[mrtg] Re: ifHighSpeed on 100Mbps

[Pavel Ruzicka]

Hello,

> Problem:
>    When using using SNMP v2 on a Cisco router with T1 interfaces the
> MaxBytes gets set using the ifHighSpeed value.  This doesn't have enough
> resolution to show the correct speed. This causes T1s to show up as
> 2000.0 kbits in MRTG. See below:
>
> snmpwalk -v2c -c xxxx x.x.x.x ifSpeed
> IF-MIB::ifSpeed.1 = Gauge32: 1544000
> IF-MIB::ifSpeed.2 = Gauge32: 1544000
> IF-MIB::ifSpeed.3 = Gauge32: 100000000
> IF-MIB::ifSpeed.4 = Gauge32: 100000000
> IF-MIB::ifSpeed.5 = Gauge32: 4294967295
> IF-MIB::ifSpeed.6 = Gauge32: 4294967295
>
> snmpwalk -v2c -c xxxx x.x.x.x ifHighSpeed
> IF-MIB::ifHighSpeed.1 = Gauge32: 2
> IF-MIB::ifHighSpeed.2 = Gauge32: 2
> IF-MIB::ifHighSpeed.3 = Gauge32: 100
> IF-MIB::ifHighSpeed.4 = Gauge32: 100
> IF-MIB::ifHighSpeed.5 = Gauge32: 10000
> IF-MIB::ifHighSpeed.6 = Gauge32: 8000

Thanks for explanation of problem.

> Solution:
>    When using SNMP v2 only use ifHighSpeed for 100Meg and up interfaces,
> otherwise use ifSpeed.

My idea is to use your solution, but set this limit for ifHighSpeed
for 20Mbps+ and match the Cisco documentation.
This is useful for interface, which have 64bit counter support, but is under 
100Mbps. For example E3 34Mbps, or T3 45Mbps interfaces.

Best regards,

Pavel Ruzicka

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