I've checked version compatibility
But, I want to make sure from this.
Our Heavy forwards is 7.1.2, Indexer and the others will be 7.3.x
So is it compatible perfectly?
did you already seen this url https://docs.splunk.com/Documentation/VersionCompatibility/current/Matrix/Compatibilitybetweenforwar... ?
Anyway, the result is that this versions 7 of forwarder can send both event data and metrics data to versions 7 of indexers.