I am designing a new LAN setup and am new to VLANs. I understand that VLANs reduce broadcast traffic and segregate the LAN into different segments/subnets. I have 4 VLANs (10, 20, 30 and 40). I have a Cisco router out to my ISP. To get all 4 VLANs to use the Internet, I have created subinterfaces on the LAN side of the outbound router. This effectively allows all four VLANs to access the Internet via the outbound router, but allows the VLANs to see each other. I can ping from VLAN to VLAN. There no longer seems to be any segregation.
How do I create a LAN that uses a shared Internet connection and maintain the integrity/security of each VLAN?
I apologize if this is a super-simple question.