3.3. Use of the Microsoft Loopback Adapter by the AFS Client Service

By itself the OpenAFS Client Service does not provide robust behavior in a plug-n-play network environment.  Changes to the number of network adapters or their assigned IP addresses will cause the service to terminate unexpectedly.  To avoid this behavior OpenAFS for Windows installs a single instance of the Microsoft Loopback Adapter (MLA) on the machine.  With the MLA installed, the OpenAFS Client Service will not be affected by the configuration changes of other network adapters installed on the system. 

The MLA is installed with a name of "AFS" and a pre-assigned IP address in the 10.x.x.x range.  The MLA is bound to the "Client for Microsoft Networks" service and not bound to the "File and Printer Sharing for Microsoft Networks".  If the MLA is unbound to "Client Microsoft Networks", the OpenAFS Client Service will become inaccessible when the machine is disconnected from the network.  If the MLA is bound to "File and Printer Sharing ..." there will be a service type collision between the name "AFS" and the name of the machine on the MLA's IP Address that will result in the OpenAFS client service becoming inaccessible and the "NET VIEW \\AFS" command will return a "System Error 52" message.  To correct the problem:

When the MLA is not installed the unique NETBIOS name published by OpenAFS SMB server is " MACHINE-AFS".  One of the benefits of using the MLA is that the NETBIOS name does not have to be published on any adapter other than the MLA.  Therefore the chosen name is no longer required to be unique.  Instead the NETBIOS name associated with the AFS Client Service is simply "AFS" and portable UNC paths of the form \\AFS\cellname\path can now be used on all machines.