How can computers on seperate subnets communicate with one another?

[emriederek]

Hello,
I have two groups of students I wish to seperate by subnetting. Students are nine in each group, and there's one Cisco router (or W-server set as a router). After giving group A an IP of 192.168.200.1, and group B an IP of 192.168.200.129 and connecting each interface to it's own seperate switch, what else does each PC user need to do to establish communication with members not in his/her own subgroup?

 

[eibgrad]

Those IPs appear to be using the same subnet (192.168.200.x). What I assume you really mean is 192.168.200.x and maybe 192.168.201.x. Now you have two subnets (assuming each is using a subnet mask of 255.255.255.0).

Assuming each subnet is using its own switch, and each switch is in turn connected to LAN porst on the same router, you don’t need to do anything!

[switch #1 (subnet 192.168.200.x)](lan)<-- wire -->(lan)[router](lan)<-- wire -->(lan)[switch #2 (subnet 192.168.201.x)]

The mere fact you have a common router accessible by both subnets, automatically makes the two subnets visible. That’s what a router does. It locates your subnets and routes between them. The fact both subnets are using the same LAN doesn’t change that equation.

What *would* create a problem is if both subnets were merely using the same switch, or each had its own switch and those switches were chained together, LAN to LAN. IOW, no router.

[switch #1 (subnet 192.168.200.x)](lan)<-- wire -->(lan)[switch #2 (subnet 192.168.201.x)]

Now each subnet is invisible to the other because there’s no router (actually, no default gateway) which can resolve how to find the other subnet.