Put another way- in some regards, the controller is one giant AP with distributed antennas in the thin model. Some important per-AP granularity of config is traded off.
Lee H. Badman Wireless/Network Engineer Information Technology and Services Syracuse University 315 443-3003 -----Original Message----- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:wireless-...@listserv.educause.edu] On Behalf Of Johnson, Bruce T Sent: Thursday, January 29, 2009 12:43 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Comments about Aruba and Cisco???? Now that would be interesting - different data rates and/or Radio Management support, per controller, based on an AP Grouping mechanism. The fatter these controllers get the more it has to be the procrustean bed for all sorts of wireless devices. Does any Thin AP vendor support this? Bruce T. Johnson | Network Engineer | Partners Healthcare Network Engineering | 617.726.9662 | Pager: 31633 | bjohns...@partners.org ________________________________ From: The EDUCAUSE Wireless Issues Constituent Group Listserv on behalf of Lee H Badman Sent: Thu 1/29/2009 12:29 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Comments about Aruba and Cisco???? Hi Chris- Sorry to be late in responding to this one, but you've got me confused on #4. But let me also touch on the others... 1. I am not sure with Aruba, But Cisco deployment can account for more AP's, depending on which specification you survey against.. Lee- anyone's hardware set should show different results if you survey for 11g versus 11a, especially at 54 Mbps rates. But if you are capacity-driven (like in a dorm, for example) versus range, this becomes less of an issue. We tend to be so dense because of rapidly escalating wireless popularity that range (and by extension the number of APs) almost becomes meaningless in general. (This is not an invitation for vendors to call me- I know there is more to this topic). 2. Another thing to consider is the uplink trunked ports needed for both devices. For Instance, the Cisco Controller 4404 desires to have 4 of the ports port channeled to the core. The amount of trunked, Port channeled, ports is a consideration in both installations. Lee- there can be some interesting differences in "oversubscription" rates when you move from 11a/g to 11n, when the same number of APs at significant higher data rates and gig uplinks connect to "the same old controllers". But the whole oversubscription discussion can be taken in a lot of directions, and proven/disproven in numerous ways- especially in the theoretical versus real-world. I find this to be a very interesting study when looking at what all vendors offer in controller uplink versus AP counts. 3. If you have any existing Standalone Wireless devices, these can cause Spanning-tree loops if close to the new access points due to the client connecting to both. Ciscos solution is to turn the power down on the standalone AP's so there is a gap between new and existing wireless. Lee- not sure why there should ever be a fat-AP cell adjacent to an LWAPP cell on the same network (other than for device management) with the same SSID- roaming would surely break, and seems like the potential for a lot of issues beyond spanning tree. 4. Cisco Controllers, although they are trying to fix this, have one power setting per controller. What this means is that if a building absorbs the radio waves more or less than the others, the controller sets the AP Power all the same. This will cause you to have gaps in your coverage. A survey might take this into account, but when the controller power setting is changed, it affects all the Access point that are controlled by it. Some buildings are like a sponge while others are not. Lee- I think you may be unique in experiencing this, or in being told this. The Cisco controllers do configure data rates controller wide (which I have been found to be limiting in certain cases), but not transmit power. See this graphic (actually two pics)- different APs, different power, same controller, multiple buildings: <https://phsexchweb.partners.org/exchange/BJOHNSON5/Drafts/RE:%20%5BWIRE LESS-LAN %5D%20Comments%20about%20Aruba%20and%20Cisco_x003F__x003F__x003F__x003F_ .EML/1_m ultipart/image001.jpg> <https://phsexchweb.partners.org/exchange/BJOHNSON5/Drafts/RE:%20%5BWIRE LESS-LAN %5D%20Comments%20about%20Aruba%20and%20Cisco_x003F__x003F__x003F__x003F_ .EML/1_m ultipart/image002.jpg> This of course, depends on the automatic stuff being enabled. Do you have any tech docs that describe RRM as you describe it? I'm not looking to prove you wrong, but your description is curious versus everything (I think) I know about this part of the system. Thanks- Lee H. Badman Wireless/Network Engineer Information Technology and Services Syracuse University 315 443-3003 ________________________________ From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:wireless-...@listserv.educause.edu] On Behalf Of Christopher DeSmit Sent: Wednesday, January 28, 2009 10:02 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: Re: [WIRELESS-LAN] Comments about Aruba and Cisco???? Ken, You might want to consider the management side of the project. With Cisco you can connect directly to the controller-WISM, but they recommend you use another product called WCS. Things to watch out for are in the following: 5. I am not sure with Aruba, But Cisco deployment can account for more AP's, depending on which specification you survey against.. 6. Another thing to consider is the uplink trunked ports needed for both devices. For Instance, the Cisco Controller 4404 desires to have 4 of the ports port channeled to the core. The amount of trunked, Port channeled, ports is a consideration in both installations. 7. If you have any existing Standalone Wireless devices, these can cause Spanning-tree loops if close to the new access points due to the client connecting to both. Ciscos solution is to turn the power down on the standalone AP's so there is a gap between new and existing wireless. 8. Cisco Controllers, although they are trying to fix this, have one power setting per controller. What this means is that if a building absorbs the radio waves more or less than the others, the controller sets the AP Power all the same. This will cause you to have gaps in your coverage. A survey might take this into account, but when the controller power setting is changed, it affects all the Access point that are controlled by it. Some buildings are like a sponge while others are not. I may not be totally accurate of all the statements above, but this is meant to spark some thought for you to consider... Good Luck! Thanks, Christopher DeSmit University of North Carolina Pembroke- Division of Information Technology Network Security Specialist 910-521-6260 chris.des...@uncp.edu From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:wireless-...@listserv.educause.edu] On Behalf Of Johnson, Ken Sent: Tuesday, January 27, 2009 9:00 PM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] Comments about Aruba and Cisco???? All, I am a member of an evaluation team at Florida State University considering Cisco and Aruba wireless products. We are focusing on LWAPs and controllers. For evaluation configuration and pricing purposes, we have requested from the companies information and pricing relating to configurations with 128 and 1200 APs. The Aruba LWAP is the AP125 while Cisco LWAP is the recently release 1142. The Aruba controller is the M3 while the Cisco product is the WiSM. There are other aspects, too. I know many of you have experience with Cisco and Aruba and have gone through similar experiences. I am interested in learning about any observations and experiences you have that we should consider in our efforts. Please send me your thoughts. Thanks. Ken ~~~~~~~~~~~~~~~~~~~~~~ Ken Johnson Director, Information Technology FSU College of Medicine 1115 Call Street Tallahassee, FL 32306-4300 e-mail: ken.john...@med.fsu.edu phone: 850.644.9396 cell: 850.443.7300 fax: 850.644.5584 "Please note: Florida has very broad public records laws. Most written communications to or from state/university employees and students are public records and available to the public and media upon request. Your e-mail communications may therefore be subject to public disclosure." ********** 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/. The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail. ********** 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/.
