Networking 4 – Local Networks

Data networks for communication between hosts on shorter distances, Local Area Networks (LAN), were created in a research department called Xerox in Palo Alto in 1973. These networks were broadcasted networks- where all the connected computers could communicate with each other on the same line they were connected to. These networks got the nickname Ethernet because of the communication that was sent on the wire was comparable with broadcasting and radio programs through the air with the help of antennas.

The first physical transmission media for ethernet was coaxial cables. The technology back then only had a capacity of 3 Mb/s. Later on, ethernet got increased up to 10 Mb/s together by Digital Equipment Corporation (DEC) and Intel. This is usually referred to as the DIX ethernet (Digital – Intel – Xerox). Not too long after, a competitor for ethernet appeared, Token Ring, which was created by IBM. This type of network used some sort of ring structure instead of the bus structure for the ethernet. Both token ring and the bus became the official standards, which is something we will come back to later.

The increasing use and need for communication have led to a continuously increasing capacity of the networks. Over time, bus technology has taken a major part in this and is leading the race. The reason for this is because the technology is relatively simple (will be explained later in the series) and is also a relatively cheap technology (the transmission media/cable is cheap). The development of this technology has also led to other transmission media like thinner and more flexible coaxial cables, as well as Twisted Pair (1990) which has now totally taken over coaxial cables. Bus is also available on fiber optics.
A sight-seeing forward to our future- The communication has increased from 10 Mb/s to 100 Mb/s (Fast Ethernet) to 1000 Mb/s – 100Gb/s (Gigabit Ethernet) to 200Gb/s and 400Gb/s (Terabit Ethernet). Companies are now also making standards for 800 Gbit/s and 1.6 Tbit/s to come after 2020. More about this later.

These pictures are an insight into a deeper dive of the ethernet standards that we will talk more about later. For experienced nerds, this picture represents the Layer 1 of the OSI model.

Ethernet also became updated with the switching technology instead of the bus technology it served in the past. The “switching technology” utilized a single switch which is connected to all the different connections, enabling switching packets to the specific point rather than being broadcast to all points. This benefit gave all machines that were connected a dedicated capacity on 10/100/1000 Mb/s, which is a huge improvement compared to sharing this capacity with all connected computers. This rapid development definitely made ethernet win the race between the “switch” technology and the ring based technology.

Bilderesultat for switching technology

The “switching technology” is an early-stage development of how our current star topology looks like.

For a while, Fibre Distributed Data Interface (FDDI) was a strong competitor. FDDI was a 100Mb/s fiber-based token ring technology. These types of networks (Ring, Bus, “switching”) were all categorized as Metropolitan Area Networks (MAN) which took part as connections between many different personal house LANs or enterprise LANs in a whole city. The MAN is located right between the LAN connections (houses or enterprises) and Wide Area Networks (WAN, from one city to another) as shown beneath. But Ethernet comes yet again with a higher capacity, cheaper and more simple equipment.

The ATM (Asynchronous Transfer Mode, a packet switching technology that decides how the packets are divided when being sent across) technology had a golden future within the different types of networks, and we thought that it was going to be the new official standard. But as we can see today, ethernet will always be the main preference for people.

Bilderesultat for atm vs ethernet
A technology with the name metro ethernet (metropolitan ethernet) has also become popular within the latest years. A metropolitan-area EthernetEthernet MAN, or metro Ethernet network is a metropolitan area network (MAN) that is deployed under a metropolitan area. It is commonly used to connect subscribers to a larger service network or the Internet. Such as businesses to connect their own offices to each other. The technology that is being used within the metro ethernet is a technology called Multiprotocol Label Switching (MPLS) that works similar to the ATM. We will get back to MPLS later in the series.

Bilderesultat for mpls vs ethernet
In Networking 2 – The Network Infrastructure we talk about PDH, also known as SONET. These are fiber optic based interfaces and were much more expensive for the same amount of bandwidth, For that reason, we yet again come back to the ethernet interfaces