[mrtg] nic ordering in snmp
Niall.oReilly at ucd.ie
Sat Jan 10 21:05:31 CET 2009
On Sat, 2009-01-10 at 14:33 -0500, R Dicaire wrote:
> Also, are the contents of [ ] critical to the resolution of interface
> name when using --ifref=name?
Not at all. The contents of the [ ] serve to identify
the data set to MRTG, and are used to name the log file.
It's the '...:public at rdb:' which specifies the interface.
If there's just a number where the dots are, it's the
numeric interface index, which may change on reboot, or
when you add or remove interfaces, whether physically or
just by enabling or disabling them.
Otherwise, the prefix character is used to indicate which
MIB table is used to resolve the string which follows, up
to the colon (:). The '#' means find a match in ifName
to determine which numeric index (SNMP need an integer)
to use. As you can see from the MRTG reference, other
prefixes correspond to other ways of referring to the
interface, and trigger a lookup in the corresponding MIB
[ There's much more to specifying how MRTG interacts with
the SNMP agent, but it's not important right now. ]
And, no: in this context, '#' doesn't cause the rest of the
line in the configuration file to be discarded as a comment.
IIUC, it works as a comment introducer only at the beginning
of a line.
> I ask because I'm going to be editing an existing mrtg.cfg to
> implement the --ifref=name changes and hope to keep existing log
Don't mess with what's between the [ ], and your log files
(or RRD files) with matching names will just keep on
accumulating the data.
More information about the mrtg