Understanding speed data from switch

[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.

[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.

[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.

[ssax]

The bandwidth checks are an average over the last 10 minutes, how long has the download been running when you're testing?

[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.

[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.

[stebbo]

Hi tgriep,

thanks for the info.

Cheers,
Chris.

[tgriep]

Your Welcome.
Shall I close up and lock the post?