Question

An ISP with a class \(\mathrm{B}\) address is working with a new company to allocate it a portion of address space based on CIDR. The new company needs IP addresses for machines in three divisions of its corporate network: Engineering, Marketing, and Sales. These divisions plan to grow as follows: Engineering has 5 machines as of the start of year 1 and intends to add 1 machine every week; Marketing will never need more than 16 machines; and Sales needs 1 machine for every two clients. As of the start of year 1, the company has no clients, but the sales model indicates that by the start of year 2 , the company will have six clients and each week thereafter gets one new client with probability \(60 \%\), loses one client with probability \(20 \%\), or maintains the same number with probability \(20 \%\). (a) What address range would be required to support the company's growth plans for at least seven years if marketing uses all 16 of its addresses and the sales and engineering plans behave as expected? (b) How long would this address assignment last? At the time when the company runs out of address space, how would the addresses be assigned to the three groups? (c) If CIDR addressing were not available for the seven-year plan, what options would the new company have in terms of getting address space?

Short answer

Total address block in Class B CIDR (/23) blocks accomodating approximately 7 years total engineers-new marketing-sales max.

Step-by-step solution

Calculate Engineering Growth

Engineering starts with 5 machines and adds 1 machine each week. Over 7 years each year has 52 weeks, hence total weeks in 7 years = 7 * 52 = 364. Total machines needed = 5 + 364 = 369.

Calculate Marketing Requirement

Marketing has fixed requirement of 16 machines.

Calculate Sales Growth

Sales start with 0 machines and adds 1 machine for every 2 clients. Initial Year 1 = 6 clients, hence, 3 machines. Subsequently, calculate using probabilities over 7 years.

Compute Weekly Client Increase Probability

Probability each week: 60% gain, 20% loss, 20% same. Over 7 years: flips = 6 + (0.6 * 52 * 6.6 - (0.2 * 52 * 6.6) = 213.12. Thus approx. 213.12 / 2 = 106 some extra rounding off for rough calcualtion. sales end.

Calculate Total Machines

Sum of machines required: Engineering: 369 Marketing: 16 Sales: 106. Total = 491

Map to CIDR Range

Aggregate total: Minimum CIDR block = 2^9 = 512 . thus we have more than 491

Address Distribution by CIDR

Address Class in octets is B with (/23 since we map 512 closest due to pow#2)

Address Conservation Duration

Projected duration consideration of Sci and Engineering growth accommodates beyond 7year term

Alternative if no CIDR

Calculate An unstructured setup risk and expand class range consideration

Key concepts

IP address allocation

In order to provide network connectivity to different machines and devices across a network, IP address allocation is essential. Each device will need its own unique IP address to communicate effectively. In CIDR, address allocation is managed by efficiently dividing the IP address space into smaller, more flexible subnetworks. These subnetworks are defined by the number of bits dedicated to the network portion of the address and allow for greater precision in allotment. For our scenario, the calculations revealed a need for 369 machines in the Engineering division, 16 machines in the Marketing division, and approximated 106 machines in the Sales division.

Breaking down these figures is crucial in avoiding wasted IP addresses. With classless addressing (CIDR), the ISP can allocate precisely the number of addresses required. Over 7 years, the total IP addresses required are about 491. This ensures the organizations can efficiently distribute addresses without reserving unnecessary large blocks of addresses.

network growth planning

Network growth planning is a strategy that helps companies anticipate their future networking needs. By predicting the growth and expansion, organizations can avoid running out of IP addresses and ensure reliable network performance. In the problem context, the Engineering division plans to grow by one machine each week over seven years, Marketing will always need up to 16 machines, and the Sales division's growth is dependent on the number of clients.

Planning ahead involves looking at these growth rates and calculating the maximum possible number of machines each division would need. For example, the Engineering division requires addresses for up to 369 machines after 7 years, considering a growth of 1 machine per week from an initial count of 5. Similarly, predictions for the Sales division, with close consideration of probabilities for gaining and losing clients each week, allow for a structured growth plan. Effective network growth planning ensures that the network can scale seamlessly as the number of devices increases, maintaining smooth operations.

address space management

Address space management is the efficient utilization and oversight of an IP address pool within a network. This ensures addresses are assigned responsibly and are readily available as the network expands.

If the company's network grows according to the given predictions, managing address space through CIDR becomes vital. CIDR facilitates more flexible and precise allocation by adjusting subnet masks, unlike traditional classful network addressing. For a total of 491 machines over 7 years, a /23 CIDR block (which allows for 512 IP addresses) is sufficient. This method of address space management ensures that no addresses are wasted, and there’s room for some unexpected growth.

Proper address space management also considers the potential saturation of allocated addresses and plans appropriately. Avoiding the exhaustion of the IP address range ensures that divisions like Engineering, Marketing, and Sales can continue to operate and expand without interruption. This approach significantly improves network efficiency and organizational scalability.