New DHCP Parameter for Switched Networks

• Microsoft Windows NT Server version 4.0

SUMMARY

The Dynamic Host Configuration Protocol (DHCP) server service in Windows NT 4.0 Service Pack 2 has a new parameter that will allow the client's default gateway to be set to its own IP address.

MORE INFORMATION

The new parameter "SwitchedNetworkFlag" is configured through Registry Editor. When enabled, this causes a DHCP client to obtain a default gateway address equal to the IP address that the client receives. This causes the client to use the Address Resolution Protocol (ARP) for all IP addresses on the local subnet, and is useful for routerless switched networks.

NOTE: In the event that routers do exist on your network, setting the SwitchedNetworkFlag will normally cause failure of your clients to connect to hosts on other networks. Only a proxy ARP device will enable this type connectivity configuration. Care must be taken to ensure that any and all routers within the network can proxy ARP and that no outside connectivity is desired.

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it.

To enable this feature for all clients in a scope, add the following value to the registry on the DHCP Server:

1. Start Registry Editor (Regedt32.exe) and locate the following subkey:
   
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DHCPServer\
   Configuration\Subnets\a.b.c.d\
   
   NOTE: The above registry key is one path; it has been wrapped for readability.
   
   Where a.b.c.d is the IP address of the DHCP subnet.



2. From the Edit menu, click Add Value and use the following entry:
   

   
         Value Name: SwitchedNetworkFlag
         Data Type:  REG_DWORD
         Value:      1 or 0 (default=0)
                     1 enables the DHCP server to send the client's IP address
                       as their default gateway. 

Keywords : kbnetwork nthowto ntnetserv ntprotocol nttcp ntregistry NTSrv
Version : WinNT:4.0
Platform : winnt
Issue type : kbinfo