We utilize
MRTG as the basis for our network performance monitoring. I had someone ask me recently about using MRTG with the Nortel VPN Routers (formerly Contivity). He was getting either no data points in his graph or only a very few during the early morning hours.
They work fine with a few caveats... you obviously need to configure SNMP support on the VPN router and you may need to 'tweak' the configuration file generated from 'cfgmaker'. For some reason the VPN router will report the ifSpeed of the IPSec tunnel interfaces as either 7Kbps or 16Kbps. I not sure why but that's what we have to live with.
In any case this particular person was having an issue because MRTG was discarding any of the values that exceeded the MaxBytes statement in the configuration file. Once he changed the MaxBytes statement to match the actual bandwidth of the remote site to which the tunnel connection everything started graphing properly.
Cheers!
