If I understand your post correctly, have you tried speciifying the OID in the mrtg "target"? Thats what I do.
Example: Get the numerical OID by using the -On snmpwalk[get] command
Code:
snmpwalk -v2c -On -c my_community hostname if
BTW: You can also specify the "name" like IP-MIB::ipNetToMediaIfIndex in the mrtg target, but you would need to "include" the linux MIB in your mrtg config file.
So using your the OID example in your post, the mrtg "target" would be (note the & separator between the input/output OID's):
Code:
Target[eth0_1]: .1.3.6.1.2.1.2.2.1.10.2&.1.3.6.1.2.1.2.2.1.16.2:public@hostname:
See the mrtg documentation for the other parameters that can be specifed in the target definition. Especially if you need to use v2c queries.