Gregory K. Ruiz-Ade wrote:
The whole point of CIDR (Classless Internet Domain Routing, i think) is to be able to divvy out portions of network space smaller than a Class C.
CIDR was created to get rid of the "classful" terminology of Class A, Class B, and Class C numbering spaces. If you recall, A/B/C address ranges all had specific areas into which they were allowed, e.g. even an address in 9.2.4.0/24 was still a Class A address, even though it's a 24 bit network (9.0.0.0/8, incedentally, is owned by IBM). Likewise, 192.168.1.1/24 is still a Class B address, because the 192.168 prefix is in Class B space. Fortunately, with the advent of CIDR, we don't have to worry about the classful declarations anymore; we merely (mistakenly) refer to /16s as "Class B", /24s as "Class C", and /8s as "Class A" -- in today's IP space, these terms are meaningless.
VLSM (variable-length subnet masking), on the other hand, *was* created to make arbitrary-length network segments possible. However, it would be rather useless if CIDR weren't around.
-Kelsey -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
