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VPN 3000 Concentrator and SNMP

pkapoor
Level 3
Level 3

We have some VPN 3000 concentrators in our network. We use "cacti", a variant of the MRTG tool to graph various things. Amongst them, we also graph circuit utilization of our Internet bandwidth.

My routers and PIXs work fine in this regard. However, I see that the VPN concentrators report their Public interface circuit speed as whatever they have negotiated as speed with the uplink. For example, if the Public interface has negotiated a 10/half-duplex with the WAN SDSL router, then it will report its circuit speed as 10 Mbps. If the concentrator negotiates the link speed as 100/full, it reports the circuit speed as 100 Mbps. In reality, both WAN circuits are T1 and therefore should have the circuit speed set to 1.544 Mbps.

This causes a problem when graphing because it never hits the right thresholds. For example, if I ask it to paint red in the graph after the utilization cross 80%, the calculation will be based on 10 Mbps or 100 Mbps (as 100%) and not 1.544 Mbps.

Can someone tell me how can I remedy this issue and have the circuit speed reported as the Link Rate set on the concentrator rather than its physical interface speed?

Thanks.

1 Reply 1

miheg
Level 5
Level 5

If cacti works with a config file like mrtg where you see what oid gets polled and put into the rdd file you should be able to replace the value of the polled OID by something fixed like 1.544.

But for monitoring the internet bandwidth you are monitoring the wrong interface.

I'm sure cacti would behave as expected when you monitor the SDSL router wan interface.

Cheers,

Michel

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