Browse Prior Art Database

Method of Measuring the Latency of a Token-Ring With Microcode

IP.com Disclosure Number: IPCOM000100430D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 1 page(s) / 46K

Publishing Venue

IBM

Related People

Geyer, JE: AUTHOR [+3]

Abstract

Disclosed is a method of measuring the ring length or latency of a token-ring through the use of certain calculations made by microcode in a token-ring adapter.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 61% of the total text.

Method of Measuring the Latency of a Token-Ring With Microcode

       Disclosed is a method of measuring the ring length or
latency of a token-ring through the use of certain calculations made
by microcode in a token-ring adapter.

      The latency of a token-ring is one of the factors affecting its
performance.  The latency of a token-ring, whose adapters do not use
early token release, is the time required for a token or frame to
circulate the ring returning to the point of origin.  The ring
latency is determined by the length of the ring and the number of
stations on the ring.

      The length of a ring can be expressed in bytes when the data
rate of the ring and the length of time required for a token to
circulate around the ring are known.  On this type of ring, there is
only one token or one frame circulating the ring at a time.  Hence, a
frame that is shorter than the length of the ring occupies the ring
for as long a time as a frame whose length is exactly equal to the
length of the ring.  Thus, to calculate the utilization of the
token-ring, one must count the total number of bytes in messages plus
the number of bytes in latency due to the transmission of frames
shorter than the ring divided by the possible number of bytes in the
measured time interval.

      In order to measure the ring length or latency, one measures
the time interval between the transmission of the end of frame and
the receipt of the end of the frame.  To do this, a mic...