I am planning to build the network in the attached diagram using a stand alone router (GCC6020 in this case) with a GWN7822P Layer 3 switch. My question is, since my switch is layer 3 there is no need to route any LAN traffic through the router. I ask because my current ISP service is 500Mbs and have no real need for anything much faster. So the router in my case just needs to support whatever speed my ISP provides and the 6Gbs routing speed of the 6020 is useless for me. I could actually use the 6010 with 2.5Gbs routing speed and 1Gbs IPsec VPN Throughput.
Great question and you’re correct. If you do L3 switching the switch can route between the VLANs at wire speed. The GCC just becomes your gateway of last resort at that point. We do this with camera systems all the time.