Re: [Boost-users] udp with virtual network cards

Subject: Re: [Boost-users] udp with virtual network cards
From: Jim Bell (Jim_at_[hidden])
Date: 2012-03-28 14:24:27

On 3/28/2012 7:41 AM, Gianni Ambrosio wrote:
>
> I mean the network adapter created by a virtualization tool (like 
> VMware).
> I verified that a client on win7 with a such network adapter active 
> does not work (I'm talking about udp multicast, while TCP works 
> perfectly). On the other side if I disable the "real" card and then 
> enable it again, udp starts magically working.
>
> Any idea?

I don't have a link for this, but I know well that, on a Windows machine 
with more than one NIC (network adapter), outgoing broadcast messages 
have the FIRST network adapter's address as the return address on 
messages going out all NICs.  The receiver on the second network uses 
that (wrong) address for the response, and the response doesn't get back 
to the PC. Disabling and enabling may switch which NIC is considered 
first (not sure about that).

I've seen this on Windows XP but haven't tried to repeat it on Windows 
7. The problem is in the OS.

Hope that helps.
-Jim