It is confirmed that the iproute problem is a bug of CentOS or Fedora linux system on OpenVZ platform.
BurstNet sent a email to me about this issue.
We are contacting you to make you aware of an issue that is affecting OpenVZ Red Hat based VPS servers. This issue can effect Fedora and Centos based systems hosted on any VZ platforms. So this is not isolated to Burstnet OpenVZ VPS servers. If you do not have a Red Hat based Linux OS installed, then you can disregard this email.
An update for Red Hat based operating systems was recently released by the developers of these Linux distributions, that breaks the IP route software installed on them. If the IP route software is broken, then the networking service for the operating system will not start and the VPS will not connect to the network. When a VPS is affected in this manner, Veportal may report that the VPS is started, however it will not be accessible over the internet. Please note that BurstNET does NOT push updates to VPS operating systems.
If the VPS user has this problem, he can create a ticket and just sit and wait. They can fix it for you.
I have same problem on my Linode VPS, mentioned last week.
There are some talks on internet forum.
1, webhostingtalk post
2, CentOS forum post