On 19/12/2018 16:24, Naslund, Steve wrote:
It has ALWAYS been the only correct way to configure equipment and is a requirement under CIDR. Here were your commonly used netmasks before CIDR/VLSM :
255.0.0.0 255.255.0.0 255.255.255.0
Which one is not contiguous?
There is an example in RFC950 on page 15. 3. A Class C Network Case (illustrating non-contiguous subnet bits) For this case, assume that the requesting host is on class C network 192.1.127.0, has address 192.1.127.19, that there is a gateway at 192.1.127.50, and that on network an 3-bit subnet field is in use (01011000), that is, the address mask is 255.255.255.88. Admittedly, page 6 contains: Since the bits that identify the subnet are specified by a bitmask, they need not be adjacent in the address. However, we recommend that the subnet bits be contiguous and located as the most significant bits of the local address. I have never seen noncontiguous network masks used in real life, but I may not be old enough. -- Adam Atkinson