Subject: Discussion about item 8333 (DLUR ACTPU Indicator)

From: "Ed Tremblay (254-5515)" <[email-masked]>
Date: Mon, 6 Nov 95 14:12:06 EST

During the Reference SIG meeting last week, a question was asked about
the use of the term "preference" instead of something like "requirement"
relating to DLUR wanting to receive an ACTPU over the CP-SVR pipe from
an adjacent DLUS.  I agreed to find out what DLUS does with the ACTPU
Indicator - too bad I didn't remember that this information is already
in the DLUR architecture reference.

Section 6.2.3.3 describes the DLUS processing of this indicator.  Sending
an ACTPU over the pipe is not guaranteed even when the indicator is set
but depends on whether the DLUS has a PU definition for the XID3-sending
PU.

So, even with an adjacent DLUS, the DLUR cannot be guaranteed that it will
receive the ACTPU over the pipe.  Therefore, I propose leaving the term
"preference" in place.

Ed Tremblay

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From: "jim (j.) cobban" <[email-masked]>
Date: Tue, 7 Nov 1995 09:14:00 -0500

In message "Discussion about item 8333 (DLUR ACTPU Indicator)", 

>receive the ACTPU over the pipe.  Therefore, I propose leaving the term

The DLUS must make every possible effort to send the ACTPU over the pipe.  As
one example, if the DLUS and DLUR are in adjacent nodes, but those nodes are
connected by ATM, then because we are only architecting HPR over ATM there
will be NO available transport to carry the ACTPU to the DLUR except over the
pipe.

One problem is that the DLUS must make this decision prior to knowing whether
the pipe will ever come into existence.  That is it is extremely unlikely
that the DLUR has already established the pipe to the DLUS over some other
route.  However just as Ed has explained that the DLUS uses local
configuration information in determining whether or not to send the ACTPU
over the TG, the DLUR's ability to establish the pipe is dependent upon its
own local configuration data.  In particular the DLUS must assume that the
DLUR knows the LU name of the DLUS.  The DLUS cannot itself establish the
pipe without somehow knowing the name of the DLUR in this node.  All that
this preference bit tells the DLUS is that there IS a DLUR in this node.

Perhaps we could consider adding an additional X'0E' Network Name control
vector to the XID3 which carries a network name type of either DLUR or DLUS.
This would guarantee the ability to establish a server pipe between adjacent
nodes, and therefore would turn the "preference" into a demand.  That is if a
node containing a DLUS received an XID3 which carried both ACTPU over pipe
preference and a DLUR name X'0E' CV then the DLUS would immediately establish
the pipe to the DLUR and deliver the ACTPU by that route.