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Error Detection/Fault Isolation for a Fiber-Optic Communication Link Using Parity

IP.com Disclosure Number: IPCOM000120506D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 97K

Publishing Venue

IBM

Related People

Ferraiolo, FD: AUTHOR [+2]

Abstract

This article describes a technique for real-time error detection/fault isolation in a fiber-optic communication link using parity.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Error Detection/Fault Isolation for a Fiber-Optic Communication Link
Using Parity

      This article describes a technique for real-time error
detection/fault isolation in a fiber-optic communication link using
parity.

      High speed fiber-optic communication links offer excellent
performance and flexibility for computer interconnections.
Fiber-optic data links can transfer several hundred megabits of data
per second over distances of several miles.  Although this adds new
dimensions to the way a computer system can be configured, it also
creates new problems in the servicing of the subsystems.  Subsystems
which were once located several hundred feet from one another can now
be located several miles apart.  In an effort to provide good service
to the customer, the time and cost of repair action should be held to
a minimum.  As fiber optics extend the distance between computers and
computer subsystems the time and cost of a service call can
significantly increase if the representative cannot be properly
directed to the end of the link in need of repair. Therefore, it is
very important to accurately diagnose and isolate a failure.  One
commonly used method of providing diagnostic information is to check
data integrity at strategic locations in the system.  Real-time
checking of the data integrity provides diagnostic information for
both soft and hard errors.  Confirming data integrity after the
signal has been launched into the fiber cable provides the most
complete diagnostic information, but it is very costly and complex to
carry out.

      This article describes a simple, low-cost method to detect and
isolate errors to either the sending side or receiving side of a
fiber-optic link.  Although this technique does not provide as much
diagnostic information as performing a check on the optical signal in
the fiber, it is much simpler, far less costly to implement, and
detects a significant percentage of both hard and soft errors.

      The technique described here is to generate parity from the
serial data signal on a per byte basis to provide diagnostic
information.  Parity is generated in real time just prior to
transmission or just after receiving data. The serial data signal may
be derived in an indirect way to gain greater diagnostic coverage.
As a...