Multi Router Traffic Grapher

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Revision as of 21:19, 26 August 2006 by Tmitchell (Talk | contribs)
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From the MRTG website:
The Multi Router Traffic Grapher (MRTG) is a tool to monitor the traffic load on network-links. MRTG generates HTML pages containing graphical images which provide a LIVE visual representation of this traffic. Check for an example. MRTG is based on Perl and C and works under UNIX and Windows NT. MRTG is being successfully used on many sites around the net.



From the Web Interface
-Click on the Administration Tab
-Click on the Services Sub-tab
-Mark "Enable" next to SNMP
-Click Submit
-Click Continue
-Fill in the information in the SNMP section that opened up.
(Location, Contact, Name, RO Community, RW Community)


There are a number of installation guides on the MRTG website.
In the guide, substitute:
public for the RO Community you filled in earlier with the Local IP address of your router.


You should have Windows IIS installed, or some other web server you're familiar with. Substitute D:\InetPub\wwwroot\ for the wwwroot of your IIS installation.

Follow the guide at:

Remove the line: WorkDir: c:\www\mrtg from the bottom of Make the folder D:\InetPub\wwwroot\MRTG Create a new virtual folder in IIS and point it to D:\InetPub\wwwroot\MRTG Browse to to see your traffic logs.

Alternately for a quick look, use STG which will let you monitor 2 OIDs at a time.


  • for br0 interface (intern LAN port) for download (green) ( upload(blue))
  • for vlan1 interface (extern WAN port) for download (green) ( upload(blue))
  • for eth1 interface (WLAN) for download (green) ( upload(blue))


Follow the guide at:

The OID's which MRTG will pick up in a default configuration are as follows:

  • 5 (eth0) - all routed wired traffic, WAN + LAN
  • 6 (eth1) - all routed wireless traffic
  • 7 (vlan0) - all routed LAN traffic
  • 8 (vlan1) - WAN traffic
  • 9 (br0) - vlan0-eth1 bridge traffic

Currently, there is no way to monitor switched traffic.


If you want to monitor something other than bytes in and out, you must also know the SNMPOID of what you want to monitor.
Here is a listing of SNMPOIDs for the DD-WRT firmware.
not completed

Some SNMP OIDs can be found in this forum thread:

Please copy the important OIDs here!!!

For CPU load dd-wrt snmpd provides two sets of MIBs: = 01 min avg, Value is between 0.00 and 1.00. = 05 min avg, Value is between 0.00 and 1.00. = 15 min avg, Value is between 0.00 and 1.00.

The values above need to be multiplied by 100 since mrtg does integers.


Target[]: *100 = 01 min avg, 1 means 0.01 and 150 means 1.5 = 05 min avg, 1 means 0.01 and 150 means 1.5 = 15 min avg, 1 means 0.01 and 150 means 1.5

For UP and DOWN traffic on the WAN-side: = Downrate = Uprate

For memory usage: = Total available = Used

External Resources

MRTG website