Basics of networking
Ethernet networking has allowed for an amazing level of interconnectivity between many of the machines we use today. But building even a simple home network can sometimes be confusing without a little basic information first. This article will provide some information about the basic concepts of networking that should help you in building your own system. Ethernet is standardized by the Institute of Electrical and Electronic Engineers (IEEE) under the collective standards 802.3 for wired and 802.11 for wireless (Wi-Fi).
Though there have been many earlier standards that used coax cables, today's wired Ethernet networks are connected by twisted pair Ethernet cables that are commonly referred Category 5 (Cat 5) or Category 6 (Cat 6) depending on their rated speed. There are also subsets of these to indicate other speed ratings such as Cat 5e (enhanced), Cat 6e and Cat 6a.
Each Ethernet cable has 4 twisted pairs of wires for a total of 8 conductors. They are terminated on the ends with RJ45 connectors. The RJ45's look like phone cable connectors except they are a little wider and will have 8 pins instead of the 6, 4, or 2 found on most phone lines. With regard to how the wires are arranged in relation to the pins, you'll hear the terms TIA/EIA-568-A and TIA/EIA-568-B. Of the two, TIA/EIA-568-B is the newer one and the one most commonly found and used by network equipped machines.
The standard Ethernet "Patch" or "Straight" cable will have a connector on each end that are both wired to the TIA/EIA-568-B configuration. You use straight cables whenever you connect computers and other networking devices to a switch, hub or router.
The other type of cable is called a "Crossover" cable. These cables will have one end pinned as TIA/EIA-568-B and the other end as TIA/EIA-568-A. It doesn't matter which end you plug to which device. The main purpose of these cables is to directly connect one device directly to another without a switch, hub or router in between them. It works by crossing the transmission (Tx) outgoing line on one side directly into the Receiving (Rx) incoming line on the other. This is useful when you only want to connect two computers to each other or two other like devices such as two Xboxes for head to head game play.
Most cables you find will be UTP, Unshielded Twisted Pairs. UTP became an early standard in commercial applications of Ethernet because UTP cables were much cheaper than STP, Shielded Twisted Pairs. While shielding is generally a good thing and will help to reduce transmission errors, the secret behind Ethernet technology's success is the packet framing data transmission that the technology employs. Basically, unlike linear types of transmissions, Ethernet sends data from one point to another using packets of data. Packet framing offers much better error correction therefore, though unshielded cables may result in greater error rates, the error correction technology of Ethernet is able to compensate. Ultimately, whether you want to use STP or UTP cables is up to you. One may result in fewer transmission errors that will provide better overall speed over longer runs, but the other option will tend to be more budget friendly.
If you want to forego the cables completely or at least to certain devices where it may not be convenient to run a cable to, you can connect to your network over wireless Ethernet technology often referred to as Wi-Fi. Wi-Fi follows the IEEE 802.11 standard. There are many subsets of the technology including 802.11a, b, g and n.
Initially, 802.11a and 802.11b were the choices for Wi-Fi. The tradeoff between the two are that 802.11a offers greater transmission speed than 802.11b, 54Mbps vs 11Mbps, but has a shorter effective range. 802.11a operates in the 5Ghz frequency range which means less interference but generally costs more and makes it incompatible with the other standards.
802.11b was the most popular standard for home use for many years. It has limited bandwidth but was the most cost effective solution for Wi-Fi. It operates on the 2.4Ghz range which means it shares frequencies with other common household devices like cordless phones, microwaves and bluetooth meaning signals from other devices can interfere with operation.
A newer standard, 802.11g was an effort to combine the benefits of both 802.11a and 802.11b. It has range similar to 802.11b and speeds comparable to 802.11a. Since it uses the same 2.4Ghz range as 802.11b so it is backward compatible with that standard but not with 802.11a.
The newest standard to be finalized by the IEEE is 802.11n. It utilizes MINO technology which utilizes multiple signals and antennas. It has a maximum bandwidth of over 100Mbps and offers better range than any previous standard. It is quickly being adopted as the new best solution for home networking.
Though the newer standards are backward compatible with the older 802.11b, in order to take advantage of the speed boost, you will need both a wireless network card and wireless access point that are compatible with the newer standard.
To set up a Wi-Fi connection, you'll need a router with Wi-Fi built in or a non-Wi-Fi router with a internet access point device connected to one of its wired ports with a Ethernet patch cable. Internet access point devices are basically small boxes with an Ethernet port to connect to a router and an antenna to communicate with other devices. However, it's generally easier and more common to just get a router with the Wi-Fi already built in.
To connect devices to the Wi-Fi network, they will either need Wi-Fi built in or you will need to connect a Wi-Fi adapter. The easiest and most common type of Wi-Fi adapter for connecting to a non-Wi-Fi device is a USB Wi-Fi Adapter. USB Wi-Fi adapters can be connected to any equipment with a compatible host USB Type A port. It is important to note that you cannot simply connect a USB Wi-Fi adapter to just any device that has a USB port. Most peripheral devices have a dependant USB type B connector. Type B connectors do not have a host controller behind them and must be connected on the other end to a device that does have a USB host controller like a computer. In other words, a peripheral device like a printer, must be connected to a host device like a computer. You cannot connect a printer to another printer and have one control the other. However, some peripheral devices may have USB A type connectors that were specifically designed to take and host an adapter like a USB Wi-Fi adapter in order to make the device wireless. Still others may have Type A connectors for connecting other types of devices such as flash drives and cannot be used with a Wi-Fi adapter. It's best to read the manual for the device you plan to connect to see what devices can be connected to it's USB ports.
Today's networks are not just limited to computers. You can have computers, cell phones, internet appliances, media players, and more all connecting into a single network in your home. Whether you connect by cable or wirelessly, if you want to share a single internet connection with all your devices, you'll need at least one router. Small network routers like the ones used in home networks allow multiple devices to share a common IP address. That is, while a modem will capture a single IP address to connect you to the greater outside world of the internet, typically, only one computer or device can connect to that gateway at any given time. A router will effectively distribute that connection within your network allowing all your devices to connect to the internet simultaneously. Hubs and switches can also further distribute that connectivity, but unless you have at least one router in your system, only one device will be able to connect to the internet at a time.
A router will typically have a row of LED's on the front to indicate active connections and a row of RJ45 connector jacks on the back. One of those connectors is usually labeled "Internet" or "uplink" and the rest are numbered starting from 1. The Internet port is for connecting to a Modem which will in turn be connected to your Internet Service Provider (ISP) commonly by cable TV or DSL telephone lines. Other technologies such as fiber optic lines also exist. The other ports are for connecting other devices like computers with an Ethernet cable. You will use straight cables in just about every application however, there are routers that can detect whether you are using a straight or crossover cable and allow you to use either. A wireless router will also have an antenna that will connect with devices wirelessly. With wired connections, you will need one port for each device you are connecting. You cannot split one port to more than one device. However, Wi-Fi connections will allow you to connect multiple devices even if you have only one antenna.
Of the 3, routers are the most sophisticated. They are like small dedicated computers that will not only share connections between devices, some can also provide firewall protection to guard your network from outside attack. As mentioned earlier, Switches and hubs cannot distribute internet connection throughout a network without a router, they only expand the number of connections you can make. Hubs will simply broadcast a connection to all other connections. If two devices try to send packets at the same time, a hub will show a collision, and both devices will re-transmit their packets after a random interval. Switches avoid this problem because each connection communicates independently to any other connection. This effectively speeds up network communication. So, hubs are the simplest devices. Switches are a little more sophisticated and will allow for better connection speeds. Routers allow a network to connect to the internet, can offer firewall protection and generally have the capabilities of a switch built into them in the form of wired ports, Wi-Fi or both.
The modem is connected to a router by a Cat 5e or Cat 6 ethernet straight cable. Desktop computers and devices with built-in network capability are also connected to the router with straight cables. Laptops and other Wi-Fi enabled devices connect to the router wirelessly through antennas.
Newer Modems may have the router and wireless hardware built-in.
If you have devices like mass storage devices (external hard drives), printers and webcams that do not have any Ethernet connectors or Wi-Fi capability built-in that you would like to share across your network, then you will need to connect those devices to your network through a server. A server is basically a computer to which all the devices will connect to locally and then port access to those devices to other computers on the network. Most people will simply use one or more of their desktop computer that they use as a work station for that purpose.
Others may choose to have a dedicated machine, often referred to as a file server to serve that purpose. However, if you would like to have peripheral devices connected directly to your network so that you do not built in connection so that you do not have to leave one computer on all the time, there are dedicated devices that serve the function of a server. The most common of these is the print server.
They are small devices that take the place of a computer, are always on and allow you to directly connect your devices to the network. Some limitations are that they may not support all functions of multifunction printers and they may only allow access to one computer at a time. More advanced servers will act as print servers and will also allow you to connect other types of peripherals such as external hard drives and web cams as well.
This concludes our primer on the basics of networking. If you are interested in how to terminate RJ45 connectors on to bare Ethernet cables, check out our how-to guides.