RFC 1381 anomolies?

"Ms. Sydney Feit" <feit@tigger.jvnc.net> Tue, 07 September 1993 17:11 UTC

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Date: Tue, 7 Sep 1993 12:45:06 -0400
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From: "Ms. Sydney Feit" <feit@tigger.jvnc.net>
Message-Id: <199309071645.AA25020@tigger.jvnc.net>
To: x25mib@dg-rtp.dg.com
Subject: RFC 1381 anomolies?

To the editors of RFC 1381
 
Some of the items in RFC 1381 are quite puzzling.  I am convinced 
that some items are just wrong.
 
First of all, I have the definitive 1984 CCITT X.25 Recommendation,
as well as 1992 Recommendations expanding on the original.  It is
my impression that vendors have built to CCITT (now ITU-TSS)
specifications, NOT ISO specs.  I have vendor manuals that agree with
the CCITT specs, and contradict RFC 1381.
 
I do not have the ISO 8885 document, and do not know whether it
indeed varies as much from the CCITT originals as the RFC would
imply.
 
Is the ISO document online anywhere (ANSI is expensive!)
Does ANYONE pay attention to the ISO spec?  Again, CCITT
has been the relevant spec for years.
 
Specific issues:
 
1.  lapbAdmnTransmitKWindowSize and lapbAdmnReceiveKWindow size.
(Similarly for Oper).  CCITT states that these must be the same, and 
MUST be preset by mutual agreement.  
 
The window sizes at the PACKET layer can differ, and can be negotiated 
with the service provider through facilities negotiation, if the 
service provider supports this.
 
Also, the first of these definitions refers to "this DTE".  
The interface can play the role of DTE or DCE.
 
2.  lapbAdmnReceiveFrameSize.  The default value is set to 4500 
octets.  According to RFC1356, this is an illegal size.  1600 octets 
is the maximum, and anything bigger will automatically be decreased.
 
3.  lapbAdmnT4IdleTimer.  This does not appear in any of my standards
documents.  I assume that this is a locally configured timer that I 
use to say "Hmmm, nothing going on for this link, let's close it and
save our resources."  If this is what it is, it should be explained, 
and an official sounding protocol timer name like T4 should not be 
assigned.  Something like minIdleTime would match what vendors call 
this.
 
4.  I don't have an XID in ANY of my standards documents, nor is it 
configured in my vendor manuals.  Since it looks like IP addresses 
and port numbers are involved, it should be in some RFC.  Can
you tell me where this comes from?  Do any vendors support this?
 
You also state that "dxe" can be used when the station type has not 
yet been negotiated using XID.  But the lapbXidTable contains no 
parameter that would define this role.  How is the role defined 
during XID?  Again, who supports this in a product?
 
 
I'd appreciate your comments -
 
Dr. Sidnie Feit
feit@tigger.jvnc.net
or
sfeit@pascal.math.yale.edu