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-   -   Utilization of a 100 MB switch... (

WeNdeL 02-10-2003 11:48 AM

Utilization of a 100 MB switch...
At what point (percentage wise) do I get concerned with the amount of bandwidth utilization on a given port of a 100 MB switch?

Or any switch for that matter...

SlickWilly 02-10-2003 01:50 PM

That's a rather subjective question and entirely depends on

a) what you're doing over the switch. Wether it's interactive or streaming, or bulk data transfers.

b) What sortof switch is it. I'm guessing as a 100MB it's a 'store & forward' type of switch, but I could be wrong.

c) How are you doing your measurements?

Depending on any of the above, I'd say around about 80% of capacity is when you start seeing degraded performance, but this isn't a T1 or something where your saturation will hinder the passage of 'ACK' packets for instance and the whole thing will crawl. You could conceivably reach 100% saturation of 100Mb port, and if the backplane on the switch is sufficiently capable see no speed decrease in traffic at either end.

So um... Why not tell us what you're seeing and then we can maybe clue up some more.


WeNdeL 02-10-2003 04:54 PM

Well... we have a T1 and are you're basic .com company...

We serve up public records from various databases and display them on a few websites. I rarely see a utilization of more than 15%.

I have a 3com SuperStack 3 btw. It makes use of an "intelligent" manner of forwarding where:

Packets are forwarded as soon as the destination address is received and processed. If the switch detects more than 20 errors a a second it switches to a true "store and forward" mode until the number of errors are reduced.

I would say my measurements are a percentage of bandwidth utilization.

Thanks for you're help!

SlickWilly 02-11-2003 09:47 AM

Ahh.. I've used those, and they're quite nice switches.

You can confidently see up to 100% utilisation on any port and still have plenty of bandwidth to spare on the backplane.

Your limitation here isn't going to be the switch, it's going to be your nics / machines. I doubt your machines are going to be able to force-feed your switch data quick enough to saturate it. So, you're good.


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