Are there any issues when using LoadRunner with machines that have multiple NICs?
Multiple NIC can cause communication problems between the Controller and the Load Generator
In general, having multiple NICs in a machine could cause a problem with the Controller-Load Generator connectivity.
The reason is that the communication may not always be tagged with the correct interface when sending a reply to a request from the Controller. If a message is sent out from one NIC to a host machine, but that host knows the Controller by the other interface, then that message will be considered to have come from a different Controller, and is ignored as a Load Generator can only serve one Controller at a time.
Likewise, messages sent from a Load Generator machine to the Controller on an NIC other than the one the Controller knows, will not be marked as comming from the correct host. This may cause the Controller to think the host is not responding. In cases like this, the communication gets "lost" and will result in time-out errors or similar. Removing extra interfaces resolves the problem.
Other possible solutions involve always using the "primary" interface, which is listed under Network and Dial-Up Connections -> Advanced -> Advanced Settings -> Adapters and Bindings in Windows 2000. This dialog allows you to reorder the network interfaces to change their priority. Always reference the top most adapter when connecting with the LoadRunner Controller.