Browse Prior Art Database

PPP in HDLC Framing (RFC1549)

IP.com Disclosure Number: IPCOM000002381D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2019-Feb-13
Document File: 18 page(s) / 23K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

W. Simpson: AUTHOR

Related Documents

10.17487/RFC1549: DOI

Abstract

This document describes the use of HDLC for framing PPP encapsulated packets. [STANDARDS-TRACK]

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 9% of the total text.

Network Working Group W. Simpson, Editor Request for Comments: 1549 Daydreamer Category: Standards Track December 1993

PPP in HDLC Framing

Status of this Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Abstract

The Point-to-Point Protocol (PPP) [1] provides a standard method for transporting multi-protocol datagrams over point-to-point links.

This document describes the use of HDLC for framing PPP encapsulated packets. This document is the product of the Point-to-Point Protocol Working Group of the Internet Engineering Task Force (IETF). Comments should be submitted to the ietf-ppp@ucdavis.edu mailing list.

Table of Contents

1. Introduction ..................................................2 1.1 Specification of Requirements .................................2 1.2 Terminology ...................................................3 2. Physical Layer Requirements ...................................3 3. The Data Link Layer ...........................................4 3.1 Frame Format ..................................................5 3.2 Modification of the Basic Frame ...............................7 4. Asynchronous HDLC .............................................7 5. Bit-synchronous HDLC ..........................................5 6. Octet-synchronous HDLC ........................................12 APPENDIX A. Fast Frame Check Sequence (FCS) Implementation .........13 A.1 FCS Computation Method ........................................13 A.2 Fast FCS table generator ......................................15 SECURITY CONSIDERATIONS ............................................16 REFERENCES .........................................................17 ACKNOWLEDGEMENTS ...................................................17 CHAIR’S ADDRESS ....................................................18 EDITOR’S ADDRESS ...................................................18

Simpson [Page 1]

RFC 1549 HDLC Framing Decvember 1993

1. Introduction

This specification provides for framing over both bit-oriented and octet-oriented synchronous links, and asynchronous links with 8 bits of data and no parity. These links MUST be full-duplex, but MAY be either dedicated or circuit-switched. PPP uses HDLC as a basis for the framing.

An escape mechanism is specified to allow control data such as XON/XOFF to be transmitted transparently over the link, and to remove spurious control data which may be injected into the link by intervening hardware and software.

Some protocols expect error free transmission, and either provide error detection only on a conditional basis, or do not provide it at all. PPP uses the HDLC Frame Check Sequence for error detection. This is commonly available in hardwar...

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