Protocol Architectures Simple Protocol Architecture Not an actual

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Protocol Architectures

Protocol Architectures

Simple Protocol Architecture • Not an actual architecture, but a model for how they

Simple Protocol Architecture • Not an actual architecture, but a model for how they work • Similar to “pseudocode, ” used for teaching programming • Once we understand the building blocks, we can look at specific examples – Open Systems Interconnection (OSI) 7 -Layer Model – TCP/IP

Why Use Protocol Architecture? • Data communications requires complex procedures – Sender identifies data

Why Use Protocol Architecture? • Data communications requires complex procedures – Sender identifies data path/receiver – Systems negotiate preparedness – Applications negotiate preparedness – Translation of file formats • For all tasks to occur, high level of cooperation is required

Modular Approach • Break tasks into subtasks • Each module handles specific subset of

Modular Approach • Break tasks into subtasks • Each module handles specific subset of tasks • Communication occurs – between different modules on the same system – between similar modules on different systems

Simple Modular Example • File transfer facility • Three modules – File transfer module

Simple Modular Example • File transfer facility • Three modules – File transfer module could handle translation and inter-application communication – Communication service module could handle negotiation of preparedness, data flow – Network access module could handle data path

Advantages of Modularity • Easier application development • Network can change without all programs

Advantages of Modularity • Easier application development • Network can change without all programs being modified

Three-Layer Model • Distributed data communications involves three primary components: – Applications – Computers

Three-Layer Model • Distributed data communications involves three primary components: – Applications – Computers – Networks • Three corresponding layers – Network access layer – Transport layer – Application layer

Network Access Layer • Concerned with exchange of data between computer and network •

Network Access Layer • Concerned with exchange of data between computer and network • Includes addressing, routing, prioritizing, etc • Different networks require different software at this layer

Transport Layer • Concerned with reliable transfer of information between applications • Independent of

Transport Layer • Concerned with reliable transfer of information between applications • Independent of the nature of the application • Includes aspects like flow control and error checking

Application Layer • Logic needed to support various applications • Each type of application

Application Layer • Logic needed to support various applications • Each type of application (file transfer, remote access) requires different software on this layer

Addressing • Each computer on a network requires a unique address on that network

Addressing • Each computer on a network requires a unique address on that network • Each application on the computer must have a unique address within the computer to allow the transport layer to support multiple applications • Data units must include network and application addresses

Standardized Protocol Architectures • Vendors like standards because they make their products more marketable

Standardized Protocol Architectures • Vendors like standards because they make their products more marketable • Customers like standards because they enable products from different vendors to interoperate • Two protocol standards are well-known: – TCP/IP: widely implemented – OSI: well-known, less used, still useful for modeling/conceptualizing

Protocol Architectures Simple Protocol Architecture n n nProtocol Architectures Simple Protocol Architecture n n n
Other Architectures Examples Multithreaded architectures Dataflow architectures MultiprocessorOther Architectures Examples Multithreaded architectures Dataflow architectures Multiprocessor
Chapter 2 ARCHITECTURES Software architectures and System architecturesChapter 2 ARCHITECTURES Software architectures and System architectures
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Simple Machines Simple Machines Simple machines are simpleSimple Machines Simple Machines Simple machines are simple
PAST SIMPLE PRESENT SIMPLE FUTURE SIMPLE Past SimplePAST SIMPLE PRESENT SIMPLE FUTURE SIMPLE Past Simple
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Parallel architectures Computer Architectures M Parallelism 1 ArchitectureParallel architectures Computer Architectures M Parallelism 1 Architecture