Wireless Access

Reply
Contributor I

help with understanding goodput

I am struggling to understand what the dashboard is telling me. It has tons of information but figuring it all out and deciding if ithere is a problem or not is tough.

 

Goodput is a perfect example.

pic1 shows my dashboard. AP "NHC-LA-rm1" has a goodput of only 1.5M....that sounds low I should check it out and take a look.

 

So when I click on the AP, it shows that I have 3 clients, but none of them have a goodput of 1.5M - is it an average?

 

So I click on the 4.2M goodput (which had changed to 5.5 by the time I got a screenshot) and it shows (pic3) that on the left it says a goodput of 5.5M but on the right it has a goodput of 54M.

 

So I can't tell if this client is experiencing slow throughput or not. Can someone help me understand?

Mark

Re: help with understanding goodput

Here is the explanation of goodput:

 

The average data transfer rate in all the radio bands. You can click on the hyperlinked number to view the distribution of goodput across radios. You can also do a right click on the number to view the trend of the goodput in the last 15 minutes.

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.

Seth R. Fiermonti
Consulting Systems Engineer - ACCX, ACDX, ACMX
Email: seth@hpe.com
-----
If you found my post helpful, please give kudos
Guru Elite

Re: help with understanding goodput


Mark532011 wrote:

I am struggling to understand what the dashboard is telling me. It has tons of information but figuring it all out and deciding if ithere is a problem or not is tough.

 

Goodput is a perfect example.

pic1 shows my dashboard. AP "NHC-LA-rm1" has a goodput of only 1.5M....that sounds low I should check it out and take a look.

 

So when I click on the AP, it shows that I have 3 clients, but none of them have a goodput of 1.5M - is it an average?

 

So I click on the 4.2M goodput (which had changed to 5.5 by the time I got a screenshot) and it shows (pic3) that on the left it says a goodput of 5.5M but on the right it has a goodput of 54M.

 

So I can't tell if this client is experiencing slow throughput or not. Can someone help me understand?

Mark


Mark,

 

An explanation how to interpret the information on  the dashboard is here: http://www.arubanetworks.com/techdocs/ArubaOS_64_Web_Help/Web_Help_Index.htm#ArubaFrameStyles/Dashboard_Monitoring/Dashboard_Monitoring.htm

 

The goodput can go up or down based on the performance that client is having that day, but it is not necessarily a death sentence if it is low.  If it is low and you have a complaint, you have to determine what factors could contribute:

 

- High Utilization (over 40% sustained)

- Too many access points on the same channel in the area

- Access point power too high

- Drop Broadcast and Multicast not Enabled on your Virtual APs

- Broadcasting too many SSIDs on a single access point (3 or 4 should be the maximum)

- A client issue

- Client inactivity

 

Low Goodput is a symptom but not necessarily automatically a bad thing.



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Contributor I

Re: help with understanding goodput

thanks guys. That helps

Mark

Search Airheads
cancel
Showing results for 
Search instead for 
Did you mean: