Lecture Protocol & Model Ashis Talukder, MIS, EWU.

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Network Topology Definition Classification: BUS TREE STAR RING MESH HYBRID Ashis Talukder, MIS, EWU.

Today’s Class Ashis Talukder, MIS, EWU.

Protocol & Protocol Models Introduction: Protocol OSI Model TCP/IP Model Ashis Talukder, MIS, EWU.

Protocol Protocol is defined as a set of rules that governs the exchange of data between two entities. Key elements of a protocol: Syntax: data format Semantics: control info & error handling Timing: speed matching & sequencing Ashis Talukder, MIS, EWU.

Protocol Models Open System Interface (OSI) Model Transmission Control Protocol/Internet Protocol (TCP/IP) Model Ashis Talukder, MIS, EWU.

OSI model To address the problem of network incompatibility, the International Organization for Standardization (ISO) researched networking models like Digital Equipment Corporation net (DECnet), Systems Network Architecture (SNA), and TCP/IP Proposed a generally applicable set of rules for all networks. Using this research, the ISO created a network model that helps vendors create networks that are compatible with other networks. Ashis Talukder, MIS, EWU.

OSI model The Open System Interconnection (OSI) reference model released in 1984 was the descriptive network model that the ISO created. It provided vendors with a set of standards that ensured greater compatibility and interoperability among various network technologies produced by companies around the world. Ashis Talukder, MIS, EWU.

OSI Reference Model has become the primary model for network communications. Although there are other models in existence, most network vendors relate their products to the OSI reference model. This is especially true when they want to educate users on the use of their products. It is considered the best tool available for teaching people about sending and receiving data on a network. It provided vendors with a set of standards that ensured greater compatibility and interoperability among various network technologies produced by companies around the world. Ashis Talukder, MIS, EWU.

Layers of OSI model Physical Layer Data Link layer Network Layer Transport Layer Session layer Presentation layer Application layer Ashis Talukder, MIS, EWU.

Benefits of OSI Models Ashis Talukder, MIS, EWU.

Physical Layer encoding/decoding of signals preamble generation/removal bit transmission/ reception transmission medium and topology Ashis Talukder, MIS, EWU.

Physical Layer Four Specifications: Devices: Electrical Mechanical Functional Procedural Devices: Repeater NIC Hub Ashis Talukder, MIS, EWU.

Data Link Layer Logical Link Control interface to higher levels flow and error control Media Access Control on transmit assemble data into frame on receive disassemble frame govern access to transmission medium for same LLC, may have several MAC options Ashis Talukder, MIS, EWU.

Data Link Layer where central distributed how synchronous asynchronous greater control, single point of failure distributed more complex, but more redundant how synchronous capacity dedicated to connection, not optimal asynchronous in response to demand Ashis Talukder, MIS, EWU.

Data Link Layer Devices Bridge Switch Ashis Talukder, MIS, EWU.

Data Link Layer round robin each station given turn to transmit data reservation divide medium into slots good for stream traffic contention all stations contend for time good for bursty traffic simple to implement tends to collapse under heavy load Ashis Talukder, MIS, EWU.

Network Layer Ashis Talukder, MIS, EWU.

Network Layer Non reliable Best Effort delivery Provide logical addressing (IP address) No error correction Host-to-host Connectivity Routing Selecting the best path Forward the packet through that path Device: Router Ashis Talukder, MIS, EWU.

Transport Layer encapsulation Segmentation and reassembly connection control Establish Maintain terminate ordered delivery flow control error control Detection recovery Ashis Talukder, MIS, EWU.

Transport Layer Addressing Reliable transmission Port Address Handle Multiple Conversation Reliable transmission Sends acknowledgements Also provide connectionless stream data transmission (UDP) Ashis Talukder, MIS, EWU.

Session Layer Dialogue Discipline Simplex Half Duplex Full Duplex Establish, manage & maintain session between applications Ashis Talukder, MIS, EWU.

Presentation Layer Compress/Decompress Data Structure Ensure readable/usable format Data format Ashis Talukder, MIS, EWU.

Application Layer provide support for user applications Ashis Talukder, MIS, EWU.

TCP/IP Model Ashis Talukder, MIS, EWU.

TCP/IP Protocol Model The U.S. Department of Defense (DoD) created the TCP/IP reference model because it wanted a network that could survive any conditions. Some of the layers in the TCP/IP model have the same name as layers in the OSI model. Ashis Talukder, MIS, EWU.

Network Access Layer The network access layer is concerned with all of the issues that an IP packet requires to actually make a physical link to the network media. It includes the LAN and WAN technology details, and all the details contained in the OSI physical and data link layers. Ashis Talukder, MIS, EWU.

Internet Layer The purpose of the Internet layer is to send packets from a network node and to have them arrive at the destination node independent of the path taken. Ashis Talukder, MIS, EWU.

Transport Layer Segmenting upper-layer application data Establishing end-to-end operations Sending segments from one end host to another end host Ensuring data reliability Providing flow control Ashis Talukder, MIS, EWU.

Application Layer Handles high-level protocols, issues of representation, encoding, and dialog control. The TCP/IP protocol suite combines all application related issues into one layer and ensures this data is properly packaged before passing it on to the next layer. Ashis Talukder, MIS, EWU.

Peer-to-peer Communication Ashis Talukder, MIS, EWU.

Peer-to-peer Communication Ashis Talukder, MIS, EWU.

Comparison of OSI & TCP/IP model Similarities include: Both have layers. Both have application layers, though they include very different services. Both have comparable transport and network layers. Both models need to be known by networking professionals. Both assume packets are switched. This means that individual packets may take different paths to reach the same destination. This is contrasted with circuit-switched networks where all the packets take the same path. Ashis Talukder, MIS, EWU.

Comparison of OSI & TCP/IP model Dissimilarities include: TCP/IP combines the presentation and session layer issues into its application layer. TCP/IP combines the OSI data link and physical layers into the network access layer. TCP/IP appears simpler because it has fewer layers. TCP/IP protocols are the standards around which the Internet developed, so the TCP/IP model gains credibility just because of its protocols. In contrast, networks are not usually built on the OSI protocol, even though the OSI model is used as a guide. Ashis Talukder, MIS, EWU.

Advantage of Layered Approach It breaks network communication into smaller, more manageable parts. It standardizes network components to allow multiple vendor development and support. It allows different types of network hardware and software to communicate with each other. It prevents changes in one layer from affecting other layers. It divides network communication into smaller parts to make learning it easier to understand. Ashis Talukder, MIS, EWU.

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Early Protocl Early Protocols: Ethernet: ALOHA Slotted ALOHA CSMA CSMA/CD Ethernet: 10 BASE 100BASE 1000BASE Ashis Talukder, MIS, EWU.

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