FreeBSD6 Unleashed

Network Protocols

I’ve mentioned that most Internet traffic—HTTP, email, FTP, and so on—uses TCP/IP as its transport protocol. TCP/IP itself refers to the combination of the most common “network” and “transport” protocols in use on the Internet. IP, the Internet Protocol, is the backbone of the vast majority of Internet traffic—the “network” layer of the TCP/IP stack. TCP, however, isn’t the only commonly used “transport” layer protocol. There’s also UDP, the User Datagram Protocol, which differs from TCP in a few key ways.

IP also isn’t the only means of carrying traffic at the “network” level; it has a number of contemporaries, too, but they’re mostly useful only on LANs. These include AppleTalk, IPX, NetBIOS, and so on.

Then there’s ICMP, ...