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
