[mrtg] Re: Different traffic on each side of a link

Nicolai Strøm Gylling nsg at webpartner.dk
Tue Apr 9 11:44:52 MEST 2002

>> The trafficamount on the switchport are considerably higher than on 
>> the ethernet port in the server.

>Are you sure you don't mistake bits for bytes?

Yes :)

> - bits vs. bytes
> - faulty snmp on the server
> - faulty snmp on the switch
> - not seeing all traffic on the server
> - seeing more on the switch than just traffic for this link
> - faulty settings in your mrtg.cfg file, discarding valid data
>  (MaxBytes could be too low, set it 10% above the link speed just
>  to make sure).

None of those apply, since we observe the behaviour on two different setups on different switches and NIC's.
What settings in mrtg.cfg could discard valid data?

>> Will broadcast-traffic be answered by the switch, and also appear on 
>> the switch-port as traffic?

>So?  If that's the case it should also be visible on the server.

Well, if the switch is smart, it knows what port the traffic is going to, and will not relay the broadcast on all ports, and therefore the traffic will not show up on the other end of the link, but then, would it show up on the switch port? This is where i hope our problem is, since we've had a lot of broadcasttraffic(broadcast traffic as in the broadcast tx/rx stats on our switches).

>> Is there a way to differentiate between the different kinds of 
>> traffic(broadcast vs. normal traffic), and thereby measure the same 
>> traffic-amount in each end of the link?

>Broadcast traffic *is* normal traffic.  And what broadcasts do you mean? Ethernet broadcasts or ip broadcasts?  >Or maybe even netbeui?  I don't think a switch can differentiate between ip-broadcasts and other ip. The other >two may be possible, you will have to ask HP.

Allready on my way to HP :)

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