Howdy,

We have six systems, a wireless access point, and a wireless
print server, behind a router.

The WAP, and the WPS have static IP addresses, and the
systems are all DHCP.

On occasion, we get an error on one of the systems saying
that there is a duplicate IP address.

We have checked with care, and it ain't so...

What might be causing the error, and (other than the modest
inconvenience) can I ignore it?

Also, is there a way to find out what the system displaying
the error thinks the problem is specifically?

(I should add that I have checked the event viewer tree, but
it shows nothing relevant. Oddly, the System branch shows a
string of information entries dated 7-9-09 which caused me
to check the system date, which is fine. Weird...)

Thanks for any help,
--
Kenneth

If you email... Please remove the "SPAMLESS."

Kenneth wrote:

>
> Howdy,
>
> We have six systems, a wireless access point, and a wireless
> print server, behind a router.
>
> The WAP, and the WPS have static IP addresses, and the
> systems are all DHCP.
>
> On occasion, we get an error on one of the systems saying
> that there is a duplicate IP address.
>
> We have checked with care, and it ain't so...
>
> What might be causing the error, and (other than the modest
> inconvenience) can I ignore it?
>
> Also, is there a way to find out what the system displaying
> the error thinks the problem is specifically?
>
> (I should add that I have checked the event viewer tree, but
> it shows nothing relevant. Oddly, the System branch shows a
> string of information entries dated 7-9-09 which caused me
> to check the system date, which is fine. Weird...)

My guess is that you haven't set the static IP addresses outside of the DHCP
address range. So if your print server, for ex., is 192.168.1.3 and one of
the computers gets 192.168.1.3 before the print server "wakes up" as it
were, you'll get this kind of IP conflict.

Go into your router's configuration utility and check your DHCP range. Set
it to something like 192.168.1.2-192.168.1.149 (obviously substitute your
correct subnet). Then assign static IPs for printers, print servers,
wireless access points, etc. to addresses above that.

Malke
--
MS-MVP
Elephant Boy Computers - Don't Panic!
http://www.elephantboycomputers.com/#FAQ

On Mon, 23 Feb 2009 06:57:36 -0800, Malke
<(E-Mail Removed)> wrote:

>Kenneth wrote:
>
>>
>> Howdy,
>>
>> We have six systems, a wireless access point, and a wireless
>> print server, behind a router.
>>
>> The WAP, and the WPS have static IP addresses, and the
>> systems are all DHCP.
>>
>> On occasion, we get an error on one of the systems saying
>> that there is a duplicate IP address.
>>
>> We have checked with care, and it ain't so...
>>
>> What might be causing the error, and (other than the modest
>> inconvenience) can I ignore it?
>>
>> Also, is there a way to find out what the system displaying
>> the error thinks the problem is specifically?
>>
>> (I should add that I have checked the event viewer tree, but
>> it shows nothing relevant. Oddly, the System branch shows a
>> string of information entries dated 7-9-09 which caused me
>> to check the system date, which is fine. Weird...)
>
>My guess is that you haven't set the static IP addresses outside of the DHCP
>address range. So if your print server, for ex., is 192.168.1.3 and one of
>the computers gets 192.168.1.3 before the print server "wakes up" as it
>were, you'll get this kind of IP conflict.
>
>Go into your router's configuration utility and check your DHCP range. Set
>it to something like 192.168.1.2-192.168.1.149 (obviously substitute your
>correct subnet). Then assign static IPs for printers, print servers,
>wireless access points, etc. to addresses above that.
>
>Malke

Hi Malke,

I will certainly give it a try, and thank you for the
suggestion,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Mon, 23 Feb 2009 12:42:15 -0500, Kenneth
<(E-Mail Removed)> wrote:

>On Mon, 23 Feb 2009 06:57:36 -0800, Malke
><(E-Mail Removed)> wrote:
>
>>Kenneth wrote:
>>
>>>
>>> Howdy,
>>>
>>> We have six systems, a wireless access point, and a wireless
>>> print server, behind a router.
>>>
>>> The WAP, and the WPS have static IP addresses, and the
>>> systems are all DHCP.
>>>
>>> On occasion, we get an error on one of the systems saying
>>> that there is a duplicate IP address.
>>>
>>> We have checked with care, and it ain't so...
>>>
>>> What might be causing the error, and (other than the modest
>>> inconvenience) can I ignore it?
>>>
>>> Also, is there a way to find out what the system displaying
>>> the error thinks the problem is specifically?
>>>
>>> (I should add that I have checked the event viewer tree, but
>>> it shows nothing relevant. Oddly, the System branch shows a
>>> string of information entries dated 7-9-09 which caused me
>>> to check the system date, which is fine. Weird...)
>>
>>My guess is that you haven't set the static IP addresses outside of the DHCP
>>address range. So if your print server, for ex., is 192.168.1.3 and one of
>>the computers gets 192.168.1.3 before the print server "wakes up" as it
>>were, you'll get this kind of IP conflict.
>>
>>Go into your router's configuration utility and check your DHCP range. Set
>>it to something like 192.168.1.2-192.168.1.149 (obviously substitute your
>>correct subnet). Then assign static IPs for printers, print servers,
>>wireless access points, etc. to addresses above that.
>>
>>Malke
>
>Hi Malke,
>
>I will certainly give it a try, and thank you for the
>suggestion,

Hi again Malke,

Well, it was such a good idea, that I apparently had done it
already:

The router's DHCP range is set to provide 40 addresses
starting from 192.168.1.100.

The two static addresses are 192.168.1.245, and
192.168.1.150, so they are out of range.

Might you have any other thoughts about this?

Thanks again,
--
Kenneth

If you email... Please remove the "SPAMLESS."

Kenneth wrote:

> Well, it was such a good idea, that I apparently had done it
> already:
>
> The router's DHCP range is set to provide 40 addresses
> starting from 192.168.1.100.
>
> The two static addresses are 192.168.1.245, and
> 192.168.1.150, so they are out of range.
>
> Might you have any other thoughts about this?

No, I'm sorry but I don't. But hopefully one of the networking gurus will
come around. You might want to check on MVP Jack's site to see if he covers
this.

http://www.ezlan.net

Malke
--
MS-MVP
Elephant Boy Computers - Don't Panic!
http://www.elephantboycomputers.com/#FAQ

Hi
If your Router can do IP reservation within the DHCP (aka Static IP) set it
so that the Wired and Wireless computers that you have onsite would obtain
always the same IP (it usually goes by their MAC number) and would benefit
from being on a DHCP server. This way any additional transient computers
would choose an IP that is Not reserved, and the onsite computers would
always get their personal address. It is also better for the Mapped and
Shared Drives to be on Reserved the IP since they would be always at the
same Network spot.
Jack (MS, MVP-Networking)

"Kenneth" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>
> Howdy,
>
> We have six systems, a wireless access point, and a wireless
> print server, behind a router.
>
> The WAP, and the WPS have static IP addresses, and the
> systems are all DHCP.
>
> On occasion, we get an error on one of the systems saying
> that there is a duplicate IP address.
>
> We have checked with care, and it ain't so...
>
> What might be causing the error, and (other than the modest
> inconvenience) can I ignore it?
>
> Also, is there a way to find out what the system displaying
> the error thinks the problem is specifically?
>
> (I should add that I have checked the event viewer tree, but
> it shows nothing relevant. Oddly, the System branch shows a
> string of information entries dated 7-9-09 which caused me
> to check the system date, which is fine. Weird...)
>
> Thanks for any help,
> --
> Kenneth
>
> If you email... Please remove the "SPAMLESS."

On Mon, 23 Feb 2009 15:25:30 -0500, "Jack
\(MVP-Networking\)." <(E-Mail Removed)> wrote:


>"Kenneth" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed)...
>>
>> Howdy,
>>
>> We have six systems, a wireless access point, and a wireless
>> print server, behind a router.
>>
>> The WAP, and the WPS have static IP addresses, and the
>> systems are all DHCP.
>>
>> On occasion, we get an error on one of the systems saying
>> that there is a duplicate IP address.
>>
>> We have checked with care, and it ain't so...
>>
>> What might be causing the error, and (other than the modest
>> inconvenience) can I ignore it?
>>
>> Also, is there a way to find out what the system displaying
>> the error thinks the problem is specifically?
>>
>> (I should add that I have checked the event viewer tree, but
>> it shows nothing relevant. Oddly, the System branch shows a
>> string of information entries dated 7-9-09 which caused me
>> to check the system date, which is fine. Weird...)
>>
>> Thanks for any help,
>> --
>> Kenneth
>>
>> If you email... Please remove the "SPAMLESS."

Hi Jack,

Unfortunately, my router will not do the "reserved address"
stuff.

It does seem to me that the error message is spurious, and
it seems not to have caused any difficulty (other than its
occasional appearance), but I would like to learn more about
what might be causing it.

Is there any way that this problem could be caused by
flakiness in the router itself? I ask because in the last
month or so, I have found that, on occasion, one, or more,
of our systems seems to "disappear" from the lan. When we
spot that problem, we have rebooted the router and all has
been well. The router is a Linksys, and I do suspect that it
is entering its last days.

Thanks for your thoughts,
--
Kenneth

If you email... Please remove the "SPAMLESS."

Hi
Yap, the Linksys line does not do DHCP Reservation.
However if it is a model that can be flashed with DD_WRT you might be able
to flash the firmware have Reservation and infuse new life to the Router.
Look here, http://www.dd-wrt.com/wiki/index.php/Main_Page
Jack (MS, MVP-Networking)

"Kenneth" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On Mon, 23 Feb 2009 15:25:30 -0500, "Jack
> \(MVP-Networking\)." <(E-Mail Removed)> wrote:
>
>
>>"Kenneth" <(E-Mail Removed)> wrote in message
>>news:(E-Mail Removed)...
>>>
>>> Howdy,
>>>
>>> We have six systems, a wireless access point, and a wireless
>>> print server, behind a router.
>>>
>>> The WAP, and the WPS have static IP addresses, and the
>>> systems are all DHCP.
>>>
>>> On occasion, we get an error on one of the systems saying
>>> that there is a duplicate IP address.
>>>
>>> We have checked with care, and it ain't so...
>>>
>>> What might be causing the error, and (other than the modest
>>> inconvenience) can I ignore it?
>>>
>>> Also, is there a way to find out what the system displaying
>>> the error thinks the problem is specifically?
>>>
>>> (I should add that I have checked the event viewer tree, but
>>> it shows nothing relevant. Oddly, the System branch shows a
>>> string of information entries dated 7-9-09 which caused me
>>> to check the system date, which is fine. Weird...)
>>>
>>> Thanks for any help,
>>> --
>>> Kenneth
>>>
>>> If you email... Please remove the "SPAMLESS."
>
> Hi Jack,
>
> Unfortunately, my router will not do the "reserved address"
> stuff.
>
> It does seem to me that the error message is spurious, and
> it seems not to have caused any difficulty (other than its
> occasional appearance), but I would like to learn more about
> what might be causing it.
>
> Is there any way that this problem could be caused by
> flakiness in the router itself? I ask because in the last
> month or so, I have found that, on occasion, one, or more,
> of our systems seems to "disappear" from the lan. When we
> spot that problem, we have rebooted the router and all has
> been well. The router is a Linksys, and I do suspect that it
> is entering its last days.
>
> Thanks for your thoughts,
> --
> Kenneth
>
> If you email... Please remove the "SPAMLESS."

On Mon, 23 Feb 2009 19:34:44 -0500, "Jack
\(MVP-Networking\)." <(E-Mail Removed)> wrote:

>Hi
>Yap, the Linksys line does not do DHCP Reservation.
>However if it is a model that can be flashed with DD_WRT you might be able
>to flash the firmware have Reservation and infuse new life to the Router.
>Look here, http://www.dd-wrt.com/wiki/index.php/Main_Page
>Jack (MS, MVP-Networking)

Hi Jack and All,

I had been having occasional error messages telling me that
two devices on our LAN had the same IP address, but I could
not trace it down because when I looked at each address,
they were, indeed, unique.

Well, it happened again today, but this time, something
showed up in Event Viewer.

It provided the MAC address of the device assigned the IP
address that was in conflict.

('Sounds good so far, huh...?)

Well, I can't find a device with that MAC address. I know
it's out there, but I have not been able to find it.

Is there an approach to this situation that I am missing?

Many thanks for any help,
--
Kenneth

If you email... Please remove the "SPAMLESS."

Kenneth wrote:
> On Mon, 23 Feb 2009 19:34:44 -0500, "Jack
> \(MVP-Networking\)." <(E-Mail Removed)> wrote:
>
>> Hi
>> Yap, the Linksys line does not do DHCP Reservation.
>> However if it is a model that can be flashed with DD_WRT you might be able
>> to flash the firmware have Reservation and infuse new life to the Router.
>> Look here, http://www.dd-wrt.com/wiki/index.php/Main_Page
>> Jack (MS, MVP-Networking)
>
> Hi Jack and All,
>
> I had been having occasional error messages telling me that
> two devices on our LAN had the same IP address, but I could
> not trace it down because when I looked at each address,
> they were, indeed, unique.
>
> Well, it happened again today, but this time, something
> showed up in Event Viewer.
>
> It provided the MAC address of the device assigned the IP
> address that was in conflict.
>
> ('Sounds good so far, huh...?)
>
> Well, I can't find a device with that MAC address. I know
> it's out there, but I have not been able to find it.
>
> Is there an approach to this situation that I am missing?
>
> Many thanks for any help,

The first six characters of the MAC address identify the device
manufacturer. Perhaps that would help you find it.
http://www.coffer.com/mac_find/

Otherwise ... how is your network protected from intruders?

--
Lem -- MS-MVP

To the moon and back with 2K words of RAM and 36K words of ROM.
http://en.wikipedia.org/wiki/Apollo_Guidance_Computer
http://history.nasa.gov/afj/compessay.htm