Discussion SectionWeek 3

EE122: Introduction to Communication Networks

Fall 2006

Sockets and Ports Chicken (3.4.5.6) Cow (7.7.7.7)

Dog (9.8.7.6)

OS OS

OS

Web Server

sock1

sock3

sock4

sock5

Mail Server

sock2

sock6

port80

port25

2005

8006

6001

3500

Explorer

Firefox

Explorer

Outlook

sock11

sock12

sock13

sock14

Socket 1 and 2 do not have a corresponding client. It only accepts incoming connections

In server, there can be multiple sockets for one port

Host address of client in the packet is also needed for the OS of server to forward the packet to a correct socket,and port number of client, too – four tuplesIn client, there is 1-to-1 between socket and port

select()

stdio(keyboard)

socket 1 X

socket 2

Monitor read of 3 inputs