Replaces every user-visible use of 'VLSM' / 'Variable-Length Subnet
Masking' with plain descriptions of what the allocator is doing.
Everything already lives under CIDR; the separate VLSM label was an
extra name for the same mechanism and not helpful.
Retitles the post to 'what the slash actually means'.
Expands the reserved-ranges section with proper authority links:
IANA itself, the IPv4 Special-Purpose registry, the multicast registry,
RFCs for NAT, loopback, DHCP, OSPF, PIM, limited broadcast, CGN, and
whois, plus a pointer to the five regional internet registries.
Graham McIntire
632cb96cd6