Browse Prior Art Database

Isochronous Transmission on Top of Token Ring LAN

IP.com Disclosure Number: IPCOM000105483D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 6 page(s) / 230K

Publishing Venue

IBM

Related People

Ruiz, A: AUTHOR [+2]

Abstract

The IBM TOKEN RING protocol does not support ISOCHRONOUS traffic. This is because in it's standard utilization, stations cannot be provided with the guaranteed bandwidth and fixed time delay required for isochronous transmission. It is recognized that LAN transmission of real-time isochronous traffic is a requirement of developing multimedia utilizations. Competitive LAN technologies such as ETHERNET and FDDI have plans and methodologies for isochronous implementations, (i.e. Iso-Ethernet and FDDI-II). In order for TOKEN RING to stay in the forefront of the LAN arena, a means is required to provide real-time isochronous transmission which makes use of in-place TOKEN RING equipment and enables isochronous communication between stations that are so equipped.

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This is the abbreviated version, containing approximately 24% of the total text.

Isochronous Transmission on Top of Token Ring LAN

      The IBM TOKEN RING protocol does not support ISOCHRONOUS
traffic.  This is because in it's standard utilization, stations
cannot be provided with the guaranteed bandwidth and fixed time delay
required for isochronous transmission.  It is recognized that LAN
transmission of real-time isochronous traffic is a requirement of
developing multimedia utilizations.  Competitive LAN technologies
such as ETHERNET and FDDI have plans and methodologies for
isochronous implementations, (i.e. Iso-Ethernet and FDDI-II).  In
order for TOKEN RING to stay in the forefront of the LAN arena, a
means is required to provide real-time isochronous transmission which
makes use of in-place TOKEN RING equipment and enables isochronous
communication between stations that are so equipped.  These stations
need to have connectivity to the non-isochronous capable stations of
existing TR networks.

      The connectivity to the TR system is best achieved when
accomplished so that the new capability for isochronous traffic does
not diminish from the normal bandwidth of the standard
non-isochronous TR utilization.  This invention provides such a means
by enabling the use of bandwidth on top of that used by the standard
TR  network.  This capability is supported by the use of an
'Out-of-band ISOCHRONOUS MODULE' (OIM) at each MAU closet or station
grouping.  It enables the use of both (heretofore standard)
'Non-Isochronous-Stations' (NIS) and (newly defined) 'Out-of-band
Isochronous Stations' (OIS).  The operation of the OIM and OIS is
topology independent and functions as specified herein.  The
following is a listing of the mnemonics used in this disclosure:

   Mnemonic     Meaning                             Comment

    NRT    Non Real Time                        Non-isochronous
traffic.
    ORTI   Out-of-band Real Time Isochronous    Isochronous traffic.
    OIM    Out-of-band Isochronous Module       New module.
    NIS    Non-Isochronous-Stations             Old standard TR
stations
    OIS    Out-of-band Isochronous Stations     Newly defined
stations,
    MAU    Media Access Unit                    Old standard access
    IMAU   Isochronous MAU                      Newly defined MAU

      This invention provides a means to achieve isochronous
capability on an upgraded (modified-standard) Token Ring (TR)
installation without affecting the normal performance of the TR
stations and their useable bandwidths.  It enables the independent
usage of both standard non-isochronous stations (NIS) and newly
defined (to be developed) Out-of-band Isochronous Stations (OIS) in a
non-interfering manner.  It makes use of the cabling in-place to
allow both the standard non-real-time (NRT) token based operation and
a new Out-of-band Real Time Isochron...