Re: VMware and bridged networking

["Ralf G. R. Bergs" <rabe@RWTH-Aachen.DE>]

On Fri, 11 Aug 2000 16:19:35 -0600 (MDT), Rick Macdonald wrote:

[...]
>> Are you using DHCP for your LAN, too? Or do you have dial-up networking 
>> only?
>
>This is an office LAN full of Win95/NT machines. So, my NT box uses DHCP,
>and now Linux under VMware does too. 

Hmmm, as I said I don't use DHCP. Maybe this is the problem?

BTW, I've tried assigning the virtual eth adapter an IP address out of the 
same network as my LAN machines -- to no avail. I still can only communicate 
between the guest and host OS, but I can't access the LAN from my guest OS. 
:-(((

>> >Have you tried using an IP addr on the same subnet as NT's original IP?
>> 
>> No, I didn't fiddle with it because I don't know exactly what's going on. 
>> What exactly is the purpose of the IP address that is assigned to the 
>> virtual ethernet adapter? Can I freely choose a different IP?
>
>The idea is that you don't have to go buy a second ethernet adapter. The
>end result is as if you had two cards with separate IP addrs plugged into
>the same net/hub. You need to set up the Linux side with default routes,
>etc, just as if it was a stand-alone box.

Ok, I've tried to analyze the setup.

The virtual ethernet adapter is probably just like an additional real 
ethernet adapter. Thus I have the following setup:

    LAN  --------------+-------------
                       | real eth adapter
                     +-+-+
            host OS  |   |
                     +-+-+
                       | virt. eth adapter
                     +-+-+
           guest OS  |   |
                     +---+

As I said communication between the host and guest OS does work -- I've 
already successfully FTPed between the two machines.

For communication between the guest OS and the LAN to work the host OS must 
be performing proxy ARP for the guest OS. Otherwise the host OS would NOT 
accept packets with a target IP address other than it's own IP address (that 
belongs to the real eth adapter, that is.)

Obviously there must be some problem, maybe with the proxy arping?

Do you agree to this interpretation? What can I do to gain further insight 
about what's going wrong?

Thanks,

Ralf


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