"Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
news:vuphf1dt2apv7llm2ktv1a7ucs17frq96q@4ax.com...
> On Mon, 08 Aug 2005 23:46:37 GMT, "paranoid"
> <seanNO@SPAMunhookedmusic.com> wrote:
>
>>We are responsible for fixing a wirless hotel problem. Uses about 15
>>access
>>points.
>>
>>Problem is, the network guy here says, that dhcp just stops working. It
>>seems that the wireless access points are hard-wired into a switch into a
>>router serving dhcp. The netowrk guy claims that everytime dhcp stops
>>working, he can walk the hotel with his laprop, and find someone serving a
>>wirless signal. He says he has seen cell phones going into some type of
>>wireless router serving up wireless for the user.
>
> My guess(tm) is that you have more than one DHCP server running on the
> network. I don't know where it's hiding, or in what box, but it's
> there. The usual culprit is a Windoze 2003 server which enabled the
> DHCP server by default. It also has some nifty security features
> which prevents DHCP from working.
>
> Another typical screwup is to have the DHCP server IP address
> duplicated by a client computah with a static IP address. This
> happens often when clueless users discover that DHCP had failed, and
> decide to assign their own static IP addresses to their own computah.
> They frequently punch in the IP address of the router/gateway/DCHP
> server as their own IP address and cause everything to get muddled.
>
>>This then knocks off the whole hotel wireless network. If he asks the
>>customer to turn it off, it works. He claims this is the case everytime it
>>goes down...
>
> How is this customers client configured? DHCP assigned IP's or are
> they playing static IP as a backup for the failed DHCP server?
>
>>My theory is that the wireless access points at some point must go into
>>repeater mode. We almost cannot get into these things ( ZYair b-420) ,
>>because they are in bridge mode, therefore dont have an ip address.
>
> Muddle. *ALL* (and I do mean *ALL*) wireless is bridging. Everything
> is handled at the MAC address level (layer 2). There are no IP
> addresses involved in bridging. The only thing the IP address of the
> router does is allow you access to the access point for configuration.
> You don't need this IP address for anything else, it will work the
> same with literally any unused IP address, and will not affect
> wireless bridging in any way. (It's not the IP address of the
> wireless access points).
>
>>The only way that someone serving dhcp would screw with the whole hotel
>>network would be if these things are in repeater mode?
>
> I don't think so. In the repeater mode, the ethernet port goes
> comatose to the network. It wouldn't work at all in the repeater mode
> unless configured for a mesh. The B-420 doesn't do mesh, but I thing
> the B-1000 does. I'm too lazy to look it up as I doubt it's a
> wireless configuration issue.
>
>>We are confused, and are currently trying to access the internal page of
>>these access points....
>
> What do you mean trying? They should have static IP's assigned that
> are accessible from your LAN. Hopefully, these IP's are not in the
> middle of the DHCP assigned address range or you will have yet another
> mess to deal with.
>
>>Any ideas?
>
> Sure. Download a DHCP query tool from:
> |
> http://www.weirdsolutions.com/weirdS...ytool_free.exe
> Find out which server(s) are delivering DHCP IP addresses. You should
> have only one. I'll guess(tm) that you have more than one including
> one that's delivering a default route that points to a dead end (not
> the internet). I doubt it's a cell phone doing it.
>
> In addition, I'll guess(tm) that your IP address plan for these 15
> access points and your network is a big mess.
>
> Any chance you're simply running out of available IP addresses for
> DHCP to assign? What box or server is playing DHCP server and how
> many IP's do you have available for assignment? If the DHCP lease
> time is rediculously long, the old leases will not expire in time to
> deal with new arrivals. This is fatal in a convention environment
> where literally hundreds of laptops and PDA's compete for perhaps 253
> IP addresses.
>
> You should also pay attention to roaming effects. Setup the system
> so that the ARP table (MAC address to IP mapping in the router)
> expires quickly. Run this test:
> 1. Connect to an access point and convince yourself that it works.
> 2. Now, move the laptop to another access point with the same
> SSID and channel.
> Do they track? Do you maintain the connection? Or does it go
> comatose as in your description? If so, your router is holding onto
> stale ARP table or router table entries from the initial connection
> and screwing up roaming.
> --
> Jeff Liebermann jeffl@comix.santa-cruz.ca.us
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 http://802.11junk.com
> AE6KS 831-336-2558
Thanks for the advice, ya, we figured out that whoever installed this
network are idiots....So that was the plan, was to install it as
infrastructure...We are pretty new to this wireless thing on this level, but
from what we understand, we assign each unit an ip (so we can manage it),
and we set up each unit to use the same SSID, and alternate the channels
that it will use wirelessly. Then instead of seeing maybe 2 or 3 access
points, depending on where you are in the hotel, you will just see one...and
it should work like that?
Back into it on Thursday...we will probably try a ping sweep and see if we
can find the internal pages of the units, or otherwise, were climbing into
ceilings with laptops...