VLAN with PAT and 3 networks...I need help with design!

Question

I've been tasked with a major upgrade to my current network and internet access. 
1.     I need to have an internal private network with access to the internet.  This will be for large meetings, and I'll use a private network with 2048 addresses.
2.     I also will have a small publid network with 8 routable addresses for Firewall, Web Server, PAT (NAT overload) for the above Private network internet access.
3.     I want to split a class C address into two networks to allow one network (128 addresses) for Guest use that need routable addresses, and a second network (the other 128 addresses) for specific meetings that also need routable addresses.
I have:
I have been issued a router from my ISP.  They have allocated me one .248 network with 8 addresses (6 usable) and a full class C network.
A Cisco 1841 router with 2 FA ethernet ports.  I would like to use one FA port at the outside (to my ISP router) and the other FA port as my Inside port (to all other networks).  I will do NAT Overload.
I also have a Layer 3 Catylist 3750 switch.
Do I need to set up VLANs for each Network?
Can I place my network hardware on the 10 network?
Do I need router sub interfaces for my VLANs and can I PAT on a Subinterface?

Answer 1

Hi Brian
1. Do I need to set up VLANs for each Network?
Create seperate VLANS for each subnet and do the intervlan routing on 3750
2. Can I place my network hardware on the 10 network?
Yes
3. Do I need router sub interfaces for my VLANs and can I PAT on a Subinterface?
Not required. You can do the intervlan routing on your Layer 3 3750 switch. From 3750 you can point a default-route to the router.
On the router you can perform PAT based on an ACL. Also you need to add Static NAT for your Webserver etc
Thank you
Raju