Just for information MAC OS/X Leopard (and probably Tiger) both default to an IP Address in the 192.168.1.n range when they cannot acquire an IP address, like windows machines default to a 169.254.n.n ip address. Presumably if they are being "excluded" from network access and not acquiring an IP address from DHCP they will fall back to a self-assigned IP address. Many Thanks Peter
-----Original Message----- From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[email protected]] On Behalf Of Matt Grover Sent: 28 August 2009 15:10 To: [email protected] Subject: Re: [WIRELESS-LAN] Self-assigned IP on Macs... We have seen this issue to some degree. It did not happen to all Macs but only to a small percentage of machines. In case anyone should run into it though what I found was the following... It is normal for dhcp clients to request their last used IP. Something about how the Mac dhcp clients were doing it seemed to be different though. I haven't had time to do a thorough analysis of Mac dhcp behavior. That aside, what I noticed was that the clients having the trouble showed up in the controller logs as being put into an "Exclusion" state. This was because the controllers security mechanism was kicking in and excluding the client because of "IP theft or reuse". By disabling the "IP theft or Reuse" under security, wireless protection policies, client exclusion policies caused it to stop happening. Looking into it further, the clients that were being blocked were coming in with addresses in the 192.168.1.x range. This is probably the most common range for home networking so it's no surprise they would have that address range coming in from home. I see two possibilities why it triggered "IP theft". The first possibility is that another client had come in under that address and the second one gets blocked. The more likely cause I think is that we have the service vlan on the controllers numbered in the 192.168.1.0/24 subnet just as the wism setup docs show. I think this IP space is colliding with the clients coming in and trying to use it. My guess is that the controllers see the space in use by themselves and flag it. I have not had time however to test this theory. I also do not know why the problem was only exhibited by Macs. Seems to be something different in their dhcp client behavior. -Matt > ----- Original Message ----- > > *From:* Hector J Rios <mailto:[email protected]> > > *To:* [email protected] > <mailto:[email protected]> > > *Sent:* Thursday, August 27, 2009 3:58 PM > > *Subject:* [WIRELESS-LAN] Self-assigned IP on Macs... > > > > Have you guys run into this issue? We run Cisco's lightweight APs on > WiSMs running code 5.2.193. Mac will associate to our APs but just > won't obtain an IP address. In the end it assigns itself a > self-assigned IP. We are seeing this on a lot of new MacBooks and > MacBookPros running 10.5.8. If we associate the computer to an > autonomous AP it works fine. If we boot it in safe mode it works > fine too. Everything else it just fails. > > > > Thanks, > > > > Hector Rios > > Louisiana State University -- ------------------------------------------------------------ Matt Grover === University of Florida Sr. Network Engineer === http://net-services.ufl.edu [email protected] === Florida Lambda Rail (352)273-1061 === http://www.flrnet.org/ ------------------------------------------------------------ ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. -- Heriot-Watt University is a Scottish charity registered under charity number SC000278. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
