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Sivajothi · Sep 8, 2006, 02:13 AM

Running SBS 2003 Server with 10 client machines in a domain and two laptops are in a workgroup. Laptop users having 2 NICs wired and wireless enabled and getting their IP address from Server DHCP.

Problem:

When the laptop user disable the Wireless NIC after sometimes again they enable the Wireless the following message is occuring in Server.

The system detected an address conflict for IP address 10.0.0.2 with the system having network hardware address 00:EF:BE:CF:D5:0A. Network operations on this system may be disrupted as a result.

Here IP is the server IP address and MAC address is one of the Laptop users Wireless NIC card address. With that two cards everything working fine for them, but sometimes getting that error.

Anyone can please help me out. Its very urgent.

cajalat · Sep 8, 2006, 03:31 AM

Start by checking the DHCP scope on the server and make sure that it is not handing out its own IP address. What is the current DHCP scope?

The other thing you can do is go to the Laptop that has that MAC address and issue "ipconfig /all". You should be able to verify that he indeed has 10.0.0.2 as an IP and also find out which DHCP server gave him that IP. The problem might be that he's getting an IP from another DHCP source that is handing out the IP of the SBS server.

Curlyben · Sep 8, 2006, 04:15 AM

Nuts, got to spread.
I completely agree with cajalat on this.
Sounds like your DHCP scope if trying to give out the entire range rather than a limited range.
As a rule of thumb I always set servers and printers to a static IP and then DHCP scope the remaining 200 IP's, so in your case a scope of 10.0.0.50 - 10.0.0.250 should cover everything.

Hope this helps.

Sivajothi · Sep 10, 2006, 09:51 PM

I have excluded the range for server and printer. Is there any issues because of wired and wireless in a Laptop which is not under the domain but in a network getting their IP from Server.

cajalat · Sep 11, 2006, 04:06 AM

No. The domain membership is independent of DHCP. Any system can get an IP address from the DHCP server and that PC can be Linux, Windows, Solaris, etc.

Sivajothi · Sep 11, 2006, 09:24 PM

Problem is occurring by the following action,

When the laptop user disable the Wireless NIC after sometimes again they enable the Wireless the following message is occurring in Server.

Tell me is there any other reason that causing the problem.

StuMegu · Sep 12, 2006, 05:49 AM

Have you checked that any wireless access points aren't also giving out ip addresses via DHCP?

cajalat · Sep 12, 2006, 07:32 AM

Make sure that you restart the DHCP service. When you change the scope you need for that to take effect by restarting the service.

Also have you checked the laptop to see if it is in fact getting its IP from the DHCP server? i.e. when you do a "ipconfig /all" you should see who gave it the IP.

Sivajothi · Sep 12, 2006, 09:36 PM

I have checked the Laptop getting their IP from DHCP Server only. Please help me out to solve the problem. Any special cases are there using wired and wireless in a Laptop at a time in a network.

cajalat · Sep 12, 2006, 09:48 PM

When you use a laptop and connect it via wireless AND wired at the same time here is what happens: Laptop will get an IP address from the DHCP server on wired based on the wired NIC's MAC address and will receive another IP on the wireless side based on the wireless MAC address. So you can have two separate IP's.

If you look at the output of ipconfig /all you should see two IP's (different from each other) from the same DHCP server. You will also see two default routes but your PC will only be able to use one of them.

So there shouldn't be a problem with IP conflicts.

Now, have you tried to restart the service. You didn't say if you did or not. We can only help if we know you followed the suggestions we offer. If you haven't restarted the service then do so. Even better if you can reboot the DHCP server all together if you can.

If your DHCP server is still handing out its own IP address then you should look over the scope again. Something has to be wrong with it. You can also try and clear the leases database.

Another option you can do is setup a Manual DHCP (M-DHCP) entry for the laptop's MAC address and force it to get a new IP address.

Please try these suggestions and tell us the result of each.

Good luck.

tpeters · Nov 29, 2006, 10:08 AM

Hmmm, go find the device with mac address 00:EF:BE:CF5:0A or whatever it is, and find out how it gets its ip address. If it's static, and it has the right to use the .2 address, then your DHCP scope is wrong, or there's another DHCP server operating.

Wireless access devices often have a DHCP server built in.

Somehow, someone else has that IP.

Sivajothi · Jan 31, 2007, 10:54 PM

Every weekend, we shutdown the server. Monday we up the server. Now our laptop user using only wireless NIC card.

When the user comes on Monday and start the machine, we get the error message "Address Conflict with IP". We will get the above error message in server from Mon to Wednesday. Thursday and Friday we won't get that error message.

What could be the problem. Can anyone please help me out.

cajalat · Feb 1, 2007, 04:56 AM

We're trying to help but you are not giving us much feedback to go on. Your problem of Mon-Wed is that it could be that the duplicate DHCP lease expires in 3 days and at that point the problem "seems" to go away. I still think that you have multiple DHCP servers handing out IP's.

If you want our help you need to provide more feedback. Do this on the machine that is giving you the "duplicate" message:

IPCONFIG /ALL

This will give us a lot to go on.

Casey

Sivajothi · Feb 1, 2007, 09:45 PM

Sorry if my information not enough for you.

Our Infrastructure,

1 SBS 2003 Server
1 Router with NAT enabled (DSL Modem line)
2 Switches
1 Wireless Access Point

10 Client systems
2 Laptops (in Workgroup)

We have only one DHCP server running in our network. I am the one who maintaing and administrating the company entire network.

In SBS 2003, we have our DHCP service. I have not enabled DHCP on either Router or Wireless AccessPoint.

cajalat · Feb 2, 2007, 05:09 AM

IPCONFIG /ALL

Can you do that and display the results?

Sivajothi · Feb 3, 2007, 01:43 AM

When he on his machine, we are getting the error.

Laptop machine ipconfig/all details,

Windows IP Configuration

Host Name.. . : RUDRA

Primary Dns Suffix.. . :

Node Type.. . : Hybrid

IP Routing Enabled.. . : No

WINS Proxy Enabled.. . : No

DNS Suffix Search List.. . : vss.local

Ethernet adapter {69C4EB64-7C5E-44E5-BF9B-DB8478814C37}:

Media State.. . : Media disconnected

Description.. . : Check Point Virtual Network Adapter For SecureClient - Packet Scheduler Miniport

Physical Address.. . : 52-45-63-54-32-02

Ethernet adapter Bluetooth Network:

Media State.. . : Media disconnected

Description.. . : Bluetooth LAN Access Server Driver

Physical Address.. . : 00-41-11-89-0D-B3

Ethernet adapter Local Area Connection:

Media State.. . : Media disconnected

Description.. . : Intel(R) PRO/100 VE Network Connection

Physical Address.. . : 00-27-D3-0B-52-67

Ethernet adapter Wireless Network Connection:

Connection-specific DNS Suffix . : vss.local

Description.. . : Intel(R) PRO/Wireless 3945ABG Network Connection

Physical Address.. . : 00-41-06-C0-8E-46

Dhcp Enabled.. . : Yes

Autoconfiguration Enabled.. . : Yes

IP Address.. . : 192.168.4.29

Subnet Mask.. . : 255.255.255.0

Default Gateway.. . : 192.168.4.2

DHCP Server.. . : 192.168.4.2

DNS Servers.. . : 192.168.4.2

Primary WINS Server.. . : 192.168.4.2

Lease Obtained.. . : Saturday, February 03, 2007 12:24:08 PM

Lease Expires.. . : Sunday, February 11, 2007 12:24:08 PM

He is using only the wireless adapter.

Sivajothi · Feb 6, 2007, 11:25 PM

Cajalat,

I have sent you the IPCONFIG/ALL details of Laptop machine. Can you please help me to solve the problem?

Curlyben · Feb 8, 2007, 02:22 PM

Siva, your answer is in this part:

Lease Obtained.. . : Saturday, February 03, 2007 12:24:08 PM

Lease Expires.. . : Sunday, February 11, 2007 12:24:08 PM

The length of your DHCP lease is causing the issue.
Now you shutting the SBS down over the weekend is compounding this issue.
Leave it on and it will be resolved.
I must admit I'm at a loss as why you do this, but there you go.

Sivajothi · Feb 8, 2007, 09:24 PM

Curlyben,

I will try this in coming weekend. Can you please tell me why this is happening for that particular Laptop system. What processing is going on?

Sivajothi · Feb 11, 2007, 10:33 PM

Hi Curlyben,

Server is up in last weekend. Still I am getting that issue. The problem not yet solved.

Actually we have Laptop machines using both wired and wireless.
Both machines got same issues, when they "ON" their machines by enabling wireless and wired.

So what I did was, I have configured DHCP reservation for one of the Laptop machine. Here I have reserved IP addresses for both wired and wireless. This machine is not causing problem.

Another Laptop machine now has only wireless enabled. Now the error is occurring only when this laptop machine is "Switched ON"

My Head wants me to solve this problem and try to find out the cause of this problem.
For the past 6 months, I am trying to solve this problem, but I couldn't.

Is Wireless Access Point cause any issues. Everyday we switch off the wireless access point.