Browse Prior Art Database

Redundant Media Control Unit for an 802.4 Token Bus

IP.com Disclosure Number: IPCOM000114045D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Liang, D: AUTHOR [+2]

Abstract

This article describes a Redundant Media Control Unit (RMCU) chip which connects one of two Physical (PHY) entities to one Media Access Control (MAC) entity. Fig. 1 shows a conceptual block diagram for the interconnection. Fig. 2 shows an implementation fabricated in a chip for the RMCU. The block diagram includes four main interfaces; namely, MAC Interface, PHY A Interface, PHY B Interface, and Node Processor Interface. The MUX provides both multiplexer/de-multiplexer functions for the various signals which are transmitted between the entities. The RMCU transparently connects the MAC interface to one of two Physical Interfaces via multiplexor logic. The MAC operation is independent of PHY layer selection.

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Redundant Media Control Unit for an 802.4 Token Bus

      This article describes a Redundant Media Control Unit (RMCU)
chip which connects one of two Physical (PHY) entities to one Media
Access Control (MAC) entity.  Fig. 1 shows a conceptual block diagram
for the interconnection.  Fig. 2 shows an implementation fabricated
in a chip for the RMCU.  The block diagram includes four main
interfaces; namely, MAC Interface, PHY A Interface, PHY B Interface,
and Node Processor Interface.  The MUX provides both
multiplexer/de-multiplexer functions for the various signals which
are transmitted between the entities.  The RMCU transparently
connects the MAC interface to one of two Physical Interfaces via
multiplexor logic.  The MAC operation is independent of PHY layer
selection.  The Node Processor interface consists of the following
control/status signals:
  o  Node Processor Global Switch Notification - A status signal
which
      notifies the Node Processor of a Global Switch Event.
  o  PHY Selection - A control signal which controls multiplexer
      selection.
  o  Loopback Test - A control signal used for test purposes.  When
      active, the Global Switch Detection logic monitors the active
      media instead of the non-active media.

      The receive channel of the non-active PHY connection supplies
the input to the Global Switch detection logic.  This logic monitors
for the occurrence of a Global Switch Frame.  If such a frame...