I work for a company who make a networking product.
The device we create is attached to the testing PC via a second NIC and is on a seperate subnet to the primary nic on the corporate lan.
We are running Win 7 x64 is that makes a great deal of difference!
When we run wireshark, we're seeing the usual broadcast messages etc related to domain machines (i.e. the machine itself is a member of a domain, and keeps sending out broadcasts on all nic's relating network discovery etc)
Can anyone suggest ways of stopping this traffic and guaranteeing we only have the traffic we expect on that one nic?
You need to go to the properties of the second NIC and disable the "Client for Microsoft Networks" and "File and Printer Sharing for Microsoft Networks" components; then, you should go to the advanced TCP/IP settings and disable NetBIOS over TCP/IP.
It should also be good to disable automatic DNS registration and ensure no default gateway is configured on this second NIC.
What is the traffic you expect on that NIC?
You can unbind whatever network components aren't needed on that NIC, such as:
Client for Microsoft Networks
QOS Packet Scheduler
File and Printer Sharing for Microsoft Networks
Link-Layer Topology Discovery Mapper I/O Driver
Link-Layer Topology Discovery Responder
TCP/IPv6 if it's not needed
Disable NetBIOS over TCP/IP
To unbind these components, simply uncheck the appropriate boxes and/or select the appropriate options.