結論
service network restart
すればOK
動作環境
MacOS 10.10.5
Virtual Box 5.0.30
Vagrant 1.9.1
centos/7 1610.01
Vagrantfileの該当の設定
config.vm.network "private_network", ip: "192.168.33.12"
関連していそうなIssues/PullRequest
Vagrant 1.9.1 private networking configures unreachable VirtualBox VM
[Fix service network restart
on RHEL-7 / Fedora]
(https://github.com/mitchellh/vagrant/pull/8052)