I am about to upgrade my WAN with Cisco routers and a Cisco Pix firewall. I have vendors coming in to install and configure. We have 3 locations and everything will be accessed at headquarters (including the internet). The subnets they are givingme are 10.16.19.x, 10.16.20.x, and 10.16.21.x. They are giving me a mask of 255.255.255.0. My ISP has to reconfigure my cable router for the new IP addresses. They said they have to use a mask of 255.255.0.0 for the 3 subnets. Is this going to work?
