-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 What 14 channels are you using? Are you reusing as you go around the array or using a band?
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 user?.you 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**?** Array...the**/ Air/** **is the Network?...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/. - -- James Eyrich Wireless and Wired Network Designer CITES - Network Design and Maintenance - Network Design Office University of Illinois [EMAIL PROTECTED] 217-265-6867 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (MingW32) iD8DBQFH/6tyg6vS3xxAH94RAmyeAJ0czk7BnCl+EAE3NUSGP7hsH05TVQCfQEgH ZRNui72V36+t9OewVs/wIc4= =g1Ue -----END PGP SIGNATURE----- ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
