Network Working Group W. Simpson
Request for Comments: 1333 Daydreamer
May 1992
PPP Link Quality Monitoring
Status of this Memo
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.
Abstract
The Point-to-Point Protocol (PPP) [1] provides a standard method of
encapsulating Network Layer protocol information over point-to-point
links. PPP also defines an extensible Link Control Protocol, which
allows negotiation of a Quality Protocol for continuous monitoring of
the viability of the link.
This document defines a protocol for generating Link-Quality-Reports.
This RFC is a product of the Point-to-Point Protocol Working Group of
the Internet Engineering Task Force (IETF). Comments on this memo
should be submitted to the ietf-ppp@ucdavis.edu mailing list.
Simpson [Page i]
RFC 1333 PPP Link Quality Monitoring May 1992
Table of Contents
1. Introduction .......................................... 1
2. Link Quality Monitoring ............................... 2
2.1 Design Motivation ............................... 2
2.2 Counters ........................................ 2
2.3 Counting Packets and Octets ..................... 4
2.4 Processes ....................................... 4
2.5 Configuration Option Format ..................... 6
2.6 Packet Format ................................... 8
2.7 Transmission of Reports ......................... 12
2.8 Calculations .................................... 12
2.9 Failure Detection ............................... 13
2.10 Policy Suggestions .............................. 14
SECURITY CONSIDERATIONS ...................................... 14
REFERENCES ................................................... 14
ACKNOWLEDGEMENTS ............................................. 14
CHAIR'S ADDRESS .............................................. 15
AUTHOR'S ADDRESS ............................................. 15
Simpson [Page ii]
RFC 1333 PPP Link Quality Monitoring May 1992
1. Introduction
PPP has three main components:
1. A method for encapsulating datagrams over serial links.
2. A Link Control Protocol (LCP) for establishing, configuring,
and testing the data-link connection.
3. A family of Network Control Protocols (NCPs) for establishing
and configuring different network-layer protocols.
In order to establish communications over a point-to-point link, each
end of the PPP link must first send LCP packets to configure the data
link during the Establishment phase. During the Authentication and
Network-Layer Protocol phases, the link may be tested to determine if
quality is sufficient for operation. This testing is completely
optional.
If an implementation desires that the peer use some specific link
quality monitoring protocol, then it MUST negotiate the use of that
protocol using the Quality-Protocol Configuration Option during Link
Establishment phase.
The negotiation mechanism is independent in each direction. However,
if the peer agrees to send Quality-Protocol packets, it MUST
correctly process such packets on reception, even if it does not
request such packets or implement a monitoring policy.
Simpson [Page 1]RFC 1333 PPP Link Quality Monitoring May 19922. Link Quality Monitoring
Data communications links are rarely perfect. Packets can be dropped
or corrupted for various reasons (line noise, equipment failure,
buffer overruns, etc.). Sometimes, it is desirable to determine
when, and how often, the link is dropping data. Routers, for
example, may want to temporarily allow another route to take
precedence. An implementation may also have the option of
disconnecting and switching to an alternate link. The process of
determining data loss is called "Link Quality Monitoring".
2.1. Design Motivation
datatracker.ietf.org