Yes, we vary the power by AP, but that’s more to optimize the network than it is to push devices to 5 GHz. That’s why I didn’t mention it. AP layout in dense environments has to be driven by the number of users and RF parameters adjusted accordingly. We also adjust Rx sensitivity. We do so in 3 dB increments to avoid having 15 different RF settings for 20 APs. We may compromise a bit more if it avoids having an insane number of AP groups in a building. So far our most complex building has 106 APs in 4 AP groups.
Regarding powering up to fill in coverage gaps from a failed AP, that really only works if you use extra APs, and therefore have very low power settings when operating normally. If in the event of a failure APs go from high power to really high power, client devices in the affected area are still likely to have problems. At the risk of inviting criticism, I’ve attached our AP layout and site survey strategy. That said, questions and constructive criticism are welcome. I’ve removed the Aruba AP specific stuff. You need to develop your own minimum coverage standard and figure out home many clients can be supported on your AP(s) of choice. I will say this this design approach has resulted in good performance (as measured by positive user feedback) while using less hardware than most recommendations I’ve read (up 100 occupants in the coverage area of a premium, wave-1 11ac AP.) I apologize for any difficulty understanding the part about choosing the power settings. It’s surprisingly easy to understand if you’re actually doing it, but my staff had difficulty following the text in abstract. Once they understood it they didn’t need to refer back to it. It’s pretty intuitive. Chuck Enfield Manager, Wireless Systems & Engineering Telecommunications & Networking Services The Pennsylvania State University 110H, USB2, UP, PA 16802 ph: 814.863.8715 fx: 814.865.3988 From: Jason Cook [mailto:jason.c...@adelaide.edu.au] Sent: Thursday, August 13, 2015 1:38 AM To: Chuck Enfield <chu...@psu.edu>; WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: RE: Exclusive 2.4 Ghz and 5 Ghz SSIDs Top info Chuck A few additional things to play with from that list. Do you have varying power in your set power or is it designed to be all one so very even spacing between AP’s? By varying I guess do you set to X, survey then adjust some. Or rely more on your testing and design to get it right and have them all the same. And double check with a survey I’m trying to think of any downsides, but really it would only be the lack of ability to surrounding devices to up power and cover and AP that’s failed. However design and 2.4ghz still might cover this. And we find AP failures aren’t common. -- Jason Cook The University of Adelaide, AUSTRALIA 5005 Ph : +61 8 8313 4800 From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] On Behalf Of Chuck Enfield Sent: Thursday, 13 August 2015 1:14 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU <mailto:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU> Subject: Re: [WIRELESS-LAN] Exclusive 2.4 Ghz and 5 Ghz SSIDs Yes, we use band-steering and I recommend it over the different SSID approach. If a device chooses the 2.4 GHz SSID on its own, most people won't notice for quite some time. How often have you found your device on an SSID other than the one you intended? My Netgear router at home won't let me use the same SSID on both bands. (I'll resist the temptation to comment on that "feature".) Every now and then I notice that my phone is connecting on the 2.4 GHz SSID instead of 5 GHz. It's hard to say how long my phone was connecting to the wrong SSID before I noticed. At work, my phone sometimes connects to the wrong SSID, but it ALWAYS connects at 5 GHz There are design techniques that will result in a significant majority of clients connecting to 5 GHz radios. If you make dual-band devices want to connect to 5 GHz I believe you'll end up with a higher percentage of device connected in that band than you'll get through the two SSID method. It's possible to get a majority of dual-band devices onto 5 GHz even without band-steering. Band-steering helps for those oddball devices that just won't go there by themselves, but that's less than 10%. At PSU we attempt to optimize 5 GHz coverage, then adjust 2.4 GHz to do the best it can within that AP layout. This allows us some flexibility with 2.4 GHz parameters. Even with the compromised settings, 2.4 GHz isn't usually too bad. With 75% of the devices on 5 GHz, 2.4 GHz is usually acceptable for the clients that remain on it. In summary, our approach for getting clients onto 5 GHz is: 1. Have good 5 GHz coverage everywhere. >25dB SNR. Not only will this make 5 GHz attractive, but most devices won't probe for a better AP once connected, which keeps the air cleaner. 2, Turn down power on 2.4 GHz so it is at least 3 dB weaker than 5 GHz throughout the coverage area. This is what makes the devices prefer 5 GHz. (It may go without saying given this recommendation, but we configure the AP with a fixed Tx power. RF management only chooses the channel. The benefits of optimizing the power settings of the two radios on an AP easily outweigh the benefits of the crappy power adjustment algorithms used by the AP manufacturers.) 3. Turn off 2.4 GHz radios only when necessary to avoid egregious CCI. It's usually only needed in locations with a really high AP density, like auditoriums or lots of adjacent classrooms, although it's also sometimes needed if walls are close together and construction materials have a much higher loss at 5 GHz than at 2.4 GHz, as is common in dorms. Turning off 2.4 GHz radios results in uneven coverage, which makes it hard to keep the signal weaker than 5 GHz everywhere without having gaps in the 2.4 GHz coverage. 4. Enable band steering. 5. Make sure no other settings are undermining band-steering. (Aruba's default settings for "Client Match" undermine band steering when there's a strong 2.4 GHz signal. Shout-out to Jason Mueller at Iowa for bringing that one to my attention.) 6. Adjust load balancing parameters such that clients are only pushed to 2.4 GHz if 2.4 GHz utilization is VERY low. If you do these things almost everybody with a 5 GHz radio will connect at 5 GHz. If your AP of choice doesn't support band-steering, adjustment of load balancing parameters, or a wide enough range of power settings, maybe two SSIDs is the way to go. But then I'd start shopping for a new AP, because it's not the right product for higher ed. Chuck _____ From: "Jeremy Gibbs" <jlgi...@utica.edu <mailto:jlgi...@utica.edu> > To: "EDUCAUSE Wireless Issues Constituent Group Listserv" <WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU <mailto:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU> > Sent: Wednesday, August 12, 2015 7:39:29 PM Subject: Re: [WIRELESS-LAN] Exclusive 2.4 Ghz and 5 Ghz SSIDs Does anyone employ band-steering? When we enabled it, we saw a massive jump of users connecting at 5ghz. Obviously if the client doesn't support 5ghz or it just prefers 2.4 because of various factors it can stay on 2.4. I have only seen it improve throughput for everyone. Any opinions on this? We are an extreme network shop, but our wireless is the enterasys (chantry) solution with new 3825i 3x3. On Wednesday, August 12, 2015, Jeffrey D. Sessler <j...@scrippscollege.edu <mailto:j...@scrippscollege.edu> > wrote: Single SSID – anything else just adds confusion for the end-user. Then again, I was recently visited a spot where they had a different SSID for every building. :) Thinking more about this… If residence halls (academic buildings too) are well designed around 5 GHz and use in-room AP placement, the issues with 2.4 tend to melt away (or you can ignore them), with clients only falling back to 2.4 when they transition outside of a building. If you’re a Cisco shop (I assume Aruba has something similar), their automatic RRM (radio resource management) and TPC (Transmit Power Control) tend to result in very tiny cells where there is a lot of 2.4 radios talking (which is a good thing - tiny cells). Of course, this can be really problematic if the AP layout design is not-optimal such as in a typically budget-driven “down the center of the hallway” methods of deployment where adjacent AP’s tend to have clear line-of-sight of each other. In cases such as these, the reduction in radio output to reduce AP channel overlap can result in client connection troubles i.e. The clients are probably behind fire–proof metal clad doors, brick walls, etc. Coupled with coverage hole detection (where AP power is increased for client connectivity), you now have an environment that’s in constant chaos, where someone has to do a lot of manual adjusting of AP radios or disable the auto-adjusting. On the other hand, if AP layout is optimal where you’re deploying AP’s in-room, lower on the wall, avoiding line-of-sight, etc. then you get the benefit of the room’s construction (doors, floors, walls, what inside the walls, bed, desks, etc.). All of which help promote small cell isolation and reduce the number of adjacent neighbor AP’s you’ll see, resulting in less 2.4 GHz channel overlap. Now then, the same issues can crop up in 5 GHz, but it doesn’t propagate as far, so if you're using the in-room deployment method, it’s likely not as big of an issue even in dense deployments. That said, if you do have dense 5 GHz deployments, Cisco’s 8.1 code introduces 5 GHz dynamic channel-width allocation, somewhat eliminating the issue by dynamically moving between 20, 40, and 80 MHz channels. In my opinion, 2.4 GHz is slowly marching to its demise, and I’m focusing all of my attention on 5 GHz. We have the luxury of of a robust Mac population (~80% of the students), and Apple laptops and desktops have long since had access to 5GHz, so I’m not sure how much effort should be put into maintaining 2.4 if it’s ultimately only being used by old phones, devices that move little data, or have alternative data paths such as cellular, why expend a lot of effort on it? Jeff From: "wireless-lan@listserv.educause.edu" on behalf of Stephen Oglesby Reply-To: "wireless-lan@listserv.educause.edu" Date: Wednesday, August 12, 2015 at 9:41 AM To: "wireless-lan@listserv.educause.edu" Subject: Re: [WIRELESS-LAN] Exclusive 2.4 Ghz and 5 Ghz SSIDs Paul, We're an Aruba shop and, as Bruce of Liberty mentioned, for dense deployments we turn 2.4 ghz radios off on every other AP (typically edge of building APs). Our main performance issues were due to interference and channel utilization on the 2.4 ghz spectrum. We attempted reducing 2.4 ghz (20 mhz channel) transmit power but still had issues. I also agree with keeping to the simplicity of a single SSID if at all possible. I can't imagine the number of issues that would be reported to me simply because the user exited the ideal range for 5ghz spectrum. Our student and staff networks support a wide range of client wireless cards, antenna configurations, and spectrum compatibility (many are including 2.4ghz only). Having users manually switch networks as needed may cause HelpDesk to become very popular. Good Luck, Stephen Oglesby Network and Telecommunications Architect Aims Community College 5401 W. 20th Street Greeley, CO 80634 970.339.6350 (Office) stephen.ogle...@aims.edu IT staff will never ask you for your username and password. Always decline to provide the information and report such attempts to the help desk (x6380). On Wed, Aug 12, 2015 at 8:24 AM, Philippe Hanset <phan...@anyroam.net> wrote: Paul, Dorm design is an animal of itself and each school has its own set of challenges based on locations and policies. As much as I agree that 2.4 GHz and 5 GHz shouldn’t be on separate SSIDs for main campus, I have really changed my mind for dormitories. Those buildings are really micro houses stacked on top of each other with people bringing anything and everything they want which is quite different than academic buildings. We all spend our summers designing the best coverage that we can for those residential areas, and as soon as students move in, the interference in 2.4 GHz makes our entire effort look pointless in the eyes of the complaining student who is actually partly responsible for the problem. So, in dormitories only, I would have the regular set of SSIDs that the campus provides plus and extra 5 GHz only called something like "residential-preferred". But I wouldn’t use “fast” or “5GHz” in the SSID name. Best, Philippe Philippe Hanset www.eduroam.us <http://www.eduroam.us> On Aug 11, 2015, at 4:22 PM, Paul Sedy <rps...@masters.edu> wrote: Hello everyone, We are a Cisco shop and have, up until now, employed a single SSID for students, supporting both 2.4 Ghz and 5Ghz connections. During this summer, we have been working to develop sufficient AP density to ensure good 5Ghz cells throughout our dorms. In the past, we have seen numerous instances of poorer performance on the 2.4 Ghz spectrum, but up to this point, have relied on the client to make the decision between these two options. We are thinking of deploying two separate SSIDs, a 5Ghz network and a 2.4 Ghz network, that are exclusive in order to promote a better experience for the students with devices capable of 5Ghz connectivity. We would probably use the original SSID name with an appended (5 Ghz) or (2.4 Ghz). Are any of you currently employing this type of configuration and how well has it worked for you? We would appreciate any insights that anyone might have. Paul Sedy The Master’s College Director of IT Operations 21726 Placerita Canyon Rd, Santa Clarita, CA 91321 661.362.2340 <tel:661.362.2340> | rps...@masters.edu ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at <http://www.educause.edu/groups/> http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. -- -- Jeremy L. Gibbs Sr. Network Engineer Utica College IITS T: (315) 223-2383 F: (315) 792-3814 E: <mailto:jlgi...@utica.edu> jlgi...@utica.edu <http://www.utica.edu/> http://www.utica.edu ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. -- Chuck Enfield Manager, Wireless Systems & Engineering Telecommunications & Networking Services The Pennsylvania State University 110H, USB2, UP, PA 16802 ph: 814.863.8715 fx: 814.865.3988 ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
AP Placement and RF Survey.docx
Description: MS-Word 2007 document
