The Vista Network Map
Contents:
Why the map sometimes looks wrong
There are a number of reasons why the network map might not quite look
the way you expect.
- The gateway is in the wrong place: The user interface people
thought that for non technical users it was always best to show the
internet gateway at the top right next to the user's computer,
irrespective of where it really is in the network. That is their
expert decision, but it would not have been my choice.
- Simplest observationally equivalent: The map has some
fundamental limitations in which it shows you the simplest
observationally equivalent network to your network and not what your
true network looks like. As one example, if you have a spur of
network equipment which goes nowhere, then it will not appear on the
map. Perhaps the other example you are likely to see is that if you
have an Ethernet switch which is behaving as a very expensive piece of
wire (it has exactly two connections with no computers attached, and
each of the two connections connects only to another Ethernet switch)
then it will dissapear from the network. There are several more
obscure other cases.
- The map shows extra devices: This tends to happen if you
think you've got an Wireless Access Point, but the map shows a switch
too: many Access Points have built-in switches which show up as extra
devices on the map.
- Bugs: Sadly there are a few known bugs in the Vista mapper
algorithm which will hopefully get fixed in a service pack or the next
release of Windows.
- Incompletness in the algorithm: The Vista mapper doesnt deal
with all known network equipment; there are a few cases we dont cover
including Wireless half-bridges, HomePlug, mixtures of real and
virtual computers, span-monitoring ports, and so on.
Enabling using the user interface If you
have Windows Vista you might like to know how to enable the Network
Map on your machine. Due to the "off by default" philosophy of the
Secure Windows Initiative you'll find that the Network Map is disabled
by default on your machine when you are on a domain joined network.
This is easy to control using a policy setting as follows.
First, open gpedit.msc from the start menu (this will prompt
for elevation). Then open up Computer Configuration, then
Administrative Templates, then Network, then
Link-Layer Topology Discovery. It will look like this image:
For the two settings on the right; for each right click and select the
properties. You can then ensure that it is enabled and
configure the options to Allow operation while in domain, (if
you wish, on public networks) and ensure it is not disabled on
private networks. See these images below. (Note that the text on the
"Explain" tab is known to be incorrect but the options are
self-explanatory.)
Enabling using the registry
If you want to automate the UI sequence found above then note that the
controlling registry keys can be found in
HKLM\Software\Policies\Microsoft\Windows\LLTD\ and should all be a
DWORD with a value of 1 or 0 as below. If missing they all default
to 0 except EnableLLTDio and EnableRspndr which default to 1.
- AllowLLTDioOnDomain
- AllowLLTDioOnPublicNet
- ProhibitLLTDioOnPrivateNet
- EnableLLTDio
- AllowRspndrOnDomain
- AllowRspndrOnPublicNet
- ProhibitRspndrOnPrivateNet
- EnableRspndr
Forcing the change to be noticed
These settings are supposed to change the behaviour immediately; but
somtimes it seems that that it takes a while to notice. If you want
to force this you can open an elevated cmd prompt and execute the
following.
- sc stop lltdsvc
- sc stop lltdio
- sc stop rspndr
- sc start rspndr
- sc start lltdio
- sc start lltdsvc
Getting the responder for Windows XP
The responder which allows Windows XP computers to appear in the Vista
Network Map is now finished and is available as KB article 922120 here. Note that for
Windows XP there is no control user interface and the registry
settings must be used as described above.
There is currently no official Topology Responder for Windows Server
2003. Microsoft internal users are suggested to use the original
prototype responder if required.
Uninstalling a prototype responder
If you have an early Microsoft Research version of the LLTD responder
installed on Windows XP then we now recommend that you uninstall it
and replace it with the supported product responder. To uninstall
first open a cmd window and execute the following:
Then open "Add or Remove Programs" and find the indicated Windows
Driver Package and click "Remove". If it suggests to reboot your
machine then decline; a reboot is unnecessary. Finally install the
product responder as described above.
Authorship
Richard Black, 11th December 2006, written for Windows Vista RTM.
This page is not official policy of Microsoft Corporation and has no
warrenties, express or implied.