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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.

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Presentation on theme: "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."— Presentation transcript:

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 ‘’ and CC to GA ’ ’ 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 ‘’ & CC to ‘’

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 )

4 William Stallings Data 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 1.Network Access Layer 2.Transport Layer 3.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 SAP-1SAP-2 Y+ SAP-2 Y Y Destination SAP

13 Protocol Data Units Message-1 Message-2 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. 1.Application Layer 2.Transport Layer or Host to host 3.Internet Layer or Network Layer 4.Network Access Layer or Data Link Layer 5.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 2- Network Access Layer or Data Link Layer Exchange of data between end system and 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 layersDLL is divided into 2 sub layers Network Host A Router Host B Host C Router Host D LAN-1LAN-2 DLL

24 3- Internet Layer (IP) or Network 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) Host A Router-1 Host B Host C Router-2 Host D LAN-1LAN-2 DLL Network N/W Layer R R R R

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


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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