TCP/UDP is on Transport Layer. Ethernet is on Data Link Layer. HTTP,FTP and many others are on Application Layer. Presentation Layer and Session Layer are mainly outdated. Ports belong to Transport Layer.

Classful Addressing was used mainly before 1995. Today Classless Addressing is used. Classless Addressing An IP Address has two parts: Network Portion is like the zip code of a city, it identifies a group of devices. Host Portion is like the house number of a building, it identifies the exact owner/device. The Subnet Mask […]

CSMA/CD (Carrier Sense Multiple Access with Collision Detection). In an old fashioned Bus structure all connected devices were listening and sending on the same wire one at a time. If a device initiated a communication it sent 5 volt on the cable. A collision could occur by accident if two devices try to send at […]

There used to be Bus (every device on one wire) and Token Ring by IBM (a token goes around in a ring and visits every device), but today it is mostly a Star topology (many devices connected to a single central device, such as a Hub or Switch) A Hub simply repeats incoming signals to […]

A broadcast domain is a network of computers (joined by a switch) that can receive broadcast messages. Too many devices on a broadcast domain can have a negative impact on the networks performance. That is one reason why companies split and group their devices in different isolated local area networks (LAN). Another reason is that […]

IP Routing is all about sending information from one IP address to another. That might sound like a straight forward thing to do, but it gets a bit complicated, because a destination IP address often belongs to a completely different network than the source IP address. How do we find the correct device? To properly […]