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Understanding speed data from switch
Posted: Sun Apr 17, 2016 5:21 pm
by stebbo
Hi All,
I'm having trouble correlating the speed data that is being displayed for my switch and the actual speed of the network interface. We have a 200Mbps internet connection and I can run some downloads that average around 180Mbps for a period of time.
However, my switch data never shows anymore than between 60Mbps and 90Mbps even though I know the speed is much higher. I am assuming there is some averaging going on but I'd like to try to get a speed graph that is more accurate than what I currently have.
Any pointers would be appreciated.
Cheers,
Chris.
Re: Understanding speed data from switch
Posted: Mon Apr 18, 2016 11:36 am
by ssax
I believe the plugin is showing in megabytes (MB) per second even though the label says megabits (Mb), I've already submitted a bug report for this so the developers can fix it.
If modified the files to output the proper values now (with calculations), you can select which one you want:
Bits - b, Kb, Mb, Gb
check_rrdtraf_bits.zip
Bytes - B, KB, MB, GB
check_rrdtraf_bytes.zip
You can replace your current plugin but it may be overwritten on an upgrade and need to be re-implemented.
Let me know if that works for you.
Re: Understanding speed data from switch
Posted: Tue Apr 19, 2016 1:22 am
by stebbo
Hi ssax,
thanks for the response. I'll give those a try, however I'd already assumed the label was wrong. My issue is that the switch values almost appear to be a factor of two out. I know the download is running at 180Mbps, yet the switch only reports around 90Mbps.
Cheers,
Chris.
Re: Understanding speed data from switch
Posted: Tue Apr 19, 2016 3:01 pm
by ssax
The bandwidth checks are an average over the last 10 minutes, how long has the download been running when you're testing?
Re: Understanding speed data from switch
Posted: Tue Apr 19, 2016 8:03 pm
by stebbo
Hi ssax,
I had thought maybe they were 5 minute averages so I had the downloads running for 5 minutes. Given that they're 10 minute averages I shall make some comparisons based on that.
Is there any way to get an "instantaneous" reading? As in, what is the "current" speed, or even modifying the average to a 1 minute average? For my main upstream link that would be quite handy, at least for a while.
Cheers,
Chris.
Re: Understanding speed data from switch
Posted: Wed Apr 20, 2016 4:39 pm
by tgriep
Sorry, there isn't a way to get instantaneous information and the bandwidth are running every 5 minutes through MRTG but the check averages the last 2 readings and that cannot be changed either.
Re: Understanding speed data from switch
Posted: Fri Apr 22, 2016 2:35 am
by stebbo
Hi tgriep,
thanks for the info.
Cheers,
Chris.
Re: Understanding speed data from switch
Posted: Fri Apr 22, 2016 8:20 am
by tgriep
Your Welcome.
Shall I close up and lock the post?