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Message Posted: Mon, 29 Mar 2004 @ 17:07:56 GMT


     
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Subj:   Re: ESCON vs Ethernet
 
From:   bob

Just a couple of comments mostly for clarification.

The mainframe client software works via ESCON, NOT TCP/IP. The interface is implemented to communicate with TDP via the OS' Cross Memory Services. TDP then comunicates directly with the Teradata message subsystem via EXCPVR to the ESCON devices on the Teradata nodes via the channel driver whose role is exactly analagously to the role of the Teradata Gateway for LAN clients. Teradata knows it's a mainframe and handles the data type conversions--but only from the ESCON, not LAN side.

It has been considered by NCR to provide similar capability e.g. via enabling TDP to support TCP/IP communication with the Gateway. This would be transparent to the client software (nothing would need to change except TDP). Up until now, the rationale has not been sufficienctly compelling to warrant the (non-trivial) Engineering investment that would be required.

In a local channel environment, what would be the advantage? It would use more mainframe resource to accomplish the same amount of work (TDP's I/O is the most efficient and shortest path length--EXCPVR relative to TCP/IP which is much improved since early OS/390 versions but still much heavier than EXCPVR). The installation and management are familiar to the mainframe Systems and Operations as it's just a few more devices to gen. FICON channel consolidation can be accomplished via the ESCON Director Model 5 with a FICON bridge.

IBM's advocated TCP/IP mainframe connectivity is via the Open Systems Adapter e.g. OSA, OSA2, OSA Express. TCP/IP over ESCON is deprecated. (Channel/LAN bridges such as BTI's NetShuttle).

Until and unless NCR does this work (presuming a sufficiently compelling justification), without ESCON you would no longer run TDP and Teradata utilities on the mainframe and would need to re-solve the data movement and transformation (referring to EBCDIC/ASCII, big v little endian integers, float and decimal types etc.).



     
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