RE: [WIRELESS-LAN] Cisco vs. Meru article
Multi-tenant locations such as high-rises in Manhattan where interference from floors above and below, and across the street, are potentially the most problematic in regards to co-channel interference. I think most organizations will be insulated from neighboring networks by distance, building materials, or physical isolation. Frank -Original Message- From: Dale W. Carder [mailto:[EMAIL PROTECTED] Sent: Monday, June 18, 2007 6:31 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Cisco vs. Meru article (still catching up on old email, sorry) On Jun 14, 2007, at 10:24 AM, Dave Molta wrote: > I am particuarly concerned about the intersection between private > enterprise WLANs and public metro Wi-Fi networks. Time will tell, but I estimate that public services offered on crappy unlicensed bands (where trees eat packets, and interference is king) will probably fail. The more formally run networks (such as wimax) are more poised to win, customer-experience-wise, when properly engineered. > It may not be a big problem today but I wonder if it will be a > problem in the future. If we want to stick to enterprise environments, this may not occur too frequently except at the periphery. More low-e glass may play a role, too in newer buildings. > We understand that our tests represent worst-case scenarios that > few enterprises currently experience but sometimes there is value > in pointing out the worst-case situations. Yes there is. I think we all appreciate your work. Dale ** 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] Cisco vs. Meru article
(still catching up on old email, sorry) On Jun 14, 2007, at 10:24 AM, Dave Molta wrote: Again, that could indicate that Aruba is also somehow playing foul as well (Cisco speculated that they might be using a variation of PCF interframe spacing, though Aruba denied it) but it doesn't look that way to me. Come on, we're network engineers not electrical engineers in this forum. What happened to rough consensus and running code? It's interoperability that matters, right? (flame suit in-hand). If your network has no compatibility issues, would you not use the feature? Engineers face this issue all the time, I don't think it's anything new. It's of course hilarious that Vendor C is on the other side of the standards fence this time ;-) I am particuarly concerned about the intersection between private enterprise WLANs and public metro Wi-Fi networks. Time will tell, but I estimate that public services offered on crappy unlicensed bands (where trees eat packets, and interference is king) will probably fail. The more formally run networks (such as wimax) are more poised to win, customer-experience-wise, when properly engineered. It may not be a big problem today but I wonder if it will be a problem in the future. If we want to stick to enterprise environments, this may not occur too frequently except at the periphery. More low-e glass may play a role, too in newer buildings. We understand that our tests represent worst-case scenarios that few enterprises currently experience but sometimes there is value in pointing out the worst-case situations. Yes there is. I think we all appreciate your work. If there's a silver lining here, it may be that 11n is likely to push most enterprises towards more pervasive 5 GHz deployments, where co-channel interference is not such a big issue. I think everybody will move there, it's a problem everywhere including apartment units, dense subdivisions... Dale ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
Re: [WIRELESS-LAN] Advantages of Controller-based Wireless
(Catching up on email, sorry for the delayed post) On Jun 14, 2007, at 11:17 PM, Tom Zeller wrote: Different vendor products offer different extra gravy. But in general, I see CBW as providing only a few benefits. Ditto. From the demos I have witnessed, the controllers are in my mind VERY immature (some are simply sh*t) at least for large-scale deployments. 1) True mobility - If you wireless LAN is small enough to have all users on a single subnet, you have that anyway. Some of the controllers offer mobility with varying caveats you have to weigh. 2) The ability to pop different groups of users onto different vlans without plumbing all those vlans to every access point. Be careful, as there are limits to how many vlans are supported in these systems. I'm not sure I agree these are "must have" for smaller deployments. We did just fine with per-AP management until we were approaching 100 or so. For the most part, we didn't have to log into them all that often. Maybe just the opposite? The smaller enterprise might want the controller because they don't have the ability to build the appropriate management infrastructure themselves. Point and click can be of value. However, realizing we were going to have 100s and eventually 1000s of APs we bought Airwave's AMP product, which provides an excellent central management platform for stand-alone APs (if you buy brands they support, which is most, maybe all, of the major brands). We also bought Airwave's AMP. It is very, very slick. We bought it because it could generate the reports we were looking for without having to do it ourselves. But I would NOT say that we are using it for more than as an MRTG replacement plus troubleshooting users and load. I don't see the centralized management aspect of CBW to be the driving force for us. Ditto. We chose fat AP's because we could ping/snmp/login to them like anything else. The same scripts (custom stuff on top of rancid, and a few monitoring apps) that we have managing hundreds of routers and thousands of switches can also manage our 1,715 AP's on campus with little additional effort. What a controller does not buy you is easy integration into other enterprise management systems. It's yet another console for the NOC (if you can expose the interface to them at all) and that sucks. Or you're going to waste time on this integration that will in the end cost you double. The carrot for us to move to controllers is when they are of telco-ish quality, support about 1,000 vlans arbitrarily placed throughout, allow thousands of users to roam everywhere, and provide magical load balancing. Some controllers are close, but not quite. Dale ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
Re: [WIRELESS-LAN] The strategic importance of 802.11a
I think Frank is spot-on. Wait for 'n', and don't bother with 'a' unless you "need to". On Jun 18, 2007, at 5:27 PM, Frank Bulk wrote: From two sources of anecdotal evidence it appears that those educational institutions that have deployed 802.11a for a year or two are getting between 30 to 50% of their Wi-Fi client population to use it We saw approx 25% in public spaces like libraries during peak times. This is a big advantage for critical user-density areas. One or two of our libraries get packed at finals time. Having one quarter of your users not on 2.4 makes the investment worthwhile in these areas. We also did some consultations with groups that were doing bulk laptop purchases to include 'a' support, and we put the 'a' radio in the ap's in those areas. Same issue, coordinate the offloading 2.4 where you can/need to, and everybody wins. Dale ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
RE: [WIRELESS-LAN] The strategic importance of 802.11a
If you don't mind me paraphrasing, I would suggest saying that "5 GHz is very strategic; the question is not an if, but when". Now that 802.11n is around the corner I think people executing on purchases this summer might be go for a dual-band 802.11abg solution, but starting this fall I think anyone considering an upgrade or a first-buy thinking very hard about 802.11n. As mentioned in my other e-mail, 5 GHz provides more channel selection, usually experiences less interference (less devices in that range than 2.4 GHz), resulting better overall capacity and performance. The Wi-Fi Alliance does have certification for 802.11a: http://www.wi-fi.org/pressroom_overview.php?newsid=57 Regards, Frank -Original Message- From: Jonn Martell [mailto:[EMAIL PROTECTED] Sent: Sunday, June 17, 2007 4:16 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] The strategic importance of 802.11a 802.11a is very strategic; the question is not an if, but a when. The regulatory bodies released new spectrum in the 5.35 to 5.475 GHz with better power capabilities than what was seen in the fledging UNI-1 (5.15 to 5.25). So, if you throw away UNI-1, add the four non-overlap channels in UNI-2 (5.25-5.35) to the four channels in the 5.8 GHz range and add the 11 new channels, you magically get a *lot* of real estate not available in the 2.4 GHz range. It's the best way to support a high number of users and applications such as VoWLAN and the reason why pico cells will win out in the long term (IMHO). With the new spectrum comes the requirement to use dynamic frequency selection (DFS) and Transmit Power Control (TPC) which means better battery life, less interference and generally a better RF environment. Not sure if there is a Wi-Fi certification for the "new" 802.11a products but there should be. I'd be very careful to deploy products that can't support the new frequencies in the 5 GHz range, if you do, make sure it's at "throw away" pricing... .. Jonn Martell, Martell Consulting CWNT, CWNE, CWSP, CWAP, Wireless# [EMAIL PROTECTED] www.martell.ca On 6/17/07, Tom Zeller <[EMAIL PROTECTED]> wrote: > In considering a major wireless overhaul, we're having a serious discussion > about the real importance of 802.11a in upcoming dual-mode cellular/WiFi > devices. Our current WLAN is b/g. > > 802.11a seems to be in about 10% of our laptops, judging from an > experimental AP we put in one of our busiest sites. I understand it is now > part of the Centrino set, so I would expect that to increase over time. > > The real question seems to be the role of dual-mode phones and the support > of voice over WiFi. > > 1) Is support of voice over WiFi really strategic and why? One could argue > that cell phones are sufficient in most locations. Getting "free" voice > over WiFi vs cell minutes doesn't seem to be worth the cost alone. Of > course, WiFi adds coverage for such devices in the interiors of buildings. > Does that justify a rather large additional cost for infrastructure? > > 2) If the answer to the above question is "yes", is installation of 802.11a > going to be important for mobile voice devices, especially dual-modes? > There seem to be very few 802.11a dual mode devices on the market now, > though I read there will be at least 80 more certified this year. > > For many vendors, the additional cost of adding 11a to the mix is > substantial. The cost of denser deployment (we currently have what I think > of as edge-to-edge coverage, with little overlap) is also non-trivial. > > I would be interested to hear other's opinions on these questions. > > Tom Zeller > Indiana University > [EMAIL PROTECTED] > 812-855-6214 > > ** > Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. > -- ... Jonn Martell, BSc, PMP Director of Technical Operations Fairleigh Dickenson University - Vancouver [EMAIL PROTECTED] 877-338-8002 604-802-2022 (cell) ** 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] The strategic importance of 802.11a
Tom: With the upcoming 802.11n standard I've personally lost interest in 802.11a. Why? Enterprises that haven't deployed 802.11a and are sitting happy with 802.11b/g already might as well as just hold their breath a few months (okay, maybe a small year) and wait for 802.11n products. There are only two 802.11a Vo-Fi handsets on the market, Cisco's 7921G and SpectraLink's NetLink 8000-series. I haven't heard of any plans for dual-mode vendors to develop towards 802.11a and I doubt that they'll do it now. Your reference to 80 handsets might just be dual-mode handsets (Wi-Fi and cellular), not dual-band handsets (2.4 GHz and 5 GHz). If anything, cellular handset vendors will work on improving battery consumption and RF coverage of their 802.11b/g models and develop towards 802.11n in a year or three. Again, 802.11a is probably not deployed in 50% of enterprises and likely a single digit percentage of homes, so there's little incentive for them to develop to a standard that never gained the same traction as 802.11b and 802.11g when 802.11n is around the corner. That said, the 5 GHz range is very strategic for 802.11n: adding more non-overlapping channels reduces co-channel interference which in turn maximizes performance. >From two sources of anecdotal evidence it appears that those educational institutions that have deployed 802.11a for a year or two are getting between 30 to 50% of their Wi-Fi client population to use it, which I consider to be quite impressive. Of course, it helps that approximately 1/4 or more of their client base is renewed every year, and Intel's 2915ABG has been in production for over two years. Now regarding voice minutes over dual-mode phones: T-Mobile is launching their nationwide dual-mode consumer service this month, but it's not clear to me how flexible their UMA client is for non-T-Mobile networks. Currently it's restricted to the APs that T-mobile provides at home and their own hotspots. The other wireless carriers haven't introduced their service, so there's still that wildcard. So if there's no carrier support, what does that leave your student? They can use services like Truphone or Jajah, but I don't think the college students are the primary users of these kinds of services. If you're thinking of using dual-mode phones for staff and faculty that may be more interesting. There are several enterprise PBX vendors building an FMC solution, and for PBX-neutral solutions, there's DiVitas and a few others. But their wireless support is current focused on basic WLAN connectivity. No one's working about sub-50 msec roaming or 802.1X at this time. =) Frank -Original Message- From: Tom Zeller [mailto:[EMAIL PROTECTED] Sent: Sunday, June 17, 2007 2:26 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] The strategic importance of 802.11a In considering a major wireless overhaul, we're having a serious discussion about the real importance of 802.11a in upcoming dual-mode cellular/WiFi devices. Our current WLAN is b/g. 802.11a seems to be in about 10% of our laptops, judging from an experimental AP we put in one of our busiest sites. I understand it is now part of the Centrino set, so I would expect that to increase over time. The real question seems to be the role of dual-mode phones and the support of voice over WiFi. 1) Is support of voice over WiFi really strategic and why? One could argue that cell phones are sufficient in most locations. Getting "free" voice over WiFi vs cell minutes doesn't seem to be worth the cost alone. Of course, WiFi adds coverage for such devices in the interiors of buildings. Does that justify a rather large additional cost for infrastructure? 2) If the answer to the above question is "yes", is installation of 802.11a going to be important for mobile voice devices, especially dual-modes? There seem to be very few 802.11a dual mode devices on the market now, though I read there will be at least 80 more certified this year. For many vendors, the additional cost of adding 11a to the mix is substantial. The cost of denser deployment (we currently have what I think of as edge-to-edge coverage, with little overlap) is also non-trivial. I would be interested to hear other's opinions on these questions. Tom Zeller Indiana University [EMAIL PROTECTED] 812-855-6214 ** 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] The strategic importance of 802.11a
Tom, The decision to support voice applications is a strategic one that depends on what the application will fulfill. For instance we are deploying Vocera in major clinical areas to replace a nurse's PA system. As far as having it replace the cellular service. I do not see this being too strategic. In this case you are asking the users with the mobile, with the proprietary OS, to select how they are going to make the call. Here you'd be asking a lot from the whole user population. Automatic switchover between cell service and Wi-Fi is something that cell companies are still planning and testing. At this point in time cell companies are in the pilot stages of this service, which will cost the users more money creating cost effectiveness for the cell carrier. One thing that I do recommend is that if you are going to do VoIP, make sure you keep the data and voice WLAN separate. Voice is much more time sensitive than regular data. This means your VoIP wireless network will need a higher priority than the data network. Also, VoIP might have different requirements. For instance Vocera, for our deployment, needs either a flat network or multicasting. So it is important to know exactly what you are getting into. As far as 802.11 a and b/g go, although 802.11a has a smaller cell size than the 802.11b/g does, it does provide more non-overlapping channels. This would allow you to deploy more APs in a location that has a high user density. Howie Frisch wrote: Voice over WiFi has the most value in covering areas that are not otherwise covered - particularly inside buildings. It also provides an alternative at peak times when the cellular infrastructure may be at or over capacity, considering that the cellular carriers install to serve the "paid" minuted rather than the "free" nights and weekends. As far as 802.11a versus b/g - as far as I can tell, almost all cellular/wifi phones only run b/g and some only run b. The MOT CN620 (if it is still produced) ran 802.11a, but was far too expensive for most people to buy. -Original Message- From: Tom Zeller [mailto:[EMAIL PROTECTED] Sent: Sunday, June 17, 2007 3:26 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] The strategic importance of 802.11a In considering a major wireless overhaul, we're having a serious discussion about the real importance of 802.11a in upcoming dual-mode cellular/WiFi devices. Our current WLAN is b/g. 802.11a seems to be in about 10% of our laptops, judging from an experimental AP we put in one of our busiest sites. I understand it is now part of the Centrino set, so I would expect that to increase over time. The real question seems to be the role of dual-mode phones and the support of voice over WiFi. 1) Is support of voice over WiFi really strategic and why? One could argue that cell phones are sufficient in most locations. Getting "free" voice over WiFi vs cell minutes doesn't seem to be worth the cost alone. Of course, WiFi adds coverage for such devices in the interiors of buildings. Does that justify a rather large additional cost for infrastructure? 2) If the answer to the above question is "yes", is installation of 802.11a going to be important for mobile voice devices, especially dual-modes? There seem to be very few 802.11a dual mode devices on the market now, though I read there will be at least 80 more certified this year. For many vendors, the additional cost of adding 11a to the mix is substantial. The cost of denser deployment (we currently have what I think of as edge-to-edge coverage, with little overlap) is also non-trivial. I would be interested to hear other's opinions on these questions. Tom Zeller Indiana University [EMAIL PROTECTED] 812-855-6214 ** 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/. This electronic message is intended to be for the use only of the named recipient, and may contain information that is confidential or privileged. If you are not the intended recipient, you are hereby notified that any disclosure, copying, distribution or use of the contents of this message is strictly prohibited. If you have received this message in error or are not the named recipient, please notify us immediately by contacting the sender at the electronic mail address noted above, and delete and destroy all copies of this message. Thank you. ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
Re: [WIRELESS-LAN] The strategic importance of 802.11a
Something else to consider is the fact that many PBXs now offer an integration option for many cell phones. Some are as simple as one number reach and simply forward calls, but others integrate more tightly and allow you to access your extension from your cell phone along with any corporate directory applications for example. I'm not saying it's a perfect situation, but if we can rely on the cell infrastructure to provide mobility, there should be a cost savings. Granted you still have to purchase the integration infrastructure, but I see it as far less than deploying A equipment out there. Lelio Fulgenzi, B.A. Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1 (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN) ^^ "Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo." WJR - Original Message - From: Tom Zeller To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Sent: Sunday, June 17, 2007 3:25 PM Subject: [WIRELESS-LAN] The strategic importance of 802.11a In considering a major wireless overhaul, we're having a serious discussion about the real importance of 802.11a in upcoming dual-mode cellular/WiFi devices. Our current WLAN is b/g. 802.11a seems to be in about 10% of our laptops, judging from an experimental AP we put in one of our busiest sites. I understand it is now part of the Centrino set, so I would expect that to increase over time. The real question seems to be the role of dual-mode phones and the support of voice over WiFi. 1) Is support of voice over WiFi really strategic and why? One could argue that cell phones are sufficient in most locations. Getting "free" voice over WiFi vs cell minutes doesn't seem to be worth the cost alone. Of course, WiFi adds coverage for such devices in the interiors of buildings. Does that justify a rather large additional cost for infrastructure? 2) If the answer to the above question is "yes", is installation of 802.11a going to be important for mobile voice devices, especially dual-modes? There seem to be very few 802.11a dual mode devices on the market now, though I read there will be at least 80 more certified this year. For many vendors, the additional cost of adding 11a to the mix is substantial. The cost of denser deployment (we currently have what I think of as edge-to-edge coverage, with little overlap) is also non-trivial. I would be interested to hear other's opinions on these questions. Tom Zeller Indiana University [EMAIL PROTECTED] 812-855-6214 ** 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] The strategic importance of 802.11a
I agree with Jonn, 802.11a is extremely important if you plan to grow the amount of bandwidth in your wireless deployment. We have a laptop program, so we spec'd an 11a/b/g NIC from the beginning. We configured the driver to prefer 11a over 11b/g. If you have that kind of control over the laptops on your campus, I recommend doing the same. -John Jonn Martell wrote: 802.11a is very strategic; the question is not an if, but a when. The regulatory bodies released new spectrum in the 5.35 to 5.475 GHz with better power capabilities than what was seen in the fledging UNI-1 (5.15 to 5.25). So, if you throw away UNI-1, add the four non-overlap channels in UNI-2 (5.25-5.35) to the four channels in the 5.8 GHz range and add the 11 new channels, you magically get a *lot* of real estate not available in the 2.4 GHz range. It's the best way to support a high number of users and applications such as VoWLAN and the reason why pico cells will win out in the long term (IMHO). With the new spectrum comes the requirement to use dynamic frequency selection (DFS) and Transmit Power Control (TPC) which means better battery life, less interference and generally a better RF environment. Not sure if there is a Wi-Fi certification for the "new" 802.11a products but there should be. I'd be very careful to deploy products that can't support the new frequencies in the 5 GHz range, if you do, make sure it's at "throw away" pricing... .. Jonn Martell, Martell Consulting CWNT, CWNE, CWSP, CWAP, Wireless# [EMAIL PROTECTED] www.martell.ca On 6/17/07, Tom Zeller <[EMAIL PROTECTED]> wrote: In considering a major wireless overhaul, we're having a serious discussion about the real importance of 802.11a in upcoming dual-mode cellular/WiFi devices. Our current WLAN is b/g. 802.11a seems to be in about 10% of our laptops, judging from an experimental AP we put in one of our busiest sites. I understand it is now part of the Centrino set, so I would expect that to increase over time. The real question seems to be the role of dual-mode phones and the support of voice over WiFi. 1) Is support of voice over WiFi really strategic and why? One could argue that cell phones are sufficient in most locations. Getting "free" voice over WiFi vs cell minutes doesn't seem to be worth the cost alone. Of course, WiFi adds coverage for such devices in the interiors of buildings. Does that justify a rather large additional cost for infrastructure? 2) If the answer to the above question is "yes", is installation of 802.11a going to be important for mobile voice devices, especially dual-modes? There seem to be very few 802.11a dual mode devices on the market now, though I read there will be at least 80 more certified this year. For many vendors, the additional cost of adding 11a to the mix is substantial. The cost of denser deployment (we currently have what I think of as edge-to-edge coverage, with little overlap) is also non-trivial. I would be interested to hear other's opinions on these questions. Tom Zeller Indiana University [EMAIL PROTECTED] 812-855-6214 ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. -- ... Jonn Martell, BSc, PMP Director of Technical Operations Fairleigh Dickenson University – Vancouver [EMAIL PROTECTED] 877-338-8002 604-802-2022 (cell) ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. -- John Center Villanova University ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
