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

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Transcript
TCP/IP Transport and
Application Layers
© 2003, Cisco Systems, Inc. All rights reserved.
1
Objectives
• TCP/IP Transport Layer
• TCP/IP Application Layer
© 2003, Cisco Systems, Inc. All rights reserved.
2
TCP/IP Transport Layer
© 2003, Cisco Systems, Inc. All rights reserved.
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
© 2003, Cisco Systems, Inc. All rights reserved.
4
Reliability
© 2003, Cisco Systems, Inc. All rights reserved.
5
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
© 2003, Cisco Systems, Inc. All rights reserved.
6
Session Establishment
• One function of the
transport layer is to
establish a connectionoriented session
between similar devices
at the application layer.
© 2003, Cisco Systems, Inc. All rights reserved.
7
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.
© 2003, Cisco Systems, Inc. All rights reserved.
8
Three-Way Handshake
© 2003, Cisco Systems, Inc. All rights reserved.
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
© 2003, Cisco Systems, Inc. All rights reserved.
10
Window Size
• TCP window sizes are variable during
the lifetime of a connection.
• Larger window sizes increase
communication efficiency.
© 2003, Cisco Systems, Inc. All rights reserved.
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.
© 2003, Cisco Systems, Inc. All rights reserved.
12
TCP Sequence and Acknowledgment
© 2003, Cisco Systems, Inc. All rights reserved.
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
© 2003, Cisco Systems, Inc. All rights reserved.
14
TCP Segment Format
© 2003, Cisco Systems, Inc. All rights reserved.
15
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)
© 2003, Cisco Systems, Inc. All rights reserved.
16
UDP Segment Format
© 2003, Cisco Systems, Inc. All rights reserved.
17
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.
© 2003, Cisco Systems, Inc. All rights reserved.
18
TCP and UDP Port Numbers
© 2003, Cisco Systems, Inc. All rights reserved.
19
TCP/IP Application Layer
© 2003, Cisco Systems, Inc. All rights reserved.
20
Introduction to Application Layer
© 2003, Cisco Systems, Inc. All rights reserved.
21
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
© 2003, Cisco Systems, Inc. All rights reserved.
22
Application Layer Examples
• Domain Name System
• File Transfer Protocol
• Hypertext Transfer Protocol
• Simple Mail Transport Protocol
• Simple Network Management Protocol
• Telnet
© 2003, Cisco Systems, Inc. All rights reserved.
23
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
© 2003, Cisco Systems, Inc. All rights reserved.
24
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.
© 2003, Cisco Systems, Inc. All rights reserved.
25
HTTP
© 2003, Cisco Systems, Inc. All rights reserved.
26
SMTP
• E-mail servers communicate with each other
using the Simple Mail Transport Protocol
(SMTP) to send and receive mail.
© 2003, Cisco Systems, Inc. All rights reserved.
27
SNMP
• The Simple Network Management Protocol (SNMP) is
an application layer protocol that facilitates the
exchange of management information between
network devices.
© 2003, Cisco Systems, Inc. All rights reserved.
28
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.
© 2003, Cisco Systems, Inc. All rights reserved.
29