Will this work? cable modem>switch>2 firewalls>2 separate physically wired networks

[buzzard1971]

We are subleasing an office and need to have a separate network with the same cable modem.

1) Will this work?
2) Will the networks remain separate? ie. not be able see each others networks?
3) Is the unmanaged switch a security risk or it does not matter because it is behind the firewall?

below is the layout

cable modem > unmanaged switch > 2 separate firewalls (with separate IP address's) > 2 separate physically wired networks

 

[boosted1g]

Unless you have two designated static IPs from your ISP this will not work as a normal cable modem will only provide one IP so it would give connectivity to the first firewall that connected to it.

What firewalls are you using and what is supposed to provide dhcp addresses to the rest of the computers?

Also what scale of a business is this for, this can easily be accomplished with a decent router and a couple switches, and the switches are even optional if you only need to hook up a couple of computers.

 

[buzzard1971]

Unless you have two designated static IPs from your ISP this will not work as a normal cable modem will only provide one IP so it would give connectivity to the first firewall that connected to it.

What firewalls are you using and what is supposed to provide dhcp addresses to the rest of the computers?

Also what scale of a business is this for, this can easily be accomplished with a decent router and a couple switches, and the switches are even optional if you only need to hook up a couple of computers.

We have a block of 10 static IP addresses, and 6 are not currently in use.

As for the firewalls one is a Watchguard and the other will be a Sonicwall. We need to use the two firewalls for compliance issues, so I don't think we can do it without them.

 

[boosted1g]

If the firewalls provide you with dhcp for the clients pcs (or if you have a dhcp server on both network) and set the firewalls to each use a different static wan ip then this setup would work just fine.

So to answer your questions:
1) yes - if conditions listed above are correct
2) yes - if the subnet on each network is configured differently (example is 192.168.10.0 and 192.168.11.0 networks with a 255.255.255.0 subnet)
3)unmanaged switch is not behind the firewall it is infront of the firewall, this is not an issue though as long as you prevent users from directly plugging anything else into the unmanaged switch.

One a side note, i dont know the exact verbage of your complience requirements, but this could be done with one firewall and a managed switch and you would configure the switch to have seperate vlans.

 

[boosted1g]

Also, most cable modems capabile of handling multple IPs have a switch built into them so you may not even need the unmanaged switch.