DHCP and Superscopes to assign different gateways (All for starcraft 2 great justice)

Hi everyone!  I am in a situation where I find my self helping provide network setups to LAN events.  Our last event went well, except that with Starcraft 2, WOW and other blizzard games, you can only have a certain amount of systems connected from one internet IP (I believe the number is 10 clients).  So because of this I am trying to figure out a way to assign out IP addresses so that the systems on the lan are able to intercommunicate locally, but have different internet gateways (usually at these events we are able to secure a block of public IP's).  This could take either a round robin approach, or a "once full move on to the next gateway" approach.  
In the example I will present, lets assume that we just have two gateways.
I will also assume that we only have 20 computers that we will have on the network, trying to split half of them between two gateways.
Our platform on this is likely to be windows server 2008, though that may be flexable.
In my own research it has been suggested to use a superscope.
This being said, here is the idea that I had, but have questions on:
Set up a super scope and in side that we will create a scope that uses with a subnet mask of (Half the Class C subnet)  We will give it a gateway of
We then set up a second scope which will use again with subnet mask of, and this time with a gateway of
Looking at this, each of those subnets would be just fine on their own.  I'm curious if the two subnet's can talk to each other.  So far I have done a few tests in my office and that does seem to be the case, but it ran into a couple quirks: one computer could be pinged, another couldn't (across subnets).
Will this work if implemented?  Is there an easier way?  Is there a better way?  
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There is a better way. If all you are looking at doing is giving a different public address for groups of machines on a private network then just use a router that is capable of this. I'm thinking Cisco here, even the basic 800 should do it.

The way the address masking is done means you work with groups of 2, 4, 8, 16 etc. machines, so since you don't want more than 10 going out the one address then it will have to be 8. You've mentioned 20 computers so you'll need at least 3 public IP addresses which will let you go up to a total of 24 machines.

All machines are on the same network so there shouldn't be any issues with them talking to each other and the router only needs to handle the traffic going outside.
As an example using, gateway is and the DHCP scope gives out addresses -

Configure NAT pools of 1 address for each public address
Configure an access list for each network group; .8-.15, .16-.23, .24-.31
Configure dynamic NAT rules, inside to outside, so that if List 1 use Pool 1, if List 2 use Pool 2 etc.

An example using 2 pool ranges,  different inside network ranges is here:

Miguel Angel Perez MuñozCommented:
I think that subnetting on this way, computers on first subnet couldn´t communicate with seconds. If computer number is little, you can assign IP static and change manually default gateway. Other way may be has 2 DHCP (one per scope) and other router with 2 interfaces (one per subnet). This router may be used to interconnect 2 subnets only, and the default gateway is used to access to internet.
You need to put a route to the other subnet on the gateway device.
What hardware do you have available ?
Easiest would be to have 2 VLANS (with your subnets.  Wich will work the same as you said.
Then you need a device that has an IP in both vlans so they can speak. (a router).
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GeekboxAuthor Commented:
After consulting with a friend, I am now trying to wrap my head around the idea have having a router link the two subnets.  My question is this:  In having a router that is between the two networks, does this need to be the gateway for my computers?  Or will I still have two gateways and then another router linking the two subnets?
Also, for this discussion, my hardware is unlimited... I mean to say this is a concept question and will dictate the hardware used in the future.
3rd router doesnt need to be gateway.
Maybe if you tell your budget we can suggest à config
You will need a router with two ethernet ports, and a switch(es) that can do VLANS.  The connection between the router and the switch needs to be an 802.1q trunk port that has the corresponding VLANs that you will also program on your switches (access port vlans).  Now, you will then need to either program the router to act as a DHCP relay for your Windows Server that is running the Superscope (easy way), or get another Windows server to act as the DHCP relay (harder way).  Note that on your router you must specify the ip gateway that your computer clients will use.  Your Superscope will then route out to the public ip address that you have assigned to that scope.  The key thing here are the VLANs and DHCP relay must exist in order for this to work.
There is a simple way to do this.  Most of what you are thinking about won't work so you need to stop wondering off the path even further.

1. Have multiple Internet connections.  You should already have that or you wouldn't be asking this question.  Without multiple Internet connections you are already dead-in-the-water before you even start.

2. Buy several cheap "home-user" retail routers (which are really NAT Firewalls if anyone cares to call them what they really are).  Connect each one to a different internet connection on the WAN side.   Then on the LAN side put all of them on the same physical LAN.

3. Configure the DHCP on each box to use addresses from the same IP Segment except limit the Range of each one so that they each are unique from each other.  You will want to limit the range also to the number of address that match the maximum number Hosts that can come from the same IP# on these game servers.  Where you will get screwed here is if the NAT boxes only let you set the beginning address or the range but won't let you configure the ending address in the range.  Good quality equipment will let you do that,...cheap crappy equipment will only let you set the starting address.

Now as the scope of one fills up the additional Hosts will join to one of the other NAT Boxes and they will naturally spread around across the multiple NAT boxes as the range fills up on each one.

If you have a regular DHCP Server on the LAN you could do that with a Superscope as long as you turned off DHCP on the NAT boxes and if each Child Scope gave out a different Range of addresses with different Gateways,...yet all the same IP Segment.

The only thing that may get in the way here is that all the Child Scopes will be the same subnet,...hence an overlapping subnet,...i don't mean overlapping address ranges,...I mean overlapping subnets which is defined by the mask.  I'm just not sure if the DHCP Service will allow it,...this is not normal, this is not something that "everybody does",...so I am unsure,,...and no,...you can't change the mask because all the Hosts need to be on the same IP Segment together as defined by the Mask.
On my last comment,...you could change the Mask or even use entirely different IP Segments on the LAN side of each NAT box as long as you understand that the Hosts from different IP Segment swill not be able to directly talk to Hosts on the same LAN but in different segments.  As long as all they are there simply to play games over the Internet that may not be any real hinderence.   The problem comes in when you want them to all be one big happy family together on the LAN at the same time.
It all depends on budget and throughput needed.
If this is a LAN Party with a bunch of people gathering somewhere to play games,..then I doubt there is much of a budget involved.
Let's make this even simpler.  You don't even need to worry about a LAN at all.  Probably everyone of these guesting coming to this event have broadband NAT Box at their house,..they just bring their own box,...adds new meaning to "Party!!!  BYOB" (bring your own box instead of bring your own beer).

Hook one box up to each internet connection.  Have the guests divide up evenly and attach to one of the boxes (a couple cheap switches can help add more ports).  Each group on one individual NAT Box would be their own LAN among themselves and that is good enough for what you are wanting to do.
GeekboxAuthor Commented:
Our budget is pretty open at this point.  It's not some shoestring event.  The last show brought in about 150 people with thier machines, however the show its self brought in something like 20,000 people.
I work for a sponser of the event and we ended up doing a bunch of the networking for the BYOC lan.
The next show is this October.

Here is a link for interested parties: http://www.geexshow.com
I'm going to accept Frabbles response for now and go from there.  Thanks for the thoughts and input.  I'll post about how it all works out.
GeekboxAuthor Commented:
I'm exploring purchasing a router such as this.  Will post back once I know what is up.
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