Multiple networks, simple configuration?

Without a network administration background, I am having a little trouble figuring out the most reliable method to reconfigure the following network. I recently inherited this network, I would have done things differently.

Network 1
- DSL Gateway with NAT to Router/Firewall (72.xxx.xxx.xxx external, 192.168.1.254 interal)
- Linksys RV0041 Router Firewall to server and 1 client (192.168.1.254 WAN interface, 192.168.10.1 on LAN interface)
- Dell Server with Dual NIC (192.168.10.10 NIC 1, 10.10.1.1 NIC 2) - Network interfaces are not bridged, no NAT. Purpose is to isolate clients on 10.10.1.xxx from the internet, but allow for incoming connections via RDP from the server.
- 8x client computers on 10.10.1.11 with no internet access

Network 2
- DSL Gateway with NAT running to a switch
- All clients have internet access


I am going to recommend moving to a bonded cable model connection or doing a load balancing scheme between two connections. One idea I have is to run the WAN connections to the server (utilizing both NICs), install a third NIC for the local network and figuring out how to use ISA for NAT to block the client computers from the internet on Network 1 and allow the clients from Network 2. Without any prior experience with ISA... I am concerned about the difficulty and feasibility of that setup. Another solution I am thinking about involves the use of a router with multiple networks. However, I dont' know how to configure everything to meet the above criteria... I don't even know where to start when it comes to finding the right router to run multiple networks, allow access to the WAN for some of the clients, block WAN access to others, and make sure all can see the file server. Any ideas? There are only 20 clients at this particular location, including the file server.

Why is Network 1 double NATed? The DSL modem should be running in "Bridged" mode. Have you given thought to implementing a domain? Is network 2 at the same physical location? If so, why is it isolated? You shouldn't even consider using your server for firewall duties in addition to its current role. (Which is...) Whats your total budget for an overhaul?

I inherited this network, something that I would have done differently. The double NAT seems to be causing some problems. Implementing a domain is beyond the scope of this project... it needs to be self-contained and easy to administer. I was asked to make a setup recommendation and pass the information along to get completed. Network 2 is in the same physical location... but rather than bonding the two lines or doing a load balancing scheme, two separate networks were created. At that time network 2 did not need access to the server on network 1. It should never have been isolated... not making the best out of the total bandwidth available. The server is just a file server and gateway to the network that is not bridged through the server. I have not set a budget yet... the one guideline I was given is administrative simplicity. Any suggestions on how you would configure this network within the guidelines?

I would install a L3 Cisco switch. Setup both networks on their own VLANs, throw the server on its own VLAN. Setup VLAN Maps to drop traffic from the no internets vlan whenever it tries to hit internets or the other network and allow traffic to the server.

That seems simple enough, can I use a GUI to accomplish this? Furthermore just a general question about VLAN. Traffic on the same subnet split into different VLANs divides the broadcast domain, correct? Do you have to route between the subnets? What are the main advantages of going with a VLAN over subnetting?

for most purposes, a vlan is equivalent to a subnet. that is to say, most of the time you assign a single subnet to a single vlan. vlan is really the layer 2 switching for a subnet (layer 3).

you would put different subnets on different VLANs. I am thinking you would have a hard time configuring the same network on different VLANs and then getting them to talk to each other.

The GUI will not allow you to setup the VLAN map to drop traffic between the VLANs. Yes, you will need to setup routing between the VLANs if you wish any traffic to flow between them.

I agree with berky's explaination of the vlan/subnet thing. The only time you would have multiple subnets on the same VLAN IDs is when you are routing to the closet in large enterprise networks.