Re: [WIRELESS-LAN] many clients, one room
On Apr 23, 2008, at 10:41 AM, Lee, Steven wrote: We also held a bake-off with the big 3 LWAPP vendors. The results showed that these solutions were no better and sometimes worse than what we could achieve with manual tinkering of our IOS AP's. snip We came to a decision that the cost of moving to LWAPP outweighed the benefits at this time, even with the added burden of manually fine-tuning each AP. I'd rather not be in this position, but I haven't found a controller system that meets our needs. Same story here, more or less. In addition, we found that the controllers don't yet scale to the point where it's not a kludge to support a good number of SSID's or copious roaming. Dale ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
RE: [WIRELESS-LAN] many clients, one room
Mostly defaults, but the defaults also change sometimes with the semi-frequent code upgrades. No disabled rates yet, but we may be getting closer to being able to entertain that as we are seeing our 11b devices drop to under 3% of all clients. Lee -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Earl Barfield Sent: Thursday, April 24, 2008 9:15 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Date:Wed, 23 Apr 2008 08:06:30 -0400 From:Lee H Badman [EMAIL PROTECTED] Subject: Re: many clients, one room Many moons ago when we used Cisco IOS APs for our new WLAN, we would create picocells (knowing that the term means different things to different people) by turning down the power to 1 mW, and also adding an attenuator between AP and antenna to further restrict output power. Then we'd basically fill large auditoriums with 3-5 of these, depending on the size of the venue. It worked wonderfully for supporting a couple of hundred casual users on 802.11b and then g. Fast forward to LWAPP. ... Lee, How is your LWAPP network configured for these hogh-density areas? Do you have everything set to defaults? Do you disable 1,2,5.5MBps data rates? Do you tweak any of the RRM settings like DCA refresh interval or power thresholds? -- Earl Barfield -- Academic Research Tech / Information Technology Georgia Institute of Technology, Atlanta Georgia, 30332 Internet: [EMAIL PROTECTED][EMAIL PROTECTED] ** 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/.
RE: [WIRELESS-LAN] many clients, one room
Many moons ago when we used Cisco IOS APs for our new WLAN, we would create picocells (knowing that the term means different things to different people) by turning down the power to 1 mW, and also adding an attenuator between AP and antenna to further restrict output power. Then we'd basically fill large auditoriums with 3-5 of these, depending on the size of the venue. It worked wonderfully for supporting a couple of hundred casual users on 802.11b and then g. Fast forward to LWAPP. We still provision multiple APs per large auditorium, but these rooms are seldom islands- they also are typically surrounded by other APs in adjacent areas(laterally, above, and below) where they further share cells. It was a leap of faith letting RRM decide on power and channel, but so far we have yet to be burned (that we know of). But... we do not do voice over the WLAN formally. Or multicast over wireless. And the typical Internet-delivered video stream for the casual/typical client tends to be around 500 kbps, so we're not feeling a lot of pain even when 150 users are on a small handful of a/g APs, and thus far most traffic is to the Internet where we have per-user caps anyway. Then factor in that 1/3 of these are actually using 11a and the remainder are on 11g on our dual-band APs. And at least half of all are using some version of CCX... And we still have the occasional 11b device pop up (around 2% of all of our 5000+ simultaneous clients), and we let them. And there are sometimes classroom response systems in use in 2.4 GHz in these same spaces. It gets fuzzy in our real world, but we rarely (as in almost never) hear of dissatisfaction with the WLAN throughput. In fact, as silly as it sounds, we get written compliments from visitors on occasion on how well our WLAN performs. Long winded answer to a simple question- but we are basically applying simple common-sense design for capacity and mostly ignoring much of the hysteria and hype that comes from vendors volleying the finer points of how they one-up each other on wireless, and doing just fine (for now) given that our day-to-day lab is reality. -Lee Lee H. Badman Wireless/Network Engineer Information Technology and Services Syracuse University 315 443-3003 -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Frank Bulk - iNAME Sent: Tuesday, April 22, 2008 11:49 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Can anyone on this list comment on their dense experiences with vendors other than Meru (and Xirrus)? I know I may appear to be buoying Meru in this thread, but it's only because I haven't heard a higher-ed using another vendor talk about their own good experiences. Regards, Frank -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Frank Bulk Sent: Monday, April 14, 2008 2:52 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room John's comments reflect almost exactly what I heard two years ago. Would love to hear on this list from other shops (Aruba, Cisco, Colubris, Symbol, Trapeze, Symbol) what their experiences and configurations are in similar circumstances. Frank -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of John Center Sent: Monday, April 14, 2008 10:48 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Hi Clint, The AP208 have 2 radios, 11a 11b/g. We have the laptops set up to prefer 11a, so the bulk of the connections are 11a. MathCAD is installed locally on the laptops, but the size of the student files vary - probably comparable to a Powerpoint presentation. We used to do this with Cisco AP1200s had constant complaints. No more. We had the same problem at exam times at our Law School. No more. Like I said, we are very happy with the Meru products. HTH -John Ringgold, Clint wrote: Can you please give us more information in terms of how the APs and Laptops were setup. I'm no math major and on a bad day I have trouble adding (don't laugh). Anyway, I'm just wondering if it was setup so you have 54+54+11+11=130/250(users)=.52 or 54+54+11=119/250(users)=.476. I am not implying a thing. I'm asking this just for my clarification. It sounds like the software may have been on the laptop and/or only the answer or very small packets were saved to/from a server. If it is designed to work with little bandwidth (like Citrix) then that is great. I'm just saying it is a difference. -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of John Center Sent: Monday, April 14, 2008 8:28 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Hi Don
RE: [WIRELESS-LAN] many clients, one room
We are using Cisco 7920 and 7921 phones on CCM v4 (shortly will be v6) on the Cisco LWAPP. We have no issues with the wireless voice; however, we currently only have a handful of the wireless phones deployed (primarily due to cost of the phones). We also allow RRM to adjust signal strength now and it seems to do a good job. It is interesting in WCS to see the floor maps where multiple APs are in close proximity and how the signal is adjusted between them. Matt Matthew Jenkins Network/Server Administrator Fairmont State University Visit us online at www.fairmontstate.edu -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Lee H Badman Sent: Wednesday, April 23, 2008 8:07 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Fast forward to LWAPP. We still provision multiple APs per large auditorium, but these rooms are seldom islands- they also are typically surrounded by other APs in adjacent areas(laterally, above, and below) where they further share cells. It was a leap of faith letting RRM decide on power and channel, but so far we have yet to be burned (that we know of). But... we do not do voice over the WLAN formally. Or multicast over wireless. And the typical Internet-delivered video stream for the casual/typical client tends to be around 500 kbps, so we're not feeling a lot of pain even when 150 users are on a small handful of a/g APs, and thus far most traffic is to the Internet where we have per-user caps anyway. ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
Re: [WIRELESS-LAN] many clients, one room
Frank, We are testing a dense Aruba deployment in our Info-Commons (a huge aisle of our main library is now an IT congregation area. Students love it) Seven access points are hosting about 140 users (peak usage from 11 AM till 5 PM). Those APs (Aruba 125) have b/g on one radio and a/n on the other radio (100 Mbps uplink..planning on moving those to Gig) Those Aruba APs are also surrounded by older Proxim AP-2000 and AP-4000. All APs (Proxim and Aruba) are part of the same layer two subnet (not yet using Aruba Mobility option). Lots of Broadcast and Multicast, since up to 5000 users concurrently use that subnet. Originally we had performance issues on the Aruba APs. Their engineers came on campus to analyze the problem, and after a code upgrade (fixed a bug) and cancelling the 1 Mbps rate and 2 Mbps rate (Broadcast is using the lowest rate. Since we have a lot of broadcast, is helped a lot), issues dissapeared. I was peaking at 80 Mbps over n, surrounded by tons of b/g and a clients. Some of the limitation on n is related to the uplink port being 100 Mbps. Philippe -- Philippe Hanset University of Tennessee, Knoxville Office of Information Technology Network Services 108 James D Hoskins Library 1400 Cumberland Ave Knoxville, TN 37996 Tel: 1-865-9746555 -- On Tue, 22 Apr 2008, Frank Bulk - iNAME wrote: Can anyone on this list comment on their dense experiences with vendors other than Meru (and Xirrus)? I know I may appear to be buoying Meru in this thread, but it's only because I haven't heard a higher-ed using another vendor talk about their own good experiences. Regards, Frank -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Frank Bulk Sent: Monday, April 14, 2008 2:52 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room John's comments reflect almost exactly what I heard two years ago. Would love to hear on this list from other shops (Aruba, Cisco, Colubris, Symbol, Trapeze, Symbol) what their experiences and configurations are in similar circumstances. Frank -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of John Center Sent: Monday, April 14, 2008 10:48 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Hi Clint, The AP208 have 2 radios, 11a 11b/g. We have the laptops set up to prefer 11a, so the bulk of the connections are 11a. MathCAD is installed locally on the laptops, but the size of the student files vary - probably comparable to a Powerpoint presentation. We used to do this with Cisco AP1200s had constant complaints. No more. We had the same problem at exam times at our Law School. No more. Like I said, we are very happy with the Meru products. HTH -John Ringgold, Clint wrote: Can you please give us more information in terms of how the APs and Laptops were setup. I'm no math major and on a bad day I have trouble adding (don't laugh). Anyway, I'm just wondering if it was setup so you have 54+54+11+11=130/250(users)=.52 or 54+54+11=119/250(users)=.476. I am not implying a thing. I'm asking this just for my clarification. It sounds like the software may have been on the laptop and/or only the answer or very small packets were saved to/from a server. If it is designed to work with little bandwidth (like Citrix) then that is great. I'm just saying it is a difference. -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of John Center Sent: Monday, April 14, 2008 8:28 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Hi Don, We are a Meru customer we've had great success with their system in our large lecture rooms. On Friday, we had 250 Engineering students taking an exam, which required MathCAD, on 2 Meru AP208s. The exam ran flawlessly. HTH -John Don Wright wrote: I know this has been talked about and debated on this list before, but what are people doing today when faced with a request like the need for 100 students simultaneously downloading a powerpoint presentation. Recently there was discussion on MCA vs. SCA vendors and how each handles this worst case scenario. Since we are an MCA (Aruba), I'd be interested in hearing what others have done or are planning for large classrooms and auditoriums. -- Don Wright Network Technologies Group Brown University wire --- less, wi-fi ))) more ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ** Participation
RE: Re: [WIRELESS-LAN] many clients, one room
Thanks for that input. Can you comment on the peak level of sustained throughput, per room; per AP? Are these measured over 5 minute intervals, or some other kind of measurement? I suspect that casual use may in fact work fine in dense environments. Frank -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Lee H Badman Sent: Wednesday, April 23, 2008 7:07 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Many moons ago when we used Cisco IOS APs for our new WLAN, we would create picocells (knowing that the term means different things to different people) by turning down the power to 1 mW, and also adding an attenuator between AP and antenna to further restrict output power. Then we'd basically fill large auditoriums with 3-5 of these, depending on the size of the venue. It worked wonderfully for supporting a couple of hundred casual users on 802.11b and then g. Fast forward to LWAPP. We still provision multiple APs per large auditorium, but these rooms are seldom islands- they also are typically surrounded by other APs in adjacent areas(laterally, above, and below) where they further share cells. It was a leap of faith letting RRM decide on power and channel, but so far we have yet to be burned (that we know of). But... we do not do voice over the WLAN formally. Or multicast over wireless. And the typical Internet-delivered video stream for the casual/typical client tends to be around 500 kbps, so we're not feeling a lot of pain even when 150 users are on a small handful of a/g APs, and thus far most traffic is to the Internet where we have per-user caps anyway. Then factor in that 1/3 of these are actually using 11a and the remainder are on 11g on our dual-band APs. And at least half of all are using some version of CCX... And we still have the occasional 11b device pop up (around 2% of all of our 5000+ simultaneous clients), and we let them. And there are sometimes classroom response systems in use in 2.4 GHz in these same spaces. It gets fuzzy in our real world, but we rarely (as in almost never) hear of dissatisfaction with the WLAN throughput. In fact, as silly as it sounds, we get written compliments from visitors on occasion on how well our WLAN performs. Long winded answer to a simple question- but we are basically applying simple common-sense design for capacity and mostly ignoring much of the hysteria and hype that comes from vendors volleying the finer points of how they one-up each other on wireless, and doing just fine (for now) given that our day-to-day lab is reality. -Lee Lee H. Badman Wireless/Network Engineer Information Technology and Services Syracuse University 315 443-3003 -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Frank Bulk - iNAME Sent: Tuesday, April 22, 2008 11:49 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Can anyone on this list comment on their dense experiences with vendors other than Meru (and Xirrus)? I know I may appear to be buoying Meru in this thread, but it's only because I haven't heard a higher-ed using another vendor talk about their own good experiences. Regards, Frank -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Frank Bulk Sent: Monday, April 14, 2008 2:52 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room John's comments reflect almost exactly what I heard two years ago. Would love to hear on this list from other shops (Aruba, Cisco, Colubris, Symbol, Trapeze, Symbol) what their experiences and configurations are in similar circumstances. Frank -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of John Center Sent: Monday, April 14, 2008 10:48 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Hi Clint, The AP208 have 2 radios, 11a 11b/g. We have the laptops set up to prefer 11a, so the bulk of the connections are 11a. MathCAD is installed locally on the laptops, but the size of the student files vary - probably comparable to a Powerpoint presentation. We used to do this with Cisco AP1200s had constant complaints. No more. We had the same problem at exam times at our Law School. No more. Like I said, we are very happy with the Meru products. HTH -John Ringgold, Clint wrote: Can you please give us more information in terms of how the APs and Laptops were setup. I'm no math major and on a bad day I have trouble adding (don't laugh). Anyway, I'm just wondering if it was setup so you have 54+54+11+11=130/250(users)=.52 or 54+54+11=119/250(users)=.476. I am not implying a thing. I'm asking this just for my clarification
RE: [WIRELESS-LAN] many clients, one room
Nope- and that's my point. There is very little sustained anything in our environment yet- every 15 minutes of every day on every AP is arguably different given the ebbs and flows of our current user base and their network behaviors. We have done silly tests like have half-dozen folks all on the same AP all watching Joost or Hulu, but again, some end up on 11a, some end up on 11g, and nobody needs more than 500 kbps for their stream so things tend to feel a-OK. We do occasional bandwidth tests, move huge files around, etc as verification of throughput for fun and t-shooting, but given the nature of users moving from location to location (outside of the dorms) and what they are doing, all we'd be doing right now is coming up with a baseline that may or may not be relevant an hour later as the environment changes. Have never felt the need to prove or disprove manufacturer performance claims during the course of daily business, (except when doing product reviews for NWC). That may certainly change as our applications change, but right now the general morass flows along nicely, and we are not staffed to go looking for problems that otherwise aren't revealed in monitoring or user complaints. WCS does OK for giving some stats- the stuff your asking about would best be measured in the dorms in the evening, but there are also no spaces that imitate auditoriums in the dorms, as we are very dense so we rarely see more than 10 users per AP in residence halls, even when 500 users are on in a given hall. With WCS, the reporting can be aggregated different ways depending on what you are looking for, but unfortunately some reports are either completely unreliable or take so long to generate that you stop looking after a while. But in fairness, some reports do work fine- but again, you don't tend to look more than occasionally unless there is the perception of trouble. The triggered reports are seldom kicked in. We have some high-level trends of overall usage peaks and valleys, but at the AP-level, the variances are huge depending on what's going on in that spot on any given time and day. Clear as mud, no? -Lee -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Frank Bulk - iNAME Sent: Wednesday, April 23, 2008 9:49 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Thanks for that input. Can you comment on the peak level of sustained throughput, per room; per AP? Are these measured over 5 minute intervals, or some other kind of measurement? I suspect that casual use may in fact work fine in dense environments. Frank -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Lee H Badman Sent: Wednesday, April 23, 2008 7:07 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Many moons ago when we used Cisco IOS APs for our new WLAN, we would create picocells (knowing that the term means different things to different people) by turning down the power to 1 mW, and also adding an attenuator between AP and antenna to further restrict output power. Then we'd basically fill large auditoriums with 3-5 of these, depending on the size of the venue. It worked wonderfully for supporting a couple of hundred casual users on 802.11b and then g. Fast forward to LWAPP. We still provision multiple APs per large auditorium, but these rooms are seldom islands- they also are typically surrounded by other APs in adjacent areas(laterally, above, and below) where they further share cells. It was a leap of faith letting RRM decide on power and channel, but so far we have yet to be burned (that we know of). But... we do not do voice over the WLAN formally. Or multicast over wireless. And the typical Internet-delivered video stream for the casual/typical client tends to be around 500 kbps, so we're not feeling a lot of pain even when 150 users are on a small handful of a/g APs, and thus far most traffic is to the Internet where we have per-user caps anyway. Then factor in that 1/3 of these are actually using 11a and the remainder are on 11g on our dual-band APs. And at least half of all are using some version of CCX... And we still have the occasional 11b device pop up (around 2% of all of our 5000+ simultaneous clients), and we let them. And there are sometimes classroom response systems in use in 2.4 GHz in these same spaces. It gets fuzzy in our real world, but we rarely (as in almost never) hear of dissatisfaction with the WLAN throughput. In fact, as silly as it sounds, we get written compliments from visitors on occasion on how well our WLAN performs. Long winded answer to a simple question- but we are basically applying simple common-sense design for capacity and mostly ignoring much of the hysteria and hype that comes from vendors volleying the finer points of how they one-up each other
RE: [WIRELESS-LAN] many clients, one room
We've also had great success with large lecture halls. The College of Engineering initiated a tablet PC requirement for all incoming freshman. The thought was that the tablets would be a great classroom resource for the students, replacing pad and paper. This led to them experimenting with collaborative instructional software (whatever the lecturer writes on the virtual whiteboard or presents a slide, the content gets pushed to each student where they can make annotations, replay it later, etc). Early trials where ghastly failures (many reasons for this, both application and network inefficiencies) where the latency was so bad that students would abandon the tool and revert to pencil/paper. Last year, the College trialed a SW package called DyKnow which was very efficient from a network standpoint. They then offered up a 270 student freshman Engineering class to serve as a guinea pig, and asked us if we'd help them make it work. We took the opportunity to develop parameters to tweak our Cisco IOS AP's (similar approach as Lee, pico-cell architecture, dropped power levels, denied low data rates, careful placement of AP's, etc.) and achieved great results. For this room we were and still are using 4 abg WAP's. One of the biggest difficulties encountered was balancing clients among not only all 4 of the WAPs, but also balancing them between the 2 radios on each WAP. (most if not all clients are dual-band) We also held a bake-off with the big 3 LWAPP vendors. The results showed that these solutions were no better and sometimes worse than what we could achieve with manual tinkering of our IOS AP's. In this environment, we are using 4 abg WAP's and one of the difficulties was balancing clients among not only all 4 of the WAPs, but also balancing them between the 2 radios on each WAP. In general I was disappointed with the client load balancing algorithms, what little they could reveal to us. We came to a decision that the cost of moving to LWAPP outweighed the benefits at this time, even with the added burden of manually fine-tuning each AP. I'd rather not be in this position, but I haven't found a controller system that meets our needs. As the collaborative tools get more bloated and the bandwidth needs increase, I'm anticipating we'll run into problems using this manual approach. I think 11n and eventually 11k may provide some relief, but for now our faculty and students are very happy with the performance. Steven Lee Research and Development Communications Network Services Virginia Tech 1770 Forecast Drive Blacksburg VA 24061 540-231-7957 -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Lee H Badman Sent: Wednesday, April 23, 2008 8:07 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Many moons ago when we used Cisco IOS APs for our new WLAN, we would create picocells (knowing that the term means different things to different people) by turning down the power to 1 mW, and also adding an attenuator between AP and antenna to further restrict output power. Then we'd basically fill large auditoriums with 3-5 of these, depending on the size of the venue. It worked wonderfully for supporting a couple of hundred casual users on 802.11b and then g. Fast forward to LWAPP. We still provision multiple APs per large auditorium, but these rooms are seldom islands- they also are typically surrounded by other APs in adjacent areas(laterally, above, and below) where they further share cells. It was a leap of faith letting RRM decide on power and channel, but so far we have yet to be burned (that we know of). But... we do not do voice over the WLAN formally. Or multicast over wireless. And the typical Internet-delivered video stream for the casual/typical client tends to be around 500 kbps, so we're not feeling a lot of pain even when 150 users are on a small handful of a/g APs, and thus far most traffic is to the Internet where we have per-user caps anyway. Then factor in that 1/3 of these are actually using 11a and the remainder are on 11g on our dual-band APs. And at least half of all are using some version of CCX... And we still have the occasional 11b device pop up (around 2% of all of our 5000+ simultaneous clients), and we let them. And there are sometimes classroom response systems in use in 2.4 GHz in these same spaces. It gets fuzzy in our real world, but we rarely (as in almost never) hear of dissatisfaction with the WLAN throughput. In fact, as silly as it sounds, we get written compliments from visitors on occasion on how well our WLAN performs. Long winded answer to a simple question- but we are basically applying simple common-sense design for capacity and mostly ignoring much of the hysteria and hype that comes from vendors volleying the finer points of how they one-up each other on wireless, and doing just fine (for now) given that our day-to-day lab
Re: [WIRELESS-LAN] many clients, one room
On Apr 11, 2008, at 9:59 AM, Don Wright wrote: I know this has been talked about and debated on this list before, but what are people doing today when faced with a request like the need “for 100 students simultaneously downloading a powerpoint presentation. Recently there was discussion on MCA vs. SCA vendors and how each handles this worst case scenario. Since we are an MCA (Aruba), I’d be interested in hearing what others have done or are planning for large classrooms and auditoriums. -- Don Wright Network Technologies Group Brown University This sounds like a perfect scenario for Scalable Reliable Multicast. Of course it would require that you have multicast enabled on your wireless network... http://www.digitalfountain.com/ufiles/library/file-broadcast-data-sheet.pdf http://discuss.joelonsoftware.com/default.asp?joel.3.110169.43 http://technet.microsoft.com/en-us/library/bb878066.aspx http://www.land.ufrj.br/tools/rmcast/rmcast.html http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_1-2/reliable_multicast.html http://www.icir.org/floyd/srm.html --- Bruce Curtis [EMAIL PROTECTED] Certified NetAnalyst II701-231-8527 North Dakota State University ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
RE: [WIRELESS-LAN] many clients, one room
I just wish I could get them to call me. From: The EDUCAUSE Wireless Issues Constituent Group Listserv on behalf of Jon Freeman Sent: Sat 4/12/2008 1:49 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Added a couple of notes to Frank's message below... Jon 303-808-2666 Xirrus(tm) Array...the Air is the Network(tm)...visit us at www.xirrus.com From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Frank Bulk - iNAME Sent: Saturday, April 12, 2008 2:03 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room John: Thanks for responding. Two points: - It's not reasonable to ignore retransmits. One of Meru's key technology strengths is its claim to pseudo-schedule client access. This reduces retransmits due to collisions (JON - true but what they don't point out is that this is similar to the 11g collision avoidance technique already part of the spec - I've not seen them argue they do any better than 22Mbs which is only a 10% difference resulting in a few seconds difference from the calculated result, not enough to compare to the 4 times faster demonstrated). Meru argues (and the last Novarum study appeared to demonstrate) that in dense client situations Meru's approach provides a higher aggregate throughput per AP (JON- as noted in my last comment, this may be, but the small percent difference can't come close to lighting up more total channels). If you recall one of the first graphics on their web site many years ago was of a chart with the number of clients along the x axis and aggregate throughput along the y-axis. I don't want to ignore the fact that the other vendors involved in Novarum's test didn't have an opportunity to optimize their product or want to participate, but not unlike ATM and Token Ring, it appears that Meru's approach, in situations of high client density, should outperform the traditional approach (JON - actually the opposite is true as the stand alone AP environment offers a new pool of capacity per AP where the Meru blanket approach only offers a single pool of capacity across multiple APs that everyone share, in effect creating a single hub for the entire area of coverage that is only 3 channels in size, so depending on the size of the coverage area the Meru approach could provide a significantly less amount of total bandwidth). In other words, in the PowerPoint scenario you described, Meru would do better than their competitors (JON - yes, this is true for everyone except the example used for the Xirrus Array which provides 4 times the speed, and since we're talking about classroom teaching time this difference is significant in terms of impact on the learning effect of students). Their competitors would argue that the network should be designed differently.(JON - actually most competitors might say that you can't support this number of people in a closed space since they will deal with near field interference issues) - More (non-overlapping) channels is almost always better (JON - we agree on this point completely). The enterprise WLAN vendors could stack multiple APs on top of each other, each operating at one or more non-overlapping 5 GHz frequencies, but omni-directional antennas will make channel planning difficult (JON - actually the planning would be more likely impossible as any APs placed in close proximity would cause each other near field interference, like what you hear when your cell phone is near your telephone, both operate on difference frequencies but their close proximity causes interference...the Array has several passive and active technologies that eliminate this problem, a benefit of integration that can't be solved by stacking APs, anyone who's tried stacking can offer their experience). Xirrus does a nice job of packaging that up, and it's directionality increases coverage and limits co-channel interference with neighboring arrays. (JON - agreed, and thank you!) My summary viewpoint: most enterprise WLAN vendors have been able to avoid the channel-stacking and co-channel interference challenges because actual usage levels have been low, they haven't had to worry about it (JON - true but we're seeing this problem coming to a head in about 30% of the Wi-Fi implementations today with a very rapid growth). They've been granted a reprieve with 802.11n (JON - .11n is now set for ratification in 2009, it does provide a good indication of the need for speed if you review the level of interest, FYI - the array with .11n will provide fast Ethernet switch replacement speeds - 12/24/48 port speeds, allowing you to get the switch benefit without the costs of the wires). While one might be tempted to say that this will catch up on them, I believe that raw speed will continually increase, either through
Re: [WIRELESS-LAN] many clients, one room
Hi Don, We are a Meru customer we've had great success with their system in our large lecture rooms. On Friday, we had 250 Engineering students taking an exam, which required MathCAD, on 2 Meru AP208s. The exam ran flawlessly. HTH -John Don Wright wrote: I know this has been talked about and debated on this list before, but what are people doing today when faced with a request like the need “for 100 students simultaneously downloading a powerpoint presentation. Recently there was discussion on MCA vs. SCA vendors and how each handles this worst case scenario. Since we are an MCA (Aruba), I’d be interested in hearing what others have done or are planning for large classrooms and auditoriums. -- Don Wright Network Technologies Group Brown University wire --- less, wi-fi ))) more ** 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/.
RE: [WIRELESS-LAN] many clients, one room
Can you please give us more information in terms of how the APs and Laptops were setup. I'm no math major and on a bad day I have trouble adding (don't laugh). Anyway, I'm just wondering if it was setup so you have 54+54+11+11=130/250(users)=.52 or 54+54+11=119/250(users)=.476. I am not implying a thing. I'm asking this just for my clarification. It sounds like the software may have been on the laptop and/or only the answer or very small packets were saved to/from a server. If it is designed to work with little bandwidth (like Citrix) then that is great. I'm just saying it is a difference. -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of John Center Sent: Monday, April 14, 2008 8:28 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Hi Don, We are a Meru customer we've had great success with their system in our large lecture rooms. On Friday, we had 250 Engineering students taking an exam, which required MathCAD, on 2 Meru AP208s. The exam ran flawlessly. HTH -John Don Wright wrote: I know this has been talked about and debated on this list before, but what are people doing today when faced with a request like the need for 100 students simultaneously downloading a powerpoint presentation. Recently there was discussion on MCA vs. SCA vendors and how each handles this worst case scenario. Since we are an MCA (Aruba), I'd be interested in hearing what others have done or are planning for large classrooms and auditoriums. -- Don Wright Network Technologies Group Brown University wire --- less, wi-fi ))) more ** 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/.
RE: [WIRELESS-LAN] many clients, one room
We are using multiple vendors. One of them happen to be Xirrus. We have a single XS8 (8 radio array). Capable of about: 512 users 54+54+54+54+11+11+11=249 yes, I'm still assuming there will be 802.11b We have had MAX 412 users on array. Test is given over network (exam 4) and users save answers to server or on drive if needed. This is also used to provide bandwidth in a open lobby where students gather. Single 2x2 enclosure, one conduit, 3 data pulls. Is everyone else leaving the antenna above the ceiling? -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Cal Frye Sent: Saturday, April 12, 2008 5:04 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Frank Bulk wrote: I'll let others with production networks pipe in with their experiences. I'm missing this aspect of the current discussion. Does anyone out there have real-world experience to confirm or counter Jon's claims for Xirrus? -- Regards, -- Cal Frye, Network Administrator, Oberlin College www.calfrye.com, www.pitalabs.com The United States is in no sense founded upon the Christian doctrine. -- George Washington, founding father and first President ** 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/.
RE: [WIRELESS-LAN] many clients, one room
WOW?! Two radios and 250 users? Please describe your setup! Jason D. Appah -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of John Center Sent: Monday, April 14, 2008 5:28 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Hi Don, We are a Meru customer we've had great success with their system in our large lecture rooms. On Friday, we had 250 Engineering students taking an exam, which required MathCAD, on 2 Meru AP208s. The exam ran flawlessly. HTH -John Don Wright wrote: I know this has been talked about and debated on this list before, but what are people doing today when faced with a request like the need for 100 students simultaneously downloading a powerpoint presentation. Recently there was discussion on MCA vs. SCA vendors and how each handles this worst case scenario. Since we are an MCA (Aruba), I'd be interested in hearing what others have done or are planning for large classrooms and auditoriums. -- Don Wright Network Technologies Group Brown University wire --- less, wi-fi ))) more ** 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/. smime.p7s Description: S/MIME cryptographic signature
Re: [WIRELESS-LAN] many clients, one room
Hi Clint, The AP208 have 2 radios, 11a 11b/g. We have the laptops set up to prefer 11a, so the bulk of the connections are 11a. MathCAD is installed locally on the laptops, but the size of the student files vary - probably comparable to a Powerpoint presentation. We used to do this with Cisco AP1200s had constant complaints. No more. We had the same problem at exam times at our Law School. No more. Like I said, we are very happy with the Meru products. HTH -John Ringgold, Clint wrote: Can you please give us more information in terms of how the APs and Laptops were setup. I'm no math major and on a bad day I have trouble adding (don't laugh). Anyway, I'm just wondering if it was setup so you have 54+54+11+11=130/250(users)=.52 or 54+54+11=119/250(users)=.476. I am not implying a thing. I'm asking this just for my clarification. It sounds like the software may have been on the laptop and/or only the answer or very small packets were saved to/from a server. If it is designed to work with little bandwidth (like Citrix) then that is great. I'm just saying it is a difference. -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of John Center Sent: Monday, April 14, 2008 8:28 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Hi Don, We are a Meru customer we've had great success with their system in our large lecture rooms. On Friday, we had 250 Engineering students taking an exam, which required MathCAD, on 2 Meru AP208s. The exam ran flawlessly. HTH -John Don Wright wrote: I know this has been talked about and debated on this list before, but what are people doing today when faced with a request like the need for 100 students simultaneously downloading a powerpoint presentation. Recently there was discussion on MCA vs. SCA vendors and how each handles this worst case scenario. Since we are an MCA (Aruba), I'd be interested in hearing what others have done or are planning for large classrooms and auditoriums. -- Don Wright Network Technologies Group Brown University wire --- less, wi-fi ))) more ** 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/. ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
RE: Re: [WIRELESS-LAN] many clients, one room
John: Thanks for responding. Two points: - Its not reasonable to ignore retransmits. One of Merus key technology strengths is its claim to pseudo-schedule client access. This reduces retransmits due to collisions. Meru argues (and the last Novarum study appeared to demonstrate) that in dense client situations Merus approach provides a higher aggregate throughput per AP. If you recall one of the first graphics on their web site many years ago was of a chart with the number of clients along the x axis and aggregate throughput along the y-axis. I dont want to ignore the fact that the other vendors involved in Novarums test didnt have an opportunity to optimize their product or want to participate, but not unlike ATM and Token Ring, it appears that Merus approach, in situations of high client density, should outperform the traditional approach. In other words, in the PowerPoint scenario you described, Meru would do better than their competitors. Their competitors would argue that the network should be designed differently .. - More (non-overlapping) channels is almost always better. The enterprise WLAN vendors could stack multiple APs on top of each other, each operating at one or more non-overlapping 5 GHz frequencies, but omni-directional antennas will make channel planning difficult. Xirrus does a nice job of packaging that up, and its directionality increases coverage and limits co-channel interference with neighboring arrays. My summary viewpoint: most enterprise WLAN vendors have been able to avoid the channel-stacking and co-channel interference challenges because actual usage levels have been low, they havent had to worry about it. Theyve been granted a reprieve with 802.11n. While one might be tempted to say that this will catch up on them, I believe that raw speed will continually increase, either through more efficient modulation schemes or smart antenna technologies. Its a little like enterprise-deployed Ethernet we generally dont deploy QoS in our network, it was cheaper to go from hubs to switches, 10 to 100, 100 to 1000 Mps, and later, it will be 10 Gbps. Its a lazy approach, but it deals with usage and service level issue problem 99.99% of the time. Frank From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Jon Freeman Sent: Friday, April 11, 2008 12:52 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Some math offers insight on this question Assuming the following: · were looking at a single area (i.e. lecture hall), · No retransmits are allowed (not real world, but is a best case example) · were talking about an average sized PPT of 10MB (looking through my PPT folder this was just my average) · Student and teacher expectations of speed is drawn from their homes (i.e. cable and DSL), less than this will be noticed and likely complained about · the rooms average data rate is 54Mbs (10 people by 10 people = 50ftx50ft) · 100 people, all downloading at the same time · max radio density for Meru is 3 (i.e. 3 channels of coverage, this is the most non-overlapping channels you can light in this area without interference problems using their latest gear) · Actual throughput for TCP data is 20Mbs per channel (54Mbs less Wi-Fi management overheads this is a number referred to in the 802.11 spec and one Ive observed many times) · Max radio density available from other shipping solutions today is 15 channels Meru Solution: · 20Mbs x 3 = 60Mbs converting to Bytes /8 = 7.5MB/sec /100 people = .075MB/sec (using 1024KB to the MB, this is 76KB/sec/user of TCP!) · Time to download 10MB/.075MB = 133 sec/user to download a 10MB file (about 2 minutes), so a 40MB file would take ~8min/user . · Link throughput then is 76KBs TCP for each user .you decide if thats acceptable 14 channel solution: · 20Mbs x 15 = 300Mbs · 5 times the bandwidth = 5 times the throughput · 76KBs/user x 5 = 380KBs TCP for each user of link throughput (and this is a little bit better than most uplink speeds on home broadband, http://www.speedtest.net www.speedtest.net is what Ive used on many LANs) · Instead of 2 minutes waiting, the 10MB file downloads with this solution in 26 seconds, and about 1 ½ min for a 40MB file, versus 8 minutes. So, we can assume that Franks interviews from 2 years ago dont account for the latest technologies. Sorry Frank, I dont mean to poke holes in your study, but it is 2 years old and we are talking about technology. Didnt we stop trying to manage limited bandwidth when ATM failed? When did we go back to thinking thats ok? I like more power, more speed, better, faster . Jon 303-808-2666 Xirrus Array...the Air is the Network...visit us at www.xirrus.com
RE: [WIRELESS-LAN] many clients, one room
Added a couple of notes to Frank's message below... Jon 303-808-2666 Xirrus(tm) Array...the Air is the Network(tm)...visit us at www.xirrus.com From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Frank Bulk - iNAME Sent: Saturday, April 12, 2008 2:03 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room John: Thanks for responding. Two points: - It's not reasonable to ignore retransmits. One of Meru's key technology strengths is its claim to pseudo-schedule client access. This reduces retransmits due to collisions (JON - true but what they don't point out is that this is similar to the 11g collision avoidance technique already part of the spec - I've not seen them argue they do any better than 22Mbs which is only a 10% difference resulting in a few seconds difference from the calculated result, not enough to compare to the 4 times faster demonstrated). Meru argues (and the last Novarum study appeared to demonstrate) that in dense client situations Meru's approach provides a higher aggregate throughput per AP (JON- as noted in my last comment, this may be, but the small percent difference can't come close to lighting up more total channels). If you recall one of the first graphics on their web site many years ago was of a chart with the number of clients along the x axis and aggregate throughput along the y-axis. I don't want to ignore the fact that the other vendors involved in Novarum's test didn't have an opportunity to optimize their product or want to participate, but not unlike ATM and Token Ring, it appears that Meru's approach, in situations of high client density, should outperform the traditional approach (JON - actually the opposite is true as the stand alone AP environment offers a new pool of capacity per AP where the Meru blanket approach only offers a single pool of capacity across multiple APs that everyone share, in effect creating a single hub for the entire area of coverage that is only 3 channels in size, so depending on the size of the coverage area the Meru approach could provide a significantly less amount of total bandwidth). In other words, in the PowerPoint scenario you described, Meru would do better than their competitors (JON - yes, this is true for everyone except the example used for the Xirrus Array which provides 4 times the speed, and since we're talking about classroom teaching time this difference is significant in terms of impact on the learning effect of students). Their competitors would argue that the network should be designed differently.(JON - actually most competitors might say that you can't support this number of people in a closed space since they will deal with near field interference issues) - More (non-overlapping) channels is almost always better (JON - we agree on this point completely). The enterprise WLAN vendors could stack multiple APs on top of each other, each operating at one or more non-overlapping 5 GHz frequencies, but omni-directional antennas will make channel planning difficult (JON - actually the planning would be more likely impossible as any APs placed in close proximity would cause each other near field interference, like what you hear when your cell phone is near your telephone, both operate on difference frequencies but their close proximity causes interference...the Array has several passive and active technologies that eliminate this problem, a benefit of integration that can't be solved by stacking APs, anyone who's tried stacking can offer their experience). Xirrus does a nice job of packaging that up, and it's directionality increases coverage and limits co-channel interference with neighboring arrays. (JON - agreed, and thank you!) My summary viewpoint: most enterprise WLAN vendors have been able to avoid the channel-stacking and co-channel interference challenges because actual usage levels have been low, they haven't had to worry about it (JON - true but we're seeing this problem coming to a head in about 30% of the Wi-Fi implementations today with a very rapid growth). They've been granted a reprieve with 802.11n (JON - .11n is now set for ratification in 2009, it does provide a good indication of the need for speed if you review the level of interest, FYI - the array with .11n will provide fast Ethernet switch replacement speeds - 12/24/48 port speeds, allowing you to get the switch benefit without the costs of the wires). While one might be tempted to say that this will catch up on them, I believe that raw speed will continually increase, either through more efficient modulation schemes or smart antenna technologies. It's a little like enterprise-deployed Ethernet - we generally don't deploy QoS in our network, it was cheaper to go from hubs to switches, 10 to 100, 100 to 1000 Mps, and later, it will be 10 Gbps. It's a lazy
Re: [WIRELESS-LAN] many clients, one room
Frank Bulk wrote: I’ll let others with production networks pipe in with their experiences. I'm missing this aspect of the current discussion. Does anyone out there have real-world experience to confirm or counter Jon's claims for Xirrus? -- Regards, -- Cal Frye, Network Administrator, Oberlin College www.calfrye.com, www.pitalabs.com The United States is in no sense founded upon the Christian doctrine. -- George Washington, founding father and first President ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
RE: [WIRELESS-LAN] many clients, one room
Some math offers insight on this question... Assuming the following: · we're looking at a single area (i.e. lecture hall), · No retransmits are allowed (not real world, but is a best case example) · we're talking about an average sized PPT of 10MB (looking through my PPT folder this was just my average) · Student and teacher expectations of speed is drawn from their homes (i.e. cable and DSL), less than this will be noticed and likely complained about · the room's average data rate is 54Mbs (10 people by 10 people = 50ftx50ft) · 100 people, all downloading at the same time · max radio density for Meru is 3 (i.e. 3 channels of coverage, this is the most non-overlapping channels you can light in this area without interference problems using their latest gear) · Actual throughput for TCP data is 20Mbs per channel (54Mbs less Wi-Fi management overheads - this is a number referred to in the 802.11 spec and one I've observed many times) · Max radio density available from other shipping solutions today is 15 channels Meru Solution: · 20Mbs x 3 = 60Mbs converting to Bytes /8 = 7.5MB/sec /100 people = .075MB/sec (using 1024KB to the MB, this is 76KB/sec/user of TCP!) · Time to download 10MB/.075MB = 133 sec/user to download a 10MB file (about 2 minutes), so a 40MB file would take ~8min/user · Link throughput then is 76KBs TCP for each useryou decide if that's acceptable 14 channel solution: · 20Mbs x 15 = 300Mbs · 5 times the bandwidth = 5 times the throughput · 76KBs/user x 5 = 380KBs TCP for each user of link throughput (and this is a little bit better than most uplink speeds on home broadband, www.speedtest.net http://www.speedtest.net is what I've used on many LANs) · Instead of 2 minutes waiting, the 10MB file downloads with this solution in 26 seconds, and about 1 ½ min for a 40MB file, versus 8 minutes. So, we can assume that Frank's interviews from 2 years ago don't account for the latest technologies. Sorry Frank, I don't mean to poke holes in your study, but it is 2 years old and we are talking about technology. Didn't we stop trying to manage limited bandwidth when ATM failed? When did we go back to thinking that's ok? I like more power, more speed, better, faster Jon 303-808-2666 Xirrus(tm) Array...the Air is the Network(tm)...visit us at www.xirrus.com From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Frank Bulk Sent: Friday, April 11, 2008 10:07 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Based on research and interviews I performed two years ago, it appeared that for dense client usage in a confined space, Meru was the product most often implemented. These organizations chose Meru because it worked well or better than the competitor. Competitors argued that their product wasn't set up correctly or optimally. I'll let others with production networks pipe in with their experiences. Frank From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Don Wright Sent: Friday, April 11, 2008 9:59 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] many clients, one room I know this has been talked about and debated on this list before, but what are people doing today when faced with a request like the need for 100 students simultaneously downloading a powerpoint presentation. Recently there was discussion on MCA vs. SCA vendors and how each handles this worst case scenario. Since we are an MCA (Aruba), I'd be interested in hearing what others have done or are planning for large classrooms and auditoriums. -- Don Wright Network Technologies Group Brown University wire --- less, wi-fi ))) more ** 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/.
RE: [WIRELESS-LAN] many clients, one room
Load balancing is there. There's a trick to making it work but it does (trick as in tricking the client to connect to less used channel/radio) - and, no breakage to the 802.11 spec at all i.e. fully compliant and certified. Jon 303-808-2666 Xirrus(tm) Array...the Air is the Network(tm)...visit us at www.xirrus.com -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Wilson Dillaway Sent: Friday, April 11, 2008 11:56 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] many clients, one room Jon, Given that the clients make all the decisions, how can we assure, given 14 channels, that the users will equally balance themselves across all 14, rather than bunching up? Wilson Jon Freeman wrote: Some math offers insight on this question... Assuming the following: · we're looking at a single area (i.e. lecture hall), · No retransmits are allowed (not real world, but is a best case example) · we're talking about an average sized PPT of 10MB (looking through my PPT folder this was just my average) · Student and teacher expectations of speed is drawn from their homes (i.e. cable and DSL), less than this will be noticed and likely complained about · the room's average data rate is 54Mbs (10 people by 10 people = 50ftx50ft) · 100 people, all downloading at the same time · max radio density for Meru is 3 (i.e. 3 channels of coverage, this is the most non-overlapping channels you can light in this area without interference problems using their latest gear) · Actual throughput for TCP data is 20Mbs per channel (54Mbs less Wi-Fi management overheads - this is a number referred to in the 802.11 spec and one I've observed many times) · Max radio density available from other shipping solutions today is 15 channels _Meru Solution:_ · 20Mbs x 3 = 60Mbs converting to Bytes /8 = 7.5MB/sec /100 people = .075MB/sec (using 1024KB to the MB, this is 76KB/sec/user of TCP!) · Time to download 10MB/.075MB = 133 sec/user to download a 10MB file (_about 2 minutes_), so a 40MB file would take ~8min/user · Link throughput then is 76KBs TCP for each useryou decide if that's acceptable _14 channel solution:_ · 20Mbs x 15 = 300Mbs · 5 times the bandwidth = 5 times the throughput · 76KBs/user x 5 = 380KBs TCP for each user of link throughput (and this is a little bit better than most uplink speeds on home broadband, www.speedtest.net http://www.speedtest.net is what I've used on many LANs) · Instead of 2 minutes waiting, the 10MB file downloads with this solution in _26 seconds_, and about 1 ½ min for a 40MB file, versus 8 minutes. So, we can assume that Frank's interviews from 2 years ago don't account for the latest technologies. Sorry Frank, I don't mean to poke holes in your study, but it is 2 years old and we are talking about technology. Didn't we stop trying to manage limited bandwidth when ATM failed? When did we go back to thinking that's ok? I like more power, more speed, better, faster Jon 303-808-2666 *Xirrus**(tm)** Array...the**/ Air/** **is the Network(tm)...visit us at www.xirrus.com*** *From:* The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] *On Behalf Of *Frank Bulk *Sent:* Friday, April 11, 2008 10:07 AM *To:* WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU *Subject:* Re: [WIRELESS-LAN] many clients, one room Based on research and interviews I performed two years ago, it appeared that for dense client usage in a confined space, Meru was the product most often implemented. These organizations chose Meru because it worked well or better than the competitor. Competitors argued that their product wasn't set up correctly or optimally. I'll let others with production networks pipe in with their experiences. Frank *From:* The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] *On Behalf Of *Don Wright *Sent:* Friday, April 11, 2008 9:59 AM *To:* WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU *Subject:* [WIRELESS-LAN] many clients, one room I know this has been talked about and debated on this list before, but what are people doing today when faced with a request like the need for 100 students simultaneously downloading a powerpoint presentation. Recently there was discussion on MCA vs. SCA vendors and how each handles this worst case scenario. Since we are an MCA (Aruba), I'd be interested in hearing what others have done or are planning for large classrooms and auditoriums. -- Don Wright Network Technologies Group Brown University wire --- less, wi-fi
