[Ns-developers] Requesting help for csma promiscuous mode

[Gustavo Carneiro]

CsmaNetDevice has this comment in method Receive:

//
// We never forward up packets that we sent.  Real devices don't do this
since
// their receivers are disabled during send, so we don't.  Drop the packet
// silently (no tracing) since it would really never get here in a real
device.
//
  if (header.GetSource () == GetAddress ())
    {
      NS_LOG_LOGIC ("Ignoring packet sourced by this device");
      return;
    }

It turns out that with the combination of promiscuous mode receiving and
SendFrom (for "MAC spoofing", i.e. transmit frame with another source
address), needed to implement a bridge, it is no longer true that packets
sent by this netdevice have a source mac address equal to the netdevice's
own address.  Because of this I am getting infinite packet forwarding loops.

The comment above is enlightening, and leads be to believe the best solution
is to do what real devices do, i.e. disable their receiver during packet
transmission.  I am going to try to do this, assuming it to be ok.  But any
hint is appreciated.

Thanks.

-- 
Gustavo J. A. M. Carneiro
INESC Porto, Telecommunications and Multimedia Unit
"The universe is always one step beyond logic." -- Frank Herbert