Lec-46: Disadvantages of Classful Addressing | IP addressing | Computer Networks

Summary

In this video, the host discusses the major problems with Classful IP addressing, including the wastage of IP addresses, lack of flexibility, maintenance complexities, and security concerns. Class A, B, and C networks often allocate more or fewer addresses than needed, leading to inefficiency. Large networks are hard to maintain and secure, causing issues with troubleshooting and unauthorized access. The solution proposed is to adopt classless addressing and subnetting, which offer better flexibility, efficiency, and security, while addressing these fundamental problems in Classful addressing.

Takeaways

• 😀 Classful IP addressing leads to wastage of IP addresses, especially in Class A and Class B networks.
• 😀 Class A networks provide over 16 million hosts, which is excessive for most organizations' needs.
• 😀 Class B networks provide approximately 65,000 hosts, which is still a large number, but more appropriate for some organizations.
• 😀 Class C networks have only 256 hosts, which may be insufficient for certain needs.
• 😀 Large organizations often require more IP addresses than what Class C offers, but less than what Class A or B provides.
• 😀 A key issue in Classful addressing is the inability to allocate IP addresses flexibly according to user needs.
• 😀 When a user needs a specific number of IP addresses (e.g., 1024), it is difficult to allocate the exact amount using Classful addressing.
• 😀 Class D and E IP addresses are reserved for multicasting and future use, leading to additional wastage of IP address space.
• 😀 Large networks, like those in Class A, are difficult to maintain and are more prone to errors and security issues.
• 😀 Security risks increase as network size grows, as larger networks provide more potential points of vulnerability.
• 😀 Subnetting can help reduce maintenance challenges and security risks by dividing large networks into smaller, more manageable subnets.

Q & A

What is the main issue with Classful IP addressing?

The main issue with Classful IP addressing is the wastage of IP addresses due to the fixed size of IP address blocks assigned to networks. These fixed classes do not allow flexibility in allocating the exact number of IP addresses needed.

How many hosts can be supported in a Class A network?

A Class A network can support 2^24 hosts, which equals more than 16 million hosts per network.

Why are Class A networks inefficient for large multinational companies?

Class A networks are inefficient for large multinational companies because they provide an excessive number of IP addresses (over 16 million), which is far more than most companies actually require, leading to significant wastage.

How many hosts are available in a Class B network, and is it always suitable for organizations?

A Class B network can support 2^16 hosts, approximately 65,000 hosts. While this is a moderate number, it may still be too large for some organizations, leading to unnecessary wastage of IP addresses.

What are the limitations of a Class C network in terms of host capacity?

A Class C network supports only 256 hosts, which is too small for many organizations that require more IP addresses, creating a problem of insufficiency for certain needs.

What happens in Class D and Class E networks in terms of IP address usage?

In Class D, IP addresses are reserved for multicasting, and in Class E, IP addresses are reserved for future use. These networks waste a large number of IP addresses, with 2^28 addresses being reserved in both classes.

How does Classful Addressing lack flexibility in IP address allocation?

Classful Addressing lacks flexibility because it assigns fixed address blocks based on class (A, B, C), which often results in over-allocation or under-allocation, depending on the organization's requirements.

What is subnetting, and how can it help address the problems of Classful Addressing?

Subnetting is a method of dividing large networks into smaller, more manageable sub-networks. It helps reduce the issues of IP address wastage, maintenance complexity, and security vulnerabilities by allowing more efficient use of IP address space.

What are the maintenance challenges associated with large networks in Classful Addressing?

In large networks, maintenance becomes challenging due to the complexity and size of the network. Identifying and fixing errors, along with ensuring the network's security, is much harder in a large network compared to smaller, segmented subnets.

How does Classless Addressing (CIDR) solve the problems of Classful Addressing?

Classless Addressing (CIDR) solves the problems of Classful Addressing by providing more flexible IP address allocation. It allows network administrators to allocate exactly the number of IP addresses required, reducing wastage and improving efficiency in addressing.