We use vlan pooling with 16 /24's on our network but we tuned down the dhcp lease times to 1 hour as we found that many users don't need their ip for very long. They just connect, check some mail and maybe some "class" stuff and then disconnect. Next time they connect (within your dhcp lease time scope) or lose connectivity due to poor roaming they might (likely) connect on another vlan and then chew up another ip address. We initially had 7 hour leases (and poor roaming) and found that our ip's were getting eaten up pretty quick. After we changed it to an hour, it seems to be pretty good. The /24's work good for us and I've read every Cisco wireless design doc and everyone mentions a different size for scopes. A couple years back it was "try and make them as small as possible to keep the broadcast domain small", now it seems to be creeping back up to /21's.
I hope this helps a bit. Craig Eyre Network Analyst IT Services Department Mount Royal University 4825 Mount Royal Gate SW Calgary AB T2P 3T5 P. 403.440.5199 E. [email protected] "The difference between a successful person and others is not a lack of strength, not a lack of knowledge, but rather in a lack of will." Vincent T. Lombardi From: "Osborne, Bruce W" <[email protected]> To: [email protected], Date: 08/02/2012 05:51 AM Subject: Re: [WIRELESS-LAN] Wireless Client Subnet sizing Sent by: The EDUCAUSE Wireless Issues Constituent Group Listserv <[email protected]> FYI, Aruba Networks has their knowledgebases and documentation freely available too. No registration required.` Documentation: http://support.arubanetworks.com/DOCUMENTATION/tabid/77/Default.aspx Tools & Resources: http://support.arubanetworks.com/TOOLSRESOURCES/tabid/76/Default.aspx ArubaOS KB: http://support.arubanetworks.com/ArubaOSKB/tabid/111/Default.aspx AirWave KB: http://support.arubanetworks.com/AirWaveKB/tabid/115/Default.aspx Amigopod KB: http://support.arubanetworks.com/AmigopodKB/tabid/128/Default.aspx ClearPass KB: http://support.arubanetworks.com/ClearPassKB/tabid/127/Default.aspx Bruce Osborne Network Engineer IT Network Services (434) 592-4229 LIBERTY UNIVERSITY Training Champions for Christ since 1971 From: Tristan Rhodes [mailto:[email protected]] Sent: Wednesday, August 01, 2012 5:13 PM Subject: Re: Wireless Client Subnet sizing Like it was mentioned by Anders, this excellent material is freely available after a registration. Funny though, it seems that you can access the file directly: Design and Deployment of Enterprise WLANs (BRKEWN-2010) http://d2zmdbbm9feqrf.cloudfront.net/2012/usa/pdf/BRKEWN-2010.pdf Cisco has the most technical content available, compared to any other network vendor that I am aware of. Cheers! Tristan -- Tristan Rhodes Network Engineer Weber State University (801) 626-8549 >>> On 7/31/2012 at 5:01 PM, in message < CAP8VL9hbfk669TT=XGMu5WdMt25_eopDZ=xvcvceohabjrr...@mail.gmail.com>, Mark Duling <[email protected]> wrote: Luke, it looks like that presentation isn't public. Can you say more about Cisco's recommendations on that? Or are they simply saying /21 is the maximum recommended size? I'd also be interested in anything they said about mcast as it relates to size. I've setup vlan select on a test WLAN with the intent of breaking up my /21 into smaller pieces for the fall, but I've had no problems with it (though mcast is off). But I thought I would use smaller subnets since our wireless use has gone up quite a bit in recent years and doing it is so simple to do now. I've heard conflicting info, and to my surprise one time a TAC engineer suggested they should be no larger than /24, which I think is erroneous. Mark On Tue, Jul 31, 2012 at 2:43 PM, Luke Jenkins <[email protected]> wrote: What type of gear are you using? Cisco is now recommending using /21s for their unified wireless gear (Sujit Ghosh, Cisco Live US 2012 BRKEWN-2010, Slide 75). -Luke =-=-=-=-=-=-=-=-=-=-=-= Luke Jenkins Network Engineer Weber State University On Jul 31, 2012, at 11:59 AM, Craig Simons <[email protected]> wrote: > All, > > We are looking at re-engineering our wireless networking IP space and I'm wondering what type of boundaries other have pushed their networks to. We are currently using /22 networks (14 of them) most of which during a busy period of the day will run around 75-80% utilization (at least as far as DHCP assignments go). When I look at most APs during the day, I see that most APs have users belonging to several networks (roaming), and as we have multicast disabled, it would seem that the advantages of segregating wireless networks on the basis of limiting broadcast domain are moot. Is anyone running /21 networks or larger? > > We've investigated NAT, but accurately logging internal-external IP address assignments for our users has proven difficult. Our vendor also doesn't currently support any type of "VLAN pooling" feature. > > Interested in your opinions, > Craig > > > > -------------------------------------- > Craig Simons > Network Operations > Simon Fraser University > Burnaby BC, Canada > em. [email protected] > ph. 778-782-8036 > ce. 604-649-7977 > tw. twitter.com/simonscraig > -------------------------------------- > ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found athttp:// 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/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. __________________________________________________________________________ This communication is intended for the use of the recipient to which it is addressed, and may contain confidential, personal, and or privileged information. 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