Module 5: Creating IPv4 Address Spaces

Module 5: Creating IPv4 Address Spaces

• Overview of IP Communication

• Subnetting Overview

• Subnetting for Complex Networks

Lesson 1: Overview of IP Communication

• What Are the IPv4 Address Classes?

• What Is ARP?

• IPv4 Communication Within a Single Network

• IPv4 Communication Between Networks

• Demonstration: Using ARP

What Are the IPv4 Address Classes?

Class CSmall Network

Class BMedium Network

Class ALarge Network

Network ID Host ID

1 1 0

xw y z

Network ID Host ID

1 0

xw y z

Network ID

Host ID

0

xw y z

What Is ARP?

The ARP protocol:

•Resolves IPv4 addresses to MAC addresses

•Provides MAC addresses for IP frames

•Dynamically stores MAC addresses in the ARP cache

The ARP tool:

•Displays the ARP cache

•Removes entries from the ARP cache

•Adds static entries to the ARP cache

IPv4 Communication Within a Single Network

Computer BComputer BComputer AComputer A

IP: 192.168.55.23MAC: 00:43:D2:ED:1A:98

IP: 192.168.55.99MAC: 2C:33:85:C2:AA:32

Determine local or remote network

Resolve destination IP to MAC address

Address packet

Deliver packet to destination

11

22

33

44

IPv4 Communication Between Networks

IP: 192.168.55.23MAC: 00:43:D2:ED:1A:98

IP: 192.168.37.99MAC: 2C:33:85:C2:AA:32

IP: 192.168.55.1MAC: 6B:11:43:75:CB:11

IP: 192.168.37.1MAC: 6B:11:43:75:CB:12

Determine local or remote network

Resolve default gateway IP to MAC address

Address and deliver packet to default gateway

Resolve destination IP to MAC address

Address and deliver packet to destination

11

22

33

44

55

Computer BComputer BComputer AComputer A

Demonstration: Using ARP

In this demonstration, you will see how to use ARP

Lesson 2: Subnetting Overview

• How Dotted Decimal Notation Relates to Binary Numbers

• What Is a Subnet?

• How Bits Are Used in a Subnet Mask

• How the Computer Determines Whether an IP Address Is Local or Remote

How Dotted Decimal Notation Relates to Binary Numbers

Bit 7Bit 7 Bit 6Bit 6 Bit 5Bit 5 Bit 4Bit 4 Bit 3Bit 3 Bit 2Bit 2 Bit 1Bit 1 Bit 0Bit 0

8-Bit Octet

Decimal Value

128128 6464 3232 1616 88 44 22 11

27272626

25252424

23232222

21212020

What Is a Subnet?

Subnet 1131.107.10.0

Main Network131.107.12.0

Subnet 2131.107.3.0

131.107.10.12131.107.10.12

131.107.12.31131.107.12.31

131.107.3.27131.107.3.27

131.107.12.7131.107.12.7

RouterRouter

RouterRouter

How Bits Are Used in a Subnet Mask

Class B Address with SubnetClass B Address with Subnet

Number of Subnets 254

Number of Hosts 254

Network ID Host ID

1

Subnet ID

0

128643216842

65,5348,1284,0642,0321,01650816,25632,512

0254

254

How the Computer Determines Whether an IP Address Is Local or Remote

Local and destination hosts’ IP addresses are each ANDed with their subnet masks

10011111 11100000 00000000 00000000

10011111 11100000 00000111 10000001

11111111 11111111 00000000 00000000IP AddressSubnet MaskIP AddressSubnet Mask

ResultResult

1 AND 1 = 1

Other combinations = 0

If ANDed results of source and destination hosts match, the destination is local

Lesson 3: Subnetting for Complex Networks

• Determining the Number of Subnet Bits

• Determining the Number of Host Bits

• Calculating Network Addresses

• Demonstration: Subnetting

Determining the Number of Subnet Bits

You should:

• Choose the number of subnet bits based on the number of subnets required

• Use 2n to determine the number of subnets available from n bits

For five locations, three subnet bits are required

• 5 locations = 5 subnets required

• 22 = 4 subnets (not enough)

• 23 = 8 subnets

Determining the Number of Host Bits

You should:

• Choose the number of host bits based on the number of hosts required on each subnet

• Use 2n-2 to determine the number of hosts available on each subnet available from n bits

For subnets 100 hosts, seven host bits are required

• 26-2 = 62 hosts (not enough)

• 27-2 = 126 hosts

Calculating Network Addresses

To determine the Network IDs:

• 172.16.0.0 will be subnetted using three bits

• The subnet mask is 255.255.11100000.0

• The lowest value bit in the subnet mask is the network ID increment

The network IDs increment by 32

• 172.16.0.0

• 172.16.32.0

• 172.16.64.0

• 172.16.96.0

• 172.16.128.0

• 172.16.160.0

• 172.16.192.0

• 172.16.224.0

Demonstration: Subnetting

In this demonstration, you will see how to perform subnetting

Lab: Creating IPv4 Address Spaces

• Exercise 1: Defining the Subnet Mask for a WAN

• Exercise 2: Defining the Hosts for a Network

Estimated time: 60 minutes

Lab Review

• What is the value of the host bits for the network address?

• What is the value of the host bits for the broadcast address on a subnet?

Module Review and Takeaways

• Review Questions

• Real-world Issues and Scenarios

• Best Practices