diff -up mrtg-2.17.7/bin/cfgmaker.orig mrtg-2.17.7/bin/cfgmaker
--- mrtg-2.17.7/bin/cfgmaker.orig	2018-08-08 13:14:19.609048676 +0200
+++ mrtg-2.17.7/bin/cfgmaker	2018-08-08 13:15:17.795102892 +0200
@@ -224,7 +224,7 @@ sub InterfaceInfo($$$$$) {
 #            maximum value (4,294,967,295) and ifHighSpeed must be used
 #            to report the interace's speed.  For a sub-layer which has
 #            no concept of bandwidth, this object should be zero."
-            if ( (not defined $value) || ($value == 2**32-1) ) {
+            if ( (not defined $value) || ($value == 2**32-1) || ($value == 2**32-2)) {
                 ($if, $value) = split /:/, $ifHighSpeed[$i], 2;
 	        $value = $value * 1000000;  # highSpeed = contador * 10^6
                 debug('base',"Speed: $if - $value");