Newsgroups: bit.listserv.ibmtcp-l
Date:         Thu, 9 Apr 1992 16:54:20 EDT
From:         Jack Coyle <JCOYLE@RALVMM.VNET.IBM.COM>
Subject:      CLAW
X-To:         ibmtcp-l%PUCC.bitnet@cunyvm.cuny.edu

On Thu, 9 Apr 1992 11:15:48 PST, Richard Hintz appended:

>> I ran across a new HIPER APAR for FAL V2R2 which adds new function.
>> The APAR is PN17716 and the description is:
>>
>> SUPPORT REQUIRED FOR CLAW (COMMON LINK ACCESS TO WORKSTATION)
>> DRIVER TO ENABLE DIRECT ATTACHMENT OF RISC SYSTEM/6000 DEVICES
>>
>> Would someone say what this is/does, please?

The following is the first two paragraphs from the documentation which
accompanies the PTFs shipped in support of this new function. The doc-
umentation goes on to discuss configuration issues, diagnostic traces,
and new messages introduced with the support. The publication cited
below is also an excellent source of information about CLAW. (BTW, the
applicable PTFs are UN19085 for the V2R2 base and UN19086 for the V2R2
source feature.)

-- CLAW (Common Link Access to Workstations) is a continuously-executing,
-- full-duplex channel program designed to minimize host interrupts while
-- maximizing channel utilization.  The channel commands used within CLAW
-- allow S/390 applications, such as TCP/IP, to monitor the progress of a
-- long channel program and modify it as it is running.  In a S/390
-- processor with minimal CPU activity, CLAW is driven primarily by I/O
-- interrupts, as typical S/390 devices would be.  As the system load
-- becomes heavier, CLAW is more often able to append new I/O requests to
-- the already-active channel program -- thus avoiding the overhead of
-- interrupts and "Start Subchannel" requests at a time when it can least
-- afford it.  Therefore, CLAW provides better support of a direct hard-
-- ware link between a S/370 channel and a workstation.
--
-- In support of direct attachment of RISC System/6000 devices (via its
-- Block Multiplexer Parallel Channel Adapter), there are a number of
-- considerations towards installation and proper usage of TCP/IP for
-- VM's CLAW driver.  This interim documentation will address what needs
-- to be done specifically in the TCP/IP for VM environment.  For further
-- details on installation of the RISC System/6000 Block Multiplexer
-- Channel Adapter, AIX Version 3.2 channel driver, channel operations,
-- and problem determination, please refer to the Block Multiplexer
--                                                _________________
-- Channel Adapter User's Guide and Programming Reference, IBM publica-
-- ______________________________________________________
-- tion number SC23-2427-00.  It is assumed that the proper RISC
-- System/6000 connectivity is available:
--
-- o   Appropriate RISC System/6000 model with the Block Multiplexer Par-
--     allel Channel Adapter card/feature
--
-- o   Appropriate S/370 or S/390 processor with 4.5 MByte/second (rated
--     maximum) parallel channel.
--
-- o   AIX Version 3.2 for the RISC System/6000, which has the appro-
--     priate CLAW driver on the workstation side of the channel (via
--     installation of the Block Multiplexer Channel Adapter optional
--     program).


Jack Coyle - IBM Raleigh
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU