3270 controller simulation

Grant Taylor cctalk at gtaylor.tnetconsulting.net
Mon Nov 18 15:31:48 CST 2019

On 11/18/19 1:37 PM, Dave Wade via cctalk wrote:
> One thing which complicates things is that we have (roughly) layered 
> protocols in place between the 3174 and the host.


I'm trying to actually map them in my head.  I may have to transition to 
paper / white board.

> So at the physical level we have channel attached, SDLC, Token Ring 
> and bi-sync.


I think there's Ethernet in there too.

> Above that we have the channel protocols, HDLC/SDLC and bi-sync polling.


IMHO both the physical (L1 in OSI terms) and protocol (L2) are decidedly 
locally significant and probably mostly agnostic to the higher layer 

> Then we may have SNA (which encompasses many options) to transport the 
> data through the network.

I am guessing that SNA is mostly agnostic to the lower protocols and 
worries more about data movement across one or more lower layer network 

> At the top the protocols and frame formats in the Data Streams manual 
> which are broadly the same but with tweaks for SNA, Local and Bi-Sync.

Is this where APPN / APPC and the likes come into play?  Actual 
application information riding on top of SNA?

Grant. . . .
unix || die

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