Is NSX-T Edge Cluster required for T0 Gateway?

[ShuaiY]

From what I read, Edge cluster is actually optional for both T0 and T1 gateways...I am certain for T1 but I am not 100% sure about T0...

Say I only have a one-tier NSX. When I create the T0 Gateway, I did not select the edge cluster as it is not marked as mandetory field... But when I go back to edit the T0 that I just created, NSX Manage auto selects the Edge Cluster (I can also see NSX Manager created a Gateway firewall associated to this new T0)...This tells me that Edge is kinda required for T0. But I could also remove the edge cluster from the T0 and save...There is no error...

So is edge cluster required for T0 gateway if I would not use any SR function/features? If so, but is BGP (not for between T0 and T1) or just static routing running as the SR function? If the BGP/Static routing are indeed the SR function, why does NSX manager still allow me to configure those routing without selecting Edge cluster? 

[ShuaiY]

Actually just did a quick test in a NSX-T 3.0 environment, "remove the edge cluster from the T0 and save...There is no error..." might be a bug...If I switch to Manager role, the newly created T0 is still associated with the edge cluster even there is no Edge cluster shown in Policy role...

[Sreec]

If you need to host stateful services such as NAT, load balancer, or firewall you need to select Edge Cluster. That being said a service router will always be created when we select an edge cluster even if you don't use/configure a stateful service feature.