Does vCenter Enhanced Linked Mode (ELM) is a requirement for Cross-vCenter NSX implementation ?
No, that is not a requirement for Cross VC NSX.
Can I still use Universal objects (ULS, UDFW and UDLR with Local Egress) if I don't have ELM between two sites (Two vCenter Domains) ? And, if I upgrade from 6.1.5 to 6.2.2, can I convert existing objects to universal objects ?
The current implementation, we have two sites on 6.1.5 in two different vSphere domain. But, I was wondering if I upgrade both NSX instance to 6.2.2 to convert existing LS, DLR to Universal objects. Eventually use UDLR and ULS with Local Egress feature for DR.
On the Cross-vCenter NSX installation guide, Cross-Vcenter NSX mentions it is possible to use all the universal objects, only restriction is Managing vCenters seperately.
An addtitional point may be Enhanced Link mode provides vMotion from the GUI between vCenters (page 34):
NSX-V Multi-site Options and Cross-VC NSX Design Guide
Some consideration should be given to greenfield deployments when considering future growth
and needs. Cross-VC NSX and Cross-VC in general require a single shared SSO across vCenter
domains for Enhanced Link Mode and for moving workloads across vCenter boundaries from
the GUI. The reason is, when using the vSphere Web Client, both vCenter Server instances must
be in Enhanced Linked Mode for visibility and must be in the same vCenter Single Sign-On
domain so that the source vCenter Server can authenticate to the destination vCenter Server.
If these points is not very important for the design, ELM may not be deployed for both Local Egress, and Universal Objects.
ELC is not a requirement of using Cross-VC NSX. Also, any logical switch that you connect to a universal transport zone becomes a universal LS so its not really a need to "convert" as it were. With the DLR you have to deploy it as universal. You can't convert it later. You can also use local egress without the need for ELC.
Thanks both for the input. We don't have a requirement to do cross vCenter vMotion. This will be a active/passive data center implementation. Going to upgrade NSX to 6.2.2 soon and get some UDLRs going !