Lecture4_2up

Lecture4_2up - ECE-547 Introduction to Computer...

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1 Purdue University ECE ECE -547 547 Introduction to Computer Introduction to Computer Communication Networks Communication Networks Instructor: Instructor: Xiaojun Xiaojun Lin Lin Lecture 4 Lecture 4 Purdue University Basic Networking Architecture Basic Networking Architecture ¾ Layered Communication Architecture : Virtually all forms of current (and past) computer communications systems were designed on a layered architecture concept. ¾ What is this layered concept? ¾ Layering is a form of hierarchical modularity. ¾ The basic idea is that each module, corresponding to a given level of the hierarchy, performs a certain function or service in support of the overall system. ¾ These modules logically communicate with each other across geographic distances (e.g., at different nodes in the network). ¾ There is also a protocol established within a node for communication between modules. What is a protocol?
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2 Purdue University Basic Networking Architecture Basic Networking Architecture ¾ Layered Communication Architecture : Virtually all forms of current (and past) computer communications systems were designed on a layered architecture concept. ¾ What is this layered concept? ¾ Layering is a form of hierarchial modularity. ¾ The basic idea is that each module, corresponding to a given level of the hierarchy, performs a certain function or service in support of the overall system. ¾ These modules logically communicate with each other across geographic distances (e.g., at different nodes in the network). ¾ There is also a protocol established within a node for communication between modules. What is a protocol? ¾ A protocol is a set of rules that governs how communicating parties are to interact (e.g., in web browsing, the http protocol specifies how the web client and the server are to interact). ¾ A protocol’s purpose is to provide some form of services (e.g., http allows retrieval of web pages). Purdue University HTTP server HTTP client TCP TCP GET 80, # #, 80 STATUS Port 80 Client-side Port #
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3 Purdue University Heads of State Example Heads of State Example Higher Layer Module (“Head of State A ”) Higher Layer Module (“Head of State B ”) Lower Layer Module (“Local Translator A ”) Lower Layer Module (“Local Translator B ”) Physical Layer Medium Purdue University Head of State example Head of State example ¾ Example from Schwartz . Consider two heads of state that want to talk to each other but have no common language to communicate with. ¾
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Lecture4_2up - ECE-547 Introduction to Computer...

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