VHA6 is an API based content replication system. VHA6 requires no knowledge of the underlying user VCL. VHA6 works by broadcasting a replication request from an origin Varnish node to any number of Varnish peer nodes. The peers then fetch the object back from the origin node. All object attributes are exported from the origin and re-imported on the peer.
The VHA6 replication API requires every request and object to be signed with a time based HMAC-SHA256 signature. This signature is unique per object and secured against the configured VHA6 security token.