The most cost-effective solution is to upgrade the license on the existing hardware. The Citrix ADC MPX 59xx series appliances utilize a "Pay-As-You-Grow" licensing model. This allows an organization to increase the performance and capacity of their current appliance by simply applying a new license key, without needing to purchase and deploy new hardware. Upgrading the license from an MPX 5901 (1 Gbps throughput) to an MPX 5905 (5 Gbps throughput) leverages the existing hardware investment and avoids the costs and operational overhead associated with a full hardware replacement, making it the most cost-effective approach to handle the forecasted growth.

A. The addition of another MPX 5901 appliance: This would require purchasing a second physical appliance, increasing costs for hardware, power, cooling, and management overhead. It is less cost-effective than a license upgrade.

B. A hardware upgrade to a Citrix ADC MPX 8905: This is a "forklift upgrade," requiring the purchase of a new, more expensive appliance. A license upgrade to an MPX 5905 achieves the same 5 Gbps throughput on existing hardware, making this option less cost-effective.

D. A hardware upgrade to a Citrix ADC SDX 15020: This is a significant and expensive hardware upgrade to a multi-tenant platform. It provides far more capacity and features than required, making it the least cost-effective option for this scenario.

1. Citrix ADC MPX/SDX Appliance Datasheet: This document outlines the specifications for various ADC models. It details the "Pay-As-You-Grow" feature

showing that models like the MPX 5901

5905

and 5910 are on the same hardware platform and can be upgraded via a software license.

Source: Citrix. (2022). Citrix ADC MPX/SDX Appliance Datasheet.

Reference: See the table "Citrix ADC MPX appliances (1U)" which lists the MPX 5901

5905

and 5910 models and their respective throughputs. The document's overview section typically describes the Pay-As-You-Grow licensing benefits.

2. Citrix Product Documentation - Licensing for Citrix ADC: The official documentation explains how licensing controls the capacity and features of an ADC appliance. It confirms that performance upgrades on certain platforms are enabled by installing a new license file.

Source: Citrix Product Documentation.

Reference: Section: "Licensing for Citrix ADC

" subsection on "Bandwidth Licenses." This section explains that bandwidth limits are enforced by the license and can be upgraded by obtaining and applying a new license.