Modularity Features and Benefits.
The Cisco 1921 provides significantly enhanced modular capabilities (refer to Table 3) that offer you investment protection.
Most of the modules available on previous generations of Cisco routers, such as the Cisco 1841 ISR, are supported on the Cisco 1921.
Additionally, you can easily interchange modules used on the Cisco 1921 with other Cisco routers to provide maximum investment protection.
Taking advantage of common interface cards across a network greatly reduces the complexity of managing inventory requirements, implementing large network rollouts, and maintaining configurations across a variety of branch-office sizes.