I am starting the process to put together a study lab for ccsp. Beginning with the hardware requirements for secur. Is it an advantage in opting for a modular router with 16mb of flash already there? Is it easier to upgrade Dram than flash? Is adding a 2nd WAN card comparable process to PCI cards in a PC? How may routers are needed? Why would you choose a modular router such as the 3620 or 3640 over the 2600 series?