Wireless Access

Hi guys,
Inherited an Aruba Network at a School I work at and I have been slowly getting my head around the current deployment of AP61s and looking at upgrading to AP105s.

Scenario:
Main building
We have a large number (around 280) students who roam from class room to class room using laptops. The building is circular in design with 8 classrooms around a common open area.
Total area is 45m x 36m per floor
At any one time - we could have 1 class of 24 on that floor - or maybe 5 or 6 classrooms full with over a 100 users.

Deployment:
Currently 3 AP61's per floor
NO AIR MONITOR AP's
AP61's are not set to Arm Mode Aware
ARM mode is default
All AP61's are b/g
2 x 3400 Controllers
2 x 800 Controllers
Each controller performs DHCP and is allocated to a separate VLAN
Not ALL AP's in the same floor (or building are on the same Controller - hence VLAN)
IP Mobility is not enabled

Issues:
Patchy performance at best
Poor mobility

Thoughts / Suggestions:
Ensure all AP's on the same floor are provisioned to the same controller and hence VLAN
Increase the desnity of the AP's to ideally 1 per classroom (eg 1 per 24 users at peak usage)
Deploy 3 AM per floor

Considerations:
With such a high density deployment of AP61's in b/g mode - will the default ARM profile be able to manage channels and power - or should we switch to Mode ARM Aware?

I am concerned that with only 3 non overlapping channels and say 8 AP61s per floor we will get overlapping interference that ARM cannot handle

Should we instead move to manual power mgt? (cumbersome I know)

Is IP mobility required if clients are moving within the same floor building - hence on the same controller and same VLAN?

Point to note:
We have many legacy laptops that do not support a hence staying on b/g but I guess the same questions may still apply if we move to the 105's.

Any advice on the above is much appreciated!
I have learnt a lot on these forums this weekend (as well as reading 100's of pages of manuals!!) - but just want to see if I have the general picture correct.


Cheers
Wally
#3400

---

Hi guys,
Inherited an Aruba Network at a School I work at and I have been slowly getting my head around the current deployment of AP61s and looking at upgrading to AP105s.

Scenario:
Main building
We have a large number (around 280) students who roam from class room to class room using laptops. The building is circular in design with 8 classrooms around a common open area.
Total area is 45m x 36m per floor
At any one time - we could have 1 class of 24 on that floor - or maybe 5 or 6 classrooms full with over a 100 users.

Deployment:
Currently 3 AP61's per floor
NO AIR MONITOR AP's
AP61's are not set to Arm Mode Aware
ARM mode is default
All AP61's are b/g
2 x 3400 Controllers
2 x 800 Controllers
Each controller performs DHCP and is allocated to a separate VLAN
Not ALL AP's in the same floor (or building are on the same Controller - hence VLAN)
IP Mobility is not enabled

Issues:
Patchy performance at best
Poor mobility

Thoughts / Suggestions:
Ensure all AP's on the same floor are provisioned to the same controller and hence VLAN
Increase the desnity of the AP's to ideally 1 per classroom (eg 1 per 24 users at peak usage)
Deploy 3 AM per floor

Considerations:
With such a high density deployment of AP61's in b/g mode - will the default ARM profile be able to manage channels and power - or should we switch to Mode ARM Aware?

I am concerned that with only 3 non overlapping channels and say 8 AP61s per floor we will get overlapping interference that ARM cannot handle

Should we instead move to manual power mgt? (cumbersome I know)

Is IP mobility required if clients are moving within the same floor building - hence on the same controller and same VLAN?

Point to note:
We have many legacy laptops that do not support a hence staying on b/g but I guess the same questions may still apply if we move to the 105's.

Any advice on the above is much appreciated!
I have learnt a lot on these forums this weekend (as well as reading 100's of pages of manuals!!) - but just want to see if I have the general picture correct.


Cheers
Wally

---

Okay, assuming that you have to keep the AP61s for now:

- Turn on Spectrum Load Balancing in the 802.11g radio profile
- Turn on Broadcast Filtering ("Drop Broadcast and Multicast", and "Convert Broadcast ARP requests to unicast" on all your Virtual APs
ARM mode aware should be considered last, because it could negatively impact your coverage.

If you get AP105s and you still have mostly b/g clients, your reliability will still improve on legacy clients due to the increased receive sensitivity of the AP105 access points. You will also be positioned to support 802.11a clients, like Ipads and move them out of the limited 2.4ghz spectrum.

Definitely ensure APs that can hear each other are provisioned to the same controller.
Consider using an external DHCP server, since the controller's internal DHCP server is not enterprise-class. You can probably use it for up to 400 clients, before it starts having issues. Internal DHCP server is only meant for smaller guest networks.... In addition, if you use an external DHCP server, you will not have to worry about client ip addresses, if you decide to deploy controllers that back each other up. In addition, if you have an external DHCP server and multiple controllers bridging users to the same layer2 VLAN, you *could* solve your mobility issue....

Colin
Many thanks for the very quick and useful response.

Just checked the following:
- Turn on Spectrum Load Balancing in the 802.11g radio profile
- Turn on Broadcast Filtering ("Drop Broadcast and Multicast", and "Convert Broadcast ARP requests to unicast" on all your Virtual APs

Both were not turned on...will do so and monitor for any change.
Does the spectrum load balancing negate the need for say setting a client limit to hard coded at say 24 clients per AP? Or is this more designed around balancing the clients per channel rather than per AP?


We have spare AP61's in the cupboard so would another option at this stage be deploy the AP61's in "a" mode side by side with the b/g to accomodate the ipads? I know the AP61's are not 802.11n but at least as you say we could get them out of the 2.4ghz spectrum

With 2 separate AP's i assume we get no band steering for the client? ie it is up to the client which AP it connects to?

In such a deployment would you
a) NEED to have 2 different ssid's for b/g and a so clients can distinguish
b) Recommend 1 common SSID (or is this not possible)?

Lastly - still concerned about high desnity deployments (eg 1 AP or more per classroom - classrooms 9 meteres apart). Will ARM manage this and ensure power is reduced to avoid overlapping AP;s on the same channel?

Still can't find anything on how dense we can go with AP61's on b/g?

Thanks for the help.
Wally

Got it.

Please try the config changes that I mentioned first, before deploying any more AP61s. If you have classrooms and their walls are thick enough, one per classroom for coverage is a good starting point, since the attenuation will prevent APs from seeing each other strongly. Each situation is different, however, so it might be worth it to get someone in who knows wifi or Aruba to ensure that you are deployed properly.

Take a look at the controller. If the transmit power on the majority of your APs are at their lowest, you have deployed enough APs.

Do not deploy more AP61s in the A band or an additional SSID, because that will increase your complexity and will not improve much, since most of your clients are b/g.

In the meantime, please read the document about indoor access point planning here: http://www.arubanetworks.com/pdf/technology/DIG_Aruba_Site_Survey.pdf

That document will give you some ideas about what to look for.

Recap:

- If all your APs are at the lowest power, you have deployed all that you can and you should not deploy any more
- Make the broadcast changes that I mentioned. It does not hurt anything.
- Measure client sentiment to see if anything has changed
- Only deploy more APs in an Area if there is no coverage for now. Adding APs might just introduce more interference
- Start purchasing and deploying AP105s for your high capacity areas to replace an existing AP61 and keep the AP61 as a spare. You can then enable band steering and move the clients that can support A to the A band. You will also get the benefit of increased receive sensitivity for your clients

Colin
Thanks again...makes a lot of sense..

This morning I have
Provisioned all adajacent AP's to the same contollers.
Turned on spectrum load balancing
Turned on Broadcast filtering

This look a bit better already in that I was able to move around between floors in the same building whilst maintaining the same IP (as now on the same VLAN) and connectivity was almost continuous.

I am still seeing some teething problems with the iPADS...in particular - when they do drop the wirless connection they do take a long time to reconnect..I am seeing close to 1 minute before it reconnects and obtains the IP address again.
The network is visible all the time under wireless settings - just takes a long time to connect.

Is there are anecdotal evidence of issues with the iPADS as opposed to any other device?

I have posted a few other questions in the AP forum - but the help so far has been invaluable - many thanks.
Cheers
Wally

---

Colin
Thanks again...makes a lot of sense..

This morning I have
Provisioned all adajacent AP's to the same contollers.
Turned on spectrum load balancing
Turned on Broadcast filtering

This look a bit better already in that I was able to move around between floors in the same building whilst maintaining the same IP (as now on the same VLAN) and connectivity was almost continuous.

I am still seeing some teething problems with the iPADS...in particular - when they do drop the wirless connection they do take a long time to reconnect..I am seeing close to 1 minute before it reconnects and obtains the IP address again.
The network is visible all the time under wireless settings - just takes a long time to connect.

Is there are anecdotal evidence of issues with the iPADS as opposed to any other device?

I have posted a few other questions in the AP forum - but the help so far has been invaluable - many thanks.
Cheers
Wally

---

Are you sure that the iPads are not associating to APs that are on different controllers? That would explain the drops. Once you rule that out, we can explore other possible ipad issues.