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Chapter 6 The Cloud
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devices like smartwatches and fitness trackers can use Bluetooth to connect to smartphones and
send data over the Internet. More and more devices like clothing, automobiles, and sports equip-
ment are becoming Bluetooth enabled.

Connecting Your LAN to the Internet

Although you may not have realized it, when you connect your SOHO LAN, phone, iPad, or Kindle
to the Internet, you are connecting to a WAN. You must do so because you are connecting to com-
puters that are not physically located on your premises. You cannot start running wires down the
street to plug in somewhere.
When you connect to the Internet, you are actually connecting to an Internet service
provider (ISP). An ISP has three important functions. First, it provides you with a legitimate
Internet address. Second, it serves as your gateway to the Internet. The ISP receives the communi-
cations from your computer and passes them on to the Internet, and it receives communications
from the Internet and passes them on to you. Finally, ISPs pay for the Internet. They collect money
from their customers and pay access fees and other charges on your behalf.
Figure 6-6 shows the three common alternatives for connecting to the Internet. Notice that
we are discussing how your computer connects to the Internet via a WAN; we are not discussing
the structure of the WAN itself. WAN architectures and their protocols are beyond the scope
of this text. Search the Web for “leased lines” or “PSDN” if you want to learn more about WAN
architectures.
SOHO LANs (such as that in Figure 6-5) and individual home and office computers are
commonly connected to an ISP in one of three ways: a special telephone line called a DSL line, a
cable TV line, or a wireless-phone-like connection.

Digital Subscriber Line (DSL)

A digital subscriber line (DSL) operates on the same lines as voice telephones, but it operates
so it does not interfere with voice telephone service. Because DSL signals do not interfere with
telephone signals, DSL data transmission and telephone conversations can occur simultaneously.
Figure 6-6
Summary of LAN Networks

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Local area UTP or optical Common: Switch IEEE 802.3 Switches connect devices,
network fiber 10/100/1000 Mbps NIC (Ethernet) multiple switches on all but
Local area Possible: 1 Gbps UTP or optical small LANs.
network Local area UTP or optical for Up to 600 Mbps Wireless IEEE 802.11n, Access point transforms
network with nonwireless access point (802.11ac not yet wired LAN (802.3) to wireless
wireless connections Wireless NIC common) LAN (802.11).
DSL modem to DSL telephone Personal: DSL modem DSL Can have computer and
ISP Upstream to 1 Mbps, DSL-capable phone use simultaneously.
downstream to telephone line Always connected.
40 Mbps (max 10
likely in most areas)

Cable modem Cable TV lines to Upstream to Cable modem Cable Capacity is shared with other
Connections to ISP optical cable 1 Mbps Cable TV cable sites; performance varies
to the Downstream depending on others’ use.
Internet 300 Kbps to 10 Mbps
WAN wireless Wireless 500 Kbps Wireless One of several Sophisticated protocols
connection to to 1.7 Mbps WAN modem wireless enables several devices to
WAN standards use the same wireless
frequency.