1 - CDPv1 and CDPv2 are compatible with each other and should work since they are interoperable.
2 - Until 16.1 EXOS uses CDPv1 .
3 - From 16.2 and above, EXOS uses CDPv2 by default.
4 - Please be informed that both CDPv1 & v2 are not present in EXOS 16.2 or 21.1
5 - CDPv2 is just extended version of CDPv1, so there is no CDPv1 present in 16.2 or 21.1
6 -There is no command to force CDPv1 in EXOS 21.1 version.