xbt_assert(host_src != nullptr, "Network element %s does not seem to be NS3-ready", src->cname());
xbt_assert(host_dst != nullptr, "Network element %s does not seem to be NS3-ready", dst->cname());
xbt_assert(host_src != nullptr, "Network element %s does not seem to be NS3-ready", src->cname());
xbt_assert(host_dst != nullptr, "Network element %s does not seem to be NS3-ready", dst->cname());