I've set up an mrtg with rrdtool. I have a problem with one of the serials of my linux router. It is always commented out in the config file because "it has a speed of 0". I've tried editing the config file, uncommenting the lines and providing a relative speed for the serial but no rrd file was created hence no graph to display. I've also tried forcing an oid value in the mib-oid of the device in order to change the 0 value using snmpset but it does not accept it. how will i manage to monitor the serial using mrtg???