Browse Prior Art Database

Dynamic Channel Allocation

IP.com Disclosure Number: IPCOM000105545D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 71K

Publishing Venue

IBM

Related People

Iskiyan, JL: AUTHOR [+4]

Abstract

Disclosed is a system that allows the 3990 to support 8 logical channels per cluster regardless of the number of physical interface connections. Since the 3990 can handle only 8 channels per cluster, physical or logical, a method to maximize the channel usage is needed, i.e., always support 8 logical channels regardless of the number of physical interfaces attached.

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

Dynamic Channel Allocation

      Disclosed is a system that allows the 3990 to support 8 logical
channels per cluster regardless of the number of physical interface
connections.  Since the 3990 can handle only 8 channels per cluster,
physical or logical, a method to maximize the channel usage is
needed, i.e., always support 8 logical channels regardless of the
number of physical interfaces attached.

      The 3990 currently supports the attachment of 16 physical
parallel channel interfaces, 8 per cluster.  Each physical parallel
channel interface attaches a single logical channel.  Thus, the 16
physical parallel channel interfaces attach 16 logical channels to
the 3990.  The logical channels are designated as channels A, B, C,
D, E, F, G and H on each cluster.

      The physical parallel channel interfaces attach to the 3990 via
system adapter cards.  Each system adapter card attaches 4 physical
parallel channel interfaces.  Therefore, the 16 physical channel
interfaces require 4 system adapter cards for attachment, 2 per
cluster.

      On each cluster the 2 system adapter cards are hardwired such
that the 4 physical parallel channel interfaces which are attached to
the first card are assigned as logical channels A, B, C and D; the 4
physical parallel channel interfaces which are attached to the second
card are assigned as logical channels E, F, G and H.

      With the advent of Serial I/O, one physical serial interface is
capable of supporting multiple logical channels.  The need to have
the physical serial interface hardwired to specific logical channels
is not required, as it was with parallel interfaces.  Therefore, the
logical channels can be dynamically allocated on the physical
interfaces.

      The serial I/O Attachment Feature for the 3990 control unit
dynamically allocates the logical paths associated with the serial
interfaces across all of the operational serial interfaces....