Path: utzoo!attcan!uunet!seismo!ukma!psuvax1!wuarchive!gem.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucbvax!TUT.FI!jh
From: jh@TUT.FI (Hein{nen Juha)
Newsgroups: comp.protocols.iso
Subject: TP0-4 question (novice level)
Message-ID: <8910181149.AA16663@tut.fi>
Date: 18 Oct 89 11:49:02 GMT
References: <8910180850.AA05969@jerry.inria.fr>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 27


   one could very well carry isograms over X.25 virtual circuits. But this
   will have a cost, i.e. the volume charges of carrying 50 extra bytes of
   headers per packet, and also paying for extra acknowledge packets: TP
   ACK are carried as data, and charged for, while X.25 RRs are not
   accounted. To give an order of magnitude, we have observed that running
   TCP over IP over X.25 involves approximately 25% of overhead compared
   to running the application straight over X.25; as our X.25 bill runs
   here to approx 500,000FF per year, that would mean spending an extra
   125,000FF (16000 ECUs, 20000 US$) per year. We would rather not. And
   the solution for not paying any overhead is called TP-0, not TP-4.

Christian,

I agree with the estimate of 25% extra, but who says that the traffic
has to be volume charged and who asks you to use X.25 at all at the
bottom?  We have educated our PTT to accept charging by the bandwith
one is using to connect to the network and there is no X.25 bullshit
involved.

Right now the Finnish State PTT has started to marked a service called
DATANET which is a public TCP/IP (later also ISO/IP) service based on
Cisco routers and fixed bandwidth based charging.  I feel that this is
the right approach which should also be adopted by the EC monopolistic
PTT (like yours).

-- Juha