Hi Yaseen,
> I have VCNI pools configured. I read some where that 5.1 supports only VXLAN. Can someone pls tell me if I am going to have issues with vapps running with VCNI confiugrations??
VCD 5.1 supports VCNI network pools. It also support VXLAN. You should be able to upgrade without running into problems with your VCNI network pools.
> Also pls advice if upgrading only vCD and vSM to 5.1 and leaving vcenter and ESXi at 5.0 will create any problems on exiting VMs?? Pls advice if my upgrade plan is correct.
Please check support matrix and upgrade guides.
-Bhaskar.