Free CCNA | Subnetting (Part 1) | Day 13 | CCNA 200-301 Complete Course

Name: Free CCNA | Subnetting (Part 1) | Day 13 | CCNA 200-301 Complete Course
Uploaded: 2020-02-16T07:41:54.000Z
Duration: 56 min 54 s

Welcome to Jeremy’s IT Lab

In this section, Jeremy introduces his free CCNA course and emphasizes the importance of subnetting as a skill for network engineers.

Introduction to Subnetting

Subnetting is an essential skill for network engineers.

It is not difficult if approached step-by-step.

Jeremy will split subnetting into multiple videos to ensure understanding without getting lost.

There are already many subnetting videos on YouTube with different techniques, but Jeremy will focus on outlining the basic steps.

CIDR and IPv4 Address Classes

This section covers CIDR (Classless Inter-Domain Routing) and provides a review of IPv4 address classes.

Review of IPv4 Address Classes

There are five classes of IPv4 addresses: A, B, C, D, and E.

Class A addresses have a first octet range from 0 to 127.

Class B addresses have a first octet range from 128 to 191.

Class C addresses have a first octet range from 192 to 223.

Class D addresses have a first octet range from 224 to 239.

Class E addresses have a first octet range from 240 to 255.

CIDR (Classless Inter-Domain Routing)

CIDR allows for more flexibility in IPv4 networks compared to traditional address classes.

It eliminates the strict boundaries set by address classes and allows for variable-length subnet masks (prefix lengths).

Characteristics of Different Address Classes

This section explains the characteristics and available addresses per network in each IPv4 address class.

Characteristics of Address Classes

Class A Addresses

First octet identifies the network, while the other three octets are used for individual hosts.

Only 128 class A networks are available, with each network having 16,777,216 addresses.

Class B Addresses

First two octets identify the network, and the last two octets identify individual hosts.

There are 16,384 class B networks, with each network having 65,536 addresses.

Class C Addresses

First three octets identify the network, and only the last octet is used for individual hosts.

There are 2,097,152 class C networks, with each network having 256 addresses.

Address Assignment by IANA

IP addresses and networks are assigned to companies or organizations by the Internet Assigned Numbers Authority (IANA).

The assignment is based on the size of the company or organization.

Large companies may receive a Class A or Class B network with many available addresses for hosts.

Small companies typically receive a Class C network with fewer available addresses.

Introduction to Routers and Networks

In this section, the speaker introduces the concept of routers and networks. They explain that routers are used to connect different networks, with each link representing a separate Layer 3 network. The speaker also mentions the presence of switches and end hosts within these networks.

Routers connect different networks.

Each link represents a separate Layer 3 network.

Switches and end hosts are present within these networks.

Point-to-Point Networks

This section discusses point-to-point networks, which connect two specific points such as two routers or offices in different cities. The speaker explains that point-to-point networks require a smaller address block compared to larger networks.

Point-to-point networks connect two specific points.

They require a smaller address block.

Example: Connection between offices in different cities.

Addressing for Point-to-Point Network

Here, the speaker discusses addressing for point-to-point networks using an example of a class C network (203.0.113.0/24). They explain how addresses are assigned to the network, routers, and broadcast addresses.

Class C network (203.0.113.0/24) is used as an example.

Addresses assigned: Network address, broadcast address, router addresses.

Total of 4 addresses used, resulting in wasted addresses.

Address Waste in IP Addressing

This section highlights the issue of address waste in IP addressing systems. The speaker presents an example where a company needs IP addressing for 5000 end hosts but is limited by the number of available addresses in class C networks.

Class C network does not provide enough addresses for 5000 end hosts.

Class B network results in significant address waste.

Address space exhaustion is a problem due to the limited number of IPv4 addresses.

Introduction to CIDR

The speaker introduces Classless Inter-Domain Routing (CIDR) as a solution to address space exhaustion. They explain that CIDR allows for more efficient allocation of IP addresses by allowing larger networks to be split into smaller subnetworks.

CIDR introduced in 1993 as a replacement for the classful addressing system.

CIDR allows larger networks to be split into smaller subnetworks.

Greater efficiency in IP address allocation.

Splitting Networks with CIDR

This section provides an example of how CIDR allows for the splitting of larger networks into smaller subnets. The speaker uses the previous point-to-point network example and demonstrates how different prefix lengths affect the number of usable addresses.

Previous point-to-point network used as an example.

Different prefix lengths result in varying numbers of usable addresses.

Demonstrates subnetting calculations with different prefix lengths.

Binary Representation and Subnet Masks

Here, the speaker explains binary representation and subnet masks in relation to subnetting. They demonstrate how host bits and network bits are determined based on the subnet mask.

Binary representation and subnet masks explained.

Host bits and network bits determined by subnet mask.

Visual demonstration of host portion and network portion using colors.

Calculating Usable Addresses with Prefix Lengths

This section focuses on calculating the number of usable addresses based on different prefix lengths. The speaker provides examples using various prefix lengths for the 203.0.113.0 network.

Calculation of usable addresses with different prefix lengths demonstrated.

Examples provided for /25, /26, /27, /28, /29, /30, /31, and /32 prefix lengths.

Emphasis on the network portion and host portion of the address.

Usable Addresses with Different Prefix Lengths

The speaker reveals the number of usable addresses for each prefix length in the examples provided earlier. They highlight how the network portion expands with shorter prefix lengths.

Number of usable addresses revealed for each prefix length.

Expansion of network portion with shorter prefix lengths.

Special consideration for /31 and /32 prefix lengths.

Subnetting Example: 203.0.113.0/25

This section provides a specific example of subnetting using a /25 prefix length for the 203.0.113.0 network. The speaker explains how to determine the number of usable addresses based on the subnet mask.

Example subnetting with a /25 prefix length.

Determining usable addresses based on subnet mask.

Visual representation of expanded network portion.

Address Waste in Subnetting

Here, the speaker discusses address waste in subnetting using a /26 prefix length for the 203.0.113.0 network as an example. They compare the number of usable addresses to the actual requirement.

Address waste demonstrated with a /26 prefix length.

Comparison between usable addresses and actual requirement.

Highlighting continued address wastage despite improved efficiency.

Conclusion and Recap

The speaker concludes by summarizing CIDR's role in addressing space exhaustion and its ability to allocate IP addresses more efficiently through subnetting.

CIDR helps address space exhaustion issue.

Efficient allocation through subnetting.

Recap of key points discussed throughout the video

Network Mask and Subnetting

In this section, the speaker discusses network masks and subnetting. They explain how to calculate usable addresses based on different prefix lengths and demonstrate the efficiency of subnetting.

Network Mask for /28 Prefix Length

A /28 prefix length has a network mask of 255.255.255.240 in dotted decimal.

With only 4 host bits, there are 14 usable addresses.

Assigning addresses to R1 and R2 would result in only 12 wasted addresses.

Making Address Space Smaller

Using a /29 prefix length gives a network mask of 255.255.255.248.

With only 3 host bits, there are 6 usable addresses.

After assigning addresses to R1 and R2, there would be only 4 wasted addresses.

Efficiency with /30 Prefix Length

A /30 prefix length has a network mask of 255.255.255.252.

With only 2 host bits, there are 2 usable addresses.

This means no wasted addresses as there are a total of 4 addresses: network address, broadcast address, R1's address, and R2's address.

Subnetting Example with /30

Instead of using the entire range of 203.0.113.0/24, a subnet of that larger class C network is used: 203.0.113.0/30.

The subnet includes the address range from 203.0.113.0 through 203.0.113.3.

Only two usable addresses (203.0.113..1 and .2) are assigned to R1 and R2 respectively.

The remaining addresses in the range (203..113..4 - .255) can be used for other subnets.

Benefits of Subnetting

Subnetting allows for more efficient use of address space.

By using smaller subnets, fewer addresses are wasted.

Instead of using 203.0.113.0/24 and wasting 252 addresses, a /30 subnet is used with only 2 addresses.

Using /31 Prefix Length for Point-to-Point Connections

A /31 prefix length has a network mask of 255.255.255.254.

With only 1 host bit, there are no usable addresses according to the formula.

However, for point-to-point connections like this, it is possible to use a /31 mask.

The network consists of just two addresses: R1 (203.0.113..0) and R2 (203.0.113..1).

In this case, there is no need for a network or broadcast address.

Efficient Point-to-Point Connection with /31

For point-to-point networks, dedicated connections between two routers, there is no need for a network or broadcast address.

Only the two addresses in the network (R1 and R2) are assigned without wasting any additional addresses.

Validity of /32 Mask

A /32 mask has a network mask of 255.255.255.255.

There are no host bits in this case; the entire address is considered as the network portion.

According to the formula, there would be -1 usable address which doesn't work practically.

While not used to configure actual interfaces, /32 masks can be used for specific purposes like creating static routes to individual hosts.

Summary and CIDR Notation

Subnet masks can be represented in CIDR notation (prefix length) alongside dotted decimal notation.

Example: /25, /26

Previously only dotted decimal method was used.

Conclusion and Next Steps

The speaker concludes the discussion on subnetting and network masks. They mention that subnetting allows for efficient use of address space by dividing larger networks into smaller subnets. The next video will provide practice problems for hands-on subnetting practice.

Subnetting as a Tool for Efficient Address Space Usage

Subnetting allows for dividing larger networks into smaller subnets.

Instead of using the entire network, smaller subnets can be used to minimize wasted addresses.

In the example, a /30 or even better, a /31 subnet was used for point-to-point connections, resulting in significant address savings.

Next Steps: Practice Problems

In the next video, practice problems will be provided to gain hands-on experience with subnetting.

This will help reinforce the concepts discussed in this video.

New Section

This section discusses the number of hosts required and determines if there are enough addresses in the 192.168.1.0/24 network.

Number of Hosts Required

There is a need for 45 hosts per network, including R1.

Each network has a network and broadcast address, adding 2 more addresses.

Therefore, each subnet requires 47 addresses.

The total number of addresses needed for all subnets is 188, which is within the available range.

New Section

This section explains that the class C network 192.168.1.0/24 has enough addresses to accommodate four subnets.

Calculating Subnets

The class C network 192.168.1.0/24 has a total of 256 addresses.

Four equal-sized subnets are needed with at least 45 hosts each.

The first subnet is already given as 192.168.1.0/26.

New Section

This section explores different subnet masks to determine if they can accommodate the required number of hosts.

Subnet Masks Analysis

A /30 mask (255.255.255.252) provides only two usable addresses, which is insufficient for the required 45 hosts.

A /29 mask (255.255.255.248) offers six usable addresses, still not enough for the required hosts.

A /28 mask (255.255.255.240) provides fourteen usable addresses but falls short of accommodating all the hosts.

A /27 mask (255.255.255.224) offers thirty usable addresses but does not meet the requirement either.

New Section

This section continues the analysis of subnet masks to find a suitable option.

Finding a Suitable Subnet Mask

A /26 mask (255.255.255.192) provides sixty-two usable addresses, which is sufficient for the required 45 hosts.

Although it offers more address space than needed, having extra room for growth is beneficial.

Therefore, the /26 subnet mask is chosen as it meets the requirements.

New Section

This section concludes the video and introduces a quiz to determine the remaining subnets.

Recap and Quiz

The video covered CIDR (classless inter-domain routing) and the basics of subnetting.

Subnetting allows for more flexibility in network addressing based on network size.

The /27 subnet does not provide enough address space, while the /26 subnet has more than required but is chosen due to its suitability.

The remaining subnets are to be determined through a quiz by finding broadcast addresses and repeating the process for Subnets 2, 3, and 4.

New Section

This section summarizes what was covered in the video and encourages viewers to ask questions or provide feedback.

Summary and Conclusion

The video covered CIDR (classless inter-domain routing) and explained how it allows for more flexible network addressing.

The basics of subnetting were introduced, focusing on determining suitable subnet masks based on host requirements.

Viewers are encouraged to ask questions or leave comments in the comment section.

Flashcards are available for download to review key concepts from this video.

New Section

This section mentions additional features available on the channel and thanks supporters.

Additional Features and Thanks

Membership feature has been enabled on the channel, allowing viewers to leave monthly tips to support the creator.

JCNP (Jeremy Certified Network Professional) level supporters will receive a shoutout in videos.

The first JCNP-level supporter mentioned is Vance Simmons.

Viewers are encouraged to subscribe, like the video, and leave comments.

The remaining part of the transcript does not contain relevant information for note-taking purposes.