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Re: How to add new "protocols" ?

From: Luigi Rizzo <luigi@labinfo.iet.unipi.it>
Date: Wed, 19 Feb 1997 07:19:57 +0100 (MET)
Message-Id: <199702190619.HAA08902@labinfo.iet.unipi.it>
To: touch@isi.edu
Cc: ses@tipper.oit.unc.edu, masinter@parc.xerox.com, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
> > > > 	1) try  alternate protocol, and use it if it works. Cache result
> > > Increases the connection latency. Bad in general. Besides, 
> > 
> > Adds an extra RTT to first connection to host
> 
> Only if "fails" is by NACK. Otherwise, it adds
> a timeout, which is usually in the 2-3*RTT range, _at best_.

It should normally fail by NACK (with the equivalent of ICMP port
unreachable), so that's not much of an issue. Since the result of
the probe is cached, this is not more costly than a DNS lookup.
Besides, you can probe in parallel all (are they 2, 3, 4 ? not
certainly a dozen) the known protocols and continue the transaction
using the preferred one among those available.

	Luigi
-----------------------------+--------------------------------------
Luigi Rizzo                  |  Dip. di Ingegneria dell'Informazione
email: luigi@iet.unipi.it    |  Universita' di Pisa
tel: +39-50-568533           |  via Diotisalvi 2, 56126 PISA (Italy)
fax: +39-50-568522           |  http://www.iet.unipi.it/~luigi/
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Received on Tuesday, 18 February 1997 23:15:32 EST

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