Universal segment ID
The universal segment ID pool is used to assign VNIs to universal logical switches, to ensure that we don't use the same segment ID pool for local and global logical switches; there would be overlapping segment IDs in that eventually.
The following figure shows Universal Segment ID pool creation:
The whole purpose of creating universal logical switches is to span the logical network across vCenter sites without doing traditional complex routing and switching. That way, universal logical switches will be available on all the vCenter Servers in the cross domain NSX site and we can simply connect virtual machines to those logical switches. The virtual machine logical switches will always remain as port groups and NSX will take care of cross vCenter switching. Haven't we configured a more simplified Layer 2 switching than this? First of all, was it possible do a Layer 2 switching like this in the past? I strongly believe we have all already moved away from legacy network...
