Normally 'netreg' is done w/ DHCP, where a device gets an address in a
non-internet-connected network for registration, and gets a normal address
once registered.  This also means the device probably gets an address in a
different address space if it moves around a large network (say from one
building to another); in other words, many network designs are tied
geographically, where a given address space is always in a given building.

The normal operation of Cisco VMPS ties a mac to a vlan, so that whereever
that device is plugged in within the VTP domain, it's always on the same vlan.
This is useful for some purposes, but for combining netreg w/ VMPS, it didn't
work the way I wanted.  So I've extended port groups so you can have:

vmps-port-group netreg1
 default-vlan NormalVlan
 fallback-vlan RegisterVlan
 device 10.10.10.10 port Fa0/11
 device 10.10.10.11 all-ports
vmps-port-group netreg2
 default-vlan NormalVlan1
 fallback-vlan RegisterVlan2
 device 10.10.10.10 all-ports

And address entries like this:

 address 50a0.2460.c452 --DEFAULT--

Where "--DEFAULT--" is a magic vlan name meaning 'this address goes on the
default vlan'.  Thus, the geographical mapping of address space is maintained.

Note that when searching for a specific port, it looks for the specific port
first (Fa0/11), then 'all-ports'; thus it's easy to make 3 ports 'exceptions'.
(See 10.10.10.10 above).

Also:
If an address has a real vlan name instead of "--DEFAULT--", it will get
that vlan.
If an address has "--DEFAULT--", but there's no default defined, it gets
the the per-port-group fallback if defined, otherwise the global fallback vlan.

David L. Parsley, <parsley@linuxjedi.org> 6-18-2004