Conference rdgeng::cics_technical

>>     Hello,

Hi.

>>     I'm working on a proposal to move CICS transactions from Mainframe
>>     to DUNIX CICS where the remote terminals are pure 3270s or PC with 3270
>>     emulation.The configuration should be the following:
>>     
>>     
>>     
>>     3270s term --> IBM CICS-->Domain Gateway CT-->DUNIX CICS.
>>     
>>     This should work fine I suppose.

This will work but it isn't your only option.  Provided that there is
a mianframe around to manage the VTAM network, the connection from the
3270s can be direct to CICS for Digital UNIX via the Domain Gateway (notes
this is only valid for the Domain Gateway, it does not work for the
Peer Server).  The configuration looks like-

       3270s term --> Domain Gateway --> CICS for Digital UNIX (using Epi3270)

This configuration uses the optionally installed Epi3270 component of
CICS for Digital UNIX.

>>     
>>     The customer asked if it is possible to have a back-up connection for
>>     the 3270 terminals in case the mainframe go down, so that the 3270
>>     terminals can connect directly with the Unix server.

If the actually mainframe goes down they are likely to be in fairly
serious trouble unless they have modern FEP which has inbuilt telnet
support.

General speaking however if they are 'real' 3270 you need the mainframe
(you do not however need CICS up and running on it).

>>     
>>     I think that if the terminals are pure 3270 there is no way; if they
>>     are PC and they are connected for instance to an X.25 network it is
>>     possible to use a TN3270 to go to the CICS on the Unix system (using
>>     TCP/IP on X.25).Am I right?

You are right.

>>     
>>     The question is: is the tn3270 server integrated in the CICS for
>>     Digital Unix or I need some other SNA product like SNA Peer Server to
>>     handle these requestes from the PCs?

The cicsteld server is an integrated part of the CICS for Digital UNIX 
product.  You do not need any additional products to support tn3270
connections over TCP/IP.

You might also want to consider using the IBM PC CICS Client.  This provides
nice and easy connection into CICS for Diigtal UNIX and also a smooth route
if they want to move to a GUI front-end to their application at some stage.

Please contact Iain Smith (rdgeng::smithi) for the latest on IBM PC CICS
Client pricing/availability.

>>     
>>     Thanks
>>     
>>     Federico Sturn
>>     Sales Support
>>     Digital Rome
>>     
>>     
-gerry

    Thank you for the clarification.
    Another consideration is if it is possible to reduce the traffic on the
    Bus-and-Tag channel, isolating the 3270 screen-maps.I mean if it is
    possible to handle on the Mainframe CICS all the I/O with the 3270
    terminals and have only the processing and data access on the Unix CICS.
    This avoid to need to have all the maps (BMP etc) on the Unix server
    and reduce the amount of data on the bus-and-tag (somebody told me that
    the limit of Domain Gateway is ~1MByte/sec on this channel).
    This could be very usefull because in my case there will be more than
    1000 remote terminals.
    
    Thanks again.
    
    
    Federico
    	

I think you need to be fairly careful here with the design.  If there was
>1,000 terminal and each established a session via CICS/ISC back from
Mainframe back to the Digital UNIX system, I suspect the system could
be seriously impacted.  While the ISC sessions (presumably via transaction
routing) is established, the CICS for Digital UNIX system will have
an application server in use.  If the application is pseudo-conversational
and the individual transactions are short in duration this set up
would work fine.  If the transactions are not short-lived, this will
not be a viable configuration.

There are people better able than me to comment on through-put that
could be reasonably expect from the Domain Gateway, channel, and any other
components out there on the terminal network..

However, I would at a first guess not expect a 1,000 terminals using BMS
screen to use more than 1MB/s of bandwidth.  Assume each BMS map requires
1,000 bytes (not unreasonable unless than have very dense screens and
do not send data only on their CICS SEND MAPs), and a 1,000 terminals,
this is one screen/second/terminal - far in excess of what I would
normally expect.  The implications otherwise would be of an extraordinary
transaction rate.

-gerry