Hi Frank, Thanks for bringing up cabling. I've been operating under the assumption that there would be some new cabling involved with the transition to 802.11n. It's not clear to me yet if it will make sense to locate "n" APs in the same places as our current "a/g", but I'm guessing an optimal (you're free to pick what you're optimizing for) 802.11n-only layout will demand different locations.
Assuming we do go with the same locations, bandwidth and/or power demands may still require additional cables. We currently only have one UTP cable to an AP location. If we don't want a potential bottleneck where the AP meets the wired LAN, we'll need either two 100Mb connections (though in a dual-band, 4-spatial stream environment, that still may be a bottleneck) or a single GigE. I don't know what the common vendor options will be, but two cat-5's with 100Tx and 802.3af power should adequately meet both demands. The alternative is one GigE drop with either local power or proprietary UTP based power (including possible pre-standard 802.3at). I'm not sure which will solution will have the highest TCO, but pulling new cable doesn't strike me as a bad solution. Chuck -----Original Message----- From: Frank Bulk [mailto:[EMAIL PROTECTED] Sent: Thursday, June 21, 2007 1:32 AM To: [email protected] Subject: Re: [WIRELESS-LAN] The strategic importance of 5GHz Thanks for sharing your thoughts. You're right, the initial price points I'm hearing suggest a 50% to 75% premium over dual-radio, dual-band APs today. There's been a lot of Meru love on this listserv, so let me bring the romance down a notch by suggesting that their opening price of $1500 for a pre-802.11n AP is an absolutely astonishing example of "value pricing". Cisco and Aruba shared some possible price ranges with me and upon hearing them I felt only more sure than ever that most enterprises will not delay their summer purchases for pre-802.11n capable APs and that the majority of pre-802.11n APs sold this fall will be to enterprises trialing a few units. That said, I do think the most likely long-term solution is to replace existing APs with a dual-radio AP, one radio using a 2.4 GHz 802.11b/g and the other using 2.4 GHz and 5 GHz 802.11n. Some might be tempted to overlay their existing wireless infrastructure with a separate single radio, dual-band 802.11n AP, but that will require separate Ethernet cables runs and legacy clients running against the 2.4 GHz or 5 GHz bands will substantially reduce the performance advantage. Of course, if you wait 3 years then most of the legacy clients in a Higher Ed organization will have naturally aged out with 802.11n clients and it's not as much of a concern. Then the question is how much capacity you want, and the more radios you have the more channels that can be used. Regards, Frank -----Original Message----- From: Enfield, Chuck [mailto:[EMAIL PROTECTED] Sent: Wednesday, June 20, 2007 3:41 PM To: [email protected] Subject: [WIRELESS-LAN] The strategic importance of 5GHz I started responding to the thread titled "The strategic importance of 802.11a" an quickly got off topic. Frank covered that topic quite well, so I'd like to change the subject from "g" vs. "a" to 2.4GHz vs. 5GHz. I'd like to discourage the use of 2.4GHz, 802.11n APs. Since we all have to buy new hardware for 802.11n anyway, this is probably our best opportunity to get away from all the limitations of the 2.4GHz band. I believe the best way to avoid migration path issues from "a/g" to "n" will be to roll out 802.11n at 5GHz and retain 802.11g for legacy clients. I'm concerned that because MIMO APs cost more and dual-band APs cost more, dual-band MIMO APs will cost much more. A substantial premium for dual-band, 802.11n APs will lead people to buy single-band devices. If we're counting on "n" to support legacy clients, that band will have to be 2.4GHz. If we get any significant distance down that path, we may be stuck at 2.4GHz until the next technology comes out. I know the standard is being developed around backward compatibility, but that doesn't mean we have to use it. If we can convince vendors that we don't need 802.11n to support legacy clients there's hope for affordable 5GHz 802.11n. I can envision two ways to support legacy clients without using 802.11n. One is to leave our existing 802.11b/g infrastructures in place for legacy clients. I know none of us want to support two infrastructures, but until we replace everything we'll be doing that anyway. We can hope that the advantages of 802.11n will be so great that everybody will upgrade their clients before the roll-out is even completed (yes, I'm being uncharacteristically optimistic). The other is ask manufacturers to provide a relatively cheap 802.11g radio in a 5GHz, 802.11n AP. The obvious drawback to that is paying extra for a radio we hope not to use, but it shouldn't be a tremendous premium. I hope to get lots of feedback on this, even if it's just to tell me I'm nuts. I've been saying for years that the future is at 5GHz, but I fear we're in danger of missing another opportunity to exploit that potential. Chuck Enfield Sr. Communications Engineer Penn State University Telecommunications & Networking Services 110 USB2, UP, PA 16802 Ph. (814) 863-8715 Fx. (814) 865-3988 ********** 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/.
