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Old July 17th 17, 11:41 AM posted to uk.telecom.broadband,uk.comp.homebuilt
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Default How many subnets in a typical McDonalds?

In uk.telecom.broadband Adrian Caspersz wrote:
Nope, that was a badly put example.

Mcdonalds would be giving each user a publicly allocated IP address. No
NAT and hence 32-bit mask.

I very much doubt they've giving public IPv4s - there aren't enough to go
around. The only time I recall being given a public IPv4 for wifi is at a
company that has a class A (16 million addresses). (Globally-addressed
IPv6s are easy)

However, this is entirely orthogonal to the setup - you can do exactly the
same setup with a public class A as with - just in the latter
case somewhere down the road needs to be a NAT if you want internet access.

On the same SSID, I think you can configure the layer 2 switch to block
inter-station communication, ie everything is point to point with the access
point. Then you configure (DHCP) each client in layer 3 with a /32, telling
it its default route is to some other IP (which can't be on the same subnet
because a /32 contains one address). That means all traffic will be sent to
that IP, which can either NAT the packet if it's for the internet, or drop
it if it's for some other client.

I've never tried this, but I think it then avoids the problem of having a
ginormous routing table of tiny subnets.