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CS 1150 – Lab #15 – NetworkingTA – Sanjaya Wijeratne
E-mail – [email protected]
Web Page - http://knoesis.org/researchers/sanjaya/
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TA Labs, Office Hours Laboratory Polices
• Lab Hours• 2:30 PM - 4:20 PM, Monday and Friday at Room 320 - Oelman Hall
• TA Office Hours• 4:40 PM - 5:40 PM, Monday and Friday at Room 316 - Russ Engineer Center
• By appointment – Please email to [email protected]
• Refer to CS 1150 Course Syllabus for Class and Laboratory Policies• Zero tolerance policy for Academic Misconduct – All parties will get 0%
marks
CS 1150 – Lab 15 – Networking
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Lab # 15 Overview
• Study how networks route packets to various destinations
• Learn how networks ensure reliable delivery
• Read all lab activities before attempting exercises
• Answer all questions in Exercises 1, 2, 4 and 5
• Lab #15 Due Date - Nov 22, 2013 12:30 PMCS 1150 – Lab 15 – Networking
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How to Submit Lab # 15
• Hard copy (Preferred)• When you complete, hand it over to me
• Pilot• Go to Pilot Course Page and Use Dropbox Submission Link to upload your
files
• My Mailbox at CS Department • Go to CS Department Front Desk and ask them to put your assignment
into my mailbox – Please write my name on your assignment (TA – CS 1150 – Sanjaya Wijeratne)
CS 1150 – Lab 15 – Networking
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What is a Computer Network?
• Group of computers (2 or more) that are connected together to share data• Eg – Internet
• Connections between computers in a network can be physical using cables/wires or wireless via radio waves
CS 1150 – Lab 15 – Networking
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Network Protocols
• Protocol is a set of rules that governs a particular task. A network protocol governs how computers communicate in a network.
• TCP/IP• Transmission Control Protocol – Reliable
Communication
• IP – AddressingCS 1150 – Lab 15 – Networking
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Network Topology
• Network Topology is the arrangement of different elements in a computer network.• Bus
• Star
• Ring
CS 1150 – Lab 15 – Networking
Source – http://en.wikipedia.org/wiki/Network_topology
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Routing in a Network
• Each node in the network has a routing table
• Routing table keeps track of• What are the other nodes directly connected to a
given node
• What routes to take if a node is not directly connected to the given node
CS 1150 – Lab 15 – Networking
Source – http://en.wikipedia.org/wiki/Hop_(networking)#Next_hop_forwarding
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TCP/IP Applet
• TCP/IP applet simulates a reliable communication between two nodes (computers) in a network• DAT – Data packet
• ACK – Acknowledgement that data was received without errors
• NAK – Negative Acknowledgement which says there was an error in data receiving.
CS 1150 – Lab 15 – Networking
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TCP/IP Applet Cont.
CS 1150 – Lab 15 – Networking
Data Pack
et
• DAT 1 0 221• 1 – Destination
Address
• 0 – Sequence Number
• 221 – Checksum
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TCP/IP Applet Cont.
CS 1150 – Lab 15 – Networking
ACK Pack
et
• ACK 0 1 0• 0 – Destination
Address
• 1 – Sequence Number
• 0 – Checksum
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TCP/IP Applet Cont.
CS 1150 – Lab 15 – Networking
• NAK 0 1 0• 0 – Destination
Address
• 1 – Sequence Number
• 0 – Checksum
NAK Pack
et
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Exercise 1 – Q4 Help
• DAT 0 x xxx / ACK 1 x xxx – Consider all DAT and ACK messages (headers) have 9 Characters
• All DAK messages can carry up to 10 characters of data (payload)
• Your answer to this question should be 160. Show me the steps to get marks.
CS 1150 – Lab 15 – Networking
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Exercise 1 – Q5 Help
• Use the following formula to calculate overhead
CS 1150 – Lab 15 – Networking
Total No. of Characters Exchanged – Total No. Characters in Message
Total No. of Characters Exchangedx 100
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Exercise 1 – Q6 Help
• How many DAT packets are needed to transfer 1,000,000 messages? (One DAT packet can carry 10 characters)
• Each DAT packet will contain overhead of 9 characters per each message in addition to actual message content
• Each ACK packet will contain overhead of 9 character and no message content
CS 1150 – Lab 15 – Networking
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Exercise 2 Help
CS 1150 – Lab 15 – Networking
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Additional Help
• Networks (Chapter 15) Slides by Ms. Karen Meyer discussed in Class
• Chapter 15 of Course Text Book – Communications Layer
CS 1150 – Lab 15 – Networking
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Questions ?
If you have questions, please raise your hand, Colin or
myself will come to help you
CS 1150 – Lab 15 – Networking