Internet Connection Types – CompTIA A+ 220-1001 – 2.7


There are many different
ways to connect your home and your
business to the internet and in this video
we’ll look at a number of these internet
connection types. A very common internet
connection type in the home is a cable modem. We sometimes refer to this
as broadband communication because we are
sending information over many different
frequencies on the same wire. This also can be
different traffic types on these different
frequencies, so it’s not uncommon to have video,
voice, and your data coming across this single
cable modem connection. You may sometimes hear this
cable modem connection referred to as DOCSIS, which is data
over cable service interface specification. This is the standard that
is used on cable networks to send data across
to these cable modems. This is what we consider
high-speed networking. These cable networks
can go very high speeds. Very commonly you’ll find four
to 250 megabits per second, but you can get up to gigabit
speeds running on these cable modem connections. The cable company isn’t
the only one providing internet connectivity. Very commonly your
local telephone company is providing connectivity
through DSL connections. This is technically ADSL, for
asymmetric digital subscriber line. This uses your existing
telephone lines, which makes it very
easy to simply add a modem into your
home and you’re connected to the internet. One of the challenges
you have with DSL is that you have to be somewhat
close to a central office or a CO. The download speed
that you’re going to have will be directly
proportional to how far away you are from that central
office and the limitation is somewhere around
10,000 feet, which is not an incredibly long
distance when you consider how dispersed are
different homes are away from these central offices. You’ll generally get 52
megabits per second down and 16 megabits per
second upstream, but these numbers
can vary widely depending on how far
away you are from the CO. As you begin to move
farther away from the CO, you’ll start to see these
speeds get slower and slower. Another type of
internet connectivity we don’t see much any longer
are dial-up connections. These are using our existing
analog voice telephone lines and sending data communication
over that connection. You’ll commonly see 56
kilobits per second modems. This is significantly
slower than a DSL connection or a cable modem
connection, although you can’t compress the data
bit to get speeds up to 320 kilobits per second. Obviously, when you compare this
relative to cable modem or DSL, these speeds are
relatively slow, which makes using a dial-up
connection difficult to scale, especially if you need to
connect many different people to the internet. Although you no longer tend
to find a dial-up connection at home, it’s very common to
use them in large enterprise environments. If you lose the connection
to a remote site over a cable connection or a
DSL, you might be using these traditional
analog dial up modems to provide some connectivity
back to those sites. We’ve been using fiber in
the enterprise for many years to provide internet
connectivity, and we’re starting to see more
fiber rolled out to the home. This provides very
high-speed networking and allows us to send
many different services over that single fiber. So voice connectivity, our
video connections, and our data can all be running over a
single fiber to our house. This increase in
available bandwidth also brings a number
of new services. You have a lot more HD
channel connectivity than you might have with a
copper-connected service. And this also allows
you to send and transfer a lot of different types
of data out to the cloud. You might also see
enhanced capabilities with DVR and video
capabilities using this additional bandwidth. Our internet
connectivity doesn’t have to be limited to
connectivity on earth. We can sometimes connect
to the internet using satellites that are in space. This satellite networking allows
us to communicate directly to a satellite, which then sends
that data to a station down on earth and then reverses that
to get the data back to us. This has, as you might expect,
a relatively high cost compared to traditional terrestrial
networking such as cable modem or DSL connectivity, but
your speeds are pretty good. You get around 50
megabits per second down, three megabits per
second upstream are common to find with
satellite networking, but this does allow you to
connect to sites that may not have the ability to connect to
a cable modem or DSL connection and you’re able to
be in a remote site or somewhere far away
from the central office and still have relatively
high-speed internet connectivity. There are a number of challenges
with satellite networking. One of these is that you have
a relatively high latency. It does take time to get
that data up to a satellite and then back down to earth. So if you have an
application that requires a very low
amount of latency, this may not be the type
of connectivity you’d like. Those of you that have
satellite connections for your television at home
know that the other problem with this type of
connectivity is when it rains. If you have a very
heavy thunderstorm, that rain coming down can
block this two gigahertz signal from going from your dish out
to that satellite connection. So while this storm
is going on outside, you won’t have any type
of Internet connectivity. An older style of
internet connectivity, which still has some
limited functionality in today’s markets, is ISDN. It stands for integrated
services digital network. There are two different
types of ISDN you might find. One is what we call an ISDN
basic rate interface, or BRI. You’ll sometimes hear this
referred to as a 2B+D. This was referring to
the two bearer channels, which are actually sending data
over these ISDN connections, and the single signaling
channel, or D, channel. These two bearer
channels are 64 kilobits. So we’re not talking about
high-speed connectivity that you might have
with cable modem or DSL, but this is certainly
better than using a dial-up connection. The signaling
channel, or D channel, which is a 16 kilobit
per second channel when you’re working
with BRI is managing all of the communication
over this connection. So it sets up the connection,
it tears down the connection, and sends any
management information while the call is going on. A larger scale ISDN is the
primary rate interface ISDN, or a PRI. This is usually delivered
over a T1 or E1 connection depending on what
country you’re in. And a T1 connection
supports 23 bearer channels and a signaling channel. And E1 supports 30 bear
channels, a signaling channel, and a separate alarm channel. Although you could certainly
use these very large bearer channels to send internet
connectivity over a PRI, it’s also common to see PRI
used as voice channels that are coming from your
public switched telephone network, that’s your
local telephone company, and connecting to
a private branch exchange or a local phone
system inside of your company. If you’re not converting
over to voice over IP, you may be using some of
these legacy ISDN connections to provide all of your
voice communication. Modern cellular
networks allow us to have internet connectivity
from practically anywhere. We now have a mobile phone that
allows us to have both voice and data access simultaneously. These cellular networks have
many different antennas set up in a geographical area where the
land is separated into cells. That’s where the idea of a
cellular network comes from. And our mobile devices
use these antennas to be able to communicate back
and forth to the internet. Not only do our mobile phones
have internet connectivity, but we can connect a wire from
a laptop to our mobile phone and provide the laptop with the
internet connectivity as well. That’s called tethering. And if you’re
connecting many devices to your mobile phone over
802.11 wireless connectivity, you’re effectively turning your
phone into a mobile hotspot. This way anyone
in your local area is able to use your internet
connectivity on your phone to provide internet access
for all of your devices. In your metropolitan
area, you may have the option of a
line-of-sight internet service. This is a wireless
internet service that’s able to provide
access over a very wide geographical area. This is a line-of-sight
communication, so there’s usually
antennas placed very high that are able to communicate
to many different homes simultaneously in one
geographical area. There are also options
for non-line-of-sight, this would usually be slower
speeds using lower frequencies. And a very common type of
line-of-sight service is WiMAX. This is the worldwide
interoperability for microwave access. This provides wireless
high-speed internet connectivity by simply
putting an antenna outside of your house and
accessing those WiMAX antennas in your area.

Danny Hutson

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