I have written the 2nd part of the Hyper-V Networking and Configuration.
The big difference that we see between Scenario 1 and Scenario 2 is the communication to the External LAN (e.g. VM1 through VM3 talking to Server1 through Server3 on LAN). The moment you see the requirement for External communication you’ll think of using an External Virtual Switch.
To achieve the requirements of this second scenario, you can use any of the configuration methods as discussed earlier but the most suitable methods to use are:
- Using another Physical NIC Method (applies when External networking is configured).
- Using Hyper-V Virtual Switch and VLAN Tagging Method.
And the scenario looks like below:
More explained at http://www.simple-talk.com/sysadmin/virtualization/microsoft-hyper-v-networking-and-configuration—part-2/
Nirmal.