I think I see what you are doing, and it is an easy mistake to make. You started from the assumption (which is correct) that a /27 contains 32 addresses and that a /26 contains 64 addresses. So you started laying out /27 subnets every 32 addresses, and after 3 subnets you switched to /26 with 64 addresses. And you made all the subnets adjacent, which seems efficient.
This is a very logical approach but it has a flaw. Subnetting works on bit boundaries. The best way to understand where a subnet starts is to lay out the address in binary, lay out the mask in binary, where the mask in binary has zero put a zero into the address (if the address in that position had a 1 change it to 0). Then take the resulting address from binary back to decimal. This gives the real beginning of the subnet. So here is how it works:
01100000 is the 96 address in binary
11000000 is the /26 mask in binary
01000000 is the resulting address and in decimal that is 64. So your subnet for VLAN 40 does not really start at 96 but starts at 64 and so does overlap the VLAN 30.
As a note: if you had started your process by laying out the larger subnets and then going to the smaller subnets you would not have had this problem.
We are pleased to announce availability of Beta software for 16.6.3.
16.6.3 will be the second rebuild on the 16.6 release train targeted
towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are
looking for early feedback from customers befor...
Introduction Featured Speakers Luis Espejel is the Telecommunications
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