Architecture choices:

ERB: more East and west traffic of the same box , lower latency , Leaf has more feature / may be higher cost

CRB:  more traffic between leaves , Less feature ,  Leaf could be lower cost

Image Added

CRB-Access, CRB-Gateway, DC-Gateway, ERB-UCAST-Gateway, and CRB-MCAST-Gateway roles overlay roles

Centrally-Routed Bridging Overlay Design and Implementation

https://www.juniper.net/documentation/en_US/release-independent/solutions/topics/task/configuration/centrally-routed-overlay-cloud-dc-configuring.html

Edge-Routed Bridging Overlay Design and Implementation

https://www.juniper.net/documentation/en_US/release-independent/solutions/topics/task/configuration/edge-routed-overlay-cloud-dc-configuring.html

https://www.juniper.net/documentation/en_US/release-independent/solutions/information-products/pathway-pages/sg-005-data-center-fabric.pdf

Bridged Overlay Design and Implementation | 74

Centrally-Routed Bridging Overlay Design and Implementation | 95

Edge-Routed Bridging Overlay Design and Implementation | 158

Routed Overlay Design and Implementation | 176