We have the network version of Land Dev. Desktop R2, using TCP/IP on an NT 4
server. We also have a very busy campus network. For some reason, in the
last couple of months, users are getting the "license lost" message anywhere
from 5 minutes to an hour after activating ACAD. This used to never happen.
Our server is registered with the network DNS and all workstations can ping
the server by name, although as I said the network is very busy and
sometimes one or two of the packets fail. (I don't think there's anything
we can do about that.) The network administrator assures me that no changes
have been made to the network that would cause this problem.
I thought that by extending the Zombie timeout that ACAD would not do its
little "6-4-2 minute routine". That didn't work. It still zaps the users
the minute contact is lost, but doesn't yank the license right away.
I have several questions. 1) How does communication between client and
server work once a license is issued? Who queries whom? 2) Is it possible
to deactivate the feature that pulls a license once communication is lost?
Is there a way to extend the six minute time period to a couple of hours?
3) How long does the server wait after losing contact before it does
something? Why doesn't it try to reestablish contact? Can the "loss of
contact" time period be extended?
We are never going to have 100% perfect communication on our network 100% of
the time. That's just not possible. What can we do to give the users more
Right now we have a client/server setup. If we switched to having ACAD
installed on the server and not the clients, would that help? If ACAD is
running from the server, does the client still ask for a license, or does
the server ask itself for a license, since the .exe is on the server and not
1) How does communication between client and server work once a license is issued?
The server and client communicate with each other using UDP (port 1422 I think). The
client must be able to contact the server by host name (which you've said it can), and the
server must be able to contact the client by host name.
1b) Who queries whom?
The client queries the server
2) Is it possible to deactivate the feature that pulls a license once communication is
No. If this were the case you would be able to connect to the network, pull an autocad
license and then disconnect from the network and the adlm would never no if autocad were
2b) Is there a way to extend the six minute period to a couple of hours?
No. If this were the case it would allow sites to use many more licenses than they
actually own. You could connect to the network, get you license and then disconnect,
after the adlm server decided it couldn't talk to you any more it would put the license
(that you are still using) back in the active pool and someone else would be able to use
that same license.
3) How long does the server wait after losing contact before it does something?
According to what I've read the client checks about once every minute to verify that it
still has a license (heartbeat), although I've seen clients stay up for longer than this
when the adlm server is down. I've not verified the 1 minute heartbeat by sniffing etc.
3b) Why doesn't it try to reestablish contact?
The adlm uses UDP, which is connectionless. It doesn't know that the communication didn't
make it to the server (or vice-versa) and therefore simply thinks that there is no-one
answering. I'm not sure about this but based on some observations only of shutting the
adlm server down, I think that the client does get another chance. Just based on
qualitative observation I'd say that the client can skip one heartbeat, and as long as the
next one is okay it will keep running.
3c) Can the "loss of contact" time period be extended?
Not that I'm aware of. The heartbeat appears to be coded into both the client and server
sides of the adlm.
No installing AutoCAD on the server will not solve any of your problems. In fact, if your
network is as busy as you say it is it will probably do additional damage. AutoCAD is not
a server application. When you install AutoCAD to the server it is basically acting as a
file server and just giving the clients the files that they ask for. This will increase
your network utilization (as the files will have to be downloaded to the client) and the
client itself is still the one responsible for getting the license.
The zombie timeout doesn't have anything to do with the "client side" it works only on the
server side (as I understand it). The zombie timeout controls how long the server waits
(after it has decided the client is gone) before releasing the license for someone else to
If we're talking about a true campus network (and I assume we are) then there are likely a
number of subnets and different routers involved in getting from the client machine to the
adlm server. It is possible, with this large of a network, that there are multiple paths
from the clients to the adlm server and some of the routers may not be configured to allow
UDP 1422 to pass, so when it takes the path through router a everything works, but when
router a gets busy and router b is in the loop the heartbeat gets dropped. Are all (or
most) of the client machines in a single location / subnet? If so is it possible to move
the adlm server to this location / subnet?