Channel Utilization
Our team has recently been having discussions about co-channel interference and channel utilization to better understand the issues we are having in our dorms. We know we have a design issue, but we are trying to quantify the problem. In Cisco's Enterprise Best Practices for Apple Mobile Devices on Cisco Wireless LANs, they state that Using the Aloha protocol definition of channel utilization, a wireless packet network reached capacity when the utilization reaches 34%. What utilization parameters do you use to identify poor performance on a channel? In other words, at what percentage do you say that's a problem? Lane Reams | Manager, Network Design Engineering | Information Technology | Vanderbilt University lane.re...@vanderbilt.edu | phone 615.936.2677 | it.vanderbilt.eduhttp://it.vanderbilt.edu/ ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
RE: Channel Utilization
Susan DeLellis Manager, UC Strategy and Planning Harvard University Information Technology Infrastructure | Unified Communications P 617 384 6540 60 Oxford Street, Room 106 Cambridge, MA 02138 susan_delel...@harvard.edu www.harvard.edu/huit From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] On Behalf Of Reams, Lane Sent: Thursday, November 06, 2014 4:49 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] Channel Utilization Our team has recently been having discussions about co-channel interference and channel utilization to better understand the issues we are having in our dorms. We know we have a design issue, but we are trying to quantify the problem. In Cisco's Enterprise Best Practices for Apple Mobile Devices on Cisco Wireless LANs, they state that Using the Aloha protocol definition of channel utilization, a wireless packet network reached capacity when the utilization reaches 34%. What utilization parameters do you use to identify poor performance on a channel? In other words, at what percentage do you say that's a problem? Lane Reams | Manager, Network Design Engineering | Information Technology | Vanderbilt University lane.re...@vanderbilt.edumailto:lane.re...@vanderbilt.edu | phone 615.936.2677 | it.vanderbilt.eduhttp://it.vanderbilt.edu/ ** 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] Channel Utilization
Our experience is that at 40% users are going to start to wonder what's wrong, and at 60% you might as well hang it up. I'm not sure where the 34% number came from, but it matches with the maximum practical utilization of the Aloha network in the late 60's. Perhaps it is entirely a coincidence that Aloha and 802.11* show similar maximum utilization? I'd love to see graphs of throughput vs. utilization for various protocols, but can't lay my hands on any at the moment. John On Thu, Nov 6, 2014 at 1:48 PM, Reams, Lane lane.re...@vanderbilt.edu wrote: Our team has recently been having discussions about co-channel interference and channel utilization to better understand the issues we are having in our dorms. We know we have a design issue, but we are trying to quantify the problem. In Cisco’s “Enterprise Best Practices for Apple Mobile Devices on Cisco Wireless LANs”, they state that “Using the Aloha protocol definition of channel utilization, a wireless packet network reached capacity when the utilization reaches 34%.” What utilization parameters do you use to identify poor performance on a channel? In other words, at what percentage do you say “that’s a problem”? *Lane Reams | Manager, Network Design Engineering | Information Technology | Vanderbilt University* lane.re...@vanderbilt.edu | phone 615.936.2677 | it.vanderbilt.edu ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. -- ---======--- Want to quickly check a system status or report a problem to the IT team? Use http://justme.westmont.edu Have a problem that requires tracking and IT email response? Use http://mayday.westmont.edu ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
Re: [WIRELESS-LAN] Potentially big news for the 11ac minded concerned with cabling
On 07/11/14 02:00, Frank Sweetser wrote: I would strongly encourage everyone to bug all of their vendors about where this is on their roadmap. I've been asking ours, and they haven't made any commitments yet but they're all well aware of it. Our AM at Extreme hinted that 2.5Gbps will be coming in their new stackables which are due next year. 2.5GBps ethernet has been a thing for 10 years, but only on PCBs as a single lane of XAUI. I'd still argue YAGNI in a real-world environment that is limited to 40MHz channels, given that 80MHz and 160MHz don't allow for a lot of channel re-use. So then 40MHz with 8 spatial streams peaks at 1.6Gbps theoretical with all clients within 20ft of the AP. Add in overheads, 256QAM being unusable at with MU-MIMO [1] and a bit of clients sending (which I believe can't be MU-MIMO) and you're well under 1Gbps again. Even if we assume a single 3SS client, 256 QAM and 80MHz channels you're looking at 1.3GBps theoretical, which again is going to be under 1GBps. IMHO, if you really want to give good performance to everyone, install dense single-5GHz-radio APs with 1Gbps links rather than trying to push theoretical boundaries for just a few users. [1] http://www.cisco.com/c/en/us/products/collateral/wireless/aironet-3600-series/white_paper_c11-713103.html -- James Andrewartha Network Projects Engineer Christ Church Grammar School Claremont, Western Australia Ph. (08) 9442 1757 Mob. 0424 160 877 ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
