🚀 go-pugleaf

Archive-name: internet/route/pcroute/1991-05-28
Archive-directory: tacky.cs.olemiss.edu:/pub/pcroute/ [130.74.96.13]
Original-posting-by: mah@wu-wien.ac.at (Michael Haberler)
Original-subject: Re: PCROUTE?
Reposted-by: emv@msen.com (Edward Vielmetti, MSEN)


|> 				... because we have PCRoute on about
|> six trunks at 9600 and 19200. While investigating problems of lost
|> routes, it was discovered that PCRoute would go off into the woods
|> when two simultaneous transfers were in progress from each end

There was a bug in the slip code which caused PCroute to hang under high
traffic. It's been a at least a year since this was fixed by the author
of the Slip code, David Johnson <dave@tacky.cs.olemiss.edu>.

I had a similar problem as you described it, and after applying the
fix it went away. No outages in over a year.


I include Dave's message; I rather suggest you get a fresh copy of 
PCroute from tacky.cs.olemiss.edu with ftp.

- michael
----------------------------------

Subject: Re: SLIP on pcroute
In-Reply-To: Your message of "Sat, 31 Mar 90 19:01:53 EST."
             <9003311807.AA22631@tacky.cs.olemiss.edu>
Date: Sat, 31 Mar 90 17:17:39 -0600
From: David E. Johnson               ** Title:        Systems Programmer
 <dave@tacky.cs.olemiss.edu>
 
 
Michael,
 
        For the past several months our router has failed consistently
every few days.  The symptoms are the same as you reported.
The ethernet side still worked
but the SLIP side seemed to forget the Xmit interrupts.  Since this
was our connection to the Internet and also connected a PC (terminal)
lab via network to our campus IBM, this problem was significant.
 
        After trying every possible solution, we decided to order some
16550's assuming that the 8250 was at fault.  However, we have not
received these yet.  So I decided to have the router report its status
via syslog every so often so that maybe we could track the problem
down.  (A masters student here has not completed the SNMP
implementation which would have helped tremendously)  While going
through the code to place "counters" at strategic locations, I FOUND
THE PROBLEM.  Not in hardware, but in software.
 
        In the routine SLIP_DL_IP_W_ACCESS interrupts are turned off
to avoid a possible race condition with the interrupt handler.  The
problem is that the macro between turning ints off and on has a way to
jump out of this pair.  When the ethernet side overloads the SLIP side
this routine jumps automatically to "no_buffer", thus leaving
interrupts OFF.
 
        I have removed the cli and sti from this routine and the
router has not failed once (about 7 days).  If a race condition still
exists, it hasn't caused a problem thus far.  The cli and sti could be
left and a sti placed in the BUFF_CHECK routine just before jumping to
"no_buffer", but like I said, we have had no problem thus far.
 
        An update will be available soon, but since you have
re-assembled anyway, you can just take these out.  I would like to
know if this solves your problem.  I would also like to see any
changes you have made or may make for the 16550.  Since we have a few
coming, we might as well take advantage of them.
 
 
David E. Johnson               ** Title:        Systems Programmer
Department of Computer Science ** Telephone:    (601) 232-7396
The University of Mississippi  ** Internet:     dave@cs.olemiss.edu
336 Weir Hall                  **
University, MS  38677          **
 
 
 
 
 



-- 
Michael Haberler 		mah@wu-wien.ac.at,  mah@awiwuw11.bitnet
University of Economics and Business Administration
A-1090 Vienna, Augasse 2-6	    Biz:    +43 (1) 31336 x4796 Fax: 347-555
Home: +43 (1) 961-679 (voice & fax) D-Netz: +43 (663) 811-056

-- comp.archives file verification
tacky.cs.olemiss.edu
total 940
drwxr-xr-x  3 ftp           512 Apr 17 23:35 exp
drwxr-xr-x  2 ftp           512 Apr 17 23:35 analyzer
-rw-r--r--  1 ftp         26793 Apr 17 23:35 uncomp.exe
-rw-r--r--  1 ftp         28340 Apr 17 23:35 tar.exe
-rw-r--r--  1 ftp         11321 Apr 17 23:35 readme.pcroute.doc
-rw-r--r--  1 ftp          1284 Apr 17 23:35 readme.1st
-rw-r--r--  1 ftp          6683 Apr 17 23:35 readme.pcbridge.doc
-rw-r--r--  1 ftp        107327 Apr 17 23:35 pcroute2.2.tar.Z
-rw-r--r--  1 ftp        131801 Apr 17 23:35 pcroute2.2.src.tar.Z
-rw-r--r--  1 ftp         30977 Apr 17 23:35 pcbridge1.2.tar.Z
-rwxr-xr-x  1 ftp          7553 Apr 17 23:35 analyzer.doc
-rw-r--r--  1 ftp          2054 Apr 17 23:35 copywrit.doc
-rw-r--r--  1 ftp         22310 Apr 17 23:35 pcbridge1.1.tar.Z
-rwxr-xr-x  1 ftp         10598 Apr 17 23:35 analyzer.exe
-rw-r--r--  1 ftp          6577 Apr 17 23:35 compress.doc
-rw-r--r--  1 ftp         57197 Apr 17 23:35 pcbridge1.2.src.tar.Z
-rw-r--r--  1 ftp         24692 Apr 17 23:35 pcbridge1.2b.tar.Z
-rw-r--r--  1 ftp         44319 Apr 17 23:35 pcbridge1.2b.src.tar.Z
-rw-r--r--  1 ftp        118607 Apr 17 23:35 pcroute2.2b.src.tar.Z
-rw-r--r--  1 ftp         97213 Apr 17 23:35 pcroute2.1.tar.Z
-rw-r--r--  1 ftp        160611 Apr 17 23:35 pcroute2.1.src.tar.Z
found pcroute ok
tacky.cs.olemiss.edu:/pub/pcroute/