Data Flow Description - IBM 3708 Description

Data Flow Description
The following section describes the transmit and receive paths for the 3708. See also
Appendix C, "Suggested Guidelines for Increasing 3708 Performance" for more
performance information.
SNA Host
Data Stream:
Line:
I
F
I
A
I
C
I
I
I
FCS
I
F
I
SDLC Secondary, Half Data Duplex
Point-to-point or multi-point
From SNA Host
~
t
To SNA Host
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 D O
Received Transmitted
Data Data
(Multiple buffers are used
only with segmented RUs)
SDLC Link Level Headers/Trailers
removed
SNA Level Headers removed
:-------------------r---------------------~
Optional
Translation
EBCDIC to ASCII
(Host Data)
•
Additional characters may be inserted:
DEVICE
- for hard copy devices
BUFFER
- for Line Quiet.
WRITE
•
QUEUE
XMIT
ECHOPLEX
DATA
Transmitt ed
Received
RECEIVE
QUEUE
SDLC Link Level Headers/Trailers
added
SNA Level Headers added
~-----------------,---------------~
Optional
Translation
ASCII to EBCDIC
(Terminal Data)
I
I
RCV
I
t
Data
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 D O
I
Data
To ASCII Device
~
t
From ASCII Device
Terminal
Data Stream: (ASCII device data stream)
Line: SIS ASCII, Full Data Duplex
Point-to-point only
Figure 5-1. 3708 Protocol Enveloping - Internal Data Flow
Chapter 5. 3708 Protocol Enveloping Mode
5-11