Subnetting

Laboratorium Jaringan Komputer

17 Oct 202119:49

Summary

TLDRThis video tutorial focuses on IP version 4 subnetting. It explains how to divide a network into subnets, detailing how subnetting reduces the number of hosts in each network while increasing the number of network IDs. The tutorial covers key concepts such as network and broadcast addresses, subnet mask calculations, and subnetting for Class A, B, and C IP addresses. It includes practical steps using Cisco Packet Tracer to simulate and test different subnet configurations, demonstrating how packets are routed between PCs, switches, and routers while emphasizing the importance of gateways for communication across networks.

Takeaways

😀 Subnetting in IPv4 is the process of dividing a network into multiple smaller sub-networks.
🔑 Subnetting is typically performed on IP addresses from Class A, B, and C.
🌐 Subnetting increases the number of network IDs but reduces the number of hosts per network.
📉 In every subnet or network, two special IP addresses are reserved: one for the network identifier and one for the broadcast.
🔢 A simple way to calculate subnetting is by using a subnet mask, which can divide a network into multiple subnets by changing the block sizes.
⚙️ When subnetting a Class C network (/24), it can be divided into smaller blocks, such as /25, /26, etc., reducing available IP addresses per block.
🚦 The subnet mask defines how many IP addresses are available within each subnet, which reduces as more bits are used for subnetting.
🌍 Gateways are essential for routing packets between different subnets, as they handle communication between devices not in the same subnet.
📡 Packet communication between subnets requires proper routing via gateways, and without a gateway, communication may fail.
💻 In Cisco Packet Tracer, a simulation demonstrates subnetting, routing, and communication behavior, including when devices without a gateway cannot communicate across subnets.

Q & A

What is the primary objective of this practicum?
-The main objective is to understand subnetting concepts, the function of gateways, and to simulate network scenarios using Cisco Packet Tracer.
What is subnetting in IP addressing?
-Subnetting is the process of dividing a large network into smaller sub-networks (subnets). This is typically done with IP address classes A, B, and C. Subnetting reduces the number of hosts in each network but increases the number of networks.
What happens to the host ID when subnetting is applied?
-In subnetting, part of the host ID is sacrificed to create additional network IDs, resulting in a new, smaller set of host IDs for each subnet.
What are the two special IP addresses in a subnet?
-The two special IP addresses in a subnet are the Network address, which identifies the subnet, and the Broadcast address, which is used to communicate with all devices in the subnet.
How is a Class C network typically subnetted?
-In a Class C network, subnetting can divide the network into smaller blocks. For example, subnetting with a /25 prefix will create two subnets, each with 128 IP addresses. Subnetting further, such as with /26 or /27, creates more subnets but reduces the number of IP addresses in each subnet.
What is the formula used to calculate the subnet mask?
-The subnet mask is calculated by subtracting the block size from 256. For example, for a /25 subnet, the block size is 128, so the subnet mask is 255.255.255.128.
What is the impact of not assigning a gateway to certain PCs in the scenario?
-If a PC does not have a gateway assigned, it will be unable to communicate with devices outside of its own subnet. This is because the gateway is responsible for routing traffic between different subnets.
How does communication between PCs in different subnets work in this scenario?
-Communication between PCs in different subnets involves sending the packet to a router via the gateway. The router forwards the packet to the appropriate subnet, allowing communication between devices on different networks.
Why is the communication between some PCs incomplete in the simulation?
-Communication is incomplete for PCs that lack a gateway. Without a gateway, these PCs cannot route traffic to devices in other subnets, causing the communication to fail.
What is the role of simulation mode in Cisco Packet Tracer during this practicum?
-The simulation mode in Cisco Packet Tracer allows users to observe the path of packets as they move through the network, helping them understand how packets are routed between devices and subnets.

Outlines

00:00

💻 Understanding IPv4 Subnetting Concepts

This paragraph introduces the second practical lab on IPv4 subnetting. The primary objectives are to understand the concept of subnetting, the function of the gateway, and stimulate the network using Cisco Packet Tracer. It defines subnetting as the process of dividing a network into smaller subnets, usually applied to IP addresses in Class A, B, and C. The process increases the number of network IDs at the expense of host IDs, resulting in more networks but fewer hosts per network.

05:03

🔢 Subnetting Calculations for Different Classes

This section provides detailed calculations for subnetting across Class C networks. It explains how to divide networks into smaller subnets and gives examples of splitting a Class C network into subnets with different sizes (e.g., /25, /26). The example covers the conversion of network blocks, such as dividing a Class C network into four subnets, and includes the concept of network and broadcast addresses within each subnet.

10:06

🔧 Network Simulation Setup with Subnets

This paragraph walks through the process of setting up a network simulation using Cisco Packet Tracer. It includes a detailed example where two subnets (192.168.1.0/26 and 192.168.1.128/26) are connected via a router. Three PCs are assigned to each subnet with specific IP addresses and subnet masks. Some PCs are set up without a gateway, impacting their ability to communicate with other subnets.

15:08

🌐 Verifying Network Communication in Simulation

This final section discusses how to verify network communication between devices in the simulation. By sending simple PDU packets from one PC to another, it demonstrates the success or failure of communication based on gateway configurations. The explanation highlights how devices in the same subnet communicate directly, whereas communication across different subnets requires a gateway. It concludes by reiterating the importance of gateways in ensuring bidirectional communication between subnets.

Mindmap

Keywords

💡Subnetting

Subnetting is the process of dividing a larger network into smaller, more manageable sub-networks (subnets). In the video, subnetting is central to the practical exercise, allowing for the creation of multiple smaller networks by borrowing bits from the host portion of an IP address. This is done to enhance network efficiency and security by reducing broadcast traffic. The video illustrates this through subnetting examples for Class C IP addresses.

💡IP Address

An IP (Internet Protocol) address is a unique identifier assigned to each device connected to a network, allowing communication between devices. In the video, IPv4 addresses like 192.168.1.1 are used to configure devices within different subnets. The video demonstrates how subnetting affects the allocation and structure of IP addresses.

💡Class C IP

Class C IP addresses are a type of IPv4 address range commonly used for small networks. These addresses range from 192.0.0.0 to 223.255.255.255, with the first three octets representing the network portion. In the video, subnetting exercises are performed on Class C networks, showing how the available 256 IPs can be divided into smaller subnets.

💡Gateway

A Gateway is a device that connects different networks and facilitates communication between them. In the video, routers act as gateways between subnets. PCs in different subnets need a properly configured gateway to communicate across subnet boundaries, as demonstrated in the simulation exercises.

💡Broadcast

Broadcast refers to the transmission of data to all devices in a network. In the context of the video, each subnet has a specific broadcast address, which is the last address in the subnet range. This address is used to send a message to all devices within the subnet. The video highlights how subnetting reduces the scope of broadcast traffic by dividing the network.

💡Network ID

A Network ID is the portion of an IP address that identifies the network to which a device belongs. In the video, subnetting is shown to create new Network IDs by dividing the original network into smaller subnets. Each subnet has its unique Network ID, which helps distinguish it from other networks.

💡Subnet Mask

A Subnet Mask is used in conjunction with an IP address to define the network and host portions of the address. It determines which part of the IP address represents the network and which part represents the hosts within that network. In the video, different subnet masks (such as /25, /26, /27) are applied to divide a Class C network into smaller subnets.

💡Cisco Packet Tracer

Cisco Packet Tracer is a network simulation tool used for designing and testing network configurations. In the video, it is used to simulate subnetting exercises and visualize how data flows between devices in different subnets. It helps in demonstrating how subnetting and gateway configurations affect network communication.

💡Simulation Mode

Simulation Mode in Cisco Packet Tracer allows users to observe how data packets move through the network. In the video, this mode is used to track the flow of data from one PC to another, showing the role of gateways and subnetting in network communication. It helps to visualize whether data packets are properly routed or blocked due to misconfigurations.

💡Slash Notation (CIDR)

Slash notation, or Classless Inter-Domain Routing (CIDR), is a method for representing subnet masks more efficiently. It uses a slash followed by a number to indicate how many bits are used for the network portion of the IP address. In the video, notations like /24, /25, and /26 are used to describe different subnet masks and their effects on network division.

Highlights

Introduction to the concept of subnetting in IPv4, focusing on dividing a network into smaller subnets.

Explaining the practical purpose of subnetting, such as reducing the number of hosts in each network but creating additional subnets.

Describing the process of subnetting where part of the host ID is sacrificed to create additional network IDs.

Highlighting the importance of two specific IP addresses in any subnet: the network address (identifying the subnet) and the broadcast address (used to reach all devices within the subnet).

Explaining how to calculate the subnet mask for different classes of IP addresses (Class A, B, and C).

Detailed example of subnetting a Class C network into smaller subnets, starting with a block of 256 IP addresses (Class C /24).

Illustrating how dividing a Class C network into smaller subnets (e.g., /25 and /26) reduces the number of hosts in each subnet but increases the number of available subnets.

Discussion of a four-part subnetting example where the network is divided into four subnets (0-63, 64-127, 128-191, 192-255).

Using Cisco Packet Tracer for network simulation to test and visualize the subnetting concept, including the configuration of IP addresses and gateways.

Explanation of the gateway's role in allowing communication between subnets, particularly in scenarios involving routers.

Demonstrating a real-world example of a network setup involving multiple PCs and routers, with subnetting configurations, to simulate traffic flow.

Explaining why certain devices can communicate across subnets while others cannot, due to the presence or absence of properly configured gateways.

Step-by-step guide for setting up IP addresses and subnet masks in a network simulation using Cisco Packet Tracer.

Highlighting the importance of two-way communication in a network and how a lack of proper gateway configuration can prevent packet delivery.

Demonstrating successful communication between devices within the same subnet, showing how packets are sent and received correctly without routing.