Re: Miscellaneous points

Rik Harris <rik@rdt.monash.edu.au>
Message-id: <199312022305.KAA09837@daneel.rdt.monash.edu.au>
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To: J.Larmouth@iti.salford.ac.uk
Cc: www-talk@nxoc01.cern.ch
Subject: Re: Miscellaneous points 
In-reply-to: Your message of "Thu, 02 Dec 93 11:38:00 GMT."
             <9312021153.AA20102@dxmint.cern.ch> 
Date: Fri, 03 Dec 93 10:05:16 +1100
From: Rik Harris <rik@rdt.monash.edu.au>
X-Mts: smtp

> The error reports on failures to connect are not very helpful.   This is
> partly poor design of the client software and/or lack of diagnostic
> parameters in WINSOCK specifications,  and/or the fact that we are in
> early releases,  but I think it may also reflect a lack of appropriate
> information at the network level.
> 
> For example,  am I getting failures to connect and/or poor transfer rates
> and/or halts because of the link from Salford to the Janet back-bone,
> because of the pipe across the atlantic,  or because the server is very
> congested/slow,  or because my PC is too slow,  or what?   I have a
> strongish suspicion it may be the Salford link and/or routers,  but there is
> no easy way to find out.
> 
> I have no answer to these sort of problems,  but as world-wide access to
> information servers becomes more common,  pin-pointing where problems lie
> will become more important.  Certainly at present there is no way I would
> want to expose the VC to either MOSAIC or CELLO - too many failures,  and
> far,  far too slow.   Hope it changes soon tho' - the idea is great!

I don't have the experience with SGML or OSI to comment on your other
points, but with this one I would suggest that it is not up to
application software to pinpoint network failures.  This should be left
to network management software, as it is a complicated task that
requires detailed knowledge of the network topology, link types,
operating behaviour, protocols, and other factors.

I feel the most you want is distinction between "host does not exist",
"host was not contactable - temporary", "service not available at
host", "network error looking up host name" and possibly "service not
available at host - temporary".  Better still: "none of the redundant
hosts were contactable"  :-)

rik.
--
Rik Harris - rik.harris@fcit.monash.edu.au
+61 3 560-3265 (AH & ans.mach)      +61 3 565-3227 (BH)
Department of Robotics and Digital Technology, FCIT, Clayton Campus,
Monash University, Australia   http://www.vifp.monash.edu.au/people/rik.html