#LEARN TCP IP FAST HOW TO#

There are a number of different ports that are assigned into three different ranges: System Ports (0-1023), User Ports (1024-49151), and Dynamic and/or Private Ports (also called ephemeral ports) (49152-65535). Traffic can be sent using the same destination IP address that allows it to reach the correct host, but a method of traffic differentiation is required, which is done through TCP and UDP ports. The specifics of the IP header and how it is used to process traffic will be covered in more detail in the forthcoming article “Anatomy of an IPv4 and IPv6 Packet.” Transport Control Protocol (TCP)/User Datagram Protocol(UDP)īoth the TCP and UDP protocols operate on top of IP (at Layer 4) following the analogy from above, the TCP and UDP protocols would be the post office boxes.

#LEARN TCP IP FAST HOW TO#

Knowing the protocols that are run on these routers and how to configure them up correctly is the job of the network administrators/engineers. Each of these devices must make independent (relatively) decisions as to what is the best path to the destination. The first router will look up the destination address in its routing table and send the traffic via its best path towards the destination this happens as well at the second router, and the third router, and so on until the destination is reached. For the purposes of this example, every router will have routes for both the source and destination IP addresses. This router must then lookup the destination traffic’s IP address if this destination IP address is not known to the router and no default exists, the router will simply drop the traffic. Typically, the host itself is not routing protocol-aware and simply sends the traffic to the closest router (default gateway).

As shown in Figure3, there are a number of different devices that the traffic must pass through to get from Chicago to Tokyo. Take a piece of IP traffic (packet) that was being sent from an organization in Chicago to another organization located in Tokyo. To make this clearer for those just getting into networking an example is shown in Figure3. When a host device wants to send traffic to a remote destination it is typically routed through a number of different intermediary devices that make independent routing decisions. As of this writing, there are almost 390,000 active BGP routed prefixes (blocks). With this scarcity has come smaller and smaller blocks of addresses that were routed and thus more individual routes that were required to be held in the global routing tables. Of course, as the use of the Internet has become more and more common, the number of available addresses has gotten to a point where addresses are scarce and must be assigned much more carefully.

In the early years of IP deployment, organizations would be given very large blocks of addresses which they could assign internally in whatever way they saw fit the ISPs would simply route all traffic destined for all of the addresses in that range to the organization as a whole (generally a single entry point).

Each block is assigned to a specific entity, be it an Internet Service Provider (ISP), organization, or small business. To keep the size of the global routing table manageable, IP addresses are given out in blocks. All of the traffic on the network has a unique IP address that is routed based on a global routing table (held and routed with Border Gateway ProtocolBGP). An IP address (version 4) is a 32-bit address that is used to identify the different sources of traffic on networks to use an analogy, the IP address would be a post office location. There are a number of things that are provided by IP, the most important of which is an address that is used for global network routing. IP is considered to be a Layer 3 protocol (network) while TCP (and UDP) are considered to be Layer 4 protocols (transport) these will be discussed separately below: Internet Protocol (IP) Because the OSI model is referenced more than the TCP/IP model itself, the rest of this article will use the OSI model layers.Īs discussed, the name TCP/IP actually denotes two different protocols, each of which is at a different layer of the OSI model.

Learn tcp ip fast