[mrtg] Displaying VLAN traffic separately from a physical interface

Michael Silver msilver at prl.ab.ca
Tue Feb 12 20:05:00 CET 2008


I'm revisiting MRTG after a while away from it, and am having an issue
getting the results I want. I'm probably missing something, but after
reading through the documentation and doing some web searches I'm still
not getting the results I desire. I see some information about Cisco
VLAN interfaces, but I don't see how to apply them in this case.

Here's the situation:

FortiGate 200A
MRTG 2.16.0 on a CentOS Linux installation

The FortiGate reports 8 interfaces to an SNMP query - interfaces 1 - 5
are physical interfaces of type ethernetCsmacd(6). Interfaces 6 - 8 are
VLAN interfaces of type l2vlan(135) operating off of physical interface

What I want is separate graphing of the traffic on the VLAN interfaces.
The counters are there in an SNMP query, but when I try to add the
interfaces in MRTG the device information appears under the last listed
physical interface, and there is only one set of graphs for all devices
listed on that page. I believe from the filename of the graphic that the
graphs are for the physical interface.

I've tried editing the mrtg.cfg file without luck. I've tried removing
all the physical interfaces from the configuration file (nothing
generated), removing the ifType stanza for the virtual interface, using
ifInOctets.8 as part of the Target string, removing all but the
bare-bones information as shown on
http://oss.oetiker.ch/mrtg/doc/mrtg-reference.en.html. No go on any of

Any ideas?

Thank you,

Michael Silver, Network Administrator 
Parkland Regional Library 
5404 56 Avenue Lacombe, AB T4L 1G1 
Phone: 403.782.3850    Fax: 403.782.4650
http://www.prl.ab.ca/  msilver at prl.ab.ca

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