Networking: What’s a Router, a Switch, a Hub
Lets assume that you have High speed internet. But the Modem that
you got only has one wire coming out. You know that you can share a
high speed connection, but there is a lot of networking hardware that
all looks pretty much the same on the outside . How do you know what to
First off, virtually all of the communication over the internet is
done by Internet Protocol (IP) addresses. IP addresses are kind of like
a phone number for each computer. Your Internet Service Provider (ISP)
will assign you an IP address.
Routers sit on the border of the internet and a
network. In fact they create the border. If a business wants each of
their employees to have a phone. Rather than getting a phone line for
each employee, They just need one phone number, and a phone system that
can assign extensions for each employee. You make a call to
1-800-555-1234, then the extension 111 of the person you want to talk
to. When a new employee is hired, they get another extension, and when
someone leaves… their extension isn’t used any more. Routers keep track
of all of the IP addresses of all of the devices or computers connected
to it, and so when you make a request for an internet site, or when
someone tries to start an instant message session with you, the router
will make sure that it all gets sent to the right places. Most Routers
now use DHCP routing (Dynamic Host Configuration Protocol) every time a
new computer or device is connected to the network, the router will
automatically assign it an IP address. So you don’t have to worry about
any of the addressing. Most of the DSL or Cable modems provided with a
broadband connection are Routers but often only have one port coming
out. Specific Ethernet or LAN routers generally include a switch that
will give you a few ports. (just a note, there is no problem connecting
a router to a router–if you plug a ethernet router into your cable
modem the ethernet router will do all the work.. and the cable modem
A switch kind of acts like a Receptionist. Say I
want to talk to the production manager of a…golf ball factory. I call
their 1-800 number, and talk to the receptionist. She has a list of all
of the extensions for the different employees, and she can connect me
to the production manager’s extension. She doesn’t necessarily have any
control over what extension anyone has, or what to do when they move or
a new office is setup, she just uses her list and puts you through.
Switches need a router to tell them what to do.
A hub is kind of like a loudspeaker page.
â€œThere’s a phone call for Bob on line 1â€? Everyone hears
the page, it even though it’s only for Bob. That’s kind of what a Hub
does. It sends all of the information to each of the computers
Computers are smart enough to only respond to the messages that are for
them, (just like you wouldn’t answer every page on a loudspeaker) but
it means all of the internet traffic is sent to everyone, which can be
a lot if you have a big network.
It also can be a security risk, anyone on the network can set their
computer to listen to everything. Kind of like someone else picking up
another phone reciever and listening to Bob’s conversation. It isn’t
that difficult, and they can see all of the web pages you visit, read
all of your email and see into certain chat programs, without ever
needing to â€œhackâ€? into your computer. Not really a big
deal if you are just hooking your home desktop and laptop, or the kid’s
computer to a home office computer, but in bigger settings it can
become an issue. Hubs, like switches need to be connected to a Router
to work properly.
That’s the common networking devices in a nutshell… at least the
wired ones… but we will save wireless for another day.