Network Management

What does the goodput in Airwave actually represent?  It looks like it represents the total throughput a client could generate and not the actual usage.  Any ideas?

 

 

• Low goodput: Radios that have an average data rate of 24 Mbps or lower.
• Low goodput: Clients that have an average data rate of 24 Mbps or lower.

The average data transfer rate in all the radio bands.

 

Goodput is the ratio of the total bytes transmitted or received in the network to the total air time required for transmitting or receiving the bytes. The air time includes the retransmission time taken for both successful and dropped frames.

 

Suppose 1000 frames of 1500 bytes each are transmitted in the network as follows:

• 50% of frames are transmitted successfully at MCS index 11 at 108 Mbps.
• 25% of the frames were dropped in the 1st attempt at 108 Mbps but were successfully transmitted using MCS index 3 at 54 Mbps in the second attempt.
• The remaining 25% are dropped in both the attempts.

Then the effective rate is calculated as: The total bits transmitted / the total air time. In this example: (500 * 1500 + 250 * 1500) * 8 / (total air time for 50% frames + total air time for 25 % frames retransmitted + total air time for 25% dropped frames) = 40.5 Mbps.

If you are seeing radios flagged with low goodput, and not just below 24M, but say single digit Mbps, how do you troubleshoot or begin to assess what is causing the low goodput?

Bump?

How many days is the radio being flagged for low goodput?  If it's a single day or a week out of the whole year, then it's not too bad.  But if you're seeing low goodput all the time, then that's when you'll have to consider the next steps.

 

1. AP load (how many clients are typically on the AP when the radio is getting low goodput)

2. ARM (is ARM trying to make changes while my radios have low goodput)

3. AP location (is AP near interferences or high latency areas)

 

Usually, I start by looking at a VisualRF view (if AMON is enabled, can use Health overlay), and then drill down from there.

Thanks Vic - I nice Simple explanation even i can understand :-))

What does it mean when goodput is 138.5Mbps, while throughput is 300Mbps?

Does it mean the maximum throughput of a client is 138.5Mbps?

 

On the page with the controller's dashboard, there is help menu that allows you to hover over words to understand their meaning.  I am putting in the two help texts for goodput, because it explains it better than I could.

 

Hi cjoseph, 

 

Thanks for the clarification.

 

I was having the impression that ratio is like SNR (Signal-to-Noise Ratio), which is a number.

However, for Goodput, I'm still trying to figure out whether Goodput (ratio?) should have Mb associated with it... (Maybe proportion/fraction would better word...)

 

"in the last 15 minutes" means that it is based on previous results right?