Presentation on theme: "CS 4700 / CS 5700 Network Fundamentals Lecture 4.5: Review from last week Revised 1/12/14."— Presentation transcript:
CS 4700 / CS 5700 Network Fundamentals Lecture 4.5: Review from last week Revised 1/12/14
Intro to the class 2 Use Piazza for everything Really Unless it’s something truly personal/private Don’t cheat I will catch you If you have questions about what is cheating, ask Regrading policy 2 strikes and you’re out Partners allowed on all projects
History of the Internet 3 What were the newideas that revolutionized/distinguished the Internet from other prior networks? Packet switching (why is this a good thing?) No global control Layering to glue together different network types What was the original Internet called? What was its design goal? ARPANET, resilient to catastrophic failure (nuclear) What do you think is the biggest threat to Internet success?
Architecture 4 What are the 7 ISO layers? Which ones are used in practice? What does each layer specify? How do we combine layers in data transmission? What are examples of violations of strict layering?
Saltzer’s paper 5 Design principle, not a law Low-level functionality begets assumptions, and when you assume, you … More generally: Systems will fail with some nonzero probability. The Internet is a very large computer system, so something is almost always going to fail. Defining endpoint is critical Some endpoints are at the low level
Student comments 6 10/61 students submitted by deadline 40/61 by 10:30am “I feel that author's assumption of considering an error rate to be acceptable in the system is not the best approach, specially[sic] when today computer systems are used for critical functions like healthcare and can also lead to human fatalities” Lack of empirical data/analysis/statistics Not enough solutions, too vague Makes assumptions about goals of underlying system(s)
Clark’s paper 7 Primary goal: Multiplexed use of existing (disparate) communication networks, separately administered Secondary goals: Priority order shaped the Internet Make it work now, worry about accounting later (but make it cheap to build) Keep it simple, but know that it might be less efficient
Student comments 8 22/61 on time 37/61 at 10:30am Why is 100 bytes a reasonable packet size? What is fate-sharing, why is it easier to engineer? Location of service-consumer and failure are the same Why is it hard to support resource management and accountability? Cost-effectiveness & security? Why TCP? Why ACK on bytes? Dedicated network vs. Best-effort
Project 1 highlights 9 Key skills Work with TCP sockets (optionally SSL) Follow application-layer protocol Parse data Use turnin script from (most) any CCS department server It’s a valid CCS server if you can read /courses/cs5700s14/bin You can work in teams Use any language you want (doesn’t have to be C) Document your code, read instructions carefully! Get started early. I go to bed early.