25 years of TCP/IP
Happy New Year! Happy 2008! It's the New Year, but we have also other things to be happy for. Today, in fact, it's 25 years from adoption by ARPANET of the TCP/IP protocol as a standard. Without TCP/IP, without ArpaNet, Internet would not exist at all, and you couldn't be reading this article. Let's see how the story goes. TCP (Transmission Control Protocol) is the protocol which controls data transmission: it checks sent and received data, lost and wrong data. It also provides retransmission of data in case of faulty receiving. TCP has been engineered over the IP protocol, which doesn't guarantee packets arrival and delays, to offer a reliable communication channel between two processes, made by a bidirectional stream of bytes. **IP **(Internet Protocol) is a packet network protocol. Currently the widest used version is IPv4, distinct from the more recent IPv6, created to better handle the growing number of devices connected to the Internet and, therefore, needing an *IP address. *An IP(v4) address is composed by four groups, divided by dots (.), of decimal numbers from 000 to 255 (i.e. from 000.000.000.000 to 255.255.255.255), with a total of 32bits and 232 available addresses (which will soon be saturated). An IP(v6) address, instead, is composed by eight groups, divided by colons (:), of hexadecimal numbers from 0000 to FFFF (i.e. from 0000:0000:0000:0000:0000:0000:0000:0000 to FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF), with a total of 128bits and 2128 available addresses.