PROTOCOL FUNCTIONS Segmentation & Re-assembly Encapsulation Connection Control Flow Control Error Control Synchronization Sequencing Addressing Multiplexing Transmission Services SCTE VA 7.1
Segmentation & Re-Assembly User Data Blocks Data Blocks T 1 T 2 D 1 D 2 H 1 H 2 T T D D H H Different Paths Used T 3 D 3 H 3 T D H H = Header D = User Data T = Trailer SCTE VA 7.2
Encapsulation T+ D H+ Protocol Data Unit SCTE VA 7.3
Connection Control Flow Control Error Control ACK End Terminal End Terminal SCTE VA 7.4
Synchronization Sequencing For example: 1st 2nd 3rd - Establish the connection - Acknowledge data receipt - Terminate connection Put the data back together in the correct order. SCTE VA 7.5
Addressing Where is THX123? Locale A A Global Local B Local C Locale B Local NEW Locale C SCTE VA 7.6
Multiplexing Downward ONE Upper level protocol uses MANY lower level connections Upward Route diversity Improved reliability MANY Upper level protocols use ONE lower level connections Only one lower level path available Maximizes usage of a lower level connection SCTE VA 7.7
The Layer Concept (N+1) Layer (N+1) Entity (N) Layer (N) Entity Protocol (N) Service Access Point Interface P r i m a t i v e s Services (N-1) Service Access Point Interface (N-1) Layer SCTE VA 7.8
Layered Protocols OSI is the standard reference Set of rules for data flows Intra-Layer Inter-Layer Find multiple protocols in a complete data system Layers provide Specialization Segmentation Separation Functional symmetry Layers can be worked on independently SCTE VA 7.9
The OSI Model Set of Rules 7 6 5 4 3 2 Application Presentation Session Transport Datalink Physical 1 Header User Info SCTE VA 7.10
Datalink Layer 7 6 5 4 Application Presentation Session Transport 3 2 Datalink Physical 1 Header User Info Governs flow of data Provides High Throughput Fast Response Data Integrity Functionality Synchronization Flow Control Error Detection Identification of entities Identification of information SCTE VA 7.11
Layer 7 6 5 4 Application Presentation Session Transport 3 2 Datalink Physical 1 Header User Info Governs communications of a group of networks Provides resolution for issues involving: PDUs of different sizes/formats Different timers/timeouts Various quality of services Different addressing techniques Different performance levels Different routing methods Different user interfaces Different security levels Different troubleshooting, diagnostic, and maintenance methods Cost and billing determination SCTE VA 7.12
Transport Layer & Session Layer 7 6 5 4 3 Application Presentation Session Transport 2 Datalink Physical 1 Header User Info Transport Layer End to end data integrity Manages interface between upper & lower layers Connection and termination of session Detection of lost, duplicate, or out of sequence data Control data flow Session Layer Coordinates data exchange between applications Synchronization checkpoints Structures user application interactions Provides rules for users exchanging data Prevents lost data by closing dialogs properly SCTE VA 7.13
Presentation Layer & Application Layer 7 6 5 4 3 2 Application Presentation Session Transport Datalink Physical 1 Header User Info Presentation Layer Allows end users to operate with different syntax Translates User 1 s syntax so User 2 can read Application Layer Direct interface with the end user applications Application Service Elements key ASCE - Regulates user requests RTSE - Notifies sender of successes/failures ROSE - Allows interactive communications CCR - Manages database interactions SCTE VA 7.14
TCP/IP Protocol OSI Model DOD Standards DOD Model 7 6 Application Presentation FTP; SMTP TELNET Process/ Application 5 4 Session Transport TCP Host to Host 3 IP Internet 2 Data Link Access 1 Physical SCTE VA 7.15