The Saigon CTT Semester 1 CHAPTER 12 – 13 – 14 Le Chi Trung

The Saigon CTT  Content Transport layer TCP and UDP Session layer Presentation layer

The Saigon CTT  Schedule

The Saigon CTT TRANSPORT LAYER

The Saigon CTT  Why we need a transport layer? Layer 1 allows bit streams to be created and to travel. Layer 2 packages those data packets into frames to be converted to bit streams and makes data-link delivery possible. Layer 3 packages data from upper layers in packets and makes routing and network delivery possible. But they made no provision for assuring our data reliably travels end-to-end across the often vast network path. But they made no provision for assuring our data reliably travels end-to-end across the often vast network path.

The Saigon CTT  Purpose of the transport layer Transport and regulate the flow of information from source to destination, reliably and accurately. The end-to-end control: –Sliding windows. –Sequencing numbers. –Acknowledgments. –Segmentation. –Multiplexing.

The Saigon CTT  TCP and UDP The emphasis of this curriculum is on TCP/IP Ethernet networks. The TCP/IP protocol of the OSI model Layer 4 (transport layer) has two protocols - TCP and UDP.

The Saigon CTT  TCP/IP

The Saigon CTT  Port Both TCP and UDP use port (or socket) numbers to pass information to the upper layers. RFC-1700

The Saigon CTT  Range of ports 2 bytes: 0 – –Numbers below 255 : for public applications. –Numbers from : assigned to companies for marketable applications. –Numbers above 1023 : are unregulated. End systems use port numbers to select proper applications. Originating source port numbers are dynamically assigned by the source host; usually, it is a number larger than 1023.

The Saigon CTT  Telnet port number

The Saigon CTT TCP AND UDP

The Saigon CTT  TCP TCP supplies a virtual circuit between end-user applications. These are its characteristics: –connection-oriented. –reliable. –divides outgoing messages into segments. –reassembles messages at the destination station. –re-sends anything not received. –reassembles messages from incoming segments.

The Saigon CTT  TCP Header format Protocol that provides reliable full-duplex data transmission. RFC-761

The Saigon CTT  TCP Header format: Port number Source Port 16 bits. Destination Port 16 bits. Source Port 16 bits. Destination Port 16 bits.

The Saigon CTT  TCP Header format: Sequence Sequence Number: 32 bits – –The sequence number of the first data octet in this segment (except when SYN is present). Sequence Number: 32 bits – –The sequence number of the first data octet in this segment (except when SYN is present).

The Saigon CTT  TCP Header format: Acknowledgment Acknowledgment Number: 32 bits – –This field contains the value of the next sequence number the sender of the segment is expecting to receive. Acknowledgment Number: 32 bits – –This field contains the value of the next sequence number the sender of the segment is expecting to receive.

The Saigon CTT  TCP Header format: Code bits Control Bits: 8 bits – –ACK: Acknowledgment field significant – –RST: Reset the connection – –SYN: Synchronize sequence numbers – –FIN: No more data from sender Control Bits: 8 bits – –ACK: Acknowledgment field significant – –RST: Reset the connection – –SYN: Synchronize sequence numbers – –FIN: No more data from sender

The Saigon CTT  TCP Header format: Window Window: 16 bits – –The number of data octets beginning with the one indicated in the acknowledgment field which the sender of this segment is willing to accept. Window: 16 bits – –The number of data octets beginning with the one indicated in the acknowledgment field which the sender of this segment is willing to accept.

The Saigon CTT  TCP: Three way handshaking

The Saigon CTT  TCP: Simple acknowledgment

The Saigon CTT  TCP: Sliding acknowledgment

The Saigon CTT  TCP: Sequence and acknowledgment

The Saigon CTT  UDP UDP transports data unreliably between hosts. Following are the characteristics: –Connectionless. –Unreliable. –Transmit messages (called user datagrams). –Provides no software checking for message delivery (unreliable). –Does not reassemble incoming messages. –Uses no acknowledgements.

The Saigon CTT  UDP Header format UDP is a simple protocol that exchanges datagrams, without acknowledgments or guaranteed delivery. RFC-768

The Saigon CTT  Preparation for LAB Lab companion: –12.4.1

The Saigon CTT  Review Transport layer regulates information flow to ensure end-to-end connectivity between host applications reliably and accurately. TCP and UDP port numbers. Three way handshaking and sliding windows.

The Saigon CTT SESSION LAYER

The Saigon CTT  Functions

The Saigon CTT  Process Dialog control: –In the conversation, each host plays dual roles: requesting service and replying with service. Dialogue control determining which role they are playing at any given moment. –Agree a set of guidelines to use during the communicating with each other. Dialog separation: –Order to Initiate, terminate and manage of communication. –Using a checkpoint to synchronize.

The Saigon CTT  Dialog control

The Saigon CTT  Dialog separation

The Saigon CTT  Session layer protocols Discussion

The Saigon CTT  Review Communication sessions consist of mini-conversations that occur between applications located in different network devices. Dialog control. Dialog separation.

The Saigon CTT PRESENTATION LAYER

The Saigon CTT  Functions

The Saigon CTT  Three main functions

The Saigon CTT  Data formatting

The Saigon CTT  Data encryption

The Saigon CTT  Data compression

The Saigon CTT  Review Determines how graphic images, sound and movies are presented.. Provides encryption of data. Compresses text and converts graphic images into bit streams so they can be transmitted across a network.

The Saigon CTT