Re: [WIRELESS-LAN] And so it begins... 11ac- are you using 80 MHz channels yet?
Lee: What is the expected performance gain if you do not use 80 MHz channels? John On Tue, Jan 7, 2014 at 6:51 PM, Lee H Badman lhbad...@syr.edu wrote: Hi Frans- I haven't chosen 80 MHz at all- but am wondering if anyone has played with it in prod or test to see what RRM etc will do with it- if anyone has slewed the DFS thing to get the extra channels etc. Just seeing who may be doing what- not advocating for it or declaring that I have gone this way. -Lee Lee H. Badman Network Architect/Wireless TME ITS, Syracuse University 315.443.3003 From: The EDUCAUSE Wireless Issues Constituent Group Listserv [ WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] on behalf of Frans Panken [ frans.pan...@surfnet.nl] Sent: Tuesday, January 07, 2014 5:55 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] And so it begins... 11ac- are you using 80 MHz channels yet? Hi Lee, Bold indeed. Is performance your main rationale for choosing 80 Mhz channels? Are the channels set statically or do the APs fall back to 40 Mhz or 20 Mhz channels if interference is detected? Otherwise, choosing 80 Mhz channels compromises the support of 802.11a and 802.11n clients on the 802.11ac APs. By choosing 80 Mhz, the number of non-overlapping channels reduces to 2, right? Are you using 11ac as an overlay for 11n coverage? Many questions as a response on question, but I wonder about your rationales for choosing 80 Mhz channels. -Frans On Tue Jan 7 17:07:52 2014, Lee H Badman wrote: For the bold among us that have started with 11ac, are you yet running 80 MHz channels? Also, what channels have you made available in 5 GHz? Finally, any issues noted with RRM (or whatever your own WLAN vendor calls autochannel/autopower) with 11ac? Thanks- Lee Badman ** 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/. -- John Kaftan IT Infrastructure Manager Utica College ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
Re: [WIRELESS-LAN] And so it begins... 11ac- are you using 80 MHz channels yet?
Cisco has a really nice Whitepaper on this: http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps11983/white_paper_c11-713103.html And revolution wifi has a nice one on Channel Planning http://www.revolutionwifi.net/2013/03/80211ac-channel-planning.html Some Snippets: 2.3.4 RTS/CTS with Bandwidth Indication An 802.11ac AP operating on 80 MHz (or 160 MHz and so on) should still be capable of allowing 802.11a or 802.11n clients to associate. Thus beacons are sent on one 20 MHz channel, known as the primary channel, within that 80 MHz. The AP and all clients associated to the AP receive and process every transmission that overlaps this primary channel and extract virtual carrier sense from the frames they can decode. However, the AP could be nearby other uncoordinated APs. Those APs could be preexisting 802.11a or 802.11n APs, and their primary channels could be any 20 MHz within the 80 MHz of the 802.11ac AP. Then the different APs and their associated clients have a different virtual carrier sense, so can transmit at different times on the different subchannels, including overlapping times. With the wide 802.11ac channel bandwidths, this scenario becomes much more likely than with 802.11n - 80 MHz wide channels allow for five (5) non-overlapping channels in the U.S. and five (5) in the UK/EU (channels 149 and higher require light licensing for outdoor use only) when DFS is used, but only two (2) channels in the U.S. and one (1) in UK/EU without DFS. - 160 MHz wide channels allow for one (1) non-overlapping channel in the U.S. and two (2) in the UK/EU, with DFS being mandatory for their use in all circumstances. There is a saving grace that will allow enterprises to take advantage of these wider channels on a best-effort basis. Let's step back for a moment - with 802.11n, 40 MHz channels were an all-or-nothing proposition. The APs channel width was statically set at 20 or 40 MHz. On the other hand, 802.11ac allows per-frame channel width and bandwidth signalinghttp://blogs.aerohive.com/blog/the-wi-fi-security-blog/80211ac-channel-bandwidth-sharing. Practically, this means that WLAN administrators can allow the use of wider channels by APs and clients when all of the constituent smaller channels are clear. If a portion of the large channel is busy at the point in time when a frame needs to be transmitted, for instance a neighboring AP or WLAN is actively using a 20 or 40 MHz portion, then the AP or client can simply back down and use the primary 20 or 40 MHz portion of the larger channel that is clear. For the next frame transmission, if the entire 80/160 MHz channel is clear then the AP or client can ramp back up and use the full channel width. From an implementation perspective, most enterprises should plan around non-overlapping 40 MHz channels, or even 20 MHz channels in high-density areas. If the FCC frees up an additional 195 MHz of shared spectrumhttp://revolutionwifi.blogspot.com/2013/02/wi-fi-may-get-capacity-boost-thanks-to.html in late 2014 or early 2015 then designing around non-overlapping 80 MHz channels (or possibly even 160 MHz channels) in the U.S. will become much more practical. Mike On Wed, Jan 8, 2014 at 8:58 AM, John Kaftan jkaf...@utica.edu wrote: Lee: What is the expected performance gain if you do not use 80 MHz channels? John On Tue, Jan 7, 2014 at 6:51 PM, Lee H Badman lhbad...@syr.edu wrote: Hi Frans- I haven't chosen 80 MHz at all- but am wondering if anyone has played with it in prod or test to see what RRM etc will do with it- if anyone has slewed the DFS thing to get the extra channels etc. Just seeing who may be doing what- not advocating for it or declaring that I have gone this way. -Lee Lee H. Badman Network Architect/Wireless TME ITS, Syracuse University 315.443.3003 From: The EDUCAUSE Wireless Issues Constituent Group Listserv [ WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] on behalf of Frans Panken [ frans.pan...@surfnet.nl] Sent: Tuesday, January 07, 2014 5:55 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] And so it begins... 11ac- are you using 80 MHz channels yet? Hi Lee, Bold indeed. Is performance your main rationale for choosing 80 Mhz channels? Are the channels set statically or do the APs fall back to 40 Mhz or 20 Mhz channels if interference is detected? Otherwise, choosing 80 Mhz channels compromises the support of 802.11a and 802.11n clients on the 802.11ac APs. By choosing 80 Mhz, the number of non-overlapping channels reduces to 2, right? Are you using 11ac as an overlay for 11n coverage? Many questions as a response on question, but I wonder about your rationales for choosing 80 Mhz channels. -Frans On Tue Jan 7 17:07:52 2014, Lee H Badman wrote: For the bold among us that have started with 11ac, are you yet running 80 MHz channels? Also, what channels have you made available in 5 GHz? Finally, any issues
Chromebook connectivity issues
Hi WIRELESS-LAN Educausers, For a number of months, our help desk has been fielding complaints from Chromebook owners who have been reporting difficulty connecting to our .1X SSID. Packet captures show the Chromebooks will go so far as to DHCPDISCOVER, but will not respond to a DHCPOFFER. After several retries, these devices will eventually complete the DHCP process, at which point the Chromebook is online. This can sometimes take more than a minute. I have not been able to reliably reproduce this issue. Sometimes it works right away, sometimes it doesn't. I haven't received reports of similar issues with non-Chromebooks. I found that if I force the SSID to TKIP-only (disabling AES), a Chromebook will connect as expected, without having to cycle through the DHCPDISCOVER - DHCPOFFER loop. TKIP encryption implies a/g-only speeds, so this is a less than ideal workaround. Is anyone else on the list having difficulty getting Chromebooks to connect to their enterprise wireless? Thanks! --- Chris Alman Network Engineer, University of Northern Iowa Office: (319) 273-5964 --- ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
Myfi
I got my hands on someone's Verizon Myfi today and it was set to Auto choose what channel to broadcast its SSID on. The crazy thing chose channel 2! It was putting out a pretty strong signal too. I was seeing a -50 dB from 10 feet away. To anyone else connected to channel 1 or 6 a signal on channel 2 is going to be noise, i.e. interference. When doing scans I have seen this before. I have seen these things on every channel but 1,6,11 now that I think about it. I logged into its web interface and was able to force it to use channel 1. There is also an easy to use interface right on the device where I could chose the channel. I'm just alarmed that these things choose non-standandard channels. If 3-4 or more of these things show up in room hosting a conference we may have a real problem. Its hard enough to put 120 laptops in a room and get them all on and happy let alone having these things out there. I'm curious, does anybody police these devices at high density events or make an announcement requesting folks turn them off? I can't imagine these Myfis perform well in high density situations due to their competing for bandwidth on both 2.4 and cellular bands. Thanks -- John Kaftan IT Infrastructure Manager Utica College ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
