Transcript IP addressing

IP Addressing
Higher Computing
TCP/IP
► TCP/IP
is the communication protocol for
the internet.
► TCP/IP defines the rules computers must
follow to communicate with each other over
the internet.
TCP/IP
► Allows
computers on
different networks to
communicate with
each other.
► The computers could
be on different LANs in
the same building or
on two LANs in
different countries.
Browsers and Servers
► Browsers
and servers
use TCP/IP to connect
to the Internet.
► A browser uses TCP/IP
to access a server.
► A server uses TCP/IP
to send HTML back to
a browser.
TCP/IP
► TCP/IP
stands for
Transmission Control
Protocol / Internet
Protocol.
► TCP/IP defines how
electronic devices (like
computers) should be
connected to the
Internet, and how data
should be transmitted
between them.
TCP/IP
► TCP
is responsible for breaking data down
into IP packets, giving each packet a
sequence number and for assembling the
packets when they arrive.
► IP is responsible for sending the packets to
the correct destination.
IP Addressing
► Each
computer must have an IP address
before it can connect to the Internet.
► Each IP packet must have an address
before it can be sent to another computer.
Structure of IP addresses
► IP
address is a 32-bit number made up of
four parts called octets
► Usually displayed as four decimal numbers,
e.g.
 172.63.238.106
► Each
►0
octet must be in the range of 0 to 255.
and 255 are set aside for special purposes
Possible number of IP addresses
► An
IP address is 32 bits long.
► This means that there are 232 possible IP
addresses, approx 4.3 billion.
► However…
Public/Private IP addressing
 Computers on private LANs do not need a
public IP addresses, since they do not need to
be accessed by the public.
 Therefore, certain addresses that will never be
registered publicly are reserved. These are
known as private IP addresses, and are found in
the following ranges:
 From 10.0.0.0 to 10.255.255.255
From 172.16.0.0 to 172.31.255.255
From 192.168.0.0 to 192.168.255.255
Public/Private IP addressing
► Devices
with private IP addresses cannot
connect directly to the Internet
► Computers outside the network cannot
access devices with a private IP address.
► Access must be obtained through a router.
Static IP addressing
►A
static IP address is
where the computers
are given a fixed IP
address that never
changes.
► The computer always
keeps the same
address every time it
connects to the
Internet.
Dynamic IP addressing
► There
are only a limited number of IP
addresses. ISPs use dynamic IP addressing
to get around the problem.
► A dynamic IP address is when computers on
a network are given an IP address when
they are connected to the network for that
session. It can change each time they are
connected.
Benefits of Dynamic IP addressing
► Less
security riskcomputer is assigned a
new IP address each
time you connect to a
network.
Classes of IP addresses
► There
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are 4 classes of IP addresses:
Class
Class
Class
Class
A
B
C
D
Classes of IP addresses
► Different
classes of IP addresses are
achieved by splitting the octets into two
parts called the network identifier and
the node identifier.
► Network
identifier = n
► Node identifier = h
Classes of IP addresses
► The
network identifier is used to route
packets to the destination network.
► On arrival at the network, the host identifier
is used to route packets to the individual
computer.
nnn.nnn.hhh.hhh
Network Node
Class A
► Class
A addresses are structured as
follows:
 nnn.hhh.hhh.hhh
 The first octet will be in the range of 1 to 126
and identifies the network
 The remaining three octets will identify the
nodes on that network.
 This allows for 16, 277, 214 addresses. (224 -2)
Class B
► Class




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B addresses are structured as follows:
nnn.nnn.hhh.hhh
The first octet will be in the range of 128 to
191.
The first two octets identify the network.
The remaining octets identify the nodes on that
network
This allows for 65,534 addresses. (216 – 2)
Class C
► Class
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C addresses:
nnn.nnn.nnn.hhh
The first octet is in the range of 192 to 223 .
The first three octets identify the network.
The last octet identifies the nodes on that
network.
This allows for 254 different addresses (28 – 2)
Class D
► These
are not used for networks, but for
multicast messaging.
► The first octet will be in the range of 224 to
255.