New Member
Posts: 3
Registered: ‎06-01-2014

Probabily wrong data from SNMP (EdgeRouterPro)

Hello.

I'm using mrtg (set up on another machine) to monitor traffic from some routers/switches. EdgeRouter Pro is used as BGP router. The traffic from our neighbors is being sent over four vlan's on eth0 and mixed Internet is going out through eth1 with no vlans. Now mrtg gathers data from EdgeRouter via SNMP. I'm graphing traffic from each neighbor's vlan and "summary" traffic from eth1. But I don't know why - the summary traffic never exceeded 120Mbit. Adding together vlan's traffic gives about 160-200 Mbit.

Regards.

 

Previous Employee
Posts: 13,551
Registered: ‎06-10-2011
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Re: Probabily wrong data from SNMP (EdgeRouterPro)

It sounds like the comparison is between the "summary" on the WAN side (eth1) and the total VLAN traffic on the LAN side (eth0 VLANs)? If so, it might be that some traffic on the LAN side does not go to or come from WAN (e.g., broadcast, multicast, inter-VLAN traffic, etc.)?

New Member
Posts: 3
Registered: ‎06-01-2014

Re: Probabily wrong data from SNMP (EdgeRouterPro)

eth0 is WAN (four vlans from each upstream provider) and eth1 is "mixed output"- LAN. I'm graphing each of WAN vlans (each on separate graph) and all mixed traffic of "output" LAN port eth1. There's almost no other or LAN traffic, because the only thing connected to LAN is another router, doing qos and local routing. The problem is that eth1 graph can't exceed 120megs. When real traffic is bigger, the graph shows very low values. You can see it on attached image. See "upload" between 19 and 23 hour. The real traffic at this time was about 170megs. Ofcourse max bytes in mrtg is set correctly. (the footer below the graph shows 12% of load).

Could it be SNMP or MRTG problem?

Regards.

 

mrtg.png
Previous Employee
Posts: 13,551
Registered: ‎06-10-2011
Kudos: 5479
Solutions: 1656
Contributions: 2

Re: Probabily wrong data from SNMP (EdgeRouterPro)

OK so it's the reverse, so is it possible there's traffic on the WAN side that doesn't go to the LAN side? Also it sounds like there's a separate issue of "When real traffic is bigger, the graph shows very low values"?

New Member
Posts: 3
Registered: ‎06-01-2014

Re: Probabily wrong data from SNMP (EdgeRouterPro)

Yes. The graph is reverse, because it's graphing traffic leaving edgerouter. There's no other traffic between WAN and LAN. Only service running on the ER is BGP. And as you see on the attached mrtg graph, "upload" (which is download for real) drops below 10megs between hours 19 and 20, the goes back to about 90 megs, then drops again, and goes up past 11pm. The real (measured on the second router) traffic at that time was about 160-170 megs.