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NOTE:  Items highlighted in RED are defined elsewhere in this Glossary, while items highlighted in BLUE are site links for further information.


HUBS, SWITCHES & ROUTERS (also REPEATERS, AMPLIFIERS, BRIDGES):  Each of these hardware devices are used for networking computers, with varying capabilities.  Often these devices are used together, for example a cable modem connected to a router which is then connected to a switch.  The main differences between these three devices, which are frequently confused, is the degree of “intelligence” in each. 

hubThe least intelligent, expensive or complicated of the three devices is the “hub”. This “box” has several physical “ports” where computers are plugged in via ethernet cables, and assures that every computer connected to a hub sees everything and every other computer connected to that hub.  It doesn’t know or care which computers it is interconnecting, and has no idea what information passes over the network.  Basically, a hub takes one incoming cable and splits it into several other outgoing cables.  [It’s similar to a power strip, which splits an electrical outlet into several outlets.]  Of course, this sometimes causes “collisions” which can slow down the network.  But they’re inexpensive.  [There’s also another type of hub, one which connects wireless electronic devices for home automation purposes.  Click HERE for more.  And another type of HUB which connects devices together for wireless audio.]

switchA switch is more intelligent and efficient than a hub because it has the ability to remember where particular device “addresses” are.  So, for example, if a switch sees traffic coming in on the second port for computer A, it will remember the address for computer A and not waste further time in the future scanning the entire network for computer A. Most business networks use switches to connect their computers, printers and servers within a building or buildings.  On the network, the switch serves as a “controller,” enabling the devices on the network to find and talk to each other.  Switches (like those for homes) that can be used right out of the box are unmanaged or simple switches.  [On the enterprise side, more intelligent switches are known as managed switches (usually managed via software “panels”), which often use Simple Network Management Protocol (SNMP) to  supply the owner with a variety of intelligence, locally and remotely, regarding traffic flow, operating speeds and bandwidth potentials, providing control over each switch port, information about who can access the shared LAN as well as connection speeds and communication. These switches come in various “speeds,” like 10/100Mbps or Gigabit (faster).  Switches are sometimes referred to as “Layers 1 through 4,” which actually refer to the layer of the OSI model that the switch is deployed on, and is determined by how much addressing detail the switch reads as the data passes through, which is determined by an algorithm, usually on its internal processor.  For example, traditional switches operate at Layer 2 (the OSI Data Link layer), which sends packets to a specific switch port based on destination MAC addressesLayer 3 switches (a/k/a multi-layer switches) operate at the routing level of the Network Layer of OSI, where the packets are sent to a specific IP address, based on the destination IP address.  Layer 4 switches operate at the Transport Layer of the OSI, which adds the capability of identifying which application protocols (e.g. HTTP, SNTP, FTP, etc.) are included with each packet, particularly useful in enterprises because they can establish network priority for vital in-house applications, like e-mail. (Layer 1 switches have no control, and simply allow you to add 12/24 ethernet connections, much like a hub, but with more computer connections.)]

routerA router is the most intelligent of the devices because it can actually be programmed to understand and then “route” the incoming data it is being asked to handle. Routers can also modify the data, for example, to “hide” the receiving computer behind a firewall. They also listen to see how busy the network may be, and “route” the signal to the least busy part of the network, if necessary. And they are the only network hardware that can be used both cabled and wirelessly. Routers are popular because they allow users to “share” broadband internet connections so that many users may be simultaneously connected to the Internet, viewing different web pages.  An entirely new series of routers (dual-band, gigabit, app-enabled; e.g. WD MyNet N900 @1000Mbps) is now available specifically for streaming videos on tablets, for gaming and for file sharing, due to the increasing use of tablets and wireless streaming of home entertainment via HDTV and game boxes.  And, mostly for businesses, Software Defined Networking, which allows network engineers to shape traffic from a centralized control console without having to touch individual switches and routers in order to respond to changing network conditions in an agile manner, are becoming more common.  For more about types of routers and their use in networks, click HERE and HEREOften, within business enterprises, routers are connected to the switches (discussed above) so that the incoming Internet (“WAN”) connection is then directed to all of the devices on the switched network, managed through the switches. Routers, which often include built-in cable, DSL or FIOS internet modems, don’t exactly come in speeds, but do come in “versions,” like b,g,n and ac (see Wi-Fi), which refer to a standard known as IEEE (see Associations) 802.11 b, g, n, ac, ad, etc.  Each succeeding standard is faster, has more range and can go through more objects like walls.  And many router models offer the capability of working with home or business VPNs as well.

Finally, after years of relatively stagnant router hardware development, there are upcoming improvements. A crowd-funded router based on OpenWRT, the Turris Omnia, is completely different.  It automatically updates its firmware as soon as a vulnerability is discovered and patched (see Security for why this is important), it can serve as a DLNA (see Associations), with an external drive it can serve was a backup server, it can accept a SIM card to ensure connection fail-over, connect to SFP and many other features.  All for about $200.  In 2016, the Netgear Nighthawk 802.11ad supports high-speed data transfer for 4K video and VR gaming art very fast speeds (60GHz) over very short distances.  Google is working on a better mousetrap as well, the OnHub, discussed below.  For more new developments, see also Eero and Luma, which direct signals from their device.  In contrast, coming out soon, Plume, another “self-optimizing” Wi-Fi device which distinguishes itself because it is a cloud-based platform (with an associated smart phone app) which scales the streaming signal between six or more plug-in “hexagons” around a home, depending on load demand, so if you’re streaming a movie in the living room, it’ll route more bandwidth to that area. (Again, it’s not cheap, at about $250).   It’s a move from coverage to capacity.  Statistics show that a full two-thirds of IoT devices (6 billion devices, expected to triple by 2020) are installed in homes. Predictably, as usage increases and router security being relatively poor, especially among home users, hacking is becoming prevalent (see Security for ways to harden your router’s security).

The OnHub (manufactured for Google by TP-Link at about $220), allows users to prioritize the speed of their connection by simply waving a hand over the router.  It is quite useful if you live in an area with competing routers which can knock down your signal strength.  It also has a number of upcoming features that have not yet been activated, like the rear USB port or a wireless home automation feature, as well as the lack of a microphone for interaction (like the Amazon Echo), not even a volume control for the speaker which is included.  .  The drawbacks, such as requiring a Google account connection at all times, support for only one wired device, lack of web-based management make it an expensive choice until other features are added.  Until then, there are lots of 802.11ac routers on the market for less.

A gateway is used to route data between networks (even different types of networks, including your cable provider); simply, it’s your access out of your internal network.  This is different from a router, which only routes data between clients (computers) on a single network. But many routers are also gateways, such as residential sharing routers which can share between computers on a network, but also are a gateway to the Internet through the router’s WAN port. 

See also, definitions for other hardware like repeaters (which amplify a wireless signal over a long network run), signal amplifiers (which amplify a weak signal at its source) and bridges (which are actually “smart repeaters” because not only do they amplify the signal, they deliver the signals between the computers on either side of the box); see also LAN DIAGRAM.





























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