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From: collin@hpindda.HP.COM (Collin Park)
Newsgroups: comp.protocols.iso
Subject: Re: Gateway ISO8073 Cl4 <-> IEEE802 TCP
Message-ID: <5560054@hpindda.HP.COM>
Date: 28 Feb 90 00:34:10 GMT
References: <245@sposp1.UUCP>
Organization: HP Information Networks, Cupertino, CA
Lines: 45

> 1.	Is it possible to translate TCP/IP <--> ISO8073 Cl4?

In principle, no: tcp/ip has graceful release whereas 8073 has not.
also, 8073 retains record boundaries which tcp does not.

However, if your tcp/ip applications don't need graceful release (ftp
is a notable exception) then it's probably possible to use the 8073
class 4 to do the data transfer.

Even if the application does need graceful release, there may be some
klugey way to get around it...  For example, if the 8073 class 4 (i'll
call it 'tp4' from now on) sends data and then waits for ALL data to
be acknowledged before sending the DR TPDU, then the close is
'graceful' from the sender's side.  (But how does the receiver know
that the sender did this vs just being disconnected?  A problem.)

To me, it seems the more difficult problem is that of address
translation.  how do you get the destination t-address translated to
tcp port # and ip address?  And vice versa?  

You may be better off using the ISODE model of encapsulating tp0
packets inside tcp/ip.  But... this doesn't address your heterogeneous
network.  

> 2.	Is it easy to write a "black-box" and Gateway session layer programs?
>	Or maybe it exists somewhere????

I don't know how easy these would be to write... again, the hard
problem in my mind is address translation. 

> 3.	Will NFS, Rlogin,... be satisfied by such an arrangement?

Not ftp unless you do something klugey as per my comment above.  I
don't know about nfs, rlogin and others. 

Hope this helps
-collin
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collin park			Hewlett-Packard Company
collin%hpda@hplabs.hp.com	19420 Homestead Road -- MS 43LT
				Cupertino, CA  95014  USA