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Community Member

Site Survey Questions

Hello,

I have a question about surveying. I have been doing site surveys and all the site surveys that I have done were all passive mode. I use AirMagnet with Proxim card. I know that there is an active mode for doing wireless site survey. My question are:

1. When do I need to do an active site survey?

2. What is the difference between active and passive mode?

3. What is the advantages and disadvantages of each mode?

4. For post site survey, which mode should I used?

I know that the passive mode is in monitor mode and I don't need to associate with an AP whereas active mode I need to associate with the AP.

Thanks

1 ACCEPTED SOLUTION

Accepted Solutions

Site Survey Questions

Granted, this is My Opinion:

1. When do I need to do an active site survey?

     When you are troubleshooting an issue.  And/Or needing to do throughput testing, on a live network.

2. What is the difference between active and passive mode?

     Active survey's you are actually connecting to the SSID, so you can pass traffic and measure the results.

3. What is the advantages and disadvantages of each mode?

     Active Survey - Allows you to see more information on packet frames, as you are connected to the SSID.  You can watch and test roaming, throughput etc.

     Passive Survey - Is what you want to use when you are doing a pre-install survey, or even a post install validation survey.

HTH,
Steve

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HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered
11 REPLIES

Site Survey Questions

Granted, this is My Opinion:

1. When do I need to do an active site survey?

     When you are troubleshooting an issue.  And/Or needing to do throughput testing, on a live network.

2. What is the difference between active and passive mode?

     Active survey's you are actually connecting to the SSID, so you can pass traffic and measure the results.

3. What is the advantages and disadvantages of each mode?

     Active Survey - Allows you to see more information on packet frames, as you are connected to the SSID.  You can watch and test roaming, throughput etc.

     Passive Survey - Is what you want to use when you are doing a pre-install survey, or even a post install validation survey.

HTH,
Steve

------------------------------------------------------------------------------------------------
Please remember to rate useful posts, and mark questions as answered

HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered
Community Member

Site Survey Questions

Thanks for the quick reply Stephen.

Is it possible to use active site survey for pre-install?

If it is, why would I use active survey for pre-install?

I was playing with active site survey while I was waiting for a reply, and I noticed that it is very similar to passive. I can merged the data (per AP), etc.

Also, regarding active survey to see the packet frames, where should I see these packet frames in Airmagnet?

I have merged all the APs that I have on my test active survey file, and could not figure it out.

Thanks

Site Survey Questions

You can do an active survey for pre-install, I just don't see the point myself. When you just have an AP on a Stick, you're not passing any data to the LAN to be able to gather informaiton about retries, throughput etc.

I want to say it's in the Display area when you hover over the map.

HTH,
Steve

------------------------------------------------------------------------------------------------
Please remember to rate useful posts, and mark questions as answered

HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered
Community Member

Re: Site Survey Questions

I took some screenshots between the active and passive.

On the active site survey, the APs are connected to the network. the retry and lost are 0.

Active

Passive

Hall of Fame Super Silver

Re: Site Survey Questions

I agree with Steve.... we will only do an active survey if troubleshooting, but always have done passive. Even troubleshooting, I still use passive and active.

Sent from Cisco Technical Support iPad App

-Scott
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Community Member

Re: Site Survey Questions

It seems like I will be doing active survey for my site survey next week.

I am still trying to figure this out. I noticed that when doing active survey via SSID it only scans one channel. THerefore, if I need to do both 2.4GHz and 5GHz, I would need to walk twice. Am I right on this one?

I double checked my AP config and I have both 2.4GHz and 5GHz up/up. inSSIDer can see both bands, Airmagnet passive mode can too, but not in active mode.

Hall of Fame Super Silver

Re: Site Survey Questions

That is right unless you have multiple cards. How a true survey is performed using an active survey approach was to survey the floor in a certain direction, then survey the floor again going the opposite direction and then perform a passive survey and then merge the data. This is why we don't do active surveys these days.

Sent from Cisco Technical Support iPhone App

-Scott
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Community Member

Re: Site Survey Questions

Scott thanks for explaining the old ways of surveying.

I have been surveying and for the past year and there is still too much info to learn.


Sent from Cisco Technical Support iPhone App

Hall of Fame Super Silver

Re: Site Survey Questions

There is a lot to learn, but the best way is to collaborate with others in your team that survey.  I always tell me peers that is better you you to perform a site survey and do the design and install and then a validation or post survey.  This way you will know if how you surveyed was ideal or not.  This is how you learn... from experience seeing the final product.  Office areas, warehouse, manufacturing, outdoor, freezers, stadiums, schools... are a different and survey technique will change in different environments.

Thanks,

Scott

Help out other by using the rating system and marking answered questions as "Answered"

-Scott
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Community Member

Re: Site Survey Questions

Scott or Stephen,

I'm just curious when you guys do your site surveys, what is your signal propagation settings?

Hall of Fame Super Silver

Re: Site Survey Questions

It varies depending on if your supporting data only, voice, location, byod etc. for data, -72 dbm and an snr of 20 dbm or better.

Sent from Cisco Technical Support iPhone App

-Scott
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