network_graph ()
{
    last_x="$1"
    net_dev="$2"
    if [ -f $rrd_dbpath/interface/if_octets-$net_dev.rrd ]
    then
        /usr/bin/rrdtool graph /srv/www/img/network-$net_dev-$last_x.png --title "Network $net_dev - $last_x" \
            --imginfo '<IMG SRC="/img/%s" WIDTH="%lu" HEIGHT="%lu" ALT="Network">' \
            $rrd_width $rrd_height $rrd_common_opts --watermark "$rrd_watermark" \
            --end now --start end-${last_x} \
            --vertical-label "Bytes/s" \
            --font "WATERMARK:8" \
            $rrd_grid_background \
            DEF:rx=$rrd_dbpath/interface/if_octets-$net_dev.rrd:rx:AVERAGE \
            DEF:tx=$rrd_dbpath/interface/if_octets-$net_dev.rrd:tx:AVERAGE \
            LINE1:rx$rrd_col_green:"RX \n" \
            LINE1:tx$rrd_col_red_light:"TX \n" \
    	    COMMENT:"Letztes update\:\t$rrd_last_update"
    else
        show_error "$_MN_err" "no rrd-database for $net_dev"
    fi
}