1 Last Class! Today: r what have we learned? r where is the networking world going? r question and answers r evaluation

2 Course Summary What have we learned: a huge amount! r Comprehensive view of field of Computer Networks m principles m practice … using Internet to motivate examples

3 What did we do? Introduction r What is the Internet, protocol? r network edge, core, access nets r physical media r delay, loss r layers, service models r Internet backbones, NAPs, ISPs r history Application Layer r application-layer protocols r the WWW: HTTP r FTP r SMTP, POP3, IMAP r DNS r Socket programming

4 What did we do? Transport Layer r services, principles r multiplexing, demultiplexing r UDP r Principles of reliable of data transfer r TCP r Principles of congestion control r TCP congestion control Network Layer r service model(s) r routing principles r hierarchical Routing r IP protocol r routing in the Internet r what’s inside a router?

5 What did we do? Link Layer, LANs r introduction, services r error detection, correction r multiple access protocols r LAN addresses, ARP r Ethernet r hubs, bridges and switches r wireless: IEEE

6 What is the Internet? local ISP company network regional ISP router workstation server mobile A B

7 Q: Where is Networking headed? A: nobody really knows! General trends: r ubiquity of communications m IP dialtone, IP will be like electricity: it’s everywhere! m network-capable appliances (e.g., IP thermostat) m issues of scale important: 100's of millions of network- connected devices m sensor networks r mobility important: m people move, need to communicate

8 Q: Where is Networking headed? r multimedia important: m it is how people communicate m QoS not a solved problem end-end r high bandwidth to home (ADSL, cable modems) a major driver for future m games, VR, education, information, entertainment m merger of networking and telephony m broadcast entertainment (TV) and WWW r security, and network management: critical concerns r application-layer services: a network over the network: P2P, CDNs, etc.

9 The Future: a broader CS view communications computing communications computing ? communications computinginformationprocessing

10 Remember Course Goals r networking: will play a central role in computing, information processing r this course: m specific architectures, protocols m fundamental issues: APIs, reliable data transfer, flow/congestion control, routing, multiple access, addressing, security, management r remember: you learned it HERE!

11 Evaluation r on-line r need CCNY (R1/505) r instructions sent to your r follow instruction r please do it

12 Final r Short answers r Routing algorithms r Routing table r Ethernet collisions and back-off r Routing and addressing

13 The End!