Out of the box, ovirt creates a default cluster with a default mac pool of size 96. This is typically to small. Let us edit dbscripts/data/00220_insert_mac_pool_ranges.sql so that new installations have more macs by default. 00:1a:4a:16:01:00 — 00:1a:4a:16:04:ff (1024 macs) is a more reasonable size.
Verified on - 4.2.0-0.0.master.20170702100738.git46a9f67.el7.centos The default MAC Addresses Range now for freshly-installed ovirt-engine is 00:1a:4a:16:01:00 — 00:1a:4a:16:04:ff (1024 macs)
This bugzilla is included in oVirt 4.2.0 release, published on Dec 20th 2017. Since the problem described in this bug report should be resolved in oVirt 4.2.0 release, published on Dec 20th 2017, it has been closed with a resolution of CURRENT RELEASE. If the solution does not work for you, please open a new bug report.