Telnet
• Telnet client software provides the ability to log
in to a remote Internet host that is running a
Telnet server application and then to execute
commands from the command line.
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