I.e. P2P peer communication, peer networking, or referred to, the conventional client server mode (below "P2P model configuration" below) is a clear distinction, in the widely used instant messaging programs (IM applications, such as real-time audio video communication, real-time file transfer and even text chat, etc.).
But a significant contribution to our well-known IP protocol is to become the world equality. In theory, each site has an IP address in the protocol level have considerable ability to access to services and service delivery, there is no difference between different IP address. It is well known in the server and the client is actually distinguished role in the application protocol layer, but no difference at the network and transport layers. A host with an IP address can be either a client, it can also be a server, in most cases, both the client and also server.
IPv4 is released in September 1981, using 32bits integer expression IPv4 address, address maximum range is 2 to the power 32 of about 43 billion. IP-founding period can be networked device point of view, such a large space has been hard to be a short run. However, the fact that far more than people imagine, the rapid growth of computer networks in the next few decades, the explosive growth in the number of network terminals. IPv4 address as an endangered resource worth increased sharply, IPv4 addresses will run out of the question had been put in front of Internet pioneers, and thus a NAT technology, we can put him as a super large patch of IPV4.