ctx->sp.max_burst_size = max_burst;
n_custom_tx = ctx->transport_vft->custom_tx (ctx->tc, &ctx->sp);
*n_tx_packets += n_custom_tx;
ctx->sp.max_burst_size = max_burst;
n_custom_tx = ctx->transport_vft->custom_tx (ctx->tc, &ctx->sp);
*n_tx_packets += n_custom_tx;