# Solved: ip address conflict detected



## pshnfry (Sep 18, 2005)

I'm setting up a small network and learning the basics as I go along.

WAN access (internet) is via a wireless netgear modem/router (DG834G) with DHCP enabled, and DNS provided by my ISP.

4 pc's access this via wireless pci nics, 3 Ralink chipsets and 1 Atheros chipset. 2 XP SP2, 1 W2K, 1 Linux Ubuntu. WPA PSK is enabled, ssid is changed from default, admin password is changed from default.

Everything up to this point is fine, secure to date and reliable.

One of the XP wireless pc connections also has a 10/100 intel based pci nic. This is bridged to the wireless nic and connected to an 8 port switch with auto negotiation. (I think that's the term, it detects source and clients without crossover cables?)

From the switch I have 3 boxes, 1 XP SP2, 1 ME and 1 W98. All patched and updated.

Inittially I used the XP network wizard to set up the XP router box for ICS, and when that didn't succeed (despite indicating which way to the WAN and which way to the LAN it would always look to the LAN side for internet according to the tray indicators.) I tried the bridging method. I have had immediate success with that, and have progressed through manual ip addresses to now running all clients as obtaining ip addresses automatically.

I now only have manual addresses on the XP routers wireless and wired nic's, set up before the bridge is installed (which after numerous restarts is now running auto ip address for the bridge itself.). After some earlier research on this forum and in XP help I have the manual ip addresses on the XP routers adaptors outside of the range defined on the Netgear router/modem (192.168.0.2 to .230).

The problem?
When one of the wireless pc's other than the XP router box is fired up and joins the wireless network and possibly at other times (I'm still trying to define when and whether there are factors), and also as the wired side of the network is fired up I get ip address conflict messages. These seemingly sort out without intervention on wired start up, but the wireless conflicts pull down the bridge connection to the wireless modem/router. The bridge has to be deleted and the 10/100 nic disabled, then the wireless nic connection repaired, then the 10/100 nic enabled and the bridge re-installed to bring the network back up.

I'm leaning to a problem with DHCP somehow being active on the XP router but cannot see anything other than client in services, and no ICS entry in services. There is a message following post before XP boots as follows:

INTEL UNDI PXE-1.0

DHCP MAC ADDRESS ###### (didn't write the string down)

DHCP -- (and a progress spinning cursor)

I think this may be where the problme is, but can't see where to start looking to correct it. Of course I may also be way off track.


Any ideas?

Cheers,


----------



## pshnfry (Sep 18, 2005)

OK, the bridge dies every hour roughly, and can be re-enabled straight away using the process outlined above (delete, disable, repair, re-enable, re-install bridge). This would be related to ip lease renewal?


----------



## TerryNet (Mar 23, 2005)

ICS failed because, for that computer, both the wireless and the ethernet were on the same subnet (because for ICS Windows uses 192.168.0.1 for the address of the NIC "providing" internet to the other computers). I don't recommend that you do it, but you could make ICS work by changing the router's LAN to, say, 192.168.1.x.

"I'm leaning to a problem with DHCP somehow being active on the XP router ..."

I'm leaning the same way (hope the boat doesn't tip over!). When you do an ipconfig /all on that computer with the bridge does it show "IP Routing Enabled ...... Yes"? If so, I think that's a remnant of ICS and you need to get rid of it. I don't know the straightforward way to do so.

Try right clicking on the wireless connection in Network Connections and see if there is any option there or in Properties to get rid of ICS or Routing.


----------



## pshnfry (Sep 18, 2005)

Checked ipconfig/all for the xp router, output is:

C:\Documents and Settings\Peter>ipconfig/all



Windows IP Configuration



Host Name . . . . . . . . . . . . : revive-ics-ps

Primary Dns Suffix . . . . . . . :

Node Type . . . . . . . . . . . . : Unknown

IP Routing Enabled. . . . . . . . : No

WINS Proxy Enabled. . . . . . . . : No



Ethernet adapter Network Bridge (Network Bridge) 25:



 Connection-specific DNS Suffix . :

Description . . . . . . . . . . . : MAC Bridge Miniport

Physical Address. . . . . . . . . : 00-00-00-00-00-00

Dhcp Enabled. . . . . . . . . . . : Yes

Autoconfiguration Enabled . . . . : Yes

IP Address. . . . . . . . . . . . : 192.168.0.4

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : 192.168.0.254

DHCP Server . . . . . . . . . . . : 192.168.0.254

DNS Servers . . . . . . . . . . . : 192.168.0.254

Lease Obtained. . . . . . . . . . : Monday, 25 September 2006 8:29:33 PM



Lease Expires . . . . . . . . . . : Tuesday, 26 September 2006 8:29:33 PM

Re other problems, I'm looking at three different issues it seems, the message at boot re INTEL UNDI etc was a typo in boot settings of bios and is now fixed. The bridge dropping out hourly (and possibly the fact it fails to start at boot) could be the wifi card, I've downloaded updated drivers and config interface but if that fails I'll return it.

Re ipconfig conflicts and the ipconfig/all above, any suggestions? My router is currently set to 192.168.0.254 with a dhcp range 192.168.0.2 to 192.168.0.230, and the ethernet adaptor prior to installing the bridge is 192.168.0.231. All else on the network is set to obtain ip automatically.

Any suggestions appreciated.

Cheers.


----------



## telegramsam (Jul 7, 2006)

Did your router assign itself the gateway of 192.168.0.254?


----------



## pshnfry (Sep 18, 2005)

No, I changed that when attempting the ICS set up.


----------



## telegramsam (Jul 7, 2006)

I think your best bet is to delete that connection and run the wizard again. I don't know if there's a way to right what is wrong, but at this point, that would be the most simple thing to do. Let the XP box use DHCP unless you NEED a static IP (for incomming WAN connections or something on the network that requires it.) It will usually save you the IP address conflict.

Also, restart your entire network in the proper order Modem, routers, switches, computers. Give plenty of time between devices to allow for booting and negotiating.

If you do, I'd recommend letting the router set it's own gateway address. I don't think it's really a problem so much that the gateway is higher than the address range, but the default settings start at .1 and assigns ascending addresses to the LAN. Probably not the root of your problem, but....


----------



## TerryNet (Mar 23, 2005)

"The bridge dropping out hourly (and possibly the fact it fails to start at boot) could be the wifi card, I've downloaded updated drivers and config interface but if that fails I'll return it."

Could be wireless interference or something else that's not specifically a failure of the adapter. If you want to troubleshoot the disconnects, I'd suggest doing so w/o the complication of the bridge.


"Re ipconfig conflicts and the ipconfig/all above, any suggestions? ... and the ethernet adaptor prior to installing the bridge is 192.168.0.231."

Can't think of anything now, except wondering why you have the static IP on the ethernet. Don't know if this is a problem, but pretty sure it's not needed, so how about making it dynamic like all your other devices?


----------



## pshnfry (Sep 18, 2005)

IP conflict is due to a dhcp server fault in the modem/router. See Microsoft KB303743.
Problems with duplicate ip addresses using a modem/router products dhcp server function for a client behind an XP host with bridge installed. I'm waiting on a response from Netgear re their faulty implementation of dhcp.

Re the manual ip address on the ethernet nic, it was the only way the bridge worked. Manually pointing out where the gateway and dns was. I suspect it may be related to the issue above. After reading other posts I put it outside of the dhcp range of the modem/routers range. 

Re the wireless nic, and interference. It works fine for hours on end with no bridge and the ethernet nic disabled. But in the bridge config it drops out hourly, seems too regular for interference or flaky hardware. Also, if I try to access the internet from the XP router with both the ethernet nic and wireless nic enabled but no bridge it fails to connect. Again, I'm wondering if all of this is the dhcp issue.

XP network setup wizard fails to complete (with only the XP router and Modem/router fired up). I suspect it is either ip related or a conflict with the two nics. Next thing I'll try is a different wireless nic (Atheros chipset) and another ethernet nic. It'll all wait on the response from Netgear though.

If I wanted to use the XP router as a dhcp server, what do I do? I've looked around and can't see anything in the settings or in help, is this like the mp3 codecs? Not built into XP?


----------



## TerryNet (Mar 23, 2005)

"See Microsoft KB303743."

That's sure good to know. Glad you found it. Hope that Netgear has or develops a firmware update.

"If I wanted to use the XP router as a dhcp server..."

I assume you mean ICS. If you want to try it again, remember my first paragraph in post #3.


----------



## pshnfry (Sep 18, 2005)

Does ICS mean XP will function as a dhcp router? I was thinking more along the lines of setting up a subnet in a different ip range from the wireless router, and having the xp box assign ip addresses for clients on that subnet. But I didn't spot anything in all my looking that specifically said xp would act in that role.

(I thought this would be helpful if Netgear aren't forthcoming with firmware or workarounds)


----------



## TerryNet (Mar 23, 2005)

When you enable Internet Connection Sharing (ICS) in Windows (any version at least as far back as 98SE) it acts as a router and as a Dhcp server. It sets its "secondary" NIC to 192.168.0.1 and assigns clients to the 192.168.0.x subnet.

As far as I know this is the only way to get XP to act as a Dhcp server and you have no choice about the subnet it will use.

That's why I said to change the subnet of your Netgear router, which is easier to do than to type this post.


----------



## JohnWill (Oct 19, 2002)

There used to be a couple of free DHCP server utilities for Windows, don't know if they're still around. 

DHCPTURBO appears to have a free version that supports up to 5 nodes.


----------



## pshnfry (Sep 18, 2005)

Thank you TerryNet, it may be easier to say "enable ICS", but it didn't help my understanding. I can now share the knowledge gained. (which is what I like about this forum vs many others).

Thanks JohnWill, that's a nice looking piece of software and suits my needs perfectly (5 or less nodes - personal and free).

Cheers.


----------



## JohnWill (Oct 19, 2002)

I always like free if available. 

*You can mark your own threads solved using the thread tools at the upper right of the screen.*


----------



## pshnfry (Sep 18, 2005)

Aaaah, it's a beautiful thing when it all works.

Checked interrupts and I had agp card, modem and wireless nic sharing an interrupt and one of them I think wasn't playing nicely.

Then as they would all initialise without issues I changed the modem routers ip address to 192.168.1.1 and the range of ip's used for dhcp to 192.168.1.2 to 192.168.1.230. Then reran the network setup wizard for ics. All is up and running and the duplicate ip address issue from the netgear router shouldn't be an issue as there is no need for the bridge.

This may also cure the drop out (after an hour), I'll start a new threasd if it doesn't.

Thanks all for suggestions, tips, links and comments.


----------



## pshnfry (Sep 18, 2005)

For info re duplicate ip address issues for others. Netgear correspondance on the dhcp flaw built into their DG834G wireless modem router:

Case # 3816576
Problem Other
Cause HW - incorrect PC network setup
Status Open
Notes

*9/27/2006 12:13:00 AM*
Re Microsoft KB303743.
I have problems with duplicate ip addresses using this products dhcp server function for a client behind an XP host with bridge installed.
How can this be fixed?

Cheers,

Peter.

*9/29/2006 1:54:00 AM*
Dear Peter,

Thank you for contacting Netgear Online Support.

Please firstly check that you are running the most recent firmware release on your router. You can download this firmware from http://kbserver.netgear.com/release_notes/D102765.asp .

Do you have address reservation setup in this router? If so, please disable this for the moment and renew the IP addresses of computers in your network to check if you are now able to get unique IP's on the computers.

Kind Regards,

NETGEAR SUPPORT AUSTRALIA

PLEASE NOTE: To reply to a case logged through our online support system, you will need to login at http://my.netgear-support.com/myNETGEAR/ and select the online support option.

*9/29/2006 9:43:00 AM*
Firmware version was checked before logging the issue and is the latest.

No address reservation was in place and so cannot be disabled and ip addresses retried.

*10/4/2006 3:53:00 AM*
Peter,

Unfortunately there is no fix for this issue if it is router related. You may need to set static IP addresses on the computers you use and disable the DHCP server on the router.

Regards,
Netgear Support

PLEASE NOTE: To reply to a case logged through our online support system you will need to login at http://my.netgear-support.com/myNETGEAR/ and select the online support option.


----------

