[c-nsp] Buggy Cisco SNMP traffic monitoring with MRTG

[Scott Weeks]

On Sat, 28 May 2005, Belgian Network Solutions - Geert Hauwaerts wrote:

: I've configured SNMP monitoring with MRTG for several Cisco switches.
: When I configure MRTG to lo Fa0/13 it logs as Fa0/21 and visa versa.
:
: If you run cfgmaker (for MRTG) it generates the folowing config.
:
: ### Interface 13 >> Descr: 'FastEthernet0/17' | Name: 'Fa0/17' | Ip: '' | Eth: '' ###
:
: Target[XXX_13]: 13:XXXX at YYYY:

: Notice the 13 (Fa0/13) to be monitored? If you put traffic through
: Fa0/17 it will show up on the statistics for port 13?
:
: Is this behaviour normal? The folowing is some strange output on MRTG.
:
: --snpo: confcache XXX at YYY: Name Fa0/17 --> 13
: --snpo: confcache XXX at YYY: Name Fa0/13 --> 21


The 13 is the SNMP Interface Identifier, not the number of the interface.
Make sure to read all the MRTG documentation.  All the info is in there.
Snipping out the extra info in the email, you can see that the Interface
Identifier for Fa 0/13 is 21  So, when you're looking at Interface
Identifier 13 you're seeing the traffic on interface Fa 0/17.

scott