Using 3Com LanModem with Win2K DHCP Server - is it possible?

Posted on 2005-03-18
Medium Priority
Last Modified: 2010-07-27
Hey there,

I have a client with a small network (8PC's running 98 and XP, and a 2k PDC running DHCP server).  They are using a 3Com LanModem to connect to a local dial-up ISP.  

Is there a way to allow the clients to obtain IP's from the DHCP server on the 2K machine while still allowing them to access the Internet via the LanModem?

The local clients are receiving an error message stating, in essence, that there are no more available WAN connections on the lanModem.  I have gone in to the lanModem and released the old workstation connections but it seems to dole out these connections based on its own DHCP server (which is disabled).

I'd really like to keep the DHCP server on the 2K machine running as the client is part of a statewide network and if the lanModem resets to the default config (192.168.x.x) we can't see the local machines from our remote site.


Question by:ttist25
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Expert Comment

ID: 13577464
Could you incorporate proxy service (ISA on your W2K box or Squid with a cheap Linux box) and use this as the connection to the internet?

Alternatively, you could use internet connection sharing and have the server connect to the lanModem and the workstations connect to the server.

Author Comment

ID: 13578174
Hi kminfotech.

I'm providing contract support for this network in an emergency capacity while they are trying to fill a vacant position so I'm hesitant to to mess with the server too much.

Are you implying that it can't be done otherwise?  I was hoping to find a setting in the LanModem that would allow me to do this.

Thanks so much for your response.

Expert Comment

ID: 13578224
Not a lanModem expert, but found this document on 3com's site


Page 13 indicates the 4 connections are the maximum (perhaps simultaneous? since you have 8 PCs already???)...

regardless, a proxy server might improve performance of the ISDN connection (for surfing) and would definitely solve the connections issue.

Sorry couldn't be more help but will dig around a bit.

Accepted Solution

kminfotech earned 1500 total points
ID: 13578292
Okay...maybe this would help...from manual p58

Configuring the LAN
To configure LAN parameters, do the following.
1 From the ISDN LAN modem main page, click the ISDN LAN Modem graphic.
2 In the IP Address field, review the default and enter a different IP address if
3 In the Subnet Mask field, review the default and enter a different Subnet mask
if required.
4 In the Local Domain Name field, enter a name to identify this particular LAN on
a network.
5 Check the Enable DHCP server box to enable it or clear the box to disable it.
WARNING: If you changed the IP address and/or the subnet mask of your ISDN
LAN modem, the ISDN LAN modem will re-initialize itself when you submit the
changes by clicking Submit. When the re-initialization occurs, all calls are
terminated, and you may have to reconfigure the IP addresses on the computers
on the LAN.
6 Click Submit.

The example subnet mask is which would give 6 usable addresses?

I'm still going to go back to my gut which thinks this device was only ever configured to handle 4 devices.  You could try to rig something up but I imagine it has a NAT'ing pool that will handle 4, no more...

Author Comment

ID: 13578780
Ok - I think I've got it fixed.

The LanModem actually allows 25 connections.  What I did was I reserved the addresses .100-.125 in the Workstation configuration table.  Even though the workstation names are "Unknown1" through "Unknows25" it seems to be working with the specified IP's.  

I'm not sure if the Workstation name field is a netbios name or if it's just a name to make configuration easier.

Anyway, it seems to be working.  We'll see what happens when the leases expire.

I'll award the points for your work km.

Thanks so much.


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