SDLC Point-to-Point Full Duplex

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2 total messages Started by Marigowda Divya Tue, 15 Dec 1992 12:40

#985

Author: Marigowda Divya
Date: Tue, 15 Dec 1992 12:40

25 lines
1239 bytes

This is regarding SDLC Point-to-Point Full Duplex.  Question is,
if the primary sends a Poll (eg: RR-P) followed by
couple of I-frames, should the secondary stick with the original
Nr (at the time the poll was received), or should it keep updating
the Nr;  correspondingly, should the primary do the same?

If this were to be true, then isn't it possible, that within one
POLL/FINAL exchange, any number of I-frames can be exchanged
between the Primary and the Secondary.

Could someone give an explanation; or point to some document with
these details.  The IBM SDLC document, simply has one scenario
regarding the Point-to-Point Full Duplex operation, without any
detailed discussion.

Thanks in advance.

Cheers,
divya

--------------------------------------------------------------
Marigowda Divya  (mdivya@world.std.com)
GSOFT

Re: SDLC Point-to-Point Full Duplex

#988

Author: Dave Buck
Date: Sat, 19 Dec 1992 00:12

22 lines
1629 bytes

In article <BzAwJq.9nM@world.std.com> mdivya@world.std.com (Marigowda Divya) writes:
>This is regarding SDLC Point-to-Point Full Duplex.  Question is,
>if the primary sends a Poll (eg: RR-P) followed by
>couple of I-frames, should the secondary stick with the original
>Nr (at the time the poll was received), or should it keep updating
>the Nr;  correspondingly, should the primary do the same?

In fact numerous implementations including IBM's do seem to change the
Nr value from I frame to adjacent I frame or RR. But your question is
"should they", not "do they" ... that is certainly unclear from the
IBM specs. I would be so bold as to state that a good implementation
should accept such behavior from a peer, but provide an option for
this behavior for local transmissions.

>If this were to be true, then isn't it possible, that within one
>POLL/FINAL exchange, any number of I-frames can be exchanged
>between the Primary and the Secondary.

Yes. Which makes it look very much like an HDLC implementation.
-- 
Dave Buck   dave@dlb.com   {amdahl,ames,daver,netcomsv,sun,zygot}!dlb!dave
D. L. Buck and Associates, Inc.;   San Jose, California;    (408) 972-2825

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