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Term Paper

Term Paper. Phase-I is Due on Tuesday, February 19 in class timing Submit a Hard Copy of your paper (MS word Document) Follow the instructions in “Term Paper Specification” document for Deliverables Make group (3 students) by Friday, February 01

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Term Paper

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  1. Term Paper • Phase-I is Due on Tuesday, February 19 in class timing • Submit a Hard Copy of your paper (MS word Document) • Follow the instructions in “Term Paper Specification” document for Deliverables • Make group (3 students) by Friday, February 01 • Send email to me ‘srizvi@bridgeport.edu’ and CC to GA ’farain@bridgeport.edu’with the Research Topic, group member’s names, UB-IDs, and emails

  2. OPNET Lab • Lab 1 (OPNET) is due on next Tuesday, February 04 (2:30 Pm) • Group (2 students) • Make a Report in (word document) • The Report Should have Cover Page • Save the word doc starting from your “Last Name” plus the “Lab #” (e.g., Rizvi-Lab1) • Email Report to me ‘srizvi@bridgeport.edu’ & CC to ‘farain@bridgeport.edu’

  3. GA for CPEG-471 Office hours (Faraz Arain) • Tuesday (12:00 to 2:30 Pm) • Thursday (12:00 to 2:30 Pm) • Other time (send email to farain@bridgeport.edu)

  4. William StallingsData and Computer Communications Chapter 2 Protocols and Architecture

  5. Need For Protocol Architecture • E.g. File transfer • Source must activate comms. Path or inform network of destination • Source must check destination is prepared to receive • File transfer application on source must check destination file management system will accept and store file for his user • May need file format translation • Each problem needs to address separately • Task broken into subtasks • Implemented separately in layers in stack

  6. Key Elements of a Protocol • Syntax • Data formats • Signal levels • Semantics • Control information • Error handling • Timing • Speed matching (e.g., indicates flow control) • Sequencing (e.g., avoid packet duplication)

  7. Protocol Architecture • Implementation of File Transfer • File transfer example can have 4 problems • Implementation of “File Transfer” could use three modules • File transfer application (Top most layer) • Communication service module (Middle Layer) • Network access module (Lower Layer)

  8. Implementation of File Transfer Architecture Module-1 Determine weather file transfer app at sys Y is ready to receive file? Layer1 Determine weather file translation is required or not? Module-2 Determine weather Computer Y is ready to receive the Data? Module-3 Determine weather a direct link or an indirect link exists between X & Y

  9. A Three Layer Model • Network Access Layer • Transport Layer • Application Layer

  10. A Three Layer Model • Network Access Layer • Exchange of data between the computer and the network • Sending computer provides address of destination • May invoke levels of service (i.e., QoS parameters) • Dependent on type of network used (packet or CKT switched Network etc.) • Transport Layer • Ensures reliable data exchange between 2 hosts • Application Layer • Support for different user applications • e.g. e-mail, file transfer

  11. Protocol Architectures and Networks  Port  IP Address

  12. A Three Layer Architecture Destination SAP SAP-1 SAP-2 Y+ SAP-2 Y+ SAP-2 Y Y

  13. Protocol Data Units Message-2 Message-1 Protocol data unit (PDU)

  14. Operation of a Protocol Architecture

  15. Open Systems Interconnection (OSI)

  16. OSI  Definition • Open Systems Interconnection • Developed by the International Organization for Standardization (ISO) • It has seven layers • TCP/IP is the refinement of OSI • Questions • Why TCP/IP doesn’t have presentation & session layers? • How many layers a reference model should have ?

  17. OSI – Advantage of 7 Layers Model • Each layer performs a subset of the required communication functions • Sub tasks are assigned to one of the layers depending on the nature • Each layer relies on the next lower layer to perform more primitive functions • such as application layer relies on transport layer to send the data and commands.. • Each layer provides services to the next higher layer • Such as Network layer offer services to Transport layer that can be used at N/W-Layer SAP • Changes in one layer should not require changes in other layers • Layers are entirely independent and transparent to other layers

  18. The OSI 7-Layers functioning

  19. OSI as Framework for Standardization Services are well defined:(Service Definition) Protocols are well defined: (Protocol Specification)

  20. Service Primitives and Parameters • Services need to be well defined by means of service definition • Services between adjacent layers expressed in terms of primitives and parameters • Primitives specify function to be performed • Just like Op-code in Assembly • Parameters pass data and control info • Just like Op-rand in Assembly

  21. TCP/IP Protocol Architecture • TCP/IP was originally developed by the US Defense Advanced Research Project Agency (DARPA) for its packet switched network (ARPANET) • 5 Layers of TCP/IP. • Application Layer • Transport Layer or Host to host • Internet Layer or Network Layer • Network Access Layer or Data Link Layer • Physical Layer

  22. 1- Physical Layer • Responsible to deal with interface between source & destination • Physical interface between data transmission device (e.g. computers) and transmission medium or network • Characteristics of transmission medium • Signal levels • Data rates • etc.

  23. Host C Host A LAN-1 LAN-2 Router Router DLL DLL DLL Host D Host B 2- Network Access Layer or Data Link Layer • Exchange of data between end systemand the network • Responsible to deliver frames reliably from hop to hop (hop could be DLL device such as bridges or switches) • If within the LAN, upper layers can leave reliability issues (error/flow control) on the DLL • Guarantee Error Free Delivery of Data from one hop to the other (not N/W to N/W OR not end-to-end) • DLL is divided into 2 sub layers Network

  24. Host C Host A LAN-1 LAN-2 Router-1 Router-2 DLL DLL DLL Host D Host B R R R R 3- Internet Layer (IP) orNetwork Layer • Systems may be attached to different networks(such as Host-A at LAN-1 & Host-D at LAN-2) • Lowest layer that deals with end-to-end transmission • Implemented in end systems and router • Guarantee Error Free Delivery of Packets from one N/W to the other N/W (not end-to-end) Network N/W Layer N/W Layer

  25. Layer 4 and Layer 5 • Layer 4 Transport Layer • Guarantee Error Free Delivery of Message from source-host to the destination-host (End-to-End reliability) • Offers connection oriented and connection less services • Reliability includes: Error detection and correction, flow control, packet duplication etc… • Runs only on host not on the network • Layer 5  Application Layer • Provide interface between end-user & applications • Support several users applications • For example: FTP, Telnet, SSH, SMTP

  26. OSI v TCP/IP

  27. TCP and UDP • TCP (connection oriented Protocol) • Establish a reliable logical connection between the source & the destination hosts • Need to know the source & destination port addresses • Logical connection is monitored by TCP • TCP segments (TCP PDU) can be transmitted through the secure connection • TCP is reliable but allow relatively slower communication • UDP(Connection Less Protocol) • Is a connection less protocol • Does not guarantee the reliable transmission of UDP segments • UDP header has limited control information • Faster but not reliable at all • Which protocol should I use then (TCP or UDP ???)

  28. TCP/IP Concepts

  29. PDUs in TCP/IP

  30. Some Protocols in TCP/IP Suite

  31. Required Reading • Stallings chapter 2 • Comer,D. Internetworking with TCP/IP volume I • Comer,D. and Stevens,D. Internetworking with TCP/IP volume II and volume III, Prentice Hall • Halsall, F. Data Communications, Computer Networks and Open Systems, Addison Wesley • RFCs

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