Sharing internet between 2 subnets

3com Officeconnect 56k lan modem
February 3, 2011 at 10:53:20
Specs: Linux i686
So I'm working with a Netgear WNDR3300 and a 3COM OfficeConnect 56k LAN Modem. Some details on the LAN Modem here: http://www.3com.com/products/en_US/...

Basically I'm trying to connect a 56k client to my broadband network. Here's how my setup is:

56k client--->Teltone TLS3 Phone Simulator--->3COM LAN Modem--->Netgear Router--->Cable Modem

After not finding much help in the documentation on 3COM's site I decided to see if there was any information on how to set this up with a very similar product which is the Netopia(Motorola) R2000/R2020. And I was able to find some insight on how to get this working based on the technote here: http://www.netopia.com/support/hard...

So in order to get this working I need to use static routing between different subnets. In the diagram they have pictured in the netopia technote there is are 2 routers and 2 Netopia devices. On my network the "Router B" can be seen as my netgear, the "Netopia A" as my 3COM LAN Modem, and the "Netopia B" would be my 56k client (only I am connecting to a single modem that is not sharing the connection with another LAN).

Here is how I set up my network based on that technote:

Netgear LAN Settings:
IP: 192.168.1.1
Subnet Mask: 255.255.255.0

On the Netgear, under static routing:
Destination LAN NET: 192.168.1.128
Subnet Mask: 255.255.255.128
Gateway: 192.168.1.2

on the 56k LAN Modem, under LAN network parameters:
IP address: 192.168.1.2
Subnet Mask: 255.255.255.128

on the LAN Modem, under Dial-in parameters (For the remote 56k client):
LAN Modem WAN IP: 192.168.1.1
Remote LAN IP: 192.168.1.129
Remote LAN Subnet Mask: 255.255.255.128
Primary DNS: 192.168.1.1

So I'm able to connect the 56k client just fine. Once connected however I am only able to access the 56k LAN Modem and Netgear router's web interfaces at 192.168.1.2 and 192.168.1.1 respectively. The 56k client does not appear to internet at all. I thought at first it was a DNS issue, but I'm pretty sure now that it has to do with the fact that its using a different subnet mask. So I'm not sure how to share the internet between these different subnets.

Any help would be really appreciated. If you need me to clarify anything let me know.
Thanks in advance!


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#1
February 3, 2011 at 12:08:19
why are you using 128 instead of 0? Everything is in the same subnet x.x.1.x there is no routing within the same subnet

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#2
February 3, 2011 at 12:22:17
EDIT: Sorry I misread your post.

But I should mention the 56k LAN Modem does not have an rj-45 WAN port. I was just going based on the link to that netopia technote. Sorry my knowledge of networking is somewhat limited. I will try changing the IP on the LAN Modem.

I did try using 255.255.255.0 as the subnet mask at first, but the 56k client was then unable contact the netgear router.


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#3
February 3, 2011 at 12:44:53
Okay, I just tried the following 2 configurations and in both cases the Netgear router was unreachable from the 56k client.

First I tried this:

Netgear LAN Settings:
IP: 192.168.1.1
Subnet Mask: 255.255.255.0

On the Netgear, under static routing:
Destination LAN NET: 192.168.2.128
Subnet Mask: 255.255.255.128
Gateway: 192.168.2.1

on the 56k LAN Modem, under LAN network parameters:
IP address: 192.168.2.1
Subnet Mask: 255.255.255.128

on the LAN Modem, under Dial-in parameters (For the remote 56k client):
LAN Modem WAN IP: 192.168.1.1
Remote LAN IP: 192.168.2.129
Remote LAN Subnet Mask: 255.255.255.128
Primary DNS: 192.168.1.1

Then I tried this:

Netgear LAN Settings:
IP: 192.168.1.1
Subnet Mask: 255.255.255.0

On the Netgear, under static routing:
Destination LAN NET: 192.168.2.128
Subnet Mask: 255.255.255.0
Gateway: 192.168.2.1

on the 56k LAN Modem, under LAN network parameters:
IP address: 192.168.2.1
Subnet Mask: 255.255.255.0

on the LAN Modem, under Dial-in parameters (For the remote 56k client):
LAN Modem WAN IP: 192.168.1.1
Remote LAN IP: 192.168.2.129
Remote LAN Subnet Mask: 255.255.255.0
Primary DNS: 192.168.1.1

I have already tried setting it up this way without static routing and it ended up with the same result. I can access the 56k LAN Modem web interface from the 56k client with these configurations, but not the Netgear.


Does anyone else have any suggestions on what might be my issue here? I would like to get this working.


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