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Point-to-Point Protocol extensions for bridging (RFC1220)

IP.com Disclosure Number: IPCOM000002034D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2000-Sep-12
Document File: 14 page(s) / 34K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

F. Baker: AUTHOR

Abstract

1. Status of this Memo

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 9% of the total text.

Network Working Group F. Baker, Editor

Request for Comments: 1220 ACC

April 1991

Point-to-Point Protocol Extensions for Bridging

1. Status of this Memo

This document defines an extension of the Internet Point-to-Point

Protocol (PPP) described in RFC 1171, targeting the use of Point-to-

Point lines for Remote Bridging. It is a product of the Point-to-

Point Protocol Extensions Working Group of the Internet Engineering

Task Force (IETF).

This RFC specifies an IAB standards track protocol for the Internet

community, and requests discussion and suggestions for improvements.

Please refer to the current edition of the "IAB Official Protocol

Standards" for the standardization state and status of this protocol.

Distribution of this memo is unlimited.

2. Historical Perspective

Two basic algorithms are ambient in the industry for Bridging of

Local Area Networks. The more common algorithm is called

"Transparent Bridging" and has been standardized for Extended LAN

configurations by IEEE 802.1. IEEE 802.5 has proposed an alternative

approach, called "Source Routing", and is in the process of

standardizing that approach for IEEE 802.5 extended networks.

Although there is a subcommittee of IEEE 802.1 addressing remote

bridging, neither standard directly defines Remote Bridging per se,

as that would technically be beyond the IEEE 802 committee's charter.

Both allow for it, however, modeling the line as an unspecified

interface between half-bridges.

This document assumes that the devices at either end of a serial link

- have agreed to utilize the RFC 1171 line discipline in some form.

- may have agreed, by some other means, to exchange other

protocols on the line interspersed with each other and with any

bridged PDUs.

- may be willing to use the link as a vehicle for Remote Bridging.

- may have multiple point-to-point links that are configured in

parallel to simulate a single line of higher speed or

reliability, but message sequence issues are solved by the

transmitting end.

3. General Considerations

3.1. Link Quality Monitoring

It is strongly recommended that Point-to-Point Bridge Protocol

implementations utilize Magic Number Loopback Detection and Link-

Quality-Monitoring. This is because the 802.1 Spanning Tree

protocol, which is integral to both Transparent Bridging and Source

Routing (as standardized), is unidirectional during normal operation,

with HELLO PDUs emanating from the Root System in the general

direction of the leaves, without any reverse traffic except in

response to network events.

3.2. Message Sequence

The multiple link case requires consideration of message

sequentiality. The transmitting station must determine either that

the protocol being bridged requires transmissions to ...