Are the Macs in question associating at 802.11a/n (5GHz)? I've posted before 
about a bug in the Mac Broadcom driver which will cause the client to 
continuously adjust it's power and may result in an association to the AP but 
random communication issues (like failure to get an IP). Cisco added a command 
to disable the World Mode IE feature in the beacons until Apple fixes the 
problem.

config 802.11a(or 802.11b) world-mode disable

I think the above is in 5.2.193 but I'm not sure if it made it into 6.0. I 
believe however that there is an equivalent individual AP cli command for it.

Oh, and world mode IE is disabled by default on Cisco autonomous AP's, thus 
you'll likely not encounter the issue with them.

Jeff

>>> Anthony Croome <a.cro...@qut.edu.au> 10/13/2009 9:30 PM >>>
Hi

We are having this problem too.  Is there any new information from people?

We currently run Cisco wireless and have upgraded some locations to the new N 
standard.  

The problem "appears" to be isolated in the locations where we have upgraded 
but we can't be 100% sure.

It is only appearing on macs, and they claim it works in one place but not 
another.  All we can see is that it appears to be rejecting the dhcpoffer from 
the dhcp server.

We haven't tried disabling dhcp proxy as discussed earlier in this thread, but 
others have said it didn't help.

The latest temporary solution that has worked on two out of two macs is

===

All commands required at the command line:

sudo ipconfig set en1 BOOTP (case sensitive and en1 is generally the wireless 
adapter on macs but it could possibly be different?)

wait 5 seconds and then enter:

sudo ipconfig set en1 DHCP

===


Anthony Croome
QUT


-----Original Message-----
From: The EDUCAUSE Wireless Issues Constituent Group Listserv 
[mailto:wireless-...@listserv.educause.edu] On Behalf Of Earl Barfield
Sent: Friday, 28 August 2009 11:39 PM
To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU 
Subject: Re: [WIRELESS-LAN] Self-assigned IP on Macs

> Date:    Thu, 27 Aug 2009 15:58:39 -0500
> From:    Hector J Rios <hr...@lsu.edu>
> Subject: 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. 

I had the same problem after ugrading from 4.2.<something> to 5.2.193.0.

Uncheck "Enable DHCP Proxy" under controller->advanced->DHCP and see if
that fixes it.  It worked for me.


-- 
Earl Barfield -- Academic & Research Tech / Information Technology
Georgia Institute of Technology, Atlanta Georgia, 30332
Internet: earl.barfi...@oit.gatech.edu    e...@gatech.edu 

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