For software testing purposes, we have a Windows 7 box that serves as a virtual machine host. Up to seven VMs run at the same time on the VMHost machine, each in a separate VMWare Player instance. All connect to the local wireless router using the "Bridged" network option. We access the virtual machines from development machines using Windows Remote Desktop. Much of the testing involves networking, using both HTTP and a custom TCP/IP-based file-copy protocol.
For reasons we have not been able to determine, the router grants IP address leases of only one hour to each of the virtual machines. (The host receives normal seven-day leases.) Though the leases get renewed automatically, lease expiration breaks much of our testing, as all open TCP/IP connections on each virtual machine get canceled when the lease is renewed. Even internal connections to "localhost" (127.0.0.1 or ::1:) get broken. Our software does automatically reestablish broken connections, but whatever operation was in progress can fail. This wreaks havoc with the QA effort on our networking software!
Rarely, a different IP address gets assigned to a VM when the lease expires. This is an added complication, as it can take several minutes for the local DNS caches to be updated. But this is rare, and we could live with it.
We would prefer to leave current router settings for dynamic address assignment, instead of moving to a fixed-IP mechanism.
Questions:
- What causes the leases to be granted with such short (one-hour duration)? Is this an issue with the router, with VMWare Player networking settings, or with network configuration of the individual virtual machines? (For example, might the router be restricting lease duration because the same MAC address requests multiple IP addresses?)
- What can we do to change the lease duration?
- Would switching to fixed IP addresses solve the problem?
Thanks in advance for any help with this.