Ethereal-dev: RE: [Ethereal-dev] Invalid LAPB Frame for Wellfleet protocol

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From: Jeff Foster <jfoste@xxxxxxxxxxxx>
Date: Thu, 19 Dec 2002 14:24:35 -0600
This is not a LAPB frame. From RFC-1547 -

4.3.5 Wellfleet point-to-point protocol

   The Wellfleet router supports synchronous links using simple HDLC
   framing.  The HDLC framing procedure uses the HDLC address and places
   the Unnumbered Information (UI) command in all frames.  A simple
   header following the UI command provides a two octet type field using
   the same values as Ethernet.

   The Wellfleet protocol does not meet any of our requirements for
   fault detection or option negotiation.  No mechanism for future
   extensibility is currently defined, although one could be added.
 

I was checking to see if anyone would figure out how to make this decode 
properly; I wasn't pointing out that the LAPB deocde was broken. Sorry
if I misguided you.


Jeff Foster
jfoste@xxxxxxxxxxxx


-----Original Message-----
From: Richard Sharpe [mailto:rsharpe@xxxxxxxxxxxxxxxxx]
Sent: Thursday, December 19, 2002 2:45 PM
To: Jeff Foster
Cc: ethereal-dev@xxxxxxxxxxxx
Subject: RE: [Ethereal-dev] Invalid LAPB Frame for Wellfleet protocol


On Thu, 19 Dec 2002, Jeff Foster wrote:

> 
> OK, Here you go. The .syc file is the capture and the .prn 
> file is the printout.

Well, it looks like the address and control fields have been swapped by 
someone.

Secondly, the address field is always the same, 03, but that is OK, if 
each I frame contains increasing sequence numbers in the ack field. 
However, the control field does not seem to contain an I-frame command, 
either.

This really should be a different DLT-type or something, as it does seem 
to be invalid LAPB frames.

Regards
-----
Richard Sharpe, rsharpe[at]ns.aus.com, rsharpe[at]samba.org, 
sharpe[at]ethereal.com, http://www.richardsharpe.com


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