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Physical Layer Configuration in a Serial Simplex Switch

IP.com Disclosure Number: IPCOM000115008D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 6 page(s) / 378K

Publishing Venue

IBM

Related People

Cazzolla, JJ: AUTHOR [+8]

Abstract

Disclosed is the implementation of two independent buses within a serial simplex switch, where connection and disconnection operations are handled by the Connection Processing Bus, while message frame routing occurs over the Out-of-Band Bus.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 15% of the total text.

Physical Layer Configuration in a Serial Simplex Switch

      Disclosed is the implementation of two independent buses within
a serial simplex switch, where connection and disconnection
operations are handled by the Connection Processing Bus, while
message frame routing occurs over the Out-of-Band Bus.

      The Figure is a block diagram of a simplex mode switch 10
supporting the interconnection of up to sixteen subsystems 12 on the
single switch 10.  Expansion to additional subsystems is provided by
adding an additional switch 14 in a cascaded relationship with switch
10.  Each subsystem interface to the switch is called a switch "port"
16, providing the data path for transferring serially encoded data
and control frames.  This implementation includes a dual-simplex pair
of copper or fiber wires called "serial links".  One of these serial
links 18 is used for subsystem frame transmission, while the other is
used for subsystem frame reception.  Switch 10 includes an internal
crosspoint switching fabric, distributed control logic for processing
subsystem connection requests, and control logic to support the
switch port serial interfaces.  Data frames transferred within
connections are called "In-Band (IB)" data traffic, while link layer
control message frame transferred by means of the packet router
function of switch 10 are called "Out-of-Band (OB) message traffic.

      The input port control logic and output port control logic
resides in Port Input/Output (PIO) modules 20.  The crosspoint switch
fabric logic resides in Switch Element Matrix (SEM) modules 22.
Connection and disconnection operations are executed over the
Connection Processing, or CP bus 24, while message frame routing
occurs over the Out-of-Band, or OB bus.  In-Band (IB) data is
transferred from the PIO modules 20 to the SEM modules 22 over
dedicated SEM data input buses 26.  A maintenance processor complex
30 supports logic initialization and maintenance functions without
being involved in the normal processing of data between subsystems
12.  In the example of the Figure, a subsystem 32 and the cascaded
switch 14 are each connected to switch 10 through two ports.  All of
the parallel physical ports attaching a single subsystem to a switch
have a single logical address, which is the logical address of the
subsystem.

      If the number of connection request frames issued to a called
subsystem is less than or equal to the number of parallel ports
connecting the called system to the switch, and if the number of
requests for connections between switches connected by cascading is
less than or equal to the number of ports connecting these switches,
no connection request is queued or rejected.  If all the transmit
links in a required transmission path are busy, connection requests
are queued to be serviced.

      While each In-Band (IB) path for data traffic is a
circuit-switched, point-to-point connection between two subsystems in
the network,...