www.ciscopress.com copyright 2003 ccna 1 chapter 9 tcp/ip transport and application layers by your...

www.ciscopress.comCopyright 2003

CCNA 1 Chapter 9

TCP/IP Transport and Application Layers

By

Your Name


Objectives

• TCP/IP transport layer

• TCP/IP application layer


Routed Protocols Versus Routing Protocols

Routing protocols determine the path that routed protocols follow to their destinations.


The Transport Layer Functions

Five basic services:• Segmenting upper-layer application data• Establishing end-to-end operations• Sending segments from one end host to another

end host• Ensuring data reliability• Providing flow control


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


Session Establishment


Three-Way Handshake


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


Window Size

Larger window sizes increase communication efficiency.


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.


Layer 4 Protocols


TCP

• Connection oriented • Reliable • Divides outgoing messages into segments • Reassembles messages at the destination

station • Resends anything not received • Reassembles messages from incoming

segments


UDP

• Connectionless • Unreliable • Transmits messages (called user datagrams) • Provides no software checking for message

delivery (unreliable) • Does not reassemble incoming messages • Uses no acknowledgments • Provides no flow control


TCP/IP Protocol Graph


TCP Segment Format


UDP Segment Format


Port Numbers


Application Layer


TCP/IP Application Layer


Responsibilities

• Identifying and establishing the availability of intended communication partners

• Synchronizing cooperating applications • Establishing agreement on procedures for error

recovery • Controlling data integrity


Application Layer Examples

• Domain Name System• File Transfer Protocol • Hypertext Transfer Protocol • Simple Mail Transport Protocol• Simple Network Management Protocol• Telnet


Domain Name System


FTP

• FTP is a reliable, connection-oriented service that uses TCP to transfer files between systems that support FTP.


HTTP


SMTP

• E-mail servers communicate with each other using the Simple Mail Transport Protocol (SMTP) to send and receive mail.


SNMP

• The Simple Network Management Protocol (SNMP) is an application layer protocol that facilitates the exchange of management information between network devices.

• An SNMP managed network consists of the following: – Network management

system (NMS) – Managed device– Agents


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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