Hello everybody. I'm pretty new on this forum. I write because of a problem that got me stuck since many days. Hope to explain it properly. I got to give Internet access to several offices within a building. Every office’s got its own network, but all of them share the Internet connection. And this is what I want: these networks to be transparent to each other while sharing the Internet. The building's Internet access is via a router DLink 504T. Firstly I tried separating any office in a virtual way, so I assigned a subnet to every office. But this doesn’t work because the router only accept one subnet for the LAN, so I have to assign the same subnet to all of them and so the offices can have open access to each other's network. Bad idea. Maybe the solution could be having an Ethernet router for any office? In this case, I'd need my Internet router to have many ethernet interfaces, wouldn't I?. Could anybody please tell me what kind of architecture is the more suitable to my problem? Many thanks in advance. Rafael Spain

"The building's Internet access is via a router DLink 504T." That router is probably inadequate for this type of environment. Time to step up to business class stuff! "Firstly I tried separating any office in a virtual way, so I assigned a subnet to every office. But this doesn’t work because the router only accept one subnet for the LAN, so I have to assign the same subnet to all of them and so the offices can have open access to each other's network." How big is this environment? Do you have a legitimate reason to subnet each office? I'm gonna take a guess you have no experience with core infrastructure for anything other than SOHO. If that's the case, and this environment is as big as it sounds, I suggest you hire someone who knows this stuff to design it and setup it up correctly. Please help survivors of Hurricane Katrina! www.redcross.org

You can't accomplish what you want with what you have. Buy a managed switch that supports VLANS. They are easy to setup. You set every office in its own division of the ip subnet. All have the same gateway. It would look like this; router<->switch<-> all offices Office A 192.168.0.1 gateway 192.168.0.2-19 (18 addresses) Office B 192.168.0.1 gateway 192.168.0.20-39(20 addresses) etc.... Trick here is you would configure the ports each office have in common to a common vlan. Office A would be VLAN1 Office B would be VLAN2 Office X etc.... The port the router is connected to would have ALL VLANS assocated with it. This is important to note. Some switches only support up to 8 vlans. You may need more so you want a switch that supports the amount you want [plus extra just in case] This physically isolates each Office from the other but give them internet access. Best of luck. Give a person a fish, they eat for a day. Suggest they internet search and they learn a skill for a lifetime.

Thank you very much for the answer. Wanderer, I believe your solution is the best for my problem. Thanks a lot!!! Best wishes.