1. Discussion Section Week 3 EE122: Introduction to Communication Networks Fall 2006

2. Sockets and Ports Chicken (3.4.5.6)Cow (7.7.7.7) Dog (9.8.7.6) 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 tuples In client, there is 1-to-1 between socket and port

3. select() stdio(keyboard) socket 1X socket 2 Monitor read of 3 inputs