Subnetting A Class B IPv4 Network

Subnetting A Class B Ipv4 Network

Subnetting a Class B IPv4 Network. Give one (1) example of a class B IPv4 network. Next, imagine that you want to divide your example into subnets, each with 126 hosts. Identify the subnet mask that you would use and the number of networks that would be available. Provide a rationale for your chosen mask. Explain the steps you took to create the subnets. Assess the need for subnetting in an organization with which you are familiar. Determine whether or not you would recommend subnetting for such an organization. Provide a rationale for your response.

Paper For Above instruction

Subnetting a Class B IPv4 network is a fundamental practice in network management that allows organizations to efficiently allocate IP addresses, improve security, and simplify network management. In this paper, I will provide a specific example of a Class B network, explain the process of subnetting for a given host requirement, evaluate the need for subnetting in a hypothetical organization, and justify my recommendations accordingly.

Example of a Class B IPv4 Network

A typical example of a Class B IPv4 network is 172.16.0.0. This network falls within the range of 128.0.0.0 to 191.255.255.255, designated for Class B addresses. Class B networks are identified by the first two bits '10' in their binary form, allowing for a large number of hosts per network, which makes them suitable for medium to large organizations.

Subnetting for 126 Hosts per Subnet

To divide the network 172.16.0.0 into subnets that can support 126 hosts each, one must first determine the appropriate subnet mask. The key calculation involves identifying the number of host bits needed to support 126 hosts. This requires at least 7 bits for hosts (since 2^7=128 addresses), but subtracting 2 addresses for network and broadcast addresses leaves 126 usable host addresses.

The default Class B subnet mask is 255.255.0.0 or /16. To create subnets with 126 hosts, additional bits must be allocated to the network portion, borrowing from the host bits. Since 7 bits are necessary for hosts, the remaining bits in the third octet can be used for subnetting.

By borrowing 1 bit from the third octet, the new subnet mask becomes 255.255.255.128 (/25). This mask provides 2^1 = 2 subnets in the third octet, each with 128 addresses, of which 126 are usable for hosts. Specifically, this yields:

- Number of subnets: 2 (because of the borrowed bit)

- Hosts per subnet: 126 usable addresses (128 total minus network and broadcast addresses)

Steps to Create the Subnets

1. Determine the number of host bits needed: For 126 hosts, 7 bits are required.

2. Identify the subnet mask: Borrowing 1 bit from the third octet results in 255.255.255.128.

3. Calculate subnet addresses: Starting from 172.16.0.0, subnets are:

- 172.16.0.0/25 (hosts 172.16.0.1 to 172.16.0.126)

- 172.16.0.128/25 (hosts 172.16.0.129 to 172.16.0.254)

4. Determine broadcast addresses: The broadcast addresses are 172.16.0.127 and 172.16.0.255 respectively.

Organisational Need for Subnetting

In a typical organization, subnetting is crucial for managing IP address space efficiently, segregating network segments, and enhancing security. For example, a company with multiple departments—such as HR, finance, and IT—would benefit from subnetting by isolating traffic within departmental subnets, reducing congestion, and increasing control over access.

In this scenario, I would recommend subnetting because it allows better network administration, easier troubleshooting, and security controls. It also helps in conserving publicly routable IP addresses, especially when IPv4 addresses are scarce.

Rationale for Recommendations

The primary benefit of subnetting in organizations is improved network performance and security. By segmenting the network, organizations can reduce broadcast domains, control traffic flow, and enforce access policies more effectively. Additionally, subnetting enables easier scalability; future network expansion can be achieved by further subnetting existing networks rather than acquiring entirely new IP blocks (Kurose & Ross, 2017).

Conclusion

Subnetting a Class B network such as 172.16.0.0 into subnets supporting 126 hosts each involves choosing an appropriate subnet mask, which in this case is 255.255.255.128 (/25). This approach maximizes the utility of the IP address space and supports the organizational need for network segmentation. For most medium-sized organizations, subnetting is essential for effective network management, security, and scalability. Consequently, implementing subnetting in such environments is highly recommended.

References

  • Kurose, J. F., & Ross, K. W. (2017). Computer Networking: A Top-Down Approach (7th ed.). Pearson.
  • Forouzan, B. A. (2012). Data Communications and Networking (5th ed.). McGraw-Hill Education.
  • Stallings, W. (2013). Data and Computer Communications (10th ed.). Pearson.
  • Odom, W. (2017). CCNA Routing and Switching 200-125 Official Cert Guide. Cisco Press.
  • Odom, W. (2020). CCNA 200-301 Official Cert Guide. Cisco Press.
  • Hucaby, D. (2003). CCNA Certification Guide. Cisco Press.
  • Comer, D. (2018). Internetworking with TCP/IP. Pearson.
  • Alexander, K., & Judd, M. (2012). IPv4 and IPv6 Addressing and Subnetting. Network World.
  • Gordon, J., & Dutta, S. (2002). Fundamentals of Network Security. Wiley.
  • Tanenbaum, A. S., & Wetherall, D. J. (2011). Computer Networks. Pearson.

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