Computers talk to each other using protocols. One of the most important one is the IP protocol. In this section I will describe the usual steps, and the protocols used in doing as simple as going to yahoo.ca in your internet browser.

• ethernet: a physical layer protocol for sending information on copper wires (network cable)
• IP: Internet protocol
• TCP: Transmission control protocol
• HTTP: Hypertext transport protocol
• DNS: Domain name service

Each protocol the standard block of data which it can transport, and we call these chunks of data packets.

The data packets of one protocol can be enclosed inside packets of another ptocol, and in fact this is commonly the case.

By going to yahoo.com/news.html, you are sending the HTTP packet “GET /index.html”, wrapped in a TCP packet which is itself wrapped in an IP packet, which sent during a data frame over the ethernet.

  eth( IP(to=12.3.134.21, data=TCP( ..., data=HTTP("GET /index.html") ) ) )