We live in an ever-increasingly connected world, where instant communications are the norm and expectations of fast, reliable internet access are high. Yet few people understand how we got here and how this all works. Over the next few posts, we will go through some of the terms used and underlying technologies, to breakdown the mystique and help in understanding. In the end, while you won’t be certified networking engineer, you should have enough information to work out the difference between your LAN’s and your FTTP.
At its core, the internet is just a bunch of connected local networks. Established as a research project, funded by the US military and initially rolled out to universities and other establishments, the internet is now a largely decentralised communications network with massive Worldwide adoption that forms the backbone of how we all communicate.
Local networks have been in operation for decades. Companies would have lots of computers, and those computers would communicate with a large server and occasionally with each other. Different types of technology would be used to allow the communications to take place and over time, speeds and reliability improved. You will hear technicians talk about switches, routers, ethernet cable, fibre optic, VLAN’s etc. These are all networking technologies that have evolved to deliver the services you’ve come to expect.
The Journey of a Packet
A network packet is generated by a computer and delivered to a Network Interface Card. This is connected via an Ethernet Cable, normally to a floor-mounted wall port that has another cable connected to a patch panel in a rack. This then connects to a network switch that’s connected to a network router which delivers the packet to a service provided by an ISP. Once the packet is with the ISP, it is then moved around the internet. This is done via routers, switches and hundreds, sometimes thousands of kilometres of fibre optic cable until it finds its way to the recipient. This is where the router, switch, patch panel and cable journey is performed but in reverse.
The user of a computer has information to send to another device, be it an email, website or an instant message. To achieve this, it creates a special packet of information that contains where it’s come from, information about the data that’s in the packet and also its destination. The computer sends that information to the NIC.
Network Interface Card (NIC)
Often called a NIC, this is part of your computer that is attached to a port in a wall via a cable. The card usually is part of the workstation, though you can sometimes buy special cards that would fit in the workstation as additional or replacements. Network cards are mostly rated in their speed, and the current standard is 1Gbps (gigabits per second), though speeds of 10Gbps are possible with special cards and cables.
An ethernet cable is a cable that attaches the NIC to the switch, generally via a panel on a wall. Cables can come in any colour, but most often are blue. They are referred to by their rating. You will hear and see Cat5, Cat5e and Cat6 being spoken about. In general, most networks only require Cat5e to support 1Gbps speeds. Cat6 is a higher standard, supports faster, more reliable speeds and is the cables most often used to ensure support for future networks and technologies.
The cable from the wall will normally connect to a Patch Panel in a server rack, most often in a dedicated communications cabinet or room. The purpose of the patch panel is so that all cables can be wired and connected to the back of the panel and a short lead can then be used to connect to the network switch. This keeps the rack tidy, easy to manage and as the cables are hard-wired, reliable.
At its most simple, a network switch receives a packet of information on one port and sends it out another, in this case to the Network Router, though it could be another device on the same switch, such as a printer.
A router receives a network packet and, based on the source, and destination information determines what to do with it next. It could go to another part of the internal network, or it could go out to the internet via an ISP.
Internet Service Provider (ISP)
The ISP receives the packet from the client’s router, with the destination information attached. It reviews that information and determines the best way to get to that destination. It forwards that packet along, much in the same way that a parcel or letter is sent around the country. Each receiving point doesn’t know how to get the whole way but does know how to get to the next part of the trip. Eventually, the network packet arrives at the router of the destination, where a process takes place to determine the address of the device in the network it needs to be delivered. Via a combination of network switches, patch panels and cables, it will be eventually delivered to the destination. All of these takes place in at the speed of light, with round trip times typically being as low as a few milliseconds.
The destination device will send the requested information back, along with some other data, to the original device. As each packet contains only a small amount of information, this process takes can place millions of times to send and receive even a single web page.
It’s a wonder that we don’t lose all this data and know where to send it. Next time, we will discuss how the network keeps track of what needs to go where and what the best way there is.