RE: [WIRELESS-LAN] Aruba's SCA vs. MCA whitepaper [was: Open Wireless in Higher Ed]
As a grey-haired veteran of early Ethernet, I always try to keep those comparisons in mind. And for those of you who may be newer to networking, you should be aware that Chuck was the go-to guy for technical information in the early days of Ethernet. Thanks for the early education, my friend. Your points about current and future 802.11 implementations are insightful and I agree that we should all be pushing the vendors for more information about performance while also pushing them on functionality, reliability, and cost. At the same time, we need to be careful in testing the outer boundaries of network performance. While I respect Phil Belanger's work, it is really hard with wireless to know if you are measuring the right system attributes and as has been pointed out, the unique elements of the physical medium make things different in different physical locations. In the end, I think the best tests are the real-world tests that take place at .edu's every day. That's what makes these mailing lists so valuable. I've thought about different ways to accomplish these scale tests, talked to folks like Frank Bulk, Phil Belanger and Craig Mathias. Perhaps if an organization like Educause got involved, they could exert enough pressure to get the vendors to participate. But I doubt that would be in the best interest of Educause or the vendors. My own opinion is that all these systems have breaking points, it's just a matter of finding them and then deciding whether they really matter for your application use case. In the mean time, all you guys get to live with the ambiguity of supporting very large networks while I get to spend time in the classroom teaching my students how to dissect whitepapers and identify vendor misrepresentations. dm -Original Message- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[EMAIL PROTECTED] On Behalf Of Charles Spurgeon Sent: Tuesday, April 01, 2008 12:00 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Aruba's SCA vs. MCA whitepaper [was: Open Wireless in Higher Ed] On Tue, Apr 01, 2008 at 08:25:06AM -0400, Dave Molta wrote: I agree with Chuck about the need for better information about WLAN scalability. It's an issue I've struggled with for many years but I'm not optimistic about a resolution. I've discussed this issue extensively with Phil Belanger, the author of the Novarum report, and I just can't see any way to get all the vendors to agree to a single test plan and commit the resources necessary for such ambitious tests. Although it's clear that Meru designed these tests to best reflect their competitive advantage, I also believe Phil played the role of objective analyst, which is not always the case with pay for test projects. Phil pressured Meru to include test runs that were not part of their original plan and he was very transparent in disclosing his role in these tests. Still, it's highly likely that the results would have been different if Cisco and Aruba had been directly involved. Personally, I still think Meru would have performed better, but I don't think the differences would have been as great. Although the issue of co-channel interference is an important one, I think it may be reasonable to assert that its importance will be reduced with the adoption of 5 GHz 802.11n. With over 20 non-overlapping channels, I believe it will be possible to design high-density, micro-cellular WLANs that do not suffer from performance degradation as a resulting of co-channel interference. Over time, I believe 2.4 GHz will be thought of as a best-effort legacy technology for most enterprises. I'd be curious how others are viewing this. Dave, I agree with you in principle about the need to move to 5 GHz -- but we have an installed base of thousands of APs (and tens of thousands of clients) on our campus that are running 802.11b/g, and I find the vendor refusal to test scale and load issues on 802.11b/g systems to be indefensible. The wireless system on our campus has become critically important to the organization. When do the wireless vendors plan to step up to the task and provide real-world large scale testing and useful guidance on these important issues? As the author of a book on the orginal cabled Ethernet system, I can remember the days when Ethernet was being tested for scale and load. In the early days of Ethernet the scale tests were difficult to arrange, since large groups of high performance computers sharing a network were not as common. These tests resulted in a better understanding of Ethernet behavior and limits, and provided network managers with useful information on how best to configure and deploy Ethernet systems. If the wireless vendors persist in refusing to provide scale testing and persist in refusing to provide the testing results and technical information needed to better understand and operate complex 2.4 GHz wireless systems, then what can we expect when we move
RE: [WIRELESS-LAN] Cisco vs. Meru article
Just to elaborate a bit, the article James sent around was not the original Meru-Cisco feature story but rather a column that reports on results of subsequent testing. In this column, I reported three things. First, Cisco was unsuccessful in getting the Wi-Fi Alliance to rescind Meru's certification. Since WFA certifies interoperability rather than standards compliance, this is not proof that Meru isn't stretching standards a bit but it still casts a cloud over Cisco's allegations. Second, I reported findings from subsequent tests where we added Aruba to the mix and found that Cisco's performance also cratered when co-located with Aruba gear. 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. Finally, we decided to re-run these interference tests with different mixes of clients, using Atheros, Broadcom, and Intel chipsets. We found significant differences in the performance results. Atheros-based clients performed best. The broader issues here relate to standards compliance (e.g., to what degree can a vendor selectively implement certain elements of a QoS standard?) and, perhaps more importantly, performance issues with Wi-Fi that may arise in the future as the density of deployed networks results in increasing levels of co-channel interference. I am particuarly concerned about the intersection between private enterprise WLANs and public metro Wi-Fi networks. It may not be a big problem today but I wonder if it will be a problem in the future. 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. 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. dm _ From: Peter Morrissey [mailto:[EMAIL PROTECTED] Sent: Thursday, June 14, 2007 11:03 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Cisco vs. Meru article I'm with you Jamie. Standards are extremely important, but only to the extent that they serve the consumer. You still have to buy the whole system from one vendor, so what is the difference? As long as the clients will be interoperable, then I don't think it really matters. I could be missing something, but that is my take on the whole thing. Meru appears to offer some compelling QOS features. Pete Morrissey Syracuse University _ From: Jamie Savage [mailto:[EMAIL PROTECTED] Sent: Thursday, June 14, 2007 10:50 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] Cisco vs. Meru article Hi, The attached article was in the May 28th issue of Network Computing. Regarding Meru vs. Cisco and the possibility of interference with co-located APs. I'd be interested in any commentary. We're currently a Cisco shop (autonomous APs) and realize we're heading for a forklift wireless change in the near future (most of our fat APs can't be converted to thin). Even if Meru violates the 802.11 standard (as claimed by Cisco), as we control the airspace on campus, I guess we don't care if we cause interference issues with devices (ie..rogues) that shouldn't be there in the first place. ...comments anyone?...thx...J James Savage York University Senior Communications Tech. 108 Steacie Building [EMAIL PROTECTED]4700 Keele Street ph: 416-736-2100 ext. 22605Toronto, Ontario fax: 416-736-5701M3J 1P3, CANADA ** 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
Debbie, They were Intel 2915 clients. I have some pretty dense spreadsheets covering various permutations of clients and infrastructure if you are interested in seeing raw results. We didn't come away from this with any firm conclusions about what's good and what's bad (I guess we've learned our lesson about pointing the finger too soon!). What was most interesting to us was the fact that there was so much variation, which is something we didn't expect from such a mature standard. dm -Original Message- From: debbie fligor [mailto:[EMAIL PROTECTED] Sent: Thursday, June 14, 2007 11:59 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Cisco vs. Meru article On Jun 14, 2007, at 10:24, Dave Molta wrote: Just to elaborate a bit, the article James sent around was not the original Meru-Cisco feature story but rather a column that reports on results of subsequent testing. In this column, I reported three things. First, Cisco was unsuccessful in getting the Wi-Fi Alliance to rescind Meru's certification. Since WFA certifies interoperability rather than standards compliance, this is not proof that Meru isn't stretching standards a bit but it still casts a cloud over Cisco's allegations. Second, I reported findings from subsequent tests where we added Aruba to the mix and found that Cisco's performance also cratered when co-located with Aruba gear. 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. Finally, we decided to re-run these interference tests with different mixes of clients, using Atheros, Broadcom, and Intel chipsets. We found significant differences in the performance results. Atheros-based clients performed best. Something I noticed in the article was that Meru did the worst with Intel chipsets, but which chipset wasn't mentioned. The 3945 Intel micro code bug makes them work very poorly with Meru and causes some problems with other vendors APs. We've been waiting for an update from Intel, but still don't have it. What Intel has done is ceased to sell that chipset -- this worries me that there wont be a microcode fix, but at least we wont have new equipment coming in with that card. So if the testing was with all 3945 cards, I don't think that accurately indicates Meru doesn't work well with Intel in general. Dave do you happen to know what the cards were? For those not following the problem with the 3945 cards, there is a bug in the micro code that causes it to crash if it sees out-of-order packets from the same AP. I heard this from an Intel employee on a conference call with them and Meru. It had been replicated in Intel's state-side offices and finally at their development site in Haifa last February just days before our phone call. Since all Meru APs look the same to the client, it's easy for things to be out-of-order like that. The initial work around of setting the power save mode to off didn't work, not because it was the wrong work around, but because the driver kept taking it out of never power save mode. If you update to the latest Intel driver, and then again set it to not use power saving, it stays set that way and the disconnects go away, at least for the ones we've tried it on so far. The broader issues here relate to standards compliance (e.g., to what degree can a vendor selectively implement certain elements of a QoS standard?) and, perhaps more importantly, performance issues with Wi-Fi that may arise in the future as the density of deployed networks results in increasing levels of co-channel interference. I am particuarly concerned about the intersection between private enterprise WLANs and public metro Wi-Fi networks. It may not be a big problem today but I wonder if it will be a problem in the future. 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. It's always good to know what to keep an eye out for when you're designing something. We're not seeing problems in our still Cisco buildings that are near Meru buildings that we are aware of, and the users are pretty good at telling us if it quits working. 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. dm - -debbie Debbie Fligor, n9dn Network Engineer, CITES, Univ. of Il email: [EMAIL PROTECTED] http://www.uiuc.edu/ph/www/fligor My turn. -River ** Participation and subscription information for this EDUCAUSE
RE: [WIRELESS-LAN] Meru Question
The Meru "good-neighbor" issue involves some technicalquestions about how Meru uses the duration field of 802.11, which provides virtual carrier sense. Although I am a little disappointed that Cisco is tryingexploiting this issue through their sales channel (I bet less than 5% of Cisco salespeople actually understand the issue and it looks a lot like the old IBM FUD strategy), I think it is a potentially serious issue in some environments and we are working with both companies to verify/refute the claim. We're currently waiting on Meru to provide us some AP's so we can do some further testing. As Frank Bulk pointed out, this probably isn't a huge issue for college campuses where you effectibly control the airwaves but it may be a significant issue in multi-tenant office buildings. With respect to the 11n issue, Mike raises an interesting point about the challenges of implementing 11n's channel-bonding capabilities in the 2.4 GHz band. Personally, I don't think too many enterprises will choose to do this unless theyREALLY need the performance. It's more likely that bonding will be used to pump up the numbers on the boxes of retail products in order to move more product off the shelf at Best Buy. Consumers are often swayed by these performance numbers, even though the vast majority are throttled by their Internet connection rather than any performance bottleneck on their LAN. While it is true that Meru has some advantages because they are more active in scheduling the medium, it's also valid to ask whether the overhead associated with managing WLAN traffic will cause problems for them in terms of controller scalability. You take the bad with the good. On a related note, I recently learned that Aruba is currently recommendinga 4-channel model (1,4,8,11) for dense 2.4 GHz deployments, arguing that the performance benefits of one more channel offsets the co-channel interference issues. Is anyone doing this? dm From: Ruiz, Mike [mailto:[EMAIL PROTECTED] Sent: Tuesday, June 27, 2006 8:58 AMTo: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDUSubject: Re: [WIRELESS-LAN] Meru Question Don, As a Meru user I can personally tell you that Merus system does not negatively impact any other access points unless you put them on overlapping channels or use the rogue suppression. As far as the bug this is simply not true, and I can provide more detail regarding this if you want but didnt want to bore anyone. There are lots of tests here and independent tests to verify the first. Likewise Meru uses Atheros technology and 100% 802.11 standards compliant client side technology. My perspective on 802.11n is that Meru is most uniquely positioned to make 11n a workable reality. Forget the fact that they will continue to eliminate co-channel interference and contention across cells making the bandwidth promised by 11n a reality. The real core of what makes 11n work is that each channel uses more bandwidth. Thus in the 24GHz space you will essentially need two of the three available channels to serve 11n. Well if youre using 1 and 6 or 6 and 11 what are you left with for neighboring cells? A coordinated design that can overlap without interfering will be required unless another band-aid solution like micro-cells is developed. Or you can move the 5Ghz space, cut the number of channels in half and then be faced with all the problems plaguing 802.11g today. Its consistently amazing to me that vendors tout 11n as a solution when problems like the crash in available bandwidth when 3 or more users come online remains a reality. Cheers, Mike -- Michael Ruiz Network and Enterprise Systems Engineer Hobart and William Smith Colleges From: Donald R Gallerie [mailto:[EMAIL PROTECTED] Sent: Monday, June 26, 2006 3:47 PMTo: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDUSubject: [WIRELESS-LAN] Meru Question Here at the University at Albany, we had Meru come in and give us an overview on their wireless offering. From our vantage point, it does appear that Cisco is pushing the controller-based system so we decided to look at other vendors in this space. As part of this effort, we asked Cisco to come in and give us an overview of their offering as if they didnt already have a presence on campus. One of the items that came up had to do with Merus method of distributing timeframes to clients (dont know if Im phrasing this correctly). The Cisco engineers said that Merus methodology works well in a Meru-only rollout but that they would negatively impact other, non-Meru access points. Additionally, the said that there is a bug in the current 802.11b/g standard that Meru takes advantage of and that it may not be there in future (802.11n) standards. Not that I would doubt anything Cisco
RE: [WIRELESS-LAN] Tools
Some thoughts about Cisco wireless from a guy who used to manage large .edu networks but now mostly analyzes, teaches and writes about it: Ever since Symbol rolled out the first wireless switch, I've tried to remain mostly agnostic about how much intelligence should reside in the AP versus in centralized controllers. The bottom line is you have a problem to solve and a service to provide and there are probably a number of viable alternative architectures, especially since WLANs are still in the emerging stage. Like any distributed system, going too thin on the client/edge moves the scalability problems closer to the core of the network and also forces you to insure that your backhaul from the AP to the core is not a bottleneck. At the same time, when you have thousands of client/edge devices, you've just got to find a way to manage them effectively and efficiently in order to controle administrative staffing costs. I think many/most organizations mostly need a way to handle configuration management functions centrally, which can be accomplished with IOS scripts, WLSE, third-part configuration management tools like AirWave, or by centralized controllers. Beyond configuration management, history suggests that most organizations reach a point, especially when applications become mission-critical, where they want more visibility into network operations (for capacity planning, troubleshooting, etc.) and this is an area where the controller-based architecture offers significant appeal. Cisco/Airespace's implementation of management functionality is particularly strong in this regard. If wireless VoIP is the driving application (it hardly ever is outside of health-care and some other very focused verticals), you need to worry about fast roaming, but I'm not sure it's the biggest concern for most shops. You also have to worry about coverage, capacity, and co-channel interference, all really difficult issues, especially if you are trying to do it at 2.4 GHz. You won't convince too many .edu network folks that relying on proprietary approaches, including Cisco Compatible Extensions on client devices, is a good way to go, but if it solves a big problem and there aren't a lot of other options, then some organizations are willing to march in that direction. I don't profess to fully understand Cisco's overall wireless strategy but I do have regular interaction with many of the people who are making important architectural and marketing decisions. It's clear that the Airespace management has assumed control, from the wireless business unit VP to the CTO, Director of Marketing, and technical field support. All of these folks are believers in LWAPP and the controller-based architecture and they seem to have done a pretty good job of convincing others in the company that this approach makes sense, not only in delivering advanced wireless services, but also in providing higher margins. Look at the price of a WiSM module for the Cat65K and then think about how many AP's they would need to move to make as much money as they can with a single WiSM. At the same time, these folks aren't stupid. They understand that there is significant ongoing interest in smart IOS-based AP's, especially in higher education. I've been assured that WLSE isn't going away any time in the forseeable future, but you shouldn't expect to see a lot of development there, either. If you want advanced services, including RF management, mesh, location, and layer-3 roaming, Cisco expects you to migrate to LWAPP. It's not really that hard a sell because a large proportion of Cisco's customers perceive significant value in LWAPP. We could argue about whether the value-proposition really is compelling (higher ed IT folks are great at this), but that's almost a secondary consideration. There is a lot more I could write about this topic and Cisco's competitive landscape in wireless. In fact, Dan Renfroe and I are working on a Can Anyone Beat Cisco article right now, where we are not only hammering away at Cisco's gear but also engaging almost all of the competitors in a discussion about different approaches to the problem (some don't seem to want to talk to us very much, which is often a telling sign). In any case, the comments by all of you are invaluable in helping provide some of the context for our analysis and I thank you for it. The issues of greatest import for higher education aren't always the same as those in other technology markets, but they often fortell the future, particularly when it comes to scalability. dm -Original Message- From: Scott Genung [mailto:[EMAIL PROTECTED] Sent: Thursday, March 16, 2006 3:58 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Tools At 01:52 PM 3/16/2006, Philippe Hanset wrote: How will all these W-acronyms blades and appliances deal with the load generated by 802.11n? In our case, we are planning to deploy the WiSM (a controller embedded on a blade for a 6500
RE: [WIRELESS-LAN] wireless NIC evaluation
This is quite a can of worms. We just completed a WLAN client test in our labs at Syracuse University, the results of which will be published in Network Computing next month. I can't broadcast all of the detailed results prior to publication, but I can tell you what we did and what we discovered in general terms. I can provide more details to you privately if time is critical. We started this project because we were curious about how commoditized notebook computers with embedded wireless were. More specifically, we wanted to answer three questions: 1. Does the choice of radio module (Intel, Broadcom, Atheros) make a significant difference in performance? 2. How much of performance variation is attributable to the radio module or the system design (including integrated antenna). 3. Does battery life vary depending on radio module. We focused our analysis on multi-mode, dual-band integrated mini-PCI radio modules because we feel strongly that all enterprises should be supporting abg for capacity reasons. We asked the four leading notebook vendors (Dell, HP. Lenovo/IBM, and Toshiba) to send us 2 systems, one Centrino and the other whatever other radio module they supported. Dell and HP sent us Intel and Broadcom, Lenovo sent is Intel and Atheros, and Toshiba just sent us Intel (Hello, Toshiba. Please follow directions). We tested the radio modules on an Azimuth test system that allowed us to attenuate signals is 1 dB increments and measure the performance, across 11g and 11a. We discovered that most systems had similar performance profiles with 11g but there were substantial variations with 11a. Because Azimuth testing bypasses the antenna, we also did field testing in our building at 5 different locations, between midnight and 6 am with our production network turned off. We used a rotating turntable system and tested performance for each combination. The bottom line is that system design does make a difference, though not as much as some vendors may want you to believe. Finally, we used BAPCO's MobileMark to evaluate battery life, comparing identical systems with different radio modules. Again, there were differences, though they weren't major. Interestingly, we discovered that battery life is significantly shorter with Ethernet than with wireless. We also looked at client utilities and formed some impressions about what we liked and didn't like. We tried to test roaming but ran into some technical problems. Since we don't feel roaming is a critical issue with notebook computers, we don't consider this to be a huge issue but we'll continue to investigate it. We also did a sidebar on Cisco CCX. dm From: David Boyer [mailto:[EMAIL PROTECTED] Sent: Wednesday, February 15, 2006 11:56 AMTo: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDUSubject: [WIRELESS-LAN] wireless NIC evaluation We have a campus-wide wireless net with 1300 notebook computers for whom the wireless network is their only means of connectivity. We'll be replacing those computers this summer with either new notebooks or tables, and since we'll be living with the new systems for the next 2-3 years, we want to ensure their wireless cards work well with our network. We'll probably get one or more evaluation systems from a half-dozen vendors or so, so we're planning to have 10-12 different systems to test. The testing we're planning to do includes comparing throughput/bitrate from various distances at various locations on campus while classes are in session or during other typical network load. We'll also be testing the signal level at which the NIC roams to a new AP, etc. We'll verify the different types of authentication and encryption supported by each NIC, what functionality each NIC's software includes, and that sort of thing. In addition, we'll also issue these test systems to various users to use in their environment for a day or two to see how the systems behave in practice. I'd be interested in finding out what others have done in this sort of situation. I'd be grateful for any suggestions you have or experiences you might wish to share. Thanks! David BoyerNetwork AdministratorBuena Vista University610 W. 4th St.Storm Lake, IA 50588712-749-2358 (voice)781-735-8267 (fax)[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] Why 802.11 vs Wi Max or 3G or 4G
Title: Why 802.11 vs Wi Max or 3G or 4G Lee, We could write a book on the many issues involved, but the bottom line here is that at least in the short term, these are not really competitive technologies. For some organizations withgeographically mobile workforces, the 3G solution is a good one, despite the high recurring costs. But remember that one of the reasons service providers charge so much for 3G services is because there are serious scalability issues associated with this technology. It is hard to imagine how outsourcing wireless services to a cellular provider could be a viable solution for a college or university. As for WiMAX, it's probably a more viable direct competitor to Wi-Fi, but not in the short-term. In the near-term, WiMAX will achieve success as a multi-point fixed wireless solution, particularly in international markets where cable infrastructure is lacking and spectrum is available in the 3.5 GHz band. In the U.S., I think WiMAX may have some nichepenetration in rural areas and perhaps for metropolitan backhaul, but we'll need to wait for802.16e for a mobile solution. Even when that happens, I see thatas more of a competitionto 3Grather than Wi-Fi. In the end, the best strategy for you might be to simply try to educate yourcommittee about the technologies themselves, providing positive assessments of where they make sense. Given media hype about these systems -- especially WiMAX, which some have referred to as Wi-Fi on steroids --it's easy to understand why some folks might be a little confused about which way the market is moving. Give them objective information and I think most will come to the conclusion that for the next few years at least, the ubiquity of Wi-Fi, in the home and on network clients, makes it the best choice for a college or university wireless rollout. dm From: Lee Weers [mailto:[EMAIL PROTECTED] Sent: Tuesday, January 24, 2006 12:37 PMTo: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDUSubject: [WIRELESS-LAN] Why 802.11 vs Wi Max or 3G or 4G I am going to be presenting a presentation to the Technology committee about a campus wide wireless project. The preliminary project I put together is the traditional 802.11 a/b/g solution. Some of the things I'm going to be asked will be why this implementation as opposed to doing something with Wi Max, or talking to Cellular vendors and doing a 3G solution. I do not know a lot about the other wireless solutions. I would like as much feedback as possible for pros and cons of each. Thank you, Lee Weers Assistant Directorfor Network Services Central College IT Services (641) 628-7675 ** 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] Wireless-only Dorms?
It's fairly easy to understand how the scheduling capabilities of Meru allow it to maximize throughput and minimize latency using a single channel throughout a building, but I still wonder about the aggregate capacity when compared to a more traditional and well-implemented overlapping cell design that leverages all available spectrum. As long as your primary goal is coverage rather than capacity, this is an excellent solution, but the whole discussion of resnet wireless is more of a capacity issue and I'm guessing that low-latency roaming won't be a big issue in the short term since resnet users are more nomadic than mobile. Meru has been doing some interesting work with multi-radio AP's that should allow them to enhance overall system capacity but I don't think any of those products are available today. dm -Original Message- From: Phil Raymond [mailto:[EMAIL PROTECTED] Sent: Thursday, November 10, 2005 10:41 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Wireless-only Dorms? Interesting discussion ongoing... I work to remain agnostic in regards to WLAN vendors, but I do consider Meru a leader in developing/enabling 802.11 technologies. Frank is correct in that they use the NAV to holdoff data clients while voice handsets gain airtime access (even tho they don't know it). This combined with their holistic view of the network and flat channel architecture (enables very fast roaming) certainly has its advantages. Until 802.11e/r becomes prevalent in handsets these mechanisms will serve its purpose because don't forget - 802.11 was never made to handle voice clients. But that will change over the next 2-3 years as cellular mechanisms are adopted into the WLAN via IEEE 802.11k/v, etc. -Original Message- From: Frank Bulk [mailto:[EMAIL PROTECTED] Sent: Thursday, November 10, 2005 9:18 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Wireless-only Dorms? Meru does not use PCF, but does use virtual carrier sense as their main mechanism to control access to the medium. Frank -Original Message- From: Michael Griego [mailto:[EMAIL PROTECTED] Sent: Wednesday, November 09, 2005 11:47 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Wireless-only Dorms? All of the issues listed here are great examples of the complex nature of designing an 802.11 environment with such stringent requirements. With only 3 channels, even if you plan very carefully and precisely control the output power of your APs, you're going to get channel overlap. This will further reduce your capacity due to the inherent collisions/retransmissions. Especially when you factor in the client devices. A client device transmitting on a channel will force any other device operating on the same channel that can hear it (APs included if course) to wait on it to complete its transmission before it can commence. So, you have to realize that, even though 2 APs may not be able to hear each other, a client card between them that can hear both of them will tie up available bandwidth on BOTH APs while it is transmitting. Further complicating matters is a situation where two clients connected to two different APs on the same channel can hear each other but not both APs. In such a circumstance, client 1 and the AP 2 (the AP client 2 is connected) may transmit simultaneously. When this happens the signals will interfere with each other upon reaching client 2, causing client 2 to be unable to decode the packet, forcing AP 2 to retransmit the packet. Complicated indeed! Guaranteeing signal strengh and bandwidth alotments is extremely difficult. And, this totally ignores the problems inherent with outside interference or the fact that the environment (bookshelves, etc) change on a regular basis, possibly forcing you to revisit your ever-so-finely-tuned RF plan. Interestingly enough, all these issues are also extremely relevant if you're interested in looking to deploy any sort of VoIP/WiFi (VoFi). I'd suggest that, if you're truly interested in providing coverage/bandwidth that takes a lot of these issues into account, you might want to take a look at the Meru Virtual AP architecture. The controllers in these systems keep track of every 802.11 device each AP can here and employ a pretty darn impressive scheduling algorithm for getting the most out of the available channel capacity. Not only that, but they actually control when clients are allowed to transmit, further removing unknowns from the RF use equations and improving channel usage and capacity. I believe they do this using the PCF, or Point Coordination Function, in the 802.11 spec... I've not seen any other wireless switch system that makes use of it near to the level that the Meru system does. It's pretty cool. We're in the process of deploying Meru as our
RE: [WIRELESS-LAN] Wireless-only Dorms?
The other factor that shouldn't be ignored is the role that clients play in contributing to co-channel interference issues in dense deployment WLANs. It's relatively easy (albeit expensive) to design micro-cell AP configurations that maximize per-user bandwidth by reducing power output on the AP. However, it's much tougher to control power output at the client, both because some client adapters/drivers do not support this capacility and also because you need to touch the clients in order to do so. This problem is mitigated somewhat by the asymetrical nature of most client communications (more downstream than upstream bandwidth consumption) though this is beginning to change with more and more PtP applications. Also, while this problem wasn't as great an issue in the past when PC-Cards were used on notebook computers, the enhanced wireless capabilities of the latest notebook computer designs -- especially the quality of embedded antennas -- has the effect of making notebooks more powerful RF radiators. The other point I would make with respect to capacity is that it is essential to take advantage of all available spectrum. That means implementing multi-band abg access points and -- this is a tough part -- getting users to purchase notebooks with abg support. Although notebook manufacturers don't like to disclose numbers, I believe well over 85% of notebooks still ship with bg rather than abg interfaces, even though the incremental cost of abg is minimal. The good news is that it's not essential to get all of your users on 11a, but moving a significant portion of them makes performance better for everyone. dm -Original Message- From: Metzler, David [mailto:[EMAIL PROTECTED] Sent: Wednesday, November 09, 2005 12:10 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Wireless-only Dorms? Nice synopsis, Phil. I would add that the issue about bandwidth overlap in densly populated areas can be partially mitigated by making sure you select a vendor that has the ability to automatically decrease power to reduce overlap. Some do this, some don't. -Original Message- From: Phil Raymond [mailto:[EMAIL PROTECTED] Sent: Wednesday, November 09, 2005 8:58 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Wireless-only Dorms? If someone forced me to assign a rule of thumb at this high level, I would assign a conservative data rate of 1 Mbps to each student as a requirement. For an 802.11g ONLY network running at the highest data rate (aka strongest signal) using enterprise class AP's (data thruput does vary between AP vendors, be careful here), you should expect to get 15-20 Mbps of upper layer thruput per AP. That would yield 15-20 students per AP. For 802.11a, this will probably hold. For 802.11g, due to the limit of 3 channels, you will get an overall reduction in capacity due to shared bandwidth between AP's in a densely deployed AP environment. Also, this assumes that you design the network for the highest signal strength - a very important point. In most instances this won't be possible due to the environment. Thus I would reduce the available bandwidth by 33% and say that 10Mbps is available. Hence I would go with the low end of 10Mbps available per AP. To take this to a lower level of analysis, I would want to know what applications the students would be running. Perhaps you use the analogy of a low end DSL connection that provides 768Kbps downlink and 128kbps uplink. Then you stick with the 1 Mbps/student and assume it supports most if not all applications they will use. You might also consider a swag at peak operating times (evenings) and assume ~50% of the available students are online (simple queuing theory assumption). Then you could say that a single AP would cover minimally 20 students. There is my rule of thumb at this high level. I would consider it conservative if you design the network properly. In a typical dorm with a lot of walls (and bookcases...), you will probably find that your coverage requirements and capacity requirements will be in alignment (and thus balanced). What I mean by that is that you will find that in order to provide a good signal in a dorm environment you will need to place a denser AP deployment (due to the thick walls, etc.). This means that as a consequence your capacity will also be increased due to the denser deployment. Other factors not considered here are the use of client cards. Performance between different manufacturers (you get what you pay for) will vary. Some cards will be noisy and interfere, others will have higher SNR requirements, etc. Hope this helps and not confuses - as I said, it is not a trivial subject. -Original Message- From: Larry Press [mailto:[EMAIL PROTECTED] Sent: Wednesday, November 09, 2005 9:51 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re:
RE: [WIRELESS-LAN] spectrum analyzers
I don't have a ton of hands-on experience with these products so I can't provide much in the way of technical details but we are currently looking at the Cognio and Berkely Varitronics (BVS) spectrum analyzersin our Syracuse University lab. We've also had experience with Avcom Ramsey, whichhas marketed value-priced (e.g., much less expensive than Tektronix or Agilent) spectrum analyzers capable of 2.4 and 5 GHz operation. My personal feelingis that most IT organizations that manage large Wi-Fi networks have a need for a spectrum analyzer, just like Idid back in the days when I helped to manage a large university broadband CATV systemthat was used for data services. I think the only real question is how big before you need one and do you try to do this analysis in-house or look to outside experts when the need arises. Cognio hasrelationships with Air Magnet and Wild Packets and they also sell their spectrum analyzer (PC-Card and software) direct. Currently, the Air Magnet and Wild Packets versions are OEM offerings but it's likely that you will see further integration with their other product lines in the future. There's lots of potential here. Cognio started off looking to embed their technology into wireless sensors/probes, and while there is probably a long-term market here, the portable product hits a market sweet spot. The interface is nice and they have some interesting technology that characterizes wave forms and provides expert system analysis of the likely source. BVS offers multiple analyzers, including a model that focus on layer-1 as well as a modelthat has some layer-2 intelligence. Unlike Cognio, BVS uses the HP iPAQ as a platform. That provides portability but also imposes some limitations. dm From: Jamie Savage [mailto:[EMAIL PROTECTED] Sent: Friday, October 21, 2005 3:16 PMTo: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDUSubject: [WIRELESS-LAN] spectrum analyzers Hi all, I was just looking at a glossy of AirMagnet's spectrum analyzer. It's software that runs on a laptop with a wireless cardienot a typical spectrum analyzer. I was wondering if anyone had one of these. I'm guessing that it may be a little more user friendly (for those not well versed with these things) and tailored specifically for wireless environments than a standard unit. I have no idea of $$$ yet above the cost of the laptop and card. ..comments anyone?...other suitable options?...thanks in advance..Jamie James Savage York University Senior Communications Tech.108 Steacie Building[EMAIL PROTECTED] 4700 Keele Streetph: 416-736-2100 ext. 22605 Toronto, Ontariofax: 416-736-5701 M3J 1P3, CANADA ** 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] Dectecting ad-hoc networks in dorms
You may want to look at Frank Bulk's June, 2005 review of distributed security monitoring systems, which included Airtight, AirMagnet, Air Defense, Network Chemistry, and Highwall: http://www.networkcomputing.com/showitem.jhtml;jsessionid=GTY031U43EMLQQSNDB CSKH0CJUMEKJVN?docid=1612f2 These systems are pretty robust but may not be cost-effective for this kind of application. We are currently working on a review of portable wireless LAN analysis tools in our Syracuse lab. I think most of the vendors have already been mentioned, including AirMagnet, BVS Systems, and Fluke. All of these systems are effective in detecting rogue devices. You can also use protocol analysis tools from Wild Packets and Network General but it requires a little more work. Also of possible interest are WiMetrics and Airwave, both of which offer over-the-wire rogue AP scanning capabilities. Some of our testing of early WiMetrics offerings were less-than-effective in detecting SOHO AP's, but recent conversations with both vendors indicate that they've come a long way in increasing accuracy. These products won't detect ad-hoc wireless networks. We've also got a sneak-preview review of Airwave Management Platform (AMP) version 4.0 scheduled. If anyone out there would be willing to talk to me about their experiences with earlier versions of this system and provide some impressions about the value of the new features, please let me know and I will get in touch. dm -Original Message- From: Philippe Hanset [mailto:[EMAIL PROTECTED] Sent: Wednesday, October 05, 2005 9:39 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Dectecting ad-hoc networks in dorms Dan, We use our own Access-Points (Proxim) for detection but a problem occur with detection: the time to discover is taken on the time to transmit traffic. Since this solution doesn't fit all applications, we are evaluating a new one from Airthight Networks. There is a controller and a bunch of probes. The probes can do anything you want: Detect, locate (on a map) and even destroy (we have so many Ad-Hocs in some places that we are seriously thinking about Active Denial instead of Passive Search. With students taking online exams with laptops in can forsee some smart donky enabling an ad-hoc just for fun. So, in some critical classrooms we might position a few of these Airtight probes. I'll keep the list posted on the result of our testing. So far the positioning of a culprit on a map is pretty impressive, but it does require more than one probe... Airthight has also a solution that doesn't require to be connected to the network. You just drop a box (AP style) in a critical area and it detects(and if you want, prevents) other wireless devices. It costs about $995. Has anyone used Airtight? Any caveats? Regards, Philippe Hanset University of Tennesseee On Tue, 4 Oct 2005, Dan Schneider (Network Administrator) wrote: As we put in Wireless Access Points, we are discovering problems with student ad-hoc networks, wireless printers, etc... We are looking into some type of very sensitive wireless analyzer equipment that will be used to go out to the dorms, walk the halls, and pinpoint the rooms the ad-hoc, etc. signals are coming from. Anyone have suggestions on tools you are successfully using for this purpose? * Dan Schneider-Network Administrator Doane College 1014 Boswell Ave. Crete, NE 68333 E-Mail: [EMAIL PROTECTED] VOICE: (402) 826-8298 * ** 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] strategic wireless planning?
At Syracuse, we've been working on a network infrastructure plan, and while much of it is oriented towards upgrading conduits, cabling, switches and routers, wireless is also an important element. On a more tactical level, we continue to wrestle with expansion of campus Wi-Fi services and we are about to roll out a system that provides long-term sponsored wireless accounts as well as guest wireless access that is limited in bandwidth and supported protocols. Regarding a broader plan that considers cellular services, Voice over WLAN, and broadband fixed wireless, I think that would be extremely challenging given the current maturity of those technologies. As most of you know, finding the right time on the technology maturation curve to jump into things big-time is one of the greatest challenges faced by IT. I am a believer in multi-mode wireless infrastructure that combines 3G and Wi-Fi, mostly because I am skeptical about the feasibility of delivering scalable and secure Wi-Fi services across the wide area. Yes, I know lots of cities are experimenting with these initiatives, but University folks understand that it is tough enough to do this in a campus environment where you have control of facilities and, perhaps to a lesser extent, the airwaves. Perhaps Philadelphia, San Francisco, Corpus Christi and other municipalities will prove me wrong. We recently had Motorola and Avaya in to demonstrate their new multi-mode (802.11a and GSM) voice infrastructure. We were able to roam fairly transparently between the two. It's still quite early but I think it is coming. In many respects, it parallels developments in wired VoIP where many campuses discovered they didn't have the network infrastructure required to support reliable packet-based voice services and the applications for converged voice made it difficult to justify the cost. The difference with Voice over WLAN is that most universities have a significant problem with cellular coverage inside their buildings and even if you can solve that problem via smart antenna systems, you're still beholden to wireless carriers for recurring charges. Since most campuses are building out Wi-Fi services as a convenience service (prospective students and their frequently ask about this, sort of the modern day proxy measure for technology leadership), engineering these systems to support future applications like voice is very important. I think the interesting question posed by Mr. Gogan relates to applications beyond voice. My own pet application involves wireless video presentation, trying to engineer a system where faculty, staff, and students can walk into conference rooms and classrooms and easily project their screens wirelessly to a room-based projection system. While some vendors offer these capabilities, they're not really suitable for campus deployment. Dave Molta SU School of Information Studies -Original Message- From: Dewitt Latimer [mailto:[EMAIL PROTECTED] Sent: Tuesday, September 13, 2005 9:16 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] strategic wireless planning? Jim -- wouldn't say Notre Dame has a well articulated (e.g. documented) plan, but we're definitely doing things in the wireless spectrum, ranging from 802.1x, web-based WiFi AuthN/AuthZ, cellular DAS on campus, to working with the regional MetroNet and tower owners on a WiMax last-mile solution. About the only thing we're not moving on is wireless VoIP because I'm not convinced it will ever overtake cellular. I (and perhaps the list) would love to hear intelligent debate arguing the contrary. -d -Original Message- From: Jim Gogan [mailto:[EMAIL PROTECTED] Sent: Tuesday, September 13, 2005 7:24 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] strategic wireless planning? Does anyone know of any universities that either have or are developing a strategic wireless communications plan for their campus, one that deals with all forms of wireless technologies in a holistic manner, rather than piecemeal by technologies (i.e. 802.11, cellular, etc.)? I'm particularly interested in hearing of plans that deal with both the applications perspective as well as the technologies. Any pointers would be greatly appreciated. Thanks! -- Jim Gogan Director, Networking Information Technology Services Univ of North Carolina at Chapel Hill ** 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/.
WLAN Analysis Tools
I'm working with a couple of my students here at Syracuse on an article for a December issue of Network Computing magazine that we are tentatively calling the Wireless LAN Analysis Toolkit. We're hoping to provide readers with an understanding of the range of problems faced by managers of large WLANs along with a feel for the essential tools that are available, both commercial and open-source. We're thinking about everything from the physical layer (e.g., spectrum analyzers) all the way up the stack. Since Frank Bulk recently looked at distributed monitoring systems, we're not planning to cover those products explicitly. We're looking for help from current WLAN managers. You can either provide general input or answer the following two questions. I hope in most cases you would be willing to post your thoughts publicly, but if you have comments that are of a sensitive nature, you can e-mail me directly. 1. What are the most common WLAN problems you face, either in the design or operation of your network, for which WLAN analysis tools might be helpful? 2. Which specific available tools -- commercial or otherwise -- are most helpful in allowing you to do your job? Thanks, Dave Molta Director, Syracuse University Center for Emerging Network Technologies Sr. Technology Editor, Network Computing 315-443-4549 ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
RE: [WIRELESS-LAN] Q: how much same-channel overlap?
The other caveat here is that the Cirond testing was performed with older Prism II chip sets from Intersil (now Conexant). My understanding is that there were some unique properties of those chip sets that made them more conducive to the 4-channel model and that this model is not as applicable to more modern chipset implementations. dm -Original Message- From: 802.11 wireless issues listserv [mailto:[EMAIL PROTECTED] On Behalf Of Philippe Hanset Sent: Tuesday, March 22, 2005 4:27 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Q: how much same-channel overlap? caveat! Univ. of TN tested and implemented the 4 channels (1, 4, 7, 11) in 2000 and was very pleased with it until we upgraded to 802.11g (3 months ago) OFDM seems to be more sensitive to the channel overlap. Philippe Hanset On Tue, 22 Mar 2005, Gabriel Kuri wrote: you may want to check out this paper from Cirond. it discusses from an RF perspective, the use of 4 channels, given the overlap is very small with a negligible amount of interference. http://www.cirond.com/pdf/FourPoint.pdf - Gabriel Kuri | Operating Systems Network Analyst Instructional and Information Technology Division http://www.csupomona.edu/~iit | +1 909 979 6363 California State Polytechnic University, Pomona -Original Message- From: 802.11 wireless issues listserv [mailto:[EMAIL PROTECTED] On Behalf Of David Boyer Sent: Friday, March 18, 2005 4:23 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] Q: how much same-channel overlap? We have a campus-wide B/G network with pretty dense access point coverage running all the access points on either channel 1, 6, or 11. At most points on campus, our wireless clients can see 6-8 access points all of which are on either 1,6, or 11. It's possible for clients to see 3-4 access points on the same channel. I suspect this level of density is overkill and that we can optimize our wireless coverage by either relocating access points or simply turning of some of the radios. How much same-channel overlap is okay before it causes problems? Can they overlap at -70 or -80 dBm boundaries without affecting the health of our wireless network? Any suggestions are appreciated. Thanks! ** 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: [WIRELESS-LAN] Rogue WAP's
Pierre, I think you've got this one right. The best, and perhaps only, practical way to eliminate rogues AP's on a University campus is to take away the motivation. And even then, there's no guarantee that people won't still do it. But at least you can make the argumennt that it interferes with the production system, an argument that even the most irrational academics will understand. Trying to stamp out rogue AP's by making the argument that they are insecure puts IT folks is a very difficult position. In some instances, it invites the comeback question of OK, so give me a production wireless network and if you aren't prepared to respond quickly, it makes you look bad. In addition, most campus IT organizations have lots of security loopholes and deciding to draw the line at wireless might not always be the wisest thing to do politically. You end up preventing people from using a desireable service and you don't necessarily improve the overall risk level. As far as the rogue detection technologies are concerned, we've looked at most of them and the best ones are expensive to acquire and deploy, sometimes almost as expensive as the wireless services themselves. Of the sensor-based solutions, we really liked AirDefense and AirMagnet but Network Chemistry arguably offers the best value. The infrastructure vendors are also doing a better job of monitoring but we found all of them lacking when compared to dedicationed solutions. It was a tossup between Airespace and Aruba last time we looked. It's not a trivial problem to solve since you either have to dedicated sensors of have your AP's go off-channel to monitor on a probabilistic basis. The handheld solutions (AirMagnet, Fluke Waverunner, BVS, etc.)work pretty well, especially in helping you identify the precise location of an offending device, but they are manpower-intensive. Long term, I think this belongs in the infrastructure products, except in those high-security environments where the goal is to prevent any wireless networking. Whatever you choose, make sure it can scan all channels (US and International) at both 2.4 GHz and 5 GHz. Also, be leary of solutions that rely on clients to monitor since you can't always be assures that clients will be on the network, especially after-hours when the hacking threat is greatest. Dave Molta Syracuse University School of Information Studies -Original Message- From: 802.11 wireless issues listserv [mailto:[EMAIL PROTECTED] On Behalf Of Philippe Hanset Sent: Tuesday, August 10, 2004 1:02 PM To: [EMAIL PROTECTED] Subject: Re: [WIRELESS-LAN] Rogue WAP's How do you deal with rogue WAP's. What is your policy? How do you control them? We moslty see rogue APs in places where UT does not provide centralized WLAN, or places where the existing coverage is weak (yes, I admit, we do have those cases!) It seems easier and cheaper to provide service (or fix the existing one) than to deal with the consequences of rogue APs. Also, our APs being pretty ubiquitous and having a Rogue AP detection function act as WIFI spies all over campus. Our policy, in abstract, is: you will not interfere with the existing WLAN infrastructure. Call us if you have questions. When we do discover APs in places where we provide service ...you do not want to know what we do ;-) Regards, Philippe Hanset thanks, tn Thomas R. Neiss Director of Telecommunications and Information Security University at Albany State University of New York 1400 Washington Avenue MSC 209 Albany, NY 1 [EMAIL PROTECTED] (518) 437-3803 (518) 437-3810 (FAX) ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/cg/. ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/cg/. ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/cg/. ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/cg/.
