Browse Prior Art Database

Maintaining ISDN Synchronization for a Logically Offline Device

IP.com Disclosure Number: IPCOM000122365D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 36K

Publishing Venue

IBM

Related People

Darrington, DL: AUTHOR [+1]

Abstract

CCITT Recommendation I.430 defines pulse patterns and procedures that enable an Integrated Services Digital Network (ISDN) to achieve Layer 1 synchronization with an attached device. A method for stopping all coded processes associated with an ISDN adapter without disrupting the required pulse patterns is disclosed.

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This is the abbreviated version, containing approximately 91% of the total text.

Maintaining ISDN Synchronization for a Logically Offline Device

      CCITT Recommendation I.430 defines pulse patterns and
procedures that enable an Integrated Services Digital Network (ISDN)
to achieve Layer 1 synchronization with an attached device.  A method
for stopping all coded processes associated with an ISDN adapter
without disrupting the required pulse patterns is disclosed.

      Coded processes associated with an ISDN adapter may be stopped
without disrupting required ISDN Layer 1 pulse patterns as follows:
1.  While processing a request to go offline, code associated with
the adapter does the following:
     a.  The code performs operations required to terminate itself in
an orderly manner, such as masking interrupts, without writing
adapter registers that would cause loss of the INFO1/INFO3
synchronization pulse pattern defined in CCITT Recommendation I.430.
2.  While the adapter is offline, it is possible that the network may
stop transmitting an INFO2/INFO4 pulse pattern and possibly later
attempt to resume synchronization.
     a.  If this occurs, the adapter hardware will handshake with an
appropriate pulse pattern (INFO0, INFO1, or INFO3) without involving
the code.
3.  When code associated with the adapter is reactivated and it is
necessary to bring the adapter back online, code does the following:
     a.  Adapter registers are read to determine the adapter state
and network state (ranges from no pulses to fully synchronized...