CPSC 441 Computer Networks Carey Williamson Department of

CPSC 441: Computer Networks Carey Williamson Department of Computer Science University of Calgary CPSC 441 1

Today’s Agenda n Welcome! n CPSC 441 Overview n n Networking Basics and Definitions “Warriors of the Net” video Administrative Details Questions? CPSC 441 2

Some Definitions (1 of 2) n n Computer Network: a set of autonomous computers that are hooked together somehow so that they can communicate with each other Examples: n n n Your home network U of C campus network The Internet CPSC 441 3

Some Definitions (2 of 2) n n n Protocol: the rules used for communication between two parties Stack: a pile of things, usually with one thing on top of another The Internet is built using a layered stack of communication protocols CPSC 441 4

Protocols and Applications SLIP TELNET RARP Instagram FTP CSMA/CD ATM HTTP CSMA/CA DNS Wi. Fi MIMO PPP WWW SMTP FEC Ethernet RIP You. Tube QUIC UDP Snapchat ADSL Face. Book SSH TCP NNTP RTSP ARP BGP DASH HTTPS QAM IPv 4 IPv 6 Bit. Torrent CPSC 441 FDDI NTP 5

Internet Protocol Stack n Application: supports end-user services and network applications n n Transport: end to end data transfer n n IPv 4, IPv 6, BGP, RIP Application Transport Network Data Link: channel access, framing, flow/error control, hop by hop basis n n TCP, UDP Network: routing of datagrams from source to destination n n HTTP, SMTP, DNS, FTP, NTP PPP, Ethernet, IEEE 802. 11 b Physical 001101011. . . Physical: transmission of bits CPSC 441 6

Example: HTTP and TCP n The Web uses HTTP and TCP (Transmission Control Protocol) Web Client SYN/ACK GET URL Web Server ACK YOUR DATA HERE FIN ACK FIN/ACK CPSC 441 7

Network Packet Structure Protocol Headers (Control Information) Src 12: BD: 07: AF: B 0: 6 E Dst 37: F 9: 14: FD: C 1: 08 Src. IP 372. 19. 44. 108 Dst. IP Seq. Num 61842 136. 159. 99. 114 ACK 3756812 Length 1500 CRC 0 x. FC 147 E Data. Link Layer Header (e. g. , Wi. Fi, Ethernet) Src. Port 80 Dst. Port 2579 Window 8192 Flags: PA Network Layer Header (e. g. , IP) Transport Layer Header (e. g. , TCP) Payload HTTP/1. 0 200 OK Content-Type: text Content-Length: 4732 <html> Welcome to Sponge Bob’s home page! On this site, there are lots of fun activities for you: colouring pages, bath time singalongs, and more. <p> Please click <a> <href=“. /signup. html”> here </a> to learn more about membership accounts and. . . Payload (User Level Data) CPSC 441 8

Network Packet with HTTPS Protocol Headers (Control Information) Src 12: BD: 07: AF: B 0: 6 E Dst 37: F 9: 14: FD: C 1: 08 Src. IP 372. 19. 44. 108 Dst. IP Seq. Num 61842 136. 159. 99. 114 ACK 3756812 Length 1500 CRC 0 x. FC 147 E Data. Link Layer Header (e. g. , Wi. Fi, Ethernet) Src. Port 443 Dst. Port 2579 Window 8192 Flags: PA Network Layer Header (e. g. , IP) Transport Layer Header (e. g. , TCP) Payload Du. ZUVj. Xc 3 W 7 g. Yav 3 B 8 y. ENzkm. Ee. XOvd. PRn+hnd. KMv 6 DFqlm. Mfr. R 6 K 7 M 1 U 56 x+h/IJtun. Lc 7 sa 60 bz 4 kq. Fl. Bq. S/Eif. D Xwv. Ub. Mz. Xo. I 2 r. JRI 9 Kaq. PJrz. Ge 6 Kc 502 l. Dc. ADCcs 4 Yl. XQ 1 m 7 OENZIPf. M 4 ZJ/OZ 2 q 8 s 089 uy 3 Zf. GUVXla. Z 2 UB/a. RCHz Ck. O 7 w. Wc. Jv. WBto. Vu 8 b. JNSYhv 4 g. Hd 3 c. NERseb 4 g/+IQ 2 i 2 Stgfx. TGf 4 JMAAhpm. Qy. DQplbm. Rzd. HJl. YW 0 NZW 5 kb 2 Jq DTIx. IDAgb 2 Jq. DTw 8 L 0 Zpb. HRlci 9 Gb. GF 0 ZURl. Y 29 k. ZS 9 M ZW 5 nd. Ggg. NDMw. Pj 5 zd. HJl. YW 0 NCki. Jf. JTbbo. JAEIbv 9 yn 2 0 t 6 M 7 LIH 6 KWHNk 2 a. Nhpeg. Ohaa. UQt. Yh. Pfvmi. Y 7 Q 4 o 4 Yo /k+9 bdm. YQPGoew. WMw. XGv. Ls 5 JZk. Dx 7 Z 6 Ns. Wx 3 OX…. Payload (User Level Data) CPSC 441 9

Summary n n This course focuses on the principles underlying the design of modern computer communication networks The Internet and its protocol stack will be used as the primary examples Aside: The Internet is pretty amazing! My research: make the Internet bigger, better, faster, stronger, and safer for all! CPSC 441 10