On the assignment of subnet numbers
Paul F. Tsuchiya · 1991
Of This MemoThis memo suggests a new procedure for assigning subnet numbers.Use of this assignment technique within a network would be a purely local matter, and would not effect other networks.Therefore, the use of these procedures is entirely discretionary.This memo provides information for the Internet community.It does not specify an Internet standard.Distribution of this memo is unlimited.Overview RFC-950 [2] specifies a procedure for subnetting Internet addresses using a bit-mask.While RFC-950 allows the "ones" in the subnet mask to be non-contiguous, RFC-950 recommends that 1) they be contiguous, and 2) that they occupy the most significant bits of the "host" part of the internet address. On the Assignment of Subnet NumbersApril 1991 in new subnet masks, no host ever need change addresses.This technique is not new, but it is also not widely known, and even less widely implemented.With the development of new routing protocols such as OSPF, it is possible to take full advantage of this technique.The purpose of this memo, then, is to make this technique widely known, and to specify it exactly.This memo requires no changes to existing Internet standards.It does, however, require that the intra-domain routing protocol handle multiple different subnet masks.