IP Address Discovery for DHCP Networks

Platform9 provides support for either a static IP address pool or external DHCP servers on a given network.

This article describes the mechanism and troubleshooting for cases when an IP address for a given virtual machine (VM) is not visible.

Troubleshooting IP Address Discovery for DHCP Networks

Platform9 uses host's arp-cache to determine a VM's IP address. Arp-cache is typically populated when an instance has network activity.

If there is no network activity, the arp-cache is not populated and hence the instance won't show the IP address. Practically, this is not an issue as every VM has one or another entity talking over the network.

Some of the latest kernels and bridges that have bonds as their slaves do not populate the arp cache because of which IPs are not discovered. If this is something that you see please contact Platform9 support (support@platform9.com) and we can enable a more advanced IP discovery process for your hosts.

In the case of Platform9 for VMware, the IP address for an instance is retrieved via VMwareTools installed on the instance. If this is not present, you may not see the IP address populated.

 


December 17, 2015