In article , Tim Watts
scribeth thus
On Thursday 01 August 2013 22:34 Roger Mills wrote in uk.d-i-y:

On 01/08/2013 20:55, David.WE.Roberts wrote:


I assume you know that a physical LAN (set of wires) can support several
logical LANs (IP subnets).

So for example one physical Ethernet network could support 192.168.0.0,
192.168.1.0, 192.168.2.0.

As long as the router can support multiple logical LANs then there is no
requirement for all your local devices to share the same subnet.


I'm not aware that ordinary domestic routers *can* support multiple
logical LANs, hence my reference to mucking about with subnet masks.

A half decent one can - eg some of the Drayteks.

Yes they do .. as long as you can work out how to configure them..

Good units otherwise, bit pricey 'tho...


In the example you give, if you use the 'default' subnet mask of
255.255.255.0, all devices on the 168.0 subnet can see each other but
can't see anything on the 168.1 or 168.2 subnets.

However, if you were to change the mask to 255.255.252.0 the 3 subnets
would merge into one, and everything would be able to see everything.
But in that case, you'd no longer achieve the desired isolation!

--
Tony Sayer