Directing IPX Broadcast Traffic - 15 Nov 1999

More Registry tweaks that solve pesky IPX problems

In "Directing IPX Broadcast Traffic," November 1999, I mentioned common problems with NWLink IPX/SPX on RAS connections. In this issue, I discuss how you can adjust the DisableDialinNetbios and NetBiosRouting Registry subkey values to solve common NWLink IPX-based RAS problems.

In a common NWLink IPX/SPX problem, RAS clients try to log on to the network but a domain controller on the LAN can't authenticate them. This problem is particularly common when NWLink IPX/SPX is the sole transport protocol on the RAS connection. Table 1 and Table 2 list the possible values for the DisableDialinNetbios and NetBiosRouting Registry subkeys. These tables show that the subkeys' default configuration lets RAS clients send broadcasts to the LAN but doesn't permit broadcast traffic coming from the LAN to reach the clients. Thus, clients don't receive the broadcast packets that the domain controller sends in response to clients' requests for authentication. As a result, IPX RAS clients' logon authentication attempts fail.

To solve this problem, you can set the value of DisableDialinNetbios to 0, which ensures that the RAS clients receive NetBIOS broadcasts from the LAN. You can also change this value if you want to modify the behavior of broadcast forwarding as it relates to only IPX RAS clients; modifying this value won't affect the global configuration of the IPX transport.

Some situations might require you to modify the value of the NetBiosRouting Registry subkey instead of, or in addition to, changing the DisableDialinNetbios value. In "Nonbrowsing RAS Clients," May 1999, I mentioned that proper network browsing with RAS clients requires that IPX not be the sole protocol on the RAS connection. (Microsoft discusses this requirement in "RAS Client Cannot Browse RAS Server With IPX Only" at http://support.microsoft.com/support/kb/ articles/q148/1/54.asp.) However, you might be able to successfully enable network browsing with IPX-only RAS clients if you modify the NetBiosRouting value to enable two-way broadcast forwarding. To enable two-way broadcast forwarding, change the value of NetBiosRouting to 6 if the server is a single-NIC machine or 7 if the server has multiple LAN adapters and you want RAS to forward NetBIOS packets between LAN segments.

Alternatively, Microsoft recommends that you use NetBEUI or TCP/IP in addition to IPX on the RAS link to browse a remote network. Although this solution works, some IT shops prefer not to use this method—particularly IT shops that run Windows NT RAS in an IPX/NetWare-centric environment and shops that don't want to support additional protocols on their RAS servers.