Agenda Last class: Network Hardware Today: Network Protocols –How do computers talk to each other? –Needs? Same hardware Same rules (protocols) for encoding data “Standards of Interoperability”

Protocol for Data Encoding Sending data: flashing light in cable Light = 1No light = 0 Need same way to talk so all computers know What does that mean?

Protocol for Data Encoding Ex: You want to send … from Shanghia to Beijing –What info do you need to include?

Protocol for Data Encoding Ex: You want to send … from Shanghai to Beijing –What info do you need to include? Address (IP address) Where to start and end, other RULES to read it

TCP/IP TCP = transmission control protocol IP = Internet Protocol TCP/IP are communication rules so computers can understand each other Using TCP/IP, I can read it! Coded with TCP/IP rules

TCP / IP and How Internet works Ex: You want to send an from Shanghai to a friend in Beijing 1.The is cut into small ~1kb packets (TCP) 2.Each packet has the (IP) address and goes there using any route 3.The packets are put together again (TCP)

Analogy Cut up Code it (address, order) Send it in many ways Decode it To Mr Z, Hi my name is Mr Y To Mr Z Hi my To Mr Z name is To Mr Z Mr Y Packet 1Packet 2 Packet 3 Internet Packet 2 name is Packet 1 Hi my Packet 3 Mr Y Order Hi my name is Mr Y Internet

Assignment We are going to copy this process! I wrote an “ ” to each student Then I cut it up into packets Then I coded it Then I send it many ways (to YOU) Your job: Find your message and decode it

TCP: What do the numbers mean??? ??? Using TCP/IP, it makes sense! Coded with TCP/IP rules

TCP/IP Rules (just for this) HEXADECIMAL, ASCII All packets follow this rule for order: –IP address –Total number of packets (1 bit) –Packet number (1 bit) –Start message character (1 bit) –Message (2 bits each character) –End of message character Example:1154AF22ECD