enter image description here hi guys, so when my lecturer was explaining the process to do vlsm, they mentioned that for every cable linking to a device, you are suppose to add 2. eg(200,100,50,2*number of cable). but from what i have seen it seems as though you are only meant to add the 2 for routers eg(200,100,50,2,2,2).

i guess i am just wondering what the rule is in regards to VLSM and network devices?

again thanks for taking the time to read this! and thanks for all the help so far!

  • 2
    There really isn't a "rule" other than to make sure your subnets are big enough to support all the hosts (including the router interface(s).
    – Ron Trunk
    May 10 '18 at 12:28

(Actually had to look up VLSM, CIDR is probably a more common term for the real world...)

I don't think you've got that right.

You can use any available IP address from the subnet for any device. It makes sense to have a common scheme, so you don't mix up things and simply "know" how your network is laid out.

Additionally, IP addresses aren't assigned to links, they are assigned to interfaces - this is not always the same.

Think of a layer-3 switch with half of its ports assigned to one subnet (VLAN) and the other half to the another. It requires two IP addresses that are assigned to its two VLAN interfaces. Also, many routers support switched port groups which are much the same as VLAN interfaces.

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