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Hardware Fault Tolerant 3745 Communication Controller: A Major Step to a Non-disruptive Network Switching

IP.com Disclosure Number: IPCOM000109994D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 71K

Publishing Venue

IBM

Related People

Galcera, J: AUTHOR [+4]

Abstract

A way of being hardware Fault Tolerant on the 3745 engine is disclosed. Two CCUs on the same card allow switching from one to the other in case of failure, as each CCU has its own failure detection system. Each CCU is loaded by the same NCP, receives the same data from adapters through IOC buses. While one is running as Active, the second is running as Backup, which means that all its external drivers are in disable mode. In this mode, the content of the two CCUs will be exactly identical and the Backup one may continue the task if the Active fails. (Image Omitted)

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Hardware Fault Tolerant 3745 Communication Controller: A Major Step to a Non-disruptive Network Switching

       A way of being hardware Fault Tolerant on the 3745 engine
is disclosed.  Two CCUs on the same card allow switching from one to
the other in case of failure, as each CCU has its own failure
detection system.  Each CCU is loaded by the same NCP, receives the
same data from adapters through IOC buses.  While one is running as
Active, the second is running as Backup, which means that all its
external drivers are in disable mode.  In this mode, the content of
the two CCUs will be exactly identical and the Backup one may
continue the task if the Active fails.

                            (Image Omitted)

      The IBM 3745 Communication Controller is equipped with two IOC
buses to get connected to the hosts to which it is attached through a
Channel Adapter and to the low-speed scanners through which TP lines
are managed.  The machine also attaches some high-speed lines such as
T1's.  T1's take advantage of a direct memory access to cope with a
much higher data throughput.

      A switch function for both bus types is provided, which allows
connection to any CCU; today's concept is the following: on the
active side, if a hardware error at CCU occurs, an Hlir(hrdchk) is
sent to the Moss, and the CCU is stopped.  Then, under the MOSS
control, the Switch is reconfigured to connect IOC and DMA buses to
the second CCU.  Then a new IPL starts.

      The major inconvenience of this process is the Network
disruption.
Implementation

      Usi...