Chapter#4
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The document discusses protocols and the TCP/IP suite. It provides an overview of the layers of the TCP/IP protocol stack including the physical, network access, internet, transport, and application layers. It also describes common TCP/IP applications like SMTP, FTP, and TELNET. The document then compares the OSI model layers to the TCP/IP layers and discusses key internetworking terms.
Chapter#4
- 1. Protocols and the TCP/IP Suite Chapter 4
- 2. Steps in Communication of two Computer through a Network 1 The source system must either activate the direct data communication path or inform the communication network of the identity of the desired destination system. 2 The source system must ascertain that the destination system is prepared to receive data. 3 The file transfer application on the source system must ascertain that the file management program on the destination system is prepared to accept and store the file for this particular user. 4 If the file formats used on the two systems are incompatible, one or the other system must perform a format translation function
- 3. Key Features of a Protocol Syntax Concerns the format of the data blocks Semantics Includes control information for coordination and error handling Timing Includes speed matching and sequencing
- 4. TCP/IP Layer: Agents Involved in Communication Applications Exchange data between computers (e.g., electronic mail) Computers They are connected to networks & the exchange of data is through the network & between the computers Networks Transfers data from one computer to another
- 5. TCP/IP Layers Physical layer Network access layer Internet layer Host-to-host, or transport layer Application layer
- 6. TCP/IP Physical Layer Covers the physical interface between a data transmission device (e.g. workstation or computer)and a transmission medium or network Physical layer specifies: Characteristics of the transmission medium The nature of the signals The data rate Other related matters
- 7. TCP/IP Network Access Layer Concerned with the exchange of data between an end system (server or workstation) and the network to which it's attached The sending computer must provide the address of the destination computer, so that the network may route that data to the appropriate destination The sending may wish to invoke certain services, such as priority, that might be provided by the network Software used depends on type of network Circuit switching Packet switching (e.g., X.25) LANs (e.g., Ethernet) Others
- 8. TCP/IP Internet Layer Uses internet protocol (IP) Provides routing functions to allow data to traverse multiple interconnected networks Implemented in end systems but also in routers Router: “It is a processor that connect two networks & whose primary function is to relay data from one network to the other on its route from the source to the destination end system”
- 9. TCP/IP Host-to-Host, or Transport Layer Commonly uses transmission control protocol (TCP) The reliability of the data is independent of the nature of the application Provides reliability during data exchange Completeness Order
- 10. TCP/IP Application Layer It contains the logic needed to supports user applications Uses separate modules that are peculiar (abnormal/ doesn’t match) to each different type of application For example each different type of application, such as File Transfer, a separate module is needed.
- 11. Operation of TCP and IP
- 14. Protocol Data Units (PDUs)
- 16. Common TCP/IP Applications Simple mail transfer protocol (SMTP) Provides a basic electronic mail facility File Transfer Protocol (FTP) Allows files to be sent from one system to another under user command Both text and binary files are accommodated, and the protocol provides features for controlling user access TELNET Provides a remote logon capability
- 17. Layers of the OSI Model The Open Systems Interconnection (OSI) reference model was developed by the International Organization for Standardization (ISO)l as a model for a computer protocol architecture and as a framework for developing protocol standards. The OSI model consists of seven layers: Application Presentation Session Transport Network Data link Physical
- 18. OSI Application Layer The application layer enables the user, whether human or software, to access the network. It provides user interfaces and support for services such as electronic mail, remote file access and transfer, shared database management, and other types of distributed information services Provides access to the OSI environment for users Provides distributed information services
- 19. OSI Presentation Layer The presentation layer is concerned with the syntax and semantics of the information exchanged between two systems Provides independence to the application processes from differences in data representation (syntax)
- 20. OSI Session Layer The services provided by the first three layers (physical, data link, and network) are not sufficient for some processes. The session layer is the network dialog controller. It establishes, maintains, and synchronizes the interaction among communicating systems. Provides the control structure for communication between applications Establishes, manages, and terminates connections (sessions) between cooperating applications
- 21. OSI Transport Layer The transport layer is responsible for process-to-process delivery of the entire message. A process is an application program running on a host. Whereas the network layer oversees source-to-destination delivery of individual packets, it does not recognize any relationship between those packets. It treats each one independently, as though each piece belonged to a separate message, whether or not it does. The transport layer, on the other hand, ensures that the whole message arrives intact and in order, overseeing both error control and flow control at the source-to-destination level Provides reliable, transparent transfer of data between end points Provides end-to-end error recovery and flow control
- 22. OSI Network Layer The network layer is responsible for the source-to-destination delivery of a packet, possibly across multiple networks (links). Whereas the data link layer oversees the delivery of the packet between two systems on the same network (links), the network layer ensures that each packet gets from its point of origin to its final destination. Provides upper layers with independence from the data transmission and switching technologies used to connect systems Responsible for establishing, maintaining, and terminating connections
- 23. OSI Data link Layer The data link layer transforms the physical layer, a raw transmission facility, to a reliable link. It makes the physical layer appear error-free to the upper layer (network layer). Provides for the reliable transfer of information across the physical link Sends blocks (frames) with the necessary synchronization, error control, and flow control
- 24. OSI Physical Layer The physical layer coordinates the functions required to carry a bit stream over a physical medium. It deals with the mechanical and electrical specifications of the interface and transmission medium Concerned with transmission of unstructured bit stream over physical medium Deals with accessing the physical medium Mechanical characteristics Electrical characteristics Functional characteristics Procedural characteristics
- 25. Comparison of OSI and TCP/IP
- 26. TCP/IP Architecture Dominance TCP/IP protocols matured quicker than similar OSI protocols When the need for interoperability across networks was recognized, only TCP/IP was available and ready to go OSI model is unnecessarily complex Accomplishes in seven layers what TCP/IP does with fewer layers
- 27. Internetworking Terms Communication network – facility that provides a data transfer service among devices attached to the network Internet – collection of communication networks, interconnected by bridges/routers Intranet – internet used by an organization for internal purposes Provides key Internet applications Can exist as an isolated, self-contained internet
- 28. Internetworking Terms End System (ES) – device used to support end-user applications or services Intermediate System (IS) – device used to connect two networks Bridge – an IS used to connect two LANs that use similar LAN protocols Router - an IS used to connect two networks that may or may not be similar
- 29. Functions of a Router Provide a link between networks Provide for the routing and delivery of data between processes on end systems attached to different networks Provide these functions in such a way as not to require modifications of the networking architecture of any of the attached sub networks
Editor's Notes
- #9: Distributed computing is a field of computer science that studies distributed systems. A distributed system is a software system in which components located on networked computers communicate and coordinate their actions by passing messages.
- #27: Interoperability: It is the ability of a system or a product to work with other systems or products without special effort on the part of the customer.