The Internet Protocol (IP)
The Internet Protocol (IP) sits in the middle of the five-layer TCP/IP model. IT provides service to the layers above it and receives services from the layers below it. Almost every computing device on the planet communicates in some way, and most of those use IP. IP exists as an Internet standard protocol, also called ipv4, although it is mostly just referred to as IP. IP was created in the 1970s, but did not reach standard status as the IPv4 RFC until the 1980s. TCP/IP was first created from research projects by the United States Department of Defense (DOD), through the group called the Advanced Research Projects Agency (ARPA). Although IPv4 has worked well for many years, like all things it will be replaced by a better standard. IP version 6 (IPv6) will eventually replace IPv4 as the standard most commonly used. It has taken over a decade to migrate to IPv6, even though it was defined as a standard in the 1990s. Every device that sends IP packets must have an IP address. Those include every PC, phone, tablet, and other electronics such as smart televisions and game consoles. IP addressing does not happen automatically, it must be planned. To plan what IP addresses to use, you must follow some rules for IP addresses. One of those rules states that IP addresses identify an interface connected to a LAN or WAN. Another rules requires that IP addresses exist as groups. IP routing defines how a router chooses where to send an IP packet next. For each packet, the router first finds the true intended destination of the packet. The router compares that destination IP address to the router’s true intended destination of the packet. The routers compares that destination IP address to the router’s IP routing table, finding the best route to use. When routing IP packets from source host to the destination host, the Layer 3 logic focuses on the hosts and routers. IP routing must also rely on the 2 lower layers, Layer 1 and Layer 2. Those layers...
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