IP ADDRESSING AND SUBNETING PRINCIPLES.pptx

IP Address and Subnetting
By Abraham Thompson

TCP/IP addressing and subnetting
When you configure the TCP/IP protocol on a Windows computer, the TCP/IP
configuration settings require:
 An IP address
 A subnet mask
 A default gateway
To configure TCP/IP correctly, it's necessary to understand how TCP/IP
networks are addressed and divided into networks and subnetworks.

TCP/IP addressing and subnetting
The success of TCP/IP as the network protocol of the Internet is largely
because of its ability to connect together networks of different sizes and
systems of different types.
These networks are arbitrarily defined into three main classes (along with a
few others) that have predefined sizes. Each of them can be divided into
smaller subnetworks by system administrators.
A subnet mask is used to divide an IP address into two parts. One part
identifies the host (computer), the other part identifies the network to which it
belongs.

IP address
An Internet Protocol (IP) address is the unique identifying number assigned to
every device connected to the internet. An IP address definition is a numeric
label assigned to devices that use the internet to communicate. Computers
that communicate over the internet or via local networks share information to
a specific location using IP addresses.
Every device with an internet connection has an IP address, whether it's a
computer, laptop, IoT device, or even toys. The IP addresses allow for the
efficient transfer of data between two connected devices, allowing machines
on different networks to talk to each other.

Introduction of Classful IP Addressing
An IP address is an address that has information about how to reach a
specific host, especially outside the LAN. An IP address is a 32-bit unique
address having an address space of 232.
Classful IP addressing is a way of organizing and managing IP addresses,
which are used to identify devices on a network. Think of IP addresses like
street addresses for houses; each device on a network needs its unique
address to communicate with other devices.

IP address classification
The IP addresses can be classified into two classes:
Public address:
This address considered as any valid address assigned to any user, and the
organization who is responsible for registering IP ranges called Internet
Service Providers (ISPs), and this address will be unique.
Private Address:
Any number or address assigned to a device on a private TCP/IP Local Area
Network that is accessible only within the Local Area Network.

IP address versions
IP addresses have two distinct versions or standards.
• The Internet Protocol version 4 (IPv4) address is the older of the two,
which has space for up to 4 billion IP addresses and is assigned to all
computers.
• The more recent Internet Protocol version 6 (IPv6) has space for trillions of
IP addresses, which accounts for the new breed of devices in addition to
computers.
There are also several types of IP addresses, including public, private, static,
and dynamic IP addresses.

IPv4 Address
An IPv4 address is a 32-bit address that uniquely and universally defines the
connection of a host or a router to the Internet; an IP address is the address of the
interface.
It is a unique number assigned to every device that connects to the internet or a
computer network. It’s like a home address for your computer, smartphone, or any
other device, allowing it to communicate with other devices.
An IPv4 address has an address space of 232 or 4,294,967,296.

IPv6 Address
IPv6 or Internet Protocol Version 6 is a network layer protocol that allows
communication to take place over the network. IPv6 was designed by the Internet
Engineering Task Force (IETF) in December 1998 with the purpose of superseding
IPv4 due to the global exponentially growing internet of users.
IPv6 protocol is being used and deployed more often, especially in mobile phone
markets. IP address determines who and where you are in the network of billions of
digital devices that are connected to the Internet.
IPv6 has a 128-bit address length and it is meant to work in tandem with IPv4,
which is still in widespread use today, and eventually replace it.

IPv4 Address: Dotted-decimal notation
IPv4 addresses are normally expressed in dotted-decimal format, with four
numbers separated by periods, such as 192.168.123.132.
To understand how subnet masks are used to distinguish between hosts,
networks, and subnetworks, examine an IP address in binary notation.

IPv4 Address:
Binary is the language of digital electronic communication. Binary is another
name for Base2 numbering. Our usual numbering system is Base 10.
Computers use binary because it is easily represented as electrical signals in
memory or digital values on a storage media.
The (8) eight binary values found in a single octet of an IP address are
128 64 32 16 8 4 2 1

IPv4 Address
The IPv4 address is divided into two parts: Network ID and Host ID.
The main purpose of an IPv4 address is to identify devices on a network and
ensure that data sent from one device reaches the correct destination.
Example: When you type a website address into your browser, your device
uses the IPv4 address to find and connect to the server where the website is
hosted.
Think of an IPv4 address as a phone number for your device. Just as you dial
a specific number to reach a particular person, devices use IPv4 addresses to
connect and share information.

IPv4 Address: binary conversion table
IP addresses can be displayed in three typical
formats:
Dotted-decimal notation is the format that is typically
used for displaying the IP address in a human-
readable format. An example of dotted-decimal
notation is 192.168.1.100
Binary notation is the format that systems on the
network use to process the address. An example of
binary notation is
11000000.10101000.00000001.01100100.
Hexadecimal notation is the format typically used
when identifying IPv6 addresses. An example of
hexadecimal notation of an IPv4 address is
C0.A8.01.64

IPv4 Address: binary
For example, the dotted-decimal IP address 192.168.123.132 is (in binary
notation) the 32-bit number 11000000101010000111101110000100. This
number may be hard to make sense of, so divide it into four parts of eight
binary digits.
These 8-bit sections are known as octets. The example IP address, then,
becomes 11000000.10101000.01111011.10000100. This number only makes
a little more sense, so for most uses, convert the binary address into dotted-
decimal format (192.168.123.132). The decimal numbers separated by periods
are the octets converted from binary to decimal notation.

How IPv4 Address works
For a TCP/IP wide area network (WAN) to work efficiently as a collection of
networks, the routers that pass packets of data between networks don't know
the exact location of a host for which a packet of information is destined.
Routers only know what network the host is a member of and use information
stored in their route table to determine how to get the packet to the destination
host's network. After the packet is delivered to the destination's network, the
packet is delivered to the appropriate host.
For this process to work, an IP address has two parts. The first part of an IP
address is used as a network address, the last part as a host address. If you
take the example 192.168.123.132 and divide it into these two parts, you get
192.168.123. Network .132 Host or 192.168.123.0 - network address.
0.0.0.132 - host address.

How IPv4 Address works
One of the benefits of classful addresses is that they provide a hierarchy to
the network through the use of the network ID. This translates into an
efficient routing environment because it is easy for a router to determine
what networks can be grouped together and treated as a single routing entry.

Classes of IP addresses
Different networks have different sizes. Basically, there are many small networks and few
large networks. To provide efficient use of 32-bit address space, IPv4 defined several
address classes and associated address formats:
Class A: allows 128 networks, 16 million hosts each.
The IP address start from 1.0.0.0 to 127.255.255.255, and the mask address is 255.0.0.0
Class B: allows 16,382 networks, 65,534 hosts each.
The IP address start from 128.0.0.0 to 191.255.255.255, and the mask address is
255.255.0.0
Class C: allows 2 million networks, 254 hosts each. The IP address start from 192.0.0.0
to 223.255.255.255, and the mask address is 255.255.255.0
Class D: multicast networks The IP address start from 224.0.0.0 to 239.255.255.255.
Class E: reserved for future use. From 240 to 255 and the 255.255.255.255 used for
broadcast to all the subnet.

IPv4 Address: examples
Change the following IPv4 addresses from binary notation to dotted-decimal notation.
a. 10000001 00001011 00001011 11101111
b. 11000001 10000011 00011011 11111111
c. 11100111 11011011 10001011 01101111
d. 11111001 10011011 11111011 00001111
Solution
We replace each group of 8 bits with its equivalent decimal number (see Appendix B) and
add dots for separation:
a. 129.11.11.239
b. 193.131.27.255
c. 231.219.139.111
d. 249.155.251.15

Change the following IPv4 addresses from dotted-decimal notation to binary notation.
a. 111.56.45.78
b. 221.34.7.82
c. 241.8.56.12
d. 75.45.34.78
Solution
We replace each decimal number with its binary equivalent:
a. 01101111 00111000 00101101 01001110
b. 11011101 00100010 00000111 01010010
c. 11110001 00001000 00111000 00001100
d. 01001011 00101101 00100010 01001110

Find the error, if any, in the following IPv4 addresses:
a. 111.56.045.78
b. 221.34.7.8.20
c. 75.45.301.14
d. 11100010.23.14.67
Solution
a. There should be no leading zeroes (045).
b. We may not have more than 4 bytes in an IPv4 address.
c. Each byte should be less than or equal to 255.
d. A mixture of binary notation and dotted-decimal notation.

Change the following IPv4 addresses from binary notation to hexadecimal notation.
a. 10000001 00001011 00001011 11101111
b. 11000001 10000011 00011011 11111111
Solution
We replace each group of 4 bits with its hexadecimal equivalent. Note that 0X (or 0x) is
added at the beginning or the subscript 16 at the end.
a. 0X810B0BEF or 810B0BEF16
b. 0XC1831BFF or C1831BFF16

Strategies to Conserve Addresses
Several strategies have been developed and implemented to help the
Internet community on how provides a good managing of IP addresses.
These strategies help reduce the load on Internet routers and help
administrators use globally unique IP addresses more efficiently. There are
two common strategies, which are:
Private Addressing
Classless Inter-Domain Routing (CIDR)

Private Address
It means If the internetwork is limited to one organization, the IP addresses
need only be unique within that organization. Only networks that interface with
public networks such as the Internet need public addresses. Using public
addresses on the outside and private addresses for inside networks is very
effective.
Private Addresses:-
RFC1918 designates three ranges of IP addresses as private:
10.0.0.0 through 10.255.255.255
172.16.0.0 through 172.31.255.255
192.168.0.0 through 192.168.255.255

Classful Addressing
The 32-bit IP address is divided into five sub-classes. These are
given below:
•Class A
•Class B
•Class C
•Class D
•Class E
Each of these classes has a valid range of IP addresses. Classes
D and E are reserved for multicast and experimental purposes
respectively. The order of bits in the first octet determines the
classes of the IP address.
The class of IP address is used to determine the bits used for
network ID and host ID and the number of total networks and hosts
possible in that particular class. Each ISP or network administrator
assigns an IP address to each device that is connected to its
network.

Class A
IP addresses belonging to class A are assigned to the networks that contain
a large number of hosts.
•The network ID is 8 bits long.
•The host ID is 24 bits long.
The higher-order bit of the first octet in class A is always set to 0. The
remaining 7 bits in the first octet are used to determine network ID.
The 24 bits of host ID are used to determine the host in any network. The
default subnet mask for Class A is 255.x.x.x. Therefore, class A has a total
of:
2^24 – 2 = 16,777,214 host ID
IP addresses belonging to class A ranges from 0.0.0.0 – 127.255.255.255.

Class B
IP address belonging to class B is assigned to networks that range from
medium-sized to large-sized networks.
The higher-order bits of the first octet of IP addresses of class B are always
set to 10. The remaining 14 bits are used to determine the network ID. The
16 bits of host ID are used to determine the host in any network.
The default subnet mask for class B is 255.255.x.x. Class B has a total of:
•2^14 = 16384 network address
•2^16 – 2 = 65534 host address
IP addresses belonging to class B ranges from 128.0.0.0 – 191.255.255.255.

Class C
IP addresses belonging to class C are assigned to small-sized networks.
The higher-order bits of the first octet of IP addresses of class C is always set to
110. The remaining 21 bits are used to determine the network ID. The 8 bits of
host ID are used to determine the host in any network.
The default subnet mask for class C is 255.255.255.x.
Class C has a total of:
•2^21 = 2097152 network address
•2^8 – 2 = 254 host address
IP addresses belonging to class C range from 192.0.0.0 – 223.255.255.255.

Class D
IP address belonging to class D is reserved for multi-casting. The higher-order
bits of the first octet of IP addresses belonging to class D is always set to 1110.
The remaining bits are for the address that interested hosts recognize.
Class D does not possess any subnet mask. IP addresses belonging to class D
range from 224.0.0.0 – 239.255.255.255.

Class E
IP addresses belonging to class E are reserved for experimental and research
purposes.
IP addresses of class E range from 240.0.0.0 – 255.255.255.255. This class
doesn’t have any subnet mask. The higher-order bits of the first octet of class E
are always set to 1111.
Range of Special IP Addresses
169.254.0.0 – 169.254.0.16 : Link-local addresses
127.0.0.0 – 127.255.255.255 : Loop-back addresses
0.0.0.0 – 0.0.0.8: used to communicate within the current network.

Rules for Assigning Host ID
Host IDs are used to identify a host within a network. The host ID is assigned
based on the following rules:
•Within any network, the host ID must be unique to that network.
•A host ID in which all bits are set to 0 cannot be assigned because this host ID
is used to represent the network ID of the IP address.
•A Host ID in which all bits are set to 1 cannot be assigned because this host ID
is reserved as a broadcast ID or address to send packets to all the hosts
present on that particular network.
The formula for the number of Hosts on any network or subnet is 2^H – 2
Where H is the number of 0s at the end of the mask
The 2 subtracted represent the Network and Broadcast IDs

Rules for Assigning Network ID
Hosts that are located on the same physical network are identified by the
network ID, as all host on the same physical network is assigned the same
network ID.
The network ID is assigned based on the following rules:
•The network ID cannot start with 127 because 127 belongs to the class A
address and is reserved for internal loopback functions.
•All bits of network ID set to 1 are reserved for use as an IP broadcast address
and therefore, cannot be used.
•All bits of network ID set to 0 are used to denote a specific host on the local
network and are not routed and therefore, aren’t used.

Port Address Translation (PAT).
It’s another technique used to convert the private address to public. During PAT,
each computer on LAN is translated to the same IP address (public), but with a
different port number assignment. This way is much better than the NAT because
we can use one public address to translate any private address, therefore we
saved the cost. The table below shows the process of the PAT
The port address will be any random number in the allowed range, that the device
created it when wants to access the internet.
The packet will contain the port number that assign to the device that wants to
access the internet and through this port number, the router when get the response
message will translate it and make map this message to it is private address based
on the port number.

Subnets
As the number of distinct local networks grows, managing them
become a serious headache. Every time a new network is installed
the system administrator must contact NIC to get a new network
number.
The solution to the problem is to allow a network to be split into
several independent parts for internal use but still act like a single
network to the outside world. In the internet literature these parts
are called subnets.
Subnetting means divide or separate the single network into
multiple networks that can reduce the loading from one network.
The advantage of using subnetting is:-
1. Reduce the traffic and the increase the performance.
2. The smaller network can easier to manage.

Subnets
For example,
If we have a class B with a Flat Network, the number of host will be more
than 216=65536 hosts,
So the problem is here, that managing this network with this number of
host is too tricky and the performance of this network will get down
because of the heavy load. In other word, any single broadcast can
slowdown the network.
Therefore, the solution is the subnetting.

Subnet Mask
The second item, which is required for TCP/IP to work, is the Subnet
mask. The subnet mask is used by the TCP/IP protocol to determine
whether a host is on the local subnet or on a remote network.
In TCP/IP, the parts of the IP address that are used as the network and
host addresses aren't fixed. Unless you have more information, the
network and host addresses above can't be determined. This information
is supplied in another 32-bit number called a subnet mask. The subnet
mask is 255.255.255.0 in this example. It isn't obvious what this number
means unless you know 255 in binary notation equals 11111111. So, the
subnet mask is 11111111.11111111.11111111.00000000.

Subnet Mask
A mask is a 32-bit binary number that is expressed in dotted decimal
notation. By default, a mask contains two fields, the network field and the
host field. These correspond to the network number and the locally
administered part of the network address. When an administrator
subnets, they are adjusting the way they view the IP address.
Table 1: Default masks for classful addressing

Cont…
Routers and hosts still assume class subnet masks by default:
Class A /8 255.0.0.0
Class B /16 255.255.0.0
Class C/24 255.255.255.0
The figure below gives an example to class C mask address:
The first three octets represent the network part and the last octet
represent the host part.

Cont…
There three important things that should be taken into our account when
we thinking about subnetting:-
1. Network address – the first one
2. Broadcast address – the last one
3. Host addresses – everything in between
As well as, to find the number of hosts per subnet. We can use formal 2x -
2, where (x) is the number of unmasked bits (0’s) .

Cont…
For example, in 11000000, the number of zeros gives us 26 – 2 =62 hosts.
In this example, there are 62 hosts per subnet and we make subtract
because the first IP address reserve for the network address and the last
one for the network broadcast.
While when we want to find number of networks, we can use this formal 2y
Where Y represent the number of masked bits, (1’s). For example, in
11000000, the number of ones gives us 22 =4

Cont…
In any subnet, there are certain addresses that cannot be assigned
to an individual device because they have a special purpose. The
subnet address is the first address in a range that identifies the
subnet. The broadcast address is the last address in the range, and
all hosts on the subnet receive traffic if anything is sent to it.
Assume that a subnet address is 172.31.9.0 with a mask of
255.255.255.0. The subnet address is 172.31.9.0, and the
broadcast address is 172.31.9.255.

Classless Inter Domain Routing (CIDR) is a method for
assigning IP addresses without using the standard IP address
classes like Class A, Class B or Class C. In CIDR , an IP
address is represented as A.B.C.D /n, where "/n" is called the
IP prefix or network prefix. The IP prefix identifies the number
of significant bits used to identify a network.
Example, 192.9.205.22 /18 means, the first 18 bits are used to
represent the network and the remaining 14 bits are used to
identify hosts.

 It’s basically the method that ISPs (Internet Service
Providers) use to allocate an amount of addresses to a
company, a home—a customer. They provide addresses
in a certain block size
 When you receive a block of addresses from an ISP,
what you get will look something like this:
192.168.10.32/28. This is telling you what your subnet
mask is. The slash notation (/) means how many bits
are turned on (1s).
 The Class A default subnet mask, which is 255.0.0.0.
This means that the first byte of the subnet mask is all
ones (1s), or 11111111. When referring to a slash
notation, you need to count all the 1s bits to figure out
your mask. The 255.0.0.0 is considered a /8 because
it has 8 bits that are 1s—that is, 8 bits that are turned on

Subnetting Class C Addresses
In a Class C address, only 8 bits are available for defining the hosts
 that subnet bits start at the left and go to the right without skipping
bits. This means that the only Class C subnet masks can be the
following:
The Fast Way Method: Subnetting a Class C Address
start by using the second subnet mask available with a Class C address,
which borrows 2 bits for subnetting
The 1s represent the subnet bits, and the 0’s represent the host bits
available in each subnet. 192 provides 2 bits for subnetting and 6 bits for
defining the hosts in each subnet.

IP ADDRESSING AND SUBNETING PRINCIPLES.pptx

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