Home networking explained: Here's the URL for you

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26 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

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Home networking explained: Here's the URL
for you

CNET editor Dong Ngo gives all his answers to questions about the basics
of home networking.




I'll talk all about home networking basics, in layman's terms, in this post.

Advanced and experienced users won't need this, but for the rest, I'd recommend reading the
whole thing, and if you want to quickly find out what a net
working term means, you can search
for it here.

1. Wired networking

A wired local network is basically a group of devices connected to one another using network
cables, more often than not, with the help of a
router
, which brings us to the very first
networking term.

Router:

This is the central device of a home network that you can plug one end of a
network
cable

into. The other end of the cable goes into a networking device that has a
network port
. If
you want to add more
network devices

to a router, you'll need more cables and more ports on the
router. These ports, both on the router and on the end devices, are called
Local Area Network

(LAN
) ports. They are also known as
RJ45

ports. The moment you plug a device into a router,
you have yourself a wired network. Networking devices that come with an RJ45 network port are
called
Ethernet
-
ready

devices. More on this below.

Note
: Technically, you
can skip a router and connect two computers together using one network
cable to form a network of two. However, this requires manually configuring the IP addresses, or
using a special
crossover cable
, for the connection to work. You don't really want to do

that.

A typical wireless router with LAN ports for
Ethernet
-
ready devices and antennas for Wi
-
Fi
clients.

(Credit: Dong Ngo/CNET)



LAN ports:
A home router usually has four LAN ports, meaning out of the box it can host a
network of up to four wired networking devices. If you want to have a larger network, you will
need to resort to a
switch

(or a
hub
), which adds more LAN ports to the router. Ge
nerally a home
router can handle up to about 250 networking devices, and the majority of homes and even small
businesses don't need more than that. There are currently two main speed standards for LAN
ports: Ethernet, which caps at 100Mbps (or about 13MBps
), and Gigabit Ethernet, which caps at
1Gbps (or about 125MBps). In other words, it takes about a minute to transfer a CD's worth of
data (around 700MB or about 250 digital songs) over an
Ethernet connection
. With Gigabit
Ethernet, the same job takes just about 5 seconds. In real life, the average speed of an Ethernet
connection is about 8MBps, and of a Gigabit Ethernet connection is somewhere bet
ween 45 and
80MBps. The actual speed of a network connection depends on many factors, such as the end
devices, the quality of the cable, the amount of traffic, and so on.

Rule of thumb
:
The speed of a network connection is determined by the slowest speed o
f any
party involved
. For example, in order to have a wired Gigabit Ethernet connection between two
computers, both computers, the router they are connected to, and the cables used to link them
together all need to support Gigabit Ethernet. If you plug a
Gigabit Ethernet device and an
Ethernet device to a router, the connection between the two will cap at the speed of Ethernet,
which is 100Mbps.

In short, LAN ports on a router allow Ethernet
-
ready devices to connect to one another and share
data. In order
for them to also access the Internet, the router needs to also have a
Wide Area
Network

(WAN) port.


WAN port:

Generally, a router has just one WAN port. (Some business routers come with dual
WAN

ports, so that one could use two separate Internet services at a time.) On any router, the
WAN port is always separate from the LAN ports, and often comes in a different color to
distinguish itself. A WAN port is exactly the same as a LAN port, just with
a different usage: to
connect to an Internet source, such as a
broadband modem
. The WAN allows the router to
connect to the Internet and share that connection with all the Ethernet
-
ready devices connected to
it.

The back of a typical router; the WAN port is
clearly distinguished from the LANs.

(
Credit
: Dong Ngo/CNET)


A typical CAT5e network cable.

(Credit: Dong Ngo/CNET)


Note:

Since most Internet connections are sl
ower than 100Mbps (a fast cable connection, for
example, is about 50Mbps down and about 6Mbps up), an Ethernet
-
rated WAN port is sufficient
in most cases. However, Gigabit Ethernet routers tend to also come with a Gigabit WAN port.
That said, switching fro
m an Ethernet router to a Gigabit Ethernet router generally doesn't
translate into faster Internet speeds, but only helps devices within your local network (LAN) to
connect to one another faster.

Broadband modem:

Often called a
DSL modem

or
cable modem
, a
broadband modem is a
device that bridges the Internet connection from a service provider to a computer or to a router,
making the Internet available to consumers. Some providers offer a combo device that's a
combination of a modem and a router, or wireless

router, all in one.

Network cables:

These are the cables used to connect network devices to a router or a switch.
They are also known as
Category 5

cables, or
CAT5

cables. Currently, most, if not all, CAT5
cables on the market are actually
CAT5e
, which is

capable of delivering Gigabit Ethernet data
speeds. The latest network cabling standard currently in use is CAT6, which is designed to be
faster and more reliable than CAT5e. The difference between the two is the wiring inside the
cable and at both ends o
f it. CAT5e and CAT6 cables can be used interchangeably and in my
personal experience are basically the same, except CAT6 is more expensive. For most home
usage, what CAT5e has to offer is more than enough. In fact, you probably won't notice any
difference

if you switch to CAT6, but it doesn't hurt to use CAT6, either, if you can afford it.

Now that we're clear on a wired network, let's move on to a wireless network.

2. Wireless networking: Standards and devices

A wireless network is very similar to a wired

network with one big difference: devices don't use
cables to connect to the router and one another. Instead, they use wireless connections, known as
Wireless Fidelity, or Wi
-
Fi, which is a friendly name for the 802.11 networking standard
supported by the
Institute of Electrical and Electronics Engineers

(IEEE). This means wireless
networking devices don't need to have ports, but just antennas, which sometimes are

hidden
inside the device itself. In a typical home network, there are generally both wired and wireless
devices, and they can all talk to one another. In order to have a Wi
-
Fi connection, there needs to
be an
access point

and a
Wi
-
Fi client
.


Each of th
e Wi
-
Fi networks that a client, such as an
iPhone, detects generally belongs to one access point.

(Credit: Dong Ngo/CNET)


Access point:

An Access point (AP) is a central device that broadcasts the Wi
-
Fi signal for Wi
-
Fi clients to connect to. Generally,

each wireless network, like those you see popping up on your
smartphone's screen as you walk around a big city, belongs to one access point. You can buy an
AP separately and connect it to a router or a switch to add Wi
-
Fi support to a wired network, but
g
enerally, you want to buy a
wireless router
, which is a regular router (one WAN port, four LAN
ports, and so on) with a built
-
in access point. Some routers even come with more than one access
point (see dual
-
band router below).

Wi
-
Fi client:

A Wi
-
Fi client or
WLAN client

is a device that can detect the signal broadcast by
an access point, connect to it, and maintain the connection. (This type of Wi
-
Fi connection is
established in the
Infrastructure mode
, but you don't have to remember this.)
Most, if not all,
laptops, smartphones, and
tablets

on the market come with built
-
in Wi
-
Fi capability. Those that
don't can be upgraded to that via a USB or PCIe Wi
-
Fi adapter. Think of a Wi
-
Fi client as a
de
vice that has an invisible network port and an invisible network cable. This metaphorical cable
is as long as the
range

of a Wi
-
Fi signal.

Note:

Technically, you can skip an access point and make two Wi
-
Fi clients connect directly to
each other, in the
Ad
hoc mode
. However, similar to the case of the crossover network cable, this
is rather complicated and inefficient, and is far less used than the Infrastructure mode.

Wi
-
Fi range:

This is the radius distance an access point's Wi
-
Fi signal can reach. Typically, a
Wi
-
Fi network is most viable within about 150 feet from the access point. This distance,
however, changes based on the power of the devices involved, the environment, and,
most
importantly, the Wi
-
Fi standard. A good Wireless
-
N access point can offer a range of up to 300
feet or even farther. The Wi
-
Fi standard also determines how fast a wireless connection can be
and is the reason Wi
-
Fi gets complicated and confusing, espec
ially when the Wi
-
Fi frequency
bands are mentioned, which I just did.

Frequency bands:

These bands are the radio frequencies used by the Wi
-
Fi standards:
2.4GHz

and
5GHz
. The 2.4GHz band is currently the most popular, meaning, it's used by most existing
ne
twork devices. That plus the fact that home appliances, such as cordless phones, also use this
band, makes its signal quality generally worse than that of the 5GHz band due to oversaturation
and interference.


A typical Web interface of a D
-
Link wireless

router that allows users to customize their Wi
-
Fi
network.

(Credit: Dong Ngo/CNET)


Depending on the standard, some Wi
-
Fi devices use one of the two bands, while others use both.
Following are the existing Wi
-
Fi standards, starting with the oldest:

802.
11b:

This was the first commercialized wireless standard. It offers a top speed of 11Mbps
and operates only on the 2.4GHz frequency band. The standard was first available in 1999 and is
now totally obsolete; 802.11b clients, however, are still supported by

access points of later Wi
-
Fi
standards.

802.11a:

Similar to 802.11b in terms of age, 802.11a offers a cap speed of 54Mbps at the
expense of much shorter range, and uses the 5GHz band. It's also now obsolete, though still
supported by access points of late
r standards.

802.11g:

Introduced in 2003, the 802.11g standard marked the first time wireless networking
was called Wi
-
Fi. The standard offers the top speed of 54Mbps but operates on the 2.4GHz band,
hence offering better range than the 802.11a standard. I
t's still used in many mobile devices, such
as the
iPhone

3G and the
iPhone 3Gs
. This standard is supported by access points of later
standards.

802.11
n or Wireless
-
N:

Available starting in 2009, 802.11n has been the most popular Wi
-
Fi
standard, with lots of improvements over the previous ones, such as making range of the 5GHz
band comparable to that of the 2.4GHz band. The standard operates on both 2.4G
Hz and 5GHz
bands and started a new era of dual
-
band routers, those that come with two access points, one for
each band. There are two types of dual
-
band routers:
selectable dual
-
band

routers that can
operate in one band at a time, and
true dual
-
band

routers that simultaneously offer Wi
-
Fi signals
on both bands.

On each band, the Wireless
-
N standard is available in three setups:
single
-
stream
,
dual
-
stream
,
and
three
-
stream
, offering cap speeds of 150Mbps, 300Mbps, and 450Mbps, respectively. This
in tu
rns creates three types of true dual
-
band routers:
N600

(each of the two bands offers a
300Mbps speed cap), N750 (one band has a 300Mbps speed cap while the other caps at
450Mbps), and N900 (each of the two bands offers up to 450Mbps cap speed).

Note:

In o
rder to have a Wi
-
Fi connection, both the access point (router) and the client need to
operate on the same band, either 2.4GHz or 5GHz. For example, a 2.4GHz client, such as an
iPhone 4, won't be able to connect to a 5GHz access point. In case a client sup
ports both bands, it
will only use one of the bands to connect to an access point, and when applicable it tends to
"prefer" the 5GHz band to the 2.4GHz band, for better performance.

802.11ac or 5G Wi
-
Fi:

This latest Wi
-
Fi standard operates only on the 5GHz

frequency band
and offers Wi
-
Fi speeds of up to 1.3Gbps (or 1,300Mbps) when used in the three
-
stream setup.
The standard also comes with dual
-
stream and single
-
stream setups that cap at 900Mbps and
450Mbps, respectively. (Note that the single
-
stream setup

of 802.11ac is as fast as the top three
-
stream setup of 802.11n.)

Currently, there are just a few 802.11ac routers on the market, such as the
Netgear R6300
, the
Asus RT
-
AC66U
, and the
Buffalo WZR
-
D1800H
, but it's p
redicted that the standard will be
more popular by the end of 2012, when hardware devices such as laptops, tablets, and
smartphones with built
-
in 802.11ac become available.

Technically, the 802.11ac standard is about three times faster than then 802.11n (o
r Wireless
-
N)
standard and therefore is much better for battery life (since it has to work less to deliver the same
amount of data). In real
-
world testing so far, I've found that 802.11ac is about twice the speed of
Wireless
-
N, which is very good. (Note th
at the real
-
world sustained speeds of wireless standards
are always much lower than the theoretical speed cap. This is partly because the cap speed is
determined in controlled, interference
-
free environments.) The fastest real
-
world speed of an
802.11ac co
nnection I've seen so far is 42MBps, provided by the Asus RT
-
AC66U, which is
close to that of a Gigabit Ethernet wired connection.

On the same 5GHz band, 802.11ac devices are backward
-
compatible with Wireless
-
N and
802.11a devices. While 802.11ac is not av
ailable on the 2.4GHz band, for compatibility
purposes, an 802.11ac router will also come with a three
-
stream (450Mbps) Wireless
-
N access
point. In short, an 802.11ac router is basically an N900 router plus support for 802.11ac on the
5GHz band.

That said, let me restate the rule of thumb one more time:
The speed of a network connection is
determined by the slowest speed of any of the parties involve
d.

That means if you use an
802.11ac router with an 802.11a client, the connection will cap at 54Mbps. In order to get the top
802.11ac speed, you will need to use a device that's also 802.11ac
-
capable.


3. More on wireless networking

In wired networking,

a connection is established the moment you plug the ends of a network
cable into the two respective devices. In wireless networking it's more complicated than that.

Since the Wi
-
Fi signal, broadcast by the access point, is literally in the air, anybody wi
th a Wi
-
Fi
client can connect to it, and that might pose a serious security risk. To prevent this from
happening, and only let approved clients connect, the Wi
-
Fi network needs to be password
-
protected (or in more serious terms:

encrypted
). Currently, ther
e are a few methods used to
protect a Wi
-
Fi network (called "authentication methods"): WEP, WPA, and WPA 2, with the
WPA 2 being the most secure, while WEP is getting obsolete. WPA 2 (as well as WPA) offers
two ways to encrypt the signal, which are Tempora
l Key Integrity Protocol (TKIP) and
Advanced Encryption Standard (AES). The former is for compatibility (allowing legacy clients
to connect); the latter allows for faster connection speeds and is more secure but only works with
newer clients. From the side

of the access point or router, the owner can set the password (or
encryption key) that clients can use to connect to the Wi
-
Fi network.

A wirel
ess router and USB client, both with
their Wi
-
Fi Protected Setup (WPS) button.

(Credit: Dong Ngo)


If the above paragraph seems complicated, that's because Wi
-
Fi encryption is very complicated.
To help make life easier
, the Wi
-
Fi Alliance offers an easier method called Wi
-
Fi Protected
Setup.


Wi
-
Fi Protected Setup or WPS:

Introduced in 2007, Wi
-
Fi Protected Setup is a standard that
makes it easy to establish a secure Wi
-
Fi network. The most popular implementation of WPS is
the push button. Here's how it works: On the router (ac
cess point) side, you press the WPS
button. Now, within 2 minutes, you press the WPS button on the Wi
-
Fi clients, and that's all you
need for them to connect to the access point. This way you don't have to remember the password
(encryption key) or type it
in. Note that this method only works with devices that support WPS.
Most networking devices released in the last few years do, however.

Wi
-
Fi Direct:

This is a standard that enables Wi
-
Fi clients to connect to one another without a
physical access point. B
asically, this allows one Wi
-
Fi client, such as a smartphone, to turn itself
into a "soft" access point and broadcast Wi
-
Fi signals that other Wi
-
Fi clients can connect to.
This standard is very useful when you want to share an Internet connection. For exa
mple, you
can connect your laptop's LAN port to an Internet source, such as in a hotel, and turn its Wi
-
Fi
client into a soft AP. Now other Wi
-
Fi clients can also access that Internet connection. Wi
-
Fi
Direct is actually most popularly used in smartphones
and tablets, where the mobile device
shares its cellular Internet connection with other Wi
-
Fi devices, in a feature called personal hot
spot.

Personal hot spot is a feature made
available by the Wi
-
Fi Direct
standard. It temporarily turns the
Wi
-
Fi client, an iPhone in this
case, into a "soft" access point.

(Credit: D
ong Ngo/CNET)


4. Power line networking:

When it comes to networking, you probably don't want to run network cables all over the
place,
making Wi
-
Fi a great alternative. Unfortunately, in some places, such as that corner in the
basement, a Wi
-
Fi signal can't reach, either because it's too far away or because there are thick
concrete walls in between. In this case, the best solution
is a pair of power line adapters.

Power line adapters basically turn the electrical wiring of a home into network cables for a
computer network. You need at least two power line adapters to form the first power line
connection. The first adapter is connect
ed to the router and the second to the Ethernet
-
ready
device at the far end. There are some routers on the market, such as the
D
-
Link DHP
-
1320
, that
have built
-
in sup
port for power line, meaning you can skip the first adapter. More on
power line
devices can be found here
.

Currently there are two main standards for power line networking,
HomePlug AV

and
Powe
rline
AV+ 500
. They offer cap speeds of 200Mbps and 500Mbps, respectively.

That's it. Now if you haven't found your questions answered, it's probably time to
send them to
me
, or just post them in th
e comments section below. Want to learn more about how to best
optimize your Wi
-
Fi network?

Check out part 2
.

http://news.cnet.com/8301
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17938_105
-
57485724
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1/home
-
networking
-
explained
-
heres
-
the
-
url
-
for
-
you/