if (m_routingProtocol != 0)

  // RFC 791, pg.25:

  //  Every internet module must be able to forward a datagram of 68

  //  octets without further fragmentation.  This is because an internet

  //  header may be up to 60 octets, and the minimum fragment is 8 octets.

  if (interface->GetDevice ()->GetMtu () >= 68)

      m_routingProtocol->NotifyInterfaceUp (i);

      interface->SetUp ();

      if (m_routingProtocol != 0)

        {

          m_routingProtocol->NotifyInterfaceUp (i);

        }

    }

  else

    {

      NS_LOG_LOGIC ("Interface " << int(i) << " is set to be down for IPv4. Reason: not respecting minimum IPv4 MTU (68 octects)");

  interface->SetUp ();

  // RFC 2460, Section 5, pg. 24:

  //  IPv6 requires that every link in the internet have an MTU of 1280

  //  octets or greater.  On any link that cannot convey a 1280-octet

  //  packet in one piece, link-specific fragmentation and reassembly must

  //  be provided at a layer below IPv6.

  if (interface->GetDevice ()->GetMtu () >= 1280)

    {

      interface->SetUp ();

  if (m_routingProtocol != 0)

      if (m_routingProtocol != 0)

        {

          m_routingProtocol->NotifyInterfaceUp (i);

        }

    }

  else

      m_routingProtocol->NotifyInterfaceUp (i);

      NS_LOG_LOGIC ("Interface " << int(i) << " is set to be down for IPv6. Reason: not respecting minimum IPv6 MTU (1280 octects)");