View Full Version : Potentially tricky TCP/IP problem

22-11-2002, 06:03 PM
Tough question.

I have a colleague who wants to use Telecom's Office IP connect to use ADSL to connect a remote office to a head office in the city. The theory was that the remote PC (there is only one at the remote site) would effectively log into the network as if it was in the head office, as it would be able to tell it was anywhere else. This was on the basis that the remote router would be supplying an ethernet connection that flowed directly to the main office, the only difference is that the speed is slower than regular ethernet.

Nice idea, but:
The techie says the remote site must be on another subnet from the city one, so the router can tell it needs to route the packets. I say that if the router isn't being a router but is stupid enough to act like a bridge, all it does is spew everything it receives on the ethernet port out over the ADSL link and vice versa.

However, techie doesn't think the security, etc, will allow that.

But if the remote PC is on a different subnet to the server in the city office, how will it see it unless there is some translation happening somewhere with like a proxy server or something?

I was thinking maybe a PC at the city office with two ethernet cards, one on each subnet, could handle it. But nobody wants to pay installation if the damn thing isn't going to work.

The city office has IP ranges controlled by head office overseas and their geeks are really cooperative, in fact quite the reverse.

a) does this make any sense at all?
b) should this work?
c) what is needed to make it work?


Graham L
22-11-2002, 06:11 PM
Is this setup intended to be effectively a "Leased Line", using ADSL instead of modems? There are no ISPs involved, I take it ... is this some Telecom service to send (ADSL) packets between two phone lines with ADSL terminals on each. Which is the download direction? This could be a problem ... perhaps it can be switched as a half-duplex system :D

22-11-2002, 06:25 PM
Yes, it is effectively a VPN product, using ADSL, but not providing internet access. Just point to point. Nothing clever, just secure and quick.

Graham L
22-11-2002, 06:38 PM
I guess that if it provides a "transparent" link like a leased line, the remote one can be on the same network. Presumably an IP address for the remote would be assigned by the home end of the VPN system (because VPNs work by hiding the actual network configuration ;-) ) so there shouldn't be any problem.

Of course ... life is never easy in networking. :D