1. Binary Concepts
By: Nathan Miller

2. What is Binary?
The binary numbering system is a method of storing ordinary numbers such as 56 or 250 as patterns of 1’s and 0’s.
Computers can easily manipulate these binary patterns by treating 1 as “on” and “0” as off.
Binary numbers are much easier and faster to work with because the computer does not need to learn large addition or multiplication tables.

3. Counting in Decimal
The decimal numbering system is a base 10 numbering system.
Decimal employs the digits 0-9.
When counting past 9 an additional column is added. Or H T O 9 5 3
10^2
10^1
10^0 9 5 3

4. Counting in Binary
The binary numbering system is a base 2 numbering system.
Employs the digits 0-1 which represents an “off” and “on” position respectively.
Instead of columns being 10^0, 10^1, 10^2 .. They are expressed as 2^0, 2^1, 2^2

5. Example 1
Convert the decimal number 115 to binary.
Answer: 1

6. Example 2 Convert the decimal number 259 to binary Answer: 100000011
Base 2
2^8
2^7
2^6
2^5
2^4
2^3
2^2
2^1
2^0
256
128 64 32 16 8 4 2 1

7. Example 3 Convert the binary number 11101010 to decimal.
Answer: 2^7+2^6+2^5+2^3+2^1 or = 234
Base 2
2^7
2^6
2^5
2^4
2^3
2^2
2^1
2^0 1

8. IP Address

9. IPv4 Header
Source:

10. What is an IP address? Formal Definition:
Uniquely identifies host machines on a network.
This identifier is used when sharing resources with other hosts in a network.
Formal Definition:
An IP (Internet Protocol) address is a unique identifier for a node or host connection on an IP network. An IP address is a 32 bit binary number usually represented as 4 decimal values, each representing 8 bits, in the range 0 to 255 (known as octets) separated by decimal points. This is known as "dotted decimal" notation. (St. Xavier’s College, Kolkata).
Example:

11. IP Address Structure An IP address consists of four sections
Each section (or octet) is 8 bits long which comes out to a total of 32 bits.
Each octet can range from 0 to 255. The lowest being a value of and the highest respectively.

12. IP Address Structure 5 Classes of IP address A B C D and E
Class A reserved for governments and large companies
1st octet
Class B reserved for medium companies
1st octet
Class C reserved for small companies
1st octet
Class D reserved for multicasting
1st octet
Class E reserved for experimentation/research
1st octet

13. IP Address Structure Private IP ranges:
through
through
through
These address ranges are used for Private internal networks.
As a result they are not routable on the Internet.
NAT translates a private IP address to a public routable address

14. Types of Addresses
Network Address – The IPv4 address block assigned to a network.
Think of it as a collection of end-devices belonging to a club
Broadcast Address – Special address in each network that allows an end-device to communicate with all others in the same network
Host Address – The “usable” addresses assigned to end-devices that belong to a specific network
Subnet Mask (SM) – 32-bit number that masks an IP address, and separates an address into a network and host portion.

15. IP Address Structure
The Class of the IP address and subnet mask (SM) determine which part of the address belongs to the network and host.
The network portion is assigned and the network administrator determines the host portion through subnetting.
Ex with a subnet mask of
How do we determine the network and the host portion of an address?
One method is to write the subnet mask out in binary

16. IP Address Structure
Ex with a subnet mask of
How do we determine the network and the host portion of an address?
Each 1 is part of the network address. Each 0 is the host portion of the address.
255 N H

17. IP Address Structure
With that in mind. How do we tell what network an IP address is part of?
The answer: By using a bitwise AND operation
Question: Given an IP address of and a subnet mask of Determine the network this address belongs to
AND
Answer
Decimal
193
111 10
128

18. Classful Subnetting
In this scenario, the SM is fixed for the entire organization
Borrow bits from the subnet mask. However, in this scheme, the SM once chosen is a fixed length.
This is known as a contiguous addressing scheme
For instance, /25 is a class C network address. We have LANs that require 68, 32 hosts respectively.
Network Address HR BC
193
111 10
128 … N
shhhhhhh
Bit Map

19. Variable Length Subnet Masking (VLSM)
IPv4 has its limitations
Adjust the subnet mask length by borrowing additional bits from the host portion of the SM
That is, subnet the subnet
Done to conserve addressing space
If all addresses are not assigned then there is much waste
Solution: Borrow additional bits from the host portion of the address

20. Classless Inter Domain Routing (CIDR)
Is a way of notating an IP address and its corresponding Subnet Mask (prefix)
Ex. Net: SM: can be expressed as
/24
The /24 corresponds to the number of digits set to the ‘1’ position in the subnet mask
CIDR makes it possible for route summarization
Instead of keeping a routing entry for each network summarize

21. Classless Subnetting Involves VLSM addressing
We can borrow additional bits in the subnet mask to meet the demands of our network
Done to conserve addressing space
If all addresses are not assigned then there is much waste

22. Classless Subnetting Given a network address of 150.161.0.0/16
Create an addressing scheme for the following LAN requirements: LAN A (350) hosts, LAN B (200) hosts, LAN C (30) hosts, LAN D (30) hosts. Can use the .0 subnet.
LAN
Network
CIDR
Host Range BC
Subnet Mask
150
161
/16 A
/23
.1.255 B 2
/24
.2.255 C 3
/27
.3.31 D 32
.3.63

23. Sources IPv4 http://en.wikipedia.org/wiki/IPv4_Header#Header
Binary Concepts
Subnetting Concepts & Practice