Smart System Upgrade (SSU) provides the ability to upgrade the EOS image with minimal traffic disruption. SSU is supported on a standalone L2 only VTEP with EVPN-VXLAN configuration with the following scale is supported as of EOS 4.32.0F with the following scale numbers

Leaf Smart System Upgrade (SSU) provides the ability to upgrade the EOS image with minimal traffic disruption.Note: It is possible that SSU shutdown and bootup are not supported in the same image. If a product has shutdown support in image A and bootup support in a later image B, then SSU upgrade cannot be performed from image A to any images earlier than image B, including image A itself. However, upgrading from image A to image B onwards is allowed.