Cisco Cable Signal to Noise Ratio

[ngriffin69]

Hello, I'm attempting to gather the Signal to noise ratio on my cisco cable routers, via 'Oid transmission.127.1.1.4.1.5.3.' I am having trouble getting the graph populated . The only way that i can get the graph to render is to set "the Consolidation Function to Average". Any other setting will not allow the graph to be rendered.

Data Source Config:
/usr/local/rrdtool-1.0.41/bin/rrdtool create \
/www/htdocs/cacti///rra/speedway_snr.rrd \
--step 300 \ <------------------------------- Is this to high?
DS:speedway_snr:GAUGE:600:0:350 \
RRA:AVERAGE:0.5:1:600 \
RRA:AVERAGE:0.5:6:700 \
RRA:AVERAGE:0.5:24:775 \
RRA:AVERAGE:0.5:288:797 \
RRA:MAX:0.5:1:600 \
RRA:MAX:0.5:6:700 \
RRA:MAX:0.5:24:775 \
RRA:MAX:0.5:288:797 \


Data Source Config:
INTERNAL: [speedway/blahblahblahz] OID: [transmission.127.1.1.4.1.5.3]
/usr/local/rrdtool-1.0.41/bin/rrdtool update /www/htdocs/cacti///rra/speedway_snr.rrd --template speedway_snr N:279


Using snmpget from machine:
[root@clone root]# snmpget speedway blahblahblah transmission.127.1.1.4.1.5.3
transmission.127.1.1.4.1.5.3 = 279 <------- What i want to graph as 27.9

I wish to display 279 as 27.9 db, in a graph plotting the readings at 5 minute intervals, not necessarily an average, but the readings as they are at the time of the polling. Getting anything to display would be a start

Thanks in advance.

NG

[waxling]

Hi,

I recently had a similar problem while setting up some graphs for one of our UPS.

The problem was that all voltage, current and power factor readings were out by a factor of 10 when gathered via snmp.

You can't really do much about the actual data (well you can, however its not worth the drama of writing your own snmp function) but you can apply a cdef to a datasouce when you graph it. I've only just started using cacti, but I'm pretty sure this is what CDEF's are for.

I ended up setting up a cdef called "divide by 10" that does exactly that to the data in the datasource. Read the docs for CDEF info.

As for the "average" problem.. from you description what you probably want is actually the average function, once you apply the cdef the scale should be sorted out.

[ngriffin69]

THanks, my plan is to use CDEF's to get the proper values that i'm looking for, however i'm currently having issues even getting anything to graph when pulling SNR, the graph renders, but there's no data.

[waxling]

Maybe I misunderstand,
when you say

"The only way that i can get the graph to render is to set "the Consolidation Function to Average". Any other setting will not allow the graph to be rendered"

exactly what is wrong with the rendered graph with Colsolidation Function set to average? I would imagin that this is what it should be.

Do you mean that the graph will be rendered, but with (aparently) no data? (i.e. you can't see the actual data).

Have you checked that the rrd actually contains data?

If there is no data in it, from the output of the internal snmp function for the data source it looks like everything is working (it gets data) so the problem is probably with the poller. Is there any strange output for that datasource when you run the poller from the command line, i.e. not cron? If not and if you are throwing away std err & out for that cron entry, you may want to run it a few times through cron without the output being thrown away then look at the output.. It could be environment etc... something that stops php's snmp or rrdtool from working fron cron when it works fine under apache.

Hope this helps.