Transcript Introduction to Computer Networks

Introduction to
Computer Networks
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What is a Computer Network?
Computers that are connected together to share information and
resources make up a network
What is a LAN (Local Area Network)?
Computers that are connected to other computers near each other
make up a network called a LAN
What is a WAN (Wide Area Network)?
A WAN spans a large geographic area, such as a state, province or
country. WANs often connect multiple smaller networks, such as local
area networks (LANs). The most common WAN is the Internet.
What is an IP (Internet Protocol) Address?
An IP address is a series of numbers that allows
one computer to talk with another over a network.
IP addresses allow the location of literally billions
of computers that are connected to the Internet to
be pinpointed.
In the same way that someone needs your
mailing address to send you a letter, a remote
computer needs your IP address to communicate
with your computer. An IP address gives your
computer an identity.
What is an IP (Internet Protocol) Address?
IP addresses are made up of four numbers, each of which contains
one to three digits, with a single dot (.) separating each number.
This is called IPv4 (Internet Protocol version 4).
Here is an example of an IP address:
1 9 2 .1 68 .1 .2 00
Each of the four numbers can range from 0 to 255. Considering all
the number combinations, with IPv4 there are about 4.3 billion IP
addresses to choose from.
What is an IP (Internet Protocol) Address?
Each computer in a network has a
unique IP address that no other
computer in that network has.
What is an IP (Internet Protocol) Address?
Computers in different networks can use the same IP address as
long as those networks are separated from each other by routers.
Any computer or device connected directly to the Internet must
have a unique IP address that no other device in the world has.
What is a Router?
A router is a specialized computer that separates two networks
and transmits information between the two, such as a LAN and the
Internet.
A router has two IP addresses, one on the LAN side and one on
the WAN side. The one on the WAN side is unique because no
other device in the world has it, whereas the one on the LAN side
might be also used by other computers in another LAN.
Who Picks The IP Address?
IP address are determined in one of two ways:
Static – You manually select an IP address and enter it into the
computer. It does not change unless you change it.
Dynamic – A router automatically selects an available IP address
and sends it to the computer. When a router is configured to do
this it is also referred to as a DHCP (Dynamic Host Configuration
Protocol) server. It may “lease” this address for a period of time
and then assign the same number or another number when the
time is up. Computers that get an IP address automatically from a
DCHP server are “clients” whereas the server is the “host”.
What is a Subnet Mask?
In simple terms, a subnet mask allows computers to know what
“neighborhood” it is in and where in that neighborhood it is. It is
similar to a person who lives in an apartment complex. Imagine
the complex is located at 123 Main Street and that there are 100
apartments there. Your apartment might be Apt 25 and a friend of
yours may live in Apt 72. Both of you live at 123 Main Street, but
in different apartments.
An IP address has two components, the network address (the
address of the apartment complex) and the host address (the
apartment number). A subnet mask separates the IP address into
the network and host addresses (<network><host>).
What is a Subnet Mask?
Similar to IP addresses, a subnet mask is made up of four
numbers, each of which contains one to three digits, with a single
dot (.) separating each number.
Here is an example of a subnet mask:
2 5 5 .2 55 .2 55.0
What is a Subnet Mask?
In a simple subnet mask the numbers “mask” the corresponding
positions in an IP address if it’s anything but a zero (0).
Consider this example:
IP Address:
Subnet Mask:
1 9 2 .1 68 .1 .7 5
2 5 5 .2 55 .2 55.0
In the example above, the 1 9 2 .1 6 8.1 is the network address and
the 75 is the host address. The host address tells us that it is
“apartment” 75 and that there are 256 apartments because with
only one number unmasked there are 256 possibilities (0-256).
What is a Default Gateway?
A default gateway is the IP address of the computer or device that
lets you get out of your “neighborhood”. It is just like a guardhouse
in a gated community. In order to leave your neighborhood you
need to drive by the guardhouse to get to the outside world. In a
similar way a default gateway is the exit path a computer takes to
get out of its LAN and out to another network, such as the Internet.
In most cases the job of guardhouse in a network falls to routers
that monitor all traffic coming in and out of the neighborhood,
effectively isolating one network from another.
What is a Port?
As we discussed, IP addresses allow individual
computers to be pinpointed, like a house address.
Ports, on the other hand, refer to ways to get into
that computer.
Just like a house can have many ways to get in
and out, IP addresses allow for 65,535 different
openings (ports) to get in and out of a computer.
This means that many, many devices can be
communicating with a computer at the same time.
What is Port Forwarding?
Port Forwarding allow us to communicate with a Magnum at a remote
location based on the port number of the Magnum.
In the example above a PC running MCS-Connect wants to talk with a
Magnum at 67.93.125.212 on port 5001. The router on the Magnum
side sees this request and forwards all communication on that port to
the Magnum at 192.168.1.75 Routers can be programmed with these
instructions, or rules.
Magnum Ethernet Setup Screens
Magnum Ethernet Setup Screens
Magnum Ethernet Setup Screens