iPerf % packet loss question

[jdlucado1]

Hello,

I'm a noob when it comes to iPerf, I only know what i've read online over the past couple of days and have never used the application myself. My question is this, when someone runs an iPerf test on a link and the % packet loss comes back let's say at 10%, does that mean that 100 out of every 1000 UDP packets was dropped OR does it mean that the throughput on the link was 90% and that's the amount of bandwidth available to the host. 

Does that make sense? 

[Joseph W. Doherty]

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Posting

Your 10% is the lost against your total volume you try to transfer.

For example, if you have a gig link that hands off to a FE link, and the gig link sends it 110 Mbps, your FE link should transmit 100 Mbps, but drop 10 Mbps, which would be 10/110 = 9.09 % loss.

[jdlucado1]

Okay, so it's not necessarily an indication that there is 9.09%packet loss on your network, meaning that your connection is so unreliable it's going to drop 9.09% of the time.

So if I have a 50 Mbps WAN link and I run iPerf over it, and I get a 20% packet loss, that means that I pushed my content through at 40Mbps, not that one out of every five packets that runs over that circuit is dropped. Is that right? Sorry if I come off as dense, it's just that the term "packet loss" in this case comes off as a bit ambiguous (at least to me).

Appreciate the quick response!

[Joseph W. Doherty · Accepted solution]

So if I have a 50 Mbps WAN link and I run iPerf over it, and I get a 20% packet loss, that means that I pushed my content through at 40Mbps, not that one out of every five packets that runs over that circuit is dropped. Is that right?

Maybe, maybe not.

The 20% lost would represent 20% of your volume of traffic, or the missing 10 Mbps.  Whether that's 1 in 5 packets would depend on whether all your packets were the same size.  Also, even if all the packets were the same size, and you did lose 1 in 5, it doesn't follow you lose every 5th packet, just that you lost 20% of your packets across the measurement period.  (Again, percentage of loss is volume, so actual packet loss percentage might be higher or lower than your volume loss.)

[jdlucado1]

Joseph,

Ok, got it now! Thank you for the through explanation.