Re: mrtg/snmp/subinterfaces

From: Dominic News (
Date: 06/05/04

  • Next message: Burton M. Strauss III: "RE: mrtg/snmp/subinterfaces"
    Date: Sat,  5 Jun 2004 08:42:48 +0000
    To: Piotr Kowalczyk <>

    Quoting Piotr Kowalczyk <>:
    > Hello,
    > Tell me, is there any reasonable way to monitor subinterfaces
    > utilization on linux router? It's not difficult to get via snmp info
    > about phisical eg. eth1, but I have there subinterfaces which I
    > _have_to_ monitor, and I have to do that fast. Any ideas?
    > please, help
    > thanks in advance,
    > Piotr Kowalczyk, KoBa ISP

    AFAIK, there's no way to do it - the network system only tracks usage on the
    primary interfaces and you can see that when you run 'ifconfig'.

    You could track it by taking a tcpdump (and ensuring you get the whole packet
    using the -s 0 switch) of everything on the primary interface, then using a
    tool like ethereal to filter it down where the source address is that of the
    virtual interface.

    Then ethereal can display a summary of all the traffic that's been selected by
    the filter and show the throughput rate and also the amount captured. That
    should work assuming the virtual interface isn't spoofing IP addresses.


    Dominic Cleal

  • Next message: Burton M. Strauss III: "RE: mrtg/snmp/subinterfaces"