Question : Linksys RT31P2 and BEFSR41 connection, 192.168.15.1 and 192.168.1.1 respectively - talking to each other.

All,

I have a question that I hope you can assist with.  I'm not a network guru but I do know enough to get by but this has got me stumped.  It might be really, really simple and just not something I've had to deal with before.

I have a cable that plugs into one of the 4 ethernet ports on the BEFSF41 DHCP/Router and it plugs into the WAN (or "Internet") port on the RT31P2.  I connect up the phone.

I have the Linksys RT31P2 for my VoIP through Vonage and when I connect a machine to 1 of the 3 ethernet ports I can access the administration/configuration page for the RT31P2 by going to 192.168.15.1.  I can access the internet and eveything just fine.  I can access the other machines/devices that are plugged into the BEFSR41 just find (confirmed by going to mapped drives and the like and I can ping 192.168.1.100, 192.168.1.101, etc...

I have used up the ports on the BEFSR41 by using enough devices.  I have a NAS (Buffalo) drive that won't plug into the BEFSR41 because the ports are used.  So, I plugged it into one of the available ports on the RT31P2.  

The problem is when I'm connected to any the machine I have on the RT31P2 as mentioned I can access the 192.168.1.100, 192.168.1.101, etc and the 192.168.15.101 (NAS drive).  

However, and this is where the crux of the issue lies...when I'm on, like the machine that is 192.168.1.100, I cannot access anything the 192.168.15.1 side.  So, I can't access 192.168.15.1, 192.168.15.100 (my machine connect to RT31P2) or the 192.168.15.101 (NAS drive).

I do a tracert on the 192.168.1.100 machine to the 192.168.15.1...

I got that the first hop was to 192.168.1.1 then everything subsequently timed-out.

Any ideas on what may be the problem?

Any assistance would greatly be appreciated.

Thanks

Answer : Linksys RT31P2 and BEFSR41 connection, 192.168.15.1 and 192.168.1.1 respectively - talking to each other.

Yes, that is correct.  You don't need to forward any port going FROM the .15.x subnet to the .1.x subnet.  The reason for this is because your packets will automatically be forwarded through the gateway to that subnet, and the perimeter router (switch) will handle resolution there.  As you mentioned above, if I understand correctly, you can already access the .1.x subnet computers from within the .15.x subnet, right?  You can only forward ports from without the subnet to an interior PC..  Remember the analogy of a one way door.  You only need to forward ports to within the subnet, not outside it...

Now, if you were trying to access the 192.168.1.100 system from outside your entire LAN, say from the internet, you would setup port forwarding on the BEFSR41 to allow access to it.  Again, this is how I allow you to access my website, which is sitting inside my LAN, using a 192.168.1.x address...  If I were running the webserver inside another subnet, such as your 15.x subnet, I would port forward from BEFSR41 to the RT31P2 address, and then port forward again on the RT31P2 to the webserver's address.

Internet <--> BEFSR41(port forward to RT31P2 IPaddress) <--> RT31P2 (port forward to webserver IP) <--> Webserver

So in your case to access a 15.x address from your 1.x addresses..

Internet <--> BEFSR41 <--> RT31P2 (port forward to a specific 15.x IP) <--> Computer that is in the 15.x subnet

In this case, you would access the inside 15.x computer by using the RT31P2's WAN IP Address that you set statically to access the computer inside the 15.x subnet.  Any packets that are destined for the RT31P2 WAN interface 192.168.1.x would be forwarded to the 15.x computer...

Are we confused enough now?  :)

FE