Which attribute is used to tie all the controllers together by vManage?

The vManage system-ip is the IP address of the vManage controller itself, not the unifying attribute for all controllers and devices.

Region ID is an attribute used for hierarchical network segmentation and routing within the SD-WAN fabric, not the primary identifier that ties all controllers together.

The organization name is a crucial attribute in Cisco SD-WAN that acts as the primary identifier, tying all controllers (vManage, vSmart, vBond) and WAN Edge devices together into a single, cohesive overlay network. This name must be identical across all components for them to establish trust and join the same SD-WAN domain.

Secure device ID is a unique identifier assigned to each device for certificate-based authentication, but the organization name is the overarching logical grouping attribute.