Microsoft KB Archive/171860

= Duplicate IP Address in RAS Pool Causes Event ID 20050 =

Article ID: 171860

Article Last Modified on 10/31/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition

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This article was previously published under Q171860



SYMPTOMS
When a Remote Access Service (RAS) client dials into your Windows NT RAS server running remote access server, the client may be disconnected during the authentication process or shortly thereafter. Also, you may receive an event log message in the event viewer on the RAS server similar to the following:

Event ID: 20050

Source: RemoteAccess

Description: The user DOM\User connected on port Com1 on at and disconnected on at. The user was active for. 326 bytes were sent and 512 bytes were received. The port speed was 28800. The reason for disconnecting was administrator's request.



CAUSE
The cause of this problem may be a duplicate IP address on the network. This can be due to one or more of the following:
 * A user may be using an address that is in the server's RAS static pool.

-or-


 * The RAS administrator added entries to the RAS IP static pool that are already in use on the local area network (LAN).

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 * The RAS server is using Dynamic Host Configuration Protocol (DHCP) for its RAS address pool and the DHCP server has had its database rebuilt.



RESOLUTION
To resolve this issue, regardless of the cause affecting you, you must verify that the pool of addresses being used by the RAS server is not in use by other computers on the LAN. This can be done by using the following steps:  Verify that there are no RAS clients connected to the RAS server. From a command prompt, type the following:

ping 

where represents the IP addresses in the RAS pool.

 Repeat step 2 for each address in the RAS pool.

If you receive a response from another computer, either the RAS server addresses must be changed or the LAN workstation must have its address changed.

To change the RAS pool of addresses, follow these steps:
 * 1) Double-click Network in Control Panel and click Services.
 * 2) Click Remote Access Service (or Routing and Remote Access).
 * 3) Click Properties, click Network, and click Configure for the TCP/IP protocol.
 * 4) If the RAS server is configured to assign addresses through DHCP, force the RAS server to obtain a new set of leases from the DHCP Server. If the RAS server is configured with a static pool of addresses, edit the address range to include unique addresses.

For additional information, please see the following article in the Microsoft Knowledge Base:

124358 RAS Server Assigns Cached IP Addresses to RAS Clients

Keywords: kberrmsg kbnetwork kbprb KB171860

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