Re: [lwip-users] Virtual machines in the same host (bridge).

[Sylvain Rochet]

Hello Norberto,

On Thu, Jan 29, 2015 at 04:42:06PM -0200, Norberto R. de Goes Jr. wrote:
> Hi All.
> 
> I have the following environment:
> 
> - host Windows-7 Professional, 64 bits, with two virtual machines (Virtual
> Box), both  with Fedora-17 Distro, 32 bits;
> - the VM´s network configured as "Internal Network"
> 
> I wrote a small "lwip application" based on unix port (community). It runs
> in VM #1 and a "tap0" device is created with success. In the VM#2 no
> application is running.
> 
> When I "ping" the tap0 IP from the VM#1 the reply is received, no problem.
> I can see the traces reported by lwip like arp received and arp reply. But
> when I "ping" the tap0 from VM#2 I have no answer.
> 
> Faced with the situation, I followed the steps suggested by another solved
> threads from this list, for instance:
> - http://lists.nongnu.org/archive/html/lwip-users/2004-08/msg00006.html
> - http://lists.nongnu.org/archive/html/lwip-users/2012-02/msg00021.html
> Basically, the threads show how to configure a linux bridge (br0) and your
> attached devices.
> 
> But I did not get success still. The pings from VM#2 go from the ethernet
> to the "br0"(VM#1) device and after to the "tap0" device. There the lwIP
> generates an answer and sends it to the asking host. But then the packages
> disappear. They do not go back to the "br0" device (seen with dcpdump).
> 
> Please, are there any restriction in use the lwip library in virtual
> machines hosted on the same server? More specifically with linux bridge use?

Please send the "brctl show" as well as "ip a s" and "ip r s" on both 
machines.

Sylvain

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