NAT and Subnetting
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Transcript of NAT and Subnetting
Subnetting & NAT
Names ID’s
Maria Ahmed 14005065-083
Saad Tanvir 14005065-045
Talha Imdad 14005065-084
Hina Ilyas 14005065-068
Group Members
SE332 – Computer Networking
Presentation no. 1
Presented to: Sir Mustahsan Hammad Naqvi
Subnetting is a process of dividing large network into the smaller
networks .
OR
Subnetting means we borrow some bits from the Host part to add to
the Network part.
Every computer on network has an IP address that represent its
location on network.
Subnetting
• The version of IP address used is IPv4(Internet Protocol version
4).
• Each number of an IP address is made from eight individual bits
known as octet.
• Each octet can create number value from 0 to 255.
• An IP address would be 32 bits long in binary divided into
the two components, network component and host
component.
Subnetting – Classful Networks
• IP addresses are broken into the two components:
• Network component :- Defines network segment of device.
• Host component :- Defines the specific device on a particular
network segment.
IP Classes in decimal notation
Subnetting – Classful Network
Class A addresses range from 1-126
Class B addresses range from 128-191
Class C addresses range from 192-223
Class D addresses range from 224-239
Class E addresses range from 240-254
• 0 [Zero] is reserved and represents all IP addresses.
• 127 is a reserved address and is used for testing, like a loop back
on an interface.
• 255 is a reserved address and is used for broadcasting purposes.
Subnet Mask
Subnet mask is always used with IP address. Subnet mask has only
one purpose, to identify which part of an IP address is network
address and which part is host address.
Subnetting – Classful Network
• In decimal notation subnet mask value 1 to 255 represent network
address and value 0 [Zero] represent host address.
• In binary notation subnet mask ON bit [1] represent network
address while OFF bit[0] represent host address.
• Example: IP address is: 192.168.1.10 and subnet mask is
255.255.255.0
Subnetting – Classful Network
192 168 1 10
255 255 255 0
IP Address
Subnet Mask
Network Address Host Address
Subnetting – Classful Network
Class name Default
subnet mask
Networks
bits
Host bits CIDR
Class A 255.0.0.0 First 8 bits Last 24 bits /8
Class B 255.255.0.0 First 16 bits Last 16 bits /16
Class C 255.255.255.0 First 24 bits Last 8 bits /24
Subnetting – Classful Network
Notations
There are two notations to represent IP address and Subnet Mask.
• Decimal notation.
• Binary notation.
Each octet has eight individual bits which has following pattern:
192 168 1 10
255 255 255 0
IP Address
Subnet Mask
Subnetting – Classful Network
A network has following things to be calculated:
Followings are calculated using IP address and Subnet Mask
Network ID of each network
Host ID of each network
Broadcast ID of each network
Hosts per Network
Subnetting – Classful Network
A network has following things to be calculated:
Followings are calculated using IP address and Subnet Mask
First valid IP address of each network
Last valid IP address of each network
Total Subnet
Subnetting – Classful Network
Total Subnets/Number of the networks
Calculation Methodology: In order to calculate the total subnet of a network,
we need the subnet masks of the IP address class. As we know that the
classful networks uses default subnet mask according to the IP address class.
General Formula: 2^N where
N= Number of the host bits added to the network bits of a given subnet mask
as compared to the default subnet mask of given IP address class.
Considerable things while calculating total Subnets:
• Default subnet mask of the given IP address class.
• Given subnet mask.
Subnetting – Classful Network
Total Subnets/Number of the networks
Example: Given: IP address: 192.168.1.20 and we have to calculate
total subnet available.
Solution:
Step 1:
Analyze the IP address class as it is Class C (ranges 192-223). So its
default subnet mask is 255.255.255.0 and convert the default subnet
mask into doted binary notation.
. . .
As the no number of network bits added to the host bits as compared to the default
subnet mask of the IP address class. So here N will be zero . (Because no other subnet
mask is given and we uses the default subnet Mask). So Total Subnet = 2^0 = 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0
Subnetting – Classful Network
Network ID of each network
Calculation Methodology: we need the subnet masks of given IP address
class and IP address.
General Formula: Change the host bits of the IP address to 0’s while
keeping the network bits unchanged . The subnet mask successive 1’s will
tell the no. of networks bits.
Considerable things while calculating:
• Default subnet mask of the given IP address class.
• IP address.
Subnetting – Classful Network
Network ID of each network
Example: Given: IP address: 192.168.1.20 and we have to calculate
Network ID.
Solution: Step 1:
Analyze the IP address class as it is Class C (ranges 192-223). So its
default subnet mask is 255.255.255.0 and convert the IP address &
default subnet mask into doted binary notation.
. . .
. . .
Here the number of 1’s in the subnet mask tells the network bits in the IP address is 24 bits
and remaining 8 bits is host bits.
1 1 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 1 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0
IP Address
Subnet Mask
Subnetting – Classful Network
Network ID of each network
Step 2: Now by changing the host bits of the IP address to 0’s we will get the
Network ID.
. . .
. . .
1 1 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 1 0 0IP Address
1 1 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0Network ID
Decimal Network ID 192.168.1.0 /24No. of network bits
Subnetting – Classful Network
Host ID of each network
Calculation Methodology: we need the subnet masks of given IP address
class and IP address.
General Formula: Change the network bits of the IP address to 0’s while
keeping the host bits unchanged. The subnet mask successive 1’s will tell
the no. of networks bits.
Considerable things while calculating:
• Default subnet mask of the given IP address class.
• IP address.
Subnetting – Classful Network
Host ID of each network
Example: Given: IP address: 192.168.1.20 and we have to calculate
Host ID.
Solution: Step 1:
Analyze the IP address class as it is Class C (ranges 192-223). So its
default subnet mask is 255.255.255.0 and convert the IP address &
default subnet mask into doted binary notation.
. . .
. . .
Here the number of 1’s in the subnet mask tells the network bits in the IP address is 24 bits
and remaining 8 bits is host bits.
1 1 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 1 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0
IP Address
Subnet Mask
Subnetting – Classful Network
Host ID of each network
Step 2: Now by changing the network bits of the IP address to 0’s we will get
the Network ID.
. . .
. . .
1 1 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 1 0 0IP Address
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0Host ID
Decimal Host ID 0.0.0.20
Subnetting – Classful Network
Broadcast ID of each network
Calculation Methodology: we need the subnet masks of given IP address
class and IP address.
General Formula: Change the Host bits of the IP address to 1’s while
keeping the network bits unchanged. The subnet mask successive 1’s will
tell the no. of networks bits.
Considerable things while calculating:
• Default subnet mask of the given IP address class.
• IP address.
Subnetting – Classful Network
Broadcast ID of each network
Example: Given: IP address: 192.168.1.20 and we have to calculate
Broadcast ID.
Solution: Step 1:
Analyze the IP address class as it is Class C (ranges 192-223). So its
default subnet mask is 255.255.255.0 and convert the IP address &
default subnet mask into doted binary notation.
. . .
. . .
Here the number of 1’s in the subnet mask tells the network bits in the IP address is 24 bits
and remaining 8 bits is host bits.
1 1 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 1 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0
IP Address
Subnet Mask
Subnetting – Classful Network
Broadcast ID of each network
Step 2: Now by changing the host bits of the IP address to 1’s we will get the
Broadcast ID.
. . .
. . .
1 1 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 1 0 0IP Address
1 1 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1Broadcast ID
Decimal Broadcast ID 192.168.1.255/24No. of network bits
Subnetting – Classful Network
First Valid host address of each network
Calculation Methodology: we need to calculate the Network ID first
(already mentioned details in slide 14-16) then we will easily calculate the
first valid IP address.
General Formula: Find the Decimal Notation of Network Id and add
1(integer) to the address of the Network ID.
Considerable things while calculating:
• Network ID
Subnetting – Classful Network
First Valid Host Address ID of each network
Example: Given: IP address: 192.168.1.20 and we have to calculate
First valid host address.
Solution: Step 1:
Step 2:
Decimal Network ID 192.168.1.0 /24 (Already Calculated)
192.168.1.0
+ 1
192.168.1.1
Decimal Network ID
First Valid Address
Subnetting – Classful Network
Last Valid host address of each network
Calculation Methodology: we need to calculate the Broadcast ID first
(already mentioned details in slide 20-22) then we will easily calculate the
last valid IP address.
General Formula: Find the Decimal Notation of Broadcast Id and subtract
1(integer) to the address of the Broadcast ID.
Considerable things while calculating:
• Broadcast ID
Subnetting – Classful Network
First Valid Host Address ID of each network
Example: Given: IP address: 192.168.1.20 and we have to calculate
First valid host address.
Solution: Step 1:
Step 2:
Decimal Broadcast ID 192.168.1.255/24 (Already Calculated)
192.168.1.255
- 1
192.168.1.254
Decimal Broadcast ID
Last Valid Address
Subnetting – Classful Network
Hosts per network
Calculation Methodology: To calculate the hosts per network we need to
find the no. of network bits in the subnet mask.
General Formula: ((2^32-N )-2) where N = number of the network bits in
the subnet marks which is calculated by the no. of successive 1’s in the
subnet mask.
We subtract two address which is Network ID and Broadcast ID which
cannot assigned to any host.
Considerable things while calculating:
• Network bits of subnet mask.
Subnetting – Classful Network
Host per network
Example: Given: IP address: 192.168.1.20 and we have to calculate
host per network.
Solution: Step 1:
Analyze the IP address class as it is Class C (ranges 192-223). So its
default subnet mask is 255.255.255.0 and convert the default subnet
mask into doted binary notation.
. . .
Step 2:
Here N = 24 . So, Applying the formula : ((2^32-24)-2) = 2^8 – 2 = 254
hosts per network.
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 Subnet Mask
Subnetting – Classless Network
CIDR [ Classless Inter Domain Routing]:
CIDR is a slash notation of subnet mask. CIDR tells us number of on bits
in a network address.
•Class A has default subnet mask 255.0.0.0. that means first octet of the
subnet mask has all on bits. In slash notation it would be written as /8,
means address has 8 bits on.
•Class B has default subnet mask 255.255.0.0. that means first two octets
of the subnet mask have all on bits. In slash notation it would be written
as /16, means address has 16 bits on.
•Class C has default subnet mask 255.255.255.0. that means first three
octets of the subnet mask have all on bits. In slash notation it would be
written as /24, means address has 24 bits on.
Subnetting – Classless Network
Consider 200.113.20.16/28
a.Calculate
i. How many networks are possible?
ii. How many hosts per network are possible?
iii.What is the first valid IP of the first network?
iv.What is the last valid IP of the first network?
v. What is the broadcast ID of first network?
Subnetting – Classless Network
Solution:
In this question, /28 means that 28 bits are the network bits
i. How many networks are possible?
Answer:
. . .
. . .
As the number of network bits is 28 (as given) and IP address class is C.
So, Here N = 4 because 4 bits are extra used as compared to Default
subnet mask(255.255.255.0) of the class C.
Applying formula(Slide 10), we get no. of possible networks = 2^4 = 16
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 Given Subnet Mask 0 0 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 Default Subnet Mask
Subnetting – Classless Network
Solution:
In this question, /28 means that 28 bits are the network bits
ii. How many hosts per network are possible?Answer:
. . .
. . .
As the number of network bits is 28 (as given) and IP address class is C.
So, Using (Slide-27) formula, Number of host = ((2^32-28)-2) = 2^4 – 2 = 16 – 2
= 14
1 1 0 0 1 0 0 0 0 1 1 1 0 0 0 1 0 0 0 1 0 1 0 0
0 0 0 0
Given IP Address
1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1Given Subnet Mask
0 0 0 1 0 0 0 0
Subnetting – Classless Network
Solution:
In this question, /28 means that 28 bits are the network bits
iii. What is the first valid IP of the first network?Answer:
. . .
. . .
To calculate the first valid IP we have to calculate Network ID and add one to
It as already mentioned.
1 1 0 0 1 0 0 0 0 1 1 1 0 0 0 1 0 0 0 1 0 1 0 0
0 0 0 0
Given IP Address
1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1Given Subnet Mask
0 0 0 1 0 0 0 0
1 1 0 0 1 0 0 0 0 1 1 1 0 0 0 1 0 0 0 1 0 1 0 0Network ID 0 0 0 1 0 0 0 0
200.113.20.16 / 28Decimal Network ID
200.113.20.17 / 28First Valid IP
Subnetting – Classless Network
Solution:
In this question, /28 means that 28 bits are the network bits
iv. What is the Last valid IP of the first network?Answer:
. . .
. . .
To calculate the last valid IP we have to calculate Broadcast ID and subtract one to
It as already mentioned.
1 1 0 0 1 0 0 0 0 1 1 1 0 0 0 1 0 0 0 1 0 1 0 0
0 0 0 0
Given IP Address
1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1Given Subnet Mask
0 0 0 1 0 0 0 0
1 1 0 0 1 0 0 0 0 1 1 1 0 0 0 1 0 0 0 1 0 1 0 0Broadcast ID 0 0 0 1 1 1 1 1
200.113.20.31/ 28Decimal Network ID
200.113.20.30 / 28Last Valid IP
NAT(Network address translation)
Definition:
NAT is short for Network Address Translation. NAT is an Internet standard
that enables a local-area network (LAN) to use one set of IP addresses for
internal traffic and a second set of addresses for external traffic.
Purpose:
NAT serves three main purposes:
•Provides a type of firewall by hiding internal IP addresses
•Enables a company to use more internal IP addresses. Since they're used
internally only, there's no possibility of conflict with IP addresses used by
other companies and organizations.
•Allows a company to combine multiple ISDN connections into a single
Internet connection
NAT(Network address translation)
Basic Operation Of NAT
• NAT device has address translation table
• One to one address translation
NAT(Network address translation)
Types of NAT
• Static NAT:
A pool of public IP addresses are assigned to the NAT device. A private IP
address can then be statically mapped to anyone of these public addresses.
NAT(Network address translation)
Types of NAT
•Dynamic NAT:
The NAT device will consist of a pool of IP addresses. This time though the
pool of IP addresses will be used when needed and then given back to the
pool. So if computer A needed a public address, it would take one from the
pool, then hand it back when done. The next time the same computer
wanted an IP address it may be assigned a different public address from the
pool, because the one used previously may be in use by another computer,
hence the name "dynamic".
NAT(Network address translation)
Types of NAT
• NAT overload or Port Address translation:
During PAT, each computer on LAN is translated to the same IP address, but
with a different port number assignment.
NAT(Network address translation)
Terminology of NAT:
Specific terms are used to identify the various NAT addresses:
• Inside Local:
the specific IP address assigned to an inside host behind a NAT-enabled device
(usually a private address).
• Inside Global:
the address that identifies an inside host to the outside world (usually a public
address). Essentially, this is the dynamically or statically-assigned public address
assigned to a private host.
• Outside Global:
the address assigned to an outside host (usually a public address).
• Outside Local :
the address that identifies an outside host to the inside network. Often, this is the
same address as the Outside Global. However, it is occasionally necessary to translate
an outside (usually public) address to an inside (usually private) address.
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