1. CS 1150 – Lab #15 – Networking TA – Sanjaya Wijeratne E-mail – wijeratne.2@wright.eduwijeratne.2@wright.edu Web Page - http://knoesis.org/researchers/sanjaya/http://knoesis.org/researchers/sanjaya/

2. 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 wijeratne.2@wright.eduwijeratne.2@wright.edu Refer to CS 1150 Course Syllabus for Class and Laboratory Policies Zero tolerance policy for Academic Misconduct – All parties will get 0% marks 2CS 1150 – Lab 15 – Networking

3. 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 PM 3CS 1150 – Lab 15 – Networking

4. 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) 4CS 1150 – Lab 15 – Networking

5. What is a Computer Network? 5 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

6. Network Protocols 6 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 – Addressing CS 1150 – Lab 15 – Networking

7. Network Topology 7 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_topologyhttp://en.wikipedia.org/wiki/Network_topology

8. Routing in a Network 8 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_forwardinghttp://en.wikipedia.org/wiki/Hop_(networking)#Next_hop_forwarding

9. TCP/IP Applet 9 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

10. TCP/IP Applet Cont. 10CS 1150 – Lab 15 – Networking Data Packet DAT 1 0 221 1 – Destination Address 0 – Sequence Number 221 – Checksum

11. TCP/IP Applet Cont. 11CS 1150 – Lab 15 – Networking ACK Packet ACK 0 1 0 0 – Destination Address 1 – Sequence Number 0 – Checksum

12. TCP/IP Applet Cont. 12CS 1150 – Lab 15 – Networking NAK 0 1 0 0 – Destination Address 1 – Sequence Number 0 – Checksum NAK Packet

13. Exercise 1 – Q4 Help 13 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

14. Exercise 1 – Q5 Help 14 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 Exchanged x 100

15. Exercise 1 – Q6 Help 15 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

16. Exercise 2 Help 16CS 1150 – Lab 15 – Networking

17. Additional Help 17 Networks (Chapter 15) Slides by Ms. Karen Meyer discussed in Class Chapter 15 of Course Text Book – Communications Layer CS 1150 – Lab 15 – Networking

18. Questions ? If you have questions, please raise your hand, Colin or myself will come to help you CS 1150 – Lab 15 – Networking18