IP Addressing Terminology

Binary And Decimal Numbers

• Where do our numbers come from?

• Where do binary Numbers come from?

Binary vs. Decimal

Binary Number

1000

Decimal Number

1000

When Converting to Binary-Remember the 8 bit sequence

128 64 32 16 8 4 2 1

Convert Decimal to Binary

Convert 1050 ? ? ? ? ? ? ?

0 1 ? ? ? ? ? ?

0 1 1 ? ? ? ? ?

0 1 1 0 ? ? ? ?

0 1 1 0 1 ? ? ?

0 1 1 0 1 0 0 1 = 105

Can I subtract 128?No

Can I subtract 64?Yes- with 41 left

Can I subtract 32?Yes-with 9 left

Can I subtract 16?No

Can I subtract 8?Yes-1 left

Can I subtract 4? 2? 1?

128 64 32 16 8 4 2 1

Convert Binary to Decimal

Convert 10110011

Add the decimal number when the bit is a 1

128

32

16

2

__1_

179

128 64 32 16 8 4 2 1

IP addressing Scheme

• Dotted-decimal, as in 172.163.30.56

• Binary, as in 10101100.00010000.00011110.00111000

• Hexadecimal, as in AC.10.1E.38 (least likely)

IP Address Essential

• For each class you MUST know– Address Class Range– Reserved Addresses– Default Subnet Mask

• Understand Network and Broadcast Address

InternetAddress Classes

• Class A – Range 0.0.0.0 to 127.255.255.255 • Class B – Range 128.0.0.0 to 191.255.255.255 • Class C – Range 192.0.0.0 to 223.255.255.255 • Class D – Range 224 to 239 (network address

only)• Class E – Range 240 to 247 (reserved for future

use)

IP Addressing Rules

• Loopback address

• Broadcast address

• Network address

• Special-case source address

• Reserved IP addressing

Reserved Addresses

Class A

• Structure– NetworkNetwork.node.node.node

• Range– 0.0.0.0 through 126.255.255.255

• Default Subnet Mask– 255.0.0.0

• Class A Addresses– Valid hosts = 10.0.0.1 - 10.255.255.254

• 0’s & 255s are valid hosts but hosts bits cannot all be off or on at the same time!

• 224-2 = 22

• Reserved Addresses:– 10.0.0.0 through 10.255.255.255

Class B

• Structure– NetworkNetwork.NetworkNetwork.node.node

• Range– 128.0.0.0 through 191.255.255.255

• Default Subnet Mask– 255.255.0.0

• Class B Valid Host IDs– Valid hosts = 172.16.0.1 - 172.16.255.254

• 0’s & 255s are valid hosts but hosts bits cannot all be off or on at the same time!

• 216-2 = 214

• Reserved Addresses:– 172.16.0.0 through 172.31.255.255

Class C• Structure

– NetworkNetwork.NetworkNetwork.NetworkNetwork.node• Range

– 192.0.0.0 through 223.255.255.255• Default Subnet Mask

– 255.255.255.0• Class C Valid Host IDs

– Valid hosts = 192.168.100.1 - 192.168.100.254• 28-2 = 26

• Reserved Addresses:– 192.168.0.0 through 192.168.255.255

IP Addressing Rules• Loopback address

– Anything that starts with 127• 127.0.0.1

• Broadcast addresses– Host portion is all 1

• 192.168.10.255 • 255.255.255.0

• Network and special-case source addresses– Host portion is all 0

• 192.168.10.0• Reserved IP addressing

– As seen on previous slides

Subnetworks

• Subnet masks– Distinguish the network and host portions of

an IP address – Specify whether a destination address is local

or remote

• ANDing

Key Subnetting Ideas

If you know the subnet mask, figure out ranges

1.Subtract Subnet mask from 256• Result is starting network address and block size

2.Figure out network addresses• Add block size to self up to subnet mask

3.Figure out Broadcast addresses• One less than next network address

4.Figure out available addresses• Between Network and Broadcast

Figuring Out subnets

1. Figure out how many bits you have to play with• You can steal from the host portion.

2. How many subnets or hosts are needed?• Use the 2n-2>= what you need formula

3. Determine the subnet mask• Make the bits you steal into 1’s and the rest

into 0’s

Key Subnetting Ideas

If you know the subnet mask, figure out ranges

1.Subtract Subnet mask from 256• Result is starting network address and block size

2.Figure out network addresses• Add block size to self up to subnet mask

3.Figure out Broadcast addresses• One less than next network address

4.Figure out available addresses• Between Network and Broadcast

Basic Subnetting Example

What is the network address for the following IP address, subnet mask combination: IP Address 210.32.100.70 Subnet Mask 255.255.255.240A.210.32.100.0B.210.32.100.32C.210.32.100.64D.210.32.100.79

Basic Subnetting Example

IP Address 210.32.100.70

Subnet Mask 255.255.255.240

Step 1. 256-240=16

Step 2. 16, 32, 48, 64, 80, 96 (stop when you are past the number in question

Step 3. 31, 47, 63, 79, 95, 111

Step 4. Answer-C

Basic Subnetting Example

Which of the following are valid addresses for the following network (Choose 2)

IP Address 180.64.96.0

Subnet Mask 255.255.224.0

A.180.64.1.1

B.180.64.110.240

C.180.64.35.10

D.180.64.120.255

Basic Subnetting Example

IP Address 180.64.96.0

Subnet Mask 255.255.224.0

Step 1. 256-224=32

Step 2. 32, 64, 96, 128 (only need to go as far as question)

Step 3. 63, 95, 127, 159

Step 4. Network 96 Range

180.64.96.1 through 180.64.127.254

CIDR Notation and subnet Masks

/ notation shows how many bits are 1 in subnet mask.

For example:/8 = 11111111.00000000.00000000.00000000

=255.0.0.0

/12= 11111111.11110000.00000000.00000000

= 255.240.0.0

/16=11111111.11111111.00000000.00000000

=255.255.0.0

CIDR Notation and subnet MasksTo figure subnet mask from / notationStep 1. Draw out bits, figure out how many

bits are used in subnetted octetStep 2. For subnetted octect, write out 8 bit

number with powers of 2Step 3. Convert from Binary to DecimalStep 4. Write our subnet maskStep 5. Use number to figure Networks,

Broadcasts and Ranges.

CIDR ExampleWhat is the subnet mask for the following

address

IP Address: 140.34.16.240 /20

A. 255.255.0.0

B. 255.255.248.0

C. 255.240.0.0

D. 255.255.240.0

CIDR ExampleIP Address: 140.34.16.240 /20Step 1. 11111111.11111111.11110000.00000000

Step 2. 128 64 32 16 8 4 2 1

1 1 1 1 0 0 0 0

Step 3. 128+64+32+16=240

Step 4. 255.255.240.0

Step 5. Network-140.34.16.0

Broadcast-140.34.31.255

Range-140.34.16.1 through 140.34.31.254

Custom Subnet Masks• Step 1: Determine the number of subnets needed• Step 2: Determine the number of bits to borrow from the

host portion• Step 3: Determine the subnet mask• Step 4: Determine the maximum number of hosts per

subnetwork• Step 5: Determine the subnetwork addresses for each

subnet• Step 6: Determine the address ranges for each

subnetwork

Basic Subnetting Example

What is the network address for the following IP address, subnet mask combination: IP Address 210.32.100.70 Subnet Mask 255.255.255.240A.210.32.100.0B.210.32.100.32C.210.32.100.64D.210.32.100.79

Basic Subnetting Example

IP Address 210.32.100.70

Subnet Mask 255.255.255.240

Step 1. 256-240=16

Step 2. 16, 32, 48, 64, 80, 96 (stop when you are past the number in question

Step 3. 31, 47, 63, 79, 95, 111

Step 4. Answer-C

Basic Subnetting Example

What is the network address for the following IP address, subnet mask combination: IP Address 210.32.100.70 Subnet Mask 255.255.255.240A.210.32.100.0B.210.32.100.32C.210.32.100.64D.210.32.100.79

Basic Subnetting Example

Which of the following are valid addresses for the following network (Choose 2)

IP Address 180.64.96.0

Subnet Mask 255.255.224.0

A.180.64.1.1

B.180.64.110.240

C.180.64.35.10

D.180.64.120.255

Basic Subnetting Example

IP Address 180.64.96.0

Subnet Mask 255.255.224.0

Step 1. 256-224=32

Step 2. 32, 64, 96, 128 (only need to go as far as question)

Step 3. 63, 95, 127, 159

Step 4. Network 96 Range

180.64.96.1 through 180.64.127.254

Basic Subnetting Example

Which of the following are valid addresses for the following network (Choose 2)

IP Address 180.64.96.0

Subnet Mask 255.255.224.0

A.180.64.1.1

B.180.64.110.240

C.180.64.35.10

D.180.64.120.255

CIDR Notation and subnet Masks

/ notation shows how many bits are 1 in subnet mask.

For example:/8 = 11111111.00000000.00000000.00000000

=255.0.0.0

/12= 11111111.11110000.00000000.00000000

= 255.240.0.0

/16=11111111.11111111.00000000.00000000

=255.255.0.0

CIDR Notation and subnet MasksTo figure subnet mask from / notationStep 1. Draw out bits, figure out how many

bits are used in subnetted octetStep 2. For subnetted octect, write out 8 bit

number with powers of 2Step 3. Convert from Binary to DecimalStep 4. Write our subnet maskStep 5. Use number to figure Networks,

Broadcasts and Ranges.

CIDR ExampleWhat is the subnet mask for the following

address

IP Address: 140.34.16.240 /20

A. 255.255.0.0

B. 255.255.248.0

C. 255.240.0.0

D. 255.255.240.0

CIDR ExampleIP Address: 140.34.16.240 /20Step 1. 11111111.11111111.11110000.00000000

Step 2. 128 64 32 16 8 4 2 1

1 1 1 1 0 0 0 0

Step 3. 128+64+32+16=240

Step 4. 255.255.240.0

Step 5. Network-140.34.16.0

Broadcast-140.34.31.255

Range-140.34.16.1 through 140.34.31.254

CIDR ExampleWhat is the subnet mask for the following

address

IP Address: 140.34.16.240 /20

A. 255.255.0.0

B. 255.255.248.0

C. 255.240.0.0

D. 255.255.240.0

Custom Subnet Masks• Step 1: Determine the number of subnets needed• Step 2: Determine the number of bits to borrow from the

host portion• Step 3: Determine the subnet mask• Step 4: Determine the maximum number of hosts per

subnetwork• Step 5: Determine the subnetwork addresses for each

subnet• Step 6: Determine the address ranges for each

subnetwork