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Some problems with the specification of the Military Standard Internet Protocol (RFC0963)

IP.com Disclosure Number: IPCOM000004959D
Original Publication Date: 1985-Nov-01
Included in the Prior Art Database: 2001-Jul-12
Document File: 20 page(s) / 44K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

D.P. Sidhu: AUTHOR

Abstract

This paper points out several significant problems in the specification of the Military Standard Internet Protocol (MIL-STD-1777, dated August 1983 [MILS83a]). These results are based on an initial investigation of this protocol standard. The problems are: (1) a failure to reassemble fragmented messages completely; (2) a missing state transition; (3) errors in testing for reassembly completion; (4) errors in computing fragment sizes; (5) minor errors in message reassembly; (6) incorrectly computed length for certain datagrams. This note also proposes solutions to these problems.

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Network Working Group Deepinder P. Sidhu Request for Comments: 963 Iowa State University

November 1985

SOME PROBLEMS WITH THE SPECIFICATION OF THE

MILITARY STANDARD INTERNET PROTOCOL

STATUS OF THIS MEMO

The purpose of this RFC is to provide helpful information on the Military Standard Internet Protocol (MIL-STD-1777) so that one can obtain a reliable implementation of this protocol standard. Distribution of this note is unlimited.

ABSTRACT

This paper points out several significant problems in the specification of the Military Standard Internet Protocol (MIL-STD-1777, dated August 1983 [MILS83a]). These results are based on an initial investigation of this protocol standard. The problems are: (1) a failure to reassemble fragmented messages completely; (2) a missing state transition; (3) errors in testing for reassembly completion; (4) errors in computing fragment sizes; (5) minor errors in message reassembly; (6) incorrectly computed length for certain datagrams. This note also proposes solutions to these problems.

1. Introduction

In recent years, much progress has been made in creating an integrated set of tools for developing reliable communication protocols. These tools provide assistance in the specification, verification, implementation and testing of protocols. Several protocols have been analyzed and developed using such tools. Examples of automated verification and implementation of several real world protocols are discussed in [BLUT82] [BLUT83] [SIDD83] [SIDD84].

We are currently working on the automatic implementation of the Military Standard Internet Protocol (IP). This analysis will be based on the published specification [MILS83a] of IP dated 12 August 1983.

While studying the MIL Standard IP specification, we have noticed numerous errors in the specification of this protocol. One consequence of these errors is that the protocol will never deliver fragmented incoming datagrams; if this error is corrected, such datagrams will be missing some data and their lengths will be incorrectly reported. In addition, outgoing datagrams that are divided into fragments will be missing some data. The proof of these statements follows from the specification of IP [MILS83a] as discussed below.

Sidhu [Page 1]

RFC 963 November 1985 Some Problems with MIL-STD IP

2. Internet Protocol

The Internet Protocol (IP) is a network layer protocol in the DoD protocol hierarchy which provides communication across interconnected packet-switched networks in an internetwork environment. IP provides a pure datagram service with no mechanism for reliability, flow control, sequencing, etc. Instead, these features are provided by a connection-oriented protocol, DoD Transmission Control Protocol (TCP) [MILS83b], which is implemented in the layer above IP. TCP is designed to operate successfully over channels that are inherently unreliable, i.e., ...