DWL 2100AP keeps hiding....

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We have small WLAN with a D-Link DWL 2100AP and up to 9 clients with
DWL-G120 Adaptors.

It all works fine during the day, but first thing in the morning, as
the clients come up, one of them wont be able to see the AP.

The AP is powered on all the time, so as soon as the last person is
in, we power off and on the AP and then its all fine, and will run
happily all day, until the next morning (or someone comes in very
late!).

There appears to be no pattern to which client will not find/be found
by the AP (Everyone gets a turn!). Its not even the same number of
clients each time.

The AP is set with SSID not hidden, and a WEP key.

D-Link support seem to think there's some sort of problem with the
2100, but cant pin it down, and there's no firmware upgrade for this
device (as yet!).

Anyone any suggestions as to possible other causes that are fixable?

TIA

JohnK


Re: DWL 2100AP keeps hiding....
On Fri, 29 Oct 2004 16:21:57 GMT, johnk@pceffect.co.uk (John F
Kappler) wrote:

>We have small WLAN with a D-Link DWL 2100AP and up to 9 clients with
>DWL-G120 Adaptors.
>
>It all works fine during the day, but first thing in the morning, as
>the clients come up, one of them wont be able to see the AP.
>
>The AP is powered on all the time, so as soon as the last person is
>in, we power off and on the AP and then its all fine, and will run
>happily all day, until the next morning (or someone comes in very
>late!).
>
>There appears to be no pattern to which client will not find/be found
>by the AP (Everyone gets a turn!). Its not even the same number of
>clients each time.

When you say "won't be able to see the AP", does that mean:
1.  The SSID is invisible in "scan for networks" or similar SSID
display?
2.  The SSID is found, but the client cannot get a DHCP address?
3.  The SSID is found, the client has an existing DHCP address, but
cannot see the rest of the router, rest of LAN, or internet?
4.  The AP has gone invisible and you can see right through it.

If #4, there's a Nobel Prize waiting for you.

>The AP is set with SSID not hidden, and a WEP key.
>
>D-Link support seem to think there's some sort of problem with the
>2100, but cant pin it down,

Please don't use pins.  Voodoo is not supported by most access points.

>and there's no firmware upgrade for this
>device (as yet!).
>
>Anyone any suggestions as to possible other causes that are fixable?

Yep.  What's your DHCP lease time?  See  Advanced -> DHCP  as in:
http://support.dlink.com/techtool/dwl2100ap/emulator/html/dhcpdyna.html
I'm not sure exactly what's happening with DHCP but my guess(tm) is
that you either:
1.  Don't have enough DHCP assignable addresses for the 9 clients.
2.  Have too short a lease time so that the router expires the lease
overnight.  When the laptop arrives in the morning, it tries to get a
new DHCP assigned IP address, and either fails, or keeps trying to use
the old IP address.
3.  If the clients are laptops that were taken home and used on a
different wireless access point, it may have the home configuration
saved.  I've dealt with belligerent XP SP1 machines that will not
automatically release the old IP address.  I have to resort to:
  ipconfig /release
  ipconfig /renew
to force the client to let go of the old IP and ask for a new one.
This is especially a problem if you put the laptop in standby (power
save, hibernate, whatever) instead of doing a full shutdown.

As I indicated, I'm not sure of the exact problem, but methinks it has
to do with DHCP.  I suggest a much longer lease time of 86,400 (one
day) or larger.

If that doesn't work, I suggest taking advantage of the static DHCP
assignment feature, where you pre-assign an IP address to each client,
without resorting to static IP's.
http://support.dlink.com/techtool/dwl2100ap/emulator/html/dhcpstat.html?0,0,0,0,0,0,0
This way the clients always get the same IP address.  If they want to
hold onto the old one, that's fine because it's the same as the new
one.



--
Jeff Liebermann    jeffl@comix.santa-cruz.ca.us
150 Felker St #D   http://www.LearnByDestroying.com
Santa Cruz CA 95060    AE6KS  831-336-2558


Re: DWL 2100AP keeps hiding....
On Fri, 29 Oct 2004 11:53:44 -0700, Jeff Liebermann

>On Fri, 29 Oct 2004 16:21:57 GMT, johnk@pceffect.co.uk (John F
>Kappler) wrote:
>
>>We have small WLAN with a D-Link DWL 2100AP and up to 9 clients with
>>DWL-G120 Adaptors.
>>
>>It all works fine during the day, but first thing in the morning, as
>>the clients come up, one of them wont be able to see the AP.
>>
>>The AP is powered on all the time, so as soon as the last person is
>>in, we power off and on the AP and then its all fine, and will run
>>happily all day, until the next morning (or someone comes in very
>>late!).
>>
>>There appears to be no pattern to which client will not find/be found
>>by the AP (Everyone gets a turn!). Its not even the same number of
>>clients each time.
>
>When you say "won't be able to see the AP", does that mean:
>1.  The SSID is invisible in "scan for networks" or similar SSID
>display?
>2.  The SSID is found, but the client cannot get a DHCP address?
>3.  The SSID is found, the client has an existing DHCP address, but
>cannot see the rest of the router, rest of LAN, or internet?
>4.  The AP has gone invisible and you can see right through it.
>
>If #4, there's a Nobel Prize waiting for you.
>
>>The AP is set with SSID not hidden, and a WEP key.
>>
>>D-Link support seem to think there's some sort of problem with the
>>2100, but cant pin it down,
>
>Please don't use pins.  Voodoo is not supported by most access points.
>
>>and there's no firmware upgrade for this
>>device (as yet!).
>>
>>Anyone any suggestions as to possible other causes that are fixable?
>
>Yep.  What's your DHCP lease time?  See  Advanced -> DHCP  as in:
>http://support.dlink.com/techtool/dwl2100ap/emulator/html/dhcpdyna.html
>I'm not sure exactly what's happening with DHCP but my guess(tm) is
>that you either:
>1.  Don't have enough DHCP assignable addresses for the 9 clients.
>2.  Have too short a lease time so that the router expires the lease
>overnight.  When the laptop arrives in the morning, it tries to get a
>new DHCP assigned IP address, and either fails, or keeps trying to use
>the old IP address.
>3.  If the clients are laptops that were taken home and used on a
>different wireless access point, it may have the home configuration
>saved.  I've dealt with belligerent XP SP1 machines that will not
>automatically release the old IP address.  I have to resort to:
>  ipconfig /release
>  ipconfig /renew
>to force the client to let go of the old IP and ask for a new one.
>This is especially a problem if you put the laptop in standby (power
>save, hibernate, whatever) instead of doing a full shutdown.
>
>As I indicated, I'm not sure of the exact problem, but methinks it has
>to do with DHCP.  I suggest a much longer lease time of 86,400 (one
>day) or larger.
>
>If that doesn't work, I suggest taking advantage of the static DHCP
>assignment feature, where you pre-assign an IP address to each client,
>without resorting to static IP's.
>http://support.dlink.com/techtool/dwl2100ap/emulator/html/dhcpstat.html?0,0,0,0,0,0,0
>This way the clients always get the same IP address.  If they want to
>hold onto the old one, that's fine because it's the same as the new
>one.
>
>
>
>--
>Jeff Liebermann    jeffl@comix.santa-cruz.ca.us
>150 Felker St #D   http://www.LearnByDestroying.com
>Santa Cruz CA 95060    AE6KS  831-336-2558

Aaaah, a Nobel prize...... (sorry,.a Homer moment!)

No. 1. Scan for Networks find nothing (despite other systems (e.g. on
the next desk) being happily connected). As I said, re-booting the AP
immediately solves the problem (does annoy the other users though!)

All clients have static IPs
Whilst it sometimes happens to Notebooks, it more regularly happens to
Desktops.

JohnK


Re: DWL 2100AP keeps hiding....
On Sat, 30 Oct 2004 06:57:18 GMT, johnk@pceffect.co.uk (John F
Kappler) wrote:

>Aaaah, a Nobel prize...... (sorry,.a Homer moment!)

|                          (####)
|                         (#######)
|                        (########)
|                       (########)
|                      (########)
|                     (########)
|                    (########)
|                   (########)
|                  (########)
|      _&_        (########)      |///|       / /  /              /
|    /           (########)      |      |       | V  /  ---.   .----/  -----.
|   |      |       (o)(o)(##)     |      |        _         /                /
|   |  (o)(o)    ,_C     (##)     | (o)(o)         (o)(o)   <__. .-- (o)(o)  /_.
|   C   .---_)  /_____,  (##)     C      _)       _C          /        ()      /
|    |  | ___|         (#)        | ,___|       /_____,   )      >   (C_)    <
|    |   __/      |    |          |   /                 /----'  /_______/____
|   /_______      OOOOOO         /                oooooo            /|   |
| /________/     /             /______          /                /        
|/              /             /                /        
|                   The Simpsons...
|


>No. 1. Scan for Networks find nothing (despite other systems (e.g. on
>the next desk) being happily connected). As I said, re-booting the AP
>immediately solves the problem (does annoy the other users though!)
>
>All clients have static IPs
>Whilst it sometimes happens to Notebooks, it more regularly happens to
>Desktops.
>
>JohnK

Groan.  So much for my DHCP theory.  Also, forget about the Nobel
Prize.

Any chance one of your machines has a duplicate IP address?  That's a
common problem with static IP addressing.  One buggy firmware release
on a different box I had to deal with would merrily pass out the
routers IP address via DHCP.  Naw, that can't be it because it's a
random computah that screws up.  Never mind.

However, I have an experiment worth trying.  When you leave for the
evening, unplug the ethernet connection between the router and the
DWL-2100AP.  That will eliminate anything that might be coming from
the router.  If it works in the morning, then at least we know where
it's coming from.  If it works, fire up Ethereal on one of the
workstations and start capturing data on the LAN after hours.

If it's the same old problem, try the same trick, but this time on the
wireless side.  Just unplug the antenna for the night in case it's
something coming in via the wireless port.  I neither test points to
any external influences, we're down to magic, witchcraft, ghosts,
voodoo, and firmware bugs.

Also, you might wanna look at the access points status page for
anything unusual with one of the working computahs.

Incidentally, several years ago, I had a problem at a department
store.  They would shut down all the networked cash registers with a
common circuit breaker.  In the morning, 27 clients would boot
simultaneously.  The 3Com SuperStuck II 3300 switches would often hang
on random ports that required a power cycle of the switch to recover.
While this has nothing too do with wireless, by any chance is everyone
booting at exactly the same time?


--
Jeff Liebermann    jeffl@comix.santa-cruz.ca.us
150 Felker St #D   http://www.LearnByDestroying.com
Santa Cruz CA 95060    AE6KS  831-336-2558


Re: DWL 2100AP keeps hiding....
Thanks Jeff.

I'll try those steps, but it wont be until next week.

Cheers,

JK


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