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Variable Length Subnet Table For IPv4 (RFC1878)

IP.com Disclosure Number: IPCOM000004134D
Original Publication Date: 1995-Dec-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 7 page(s) / 18K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

T. Pummill: AUTHOR [+2]

Abstract

This memo clarifies issues surrounding subnetting IP networks by providing a standard subnet table. This table includes subnetting for Class A, B, and C networks, as well as Network IDs, host ranges and IP broadcast addresses with emphasis on Class C subnets.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 16% of the total text.

Network Working Group T. Pummill

Request for Comments: 1878 Alantec

Obsoletes: 1860 B. Manning

Category: Informational ISI

December 1995

Variable Length Subnet Table For IPv4

Status of this Memo

This memo provides information for the Internet community. This memo

does not specify an Internet standard of any kind. Distribution of

this memo is unlimited.

Abstract

This memo clarifies issues surrounding subnetting IP networks by

providing a standard subnet table. This table includes subnetting

for Class A, B, and C networks, as well as Network IDs, host ranges

and IP broadcast addresses with emphasis on Class C subnets.

This memo is intended as an informational companion to Subneting RFC

[1] and the Hosts Requirements RFC [2].

Introduction

The growth of networking since the time of STD 5, RFC 950 and STD 3,

RFC 1123 has resulted in larger and more complex network subnetting.

The previously mentioned RFCs comprise the available guidelines for

creating subnetted networks, however they have occassionaly been

misinterpreted leading to confusion regarding proper subnetting.

This document itemizes the potential values for IPv4 subnets.

Additional information is provided for Hex and Decmial values,

classfull equivalants, and number of addresses available within the

indicated block.

Table

The following table lists the variable length subnets from 1 to 32,

the CIDR [3] representation form (/xx) and the Decmial equivalents.

(M = Million, K=Thousand, A,B,C= traditional class values)

Mask value: # of

Hex CIDR Decimal addresses Classfull

80.00.00.00 /1 128.0.0.0 2048 M 128 A

C0.00.00.00 /2 192.0.0.0 1024 M 64 A

E0.00.00.00 /3 224.0.0.0 512 M 32 A

F0.00.00.00 /4 240.0.0.0 256 M 16 A

F8.00.00.00 /5 248.0.0.0 128 M 8 A

FC.00.00.00 /6 252.0.0.0 64 M 4 A

FE.00.00.00 /7 254.0.0.0 32 M 2 A

FF.00.00.00 /8 255.0.0.0 16 M 1 A

FF.80.00.00 /9 255.128.0.0 8 M 128 B

FF.C0.00.00 /10 255.192.0.0 4 M 64 B

FF.E0.00.00 /11 255.224.0.0 2 M 32 B

FF.F0.00.00 /12 255.240.0.0 1024 K 16 B

FF.F8.00.00 /13 255.248.0.0 512 K 8 B

FF.FC.00.00 /14 255.252.0.0 256 K 4 B

FF.FE.00.00 /15 255.254.0.0 128 K 2 B

FF.FF.00.00 /16 255.255.0.0 64 K 1 B

FF.FF.80.00 /17 255.255.128.0 32 K 128 C

FF.FF.C0.00 /18 255.255.192.0 16 K 64 C

FF.FF.E0.00 /19 255.255.224.0 8 K ...