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From: jr@bbncc5.UUCP (John Robinson)
Newsgroups: net.dcom
Subject: Re: Need pointers to Internet, Arpanet 1822, X.25 standards...
Message-ID: <675@bbncc5.UUCP>
Date: Fri, 11-Oct-85 15:46:58 EDT
Article-I.D.: bbncc5.675
Posted: Fri Oct 11 15:46:58 1985
Date-Received: Mon, 14-Oct-85 03:28:31 EDT
References: <1062@trwrdc.UUCP> <10592@ucbvax.ARPA>
Reply-To: jr@bbncc5.UUCP (John Robinson)
Organization: Bolt Beranek and Newman, Cambridge, MA
Lines: 50
Keywords: X.25 1822
Summary: more pointers to requested standards

X.25 is a widely-used network interface standard promulgated by the
CCITT, a part of the International Telephone Union (Telegraph maybe?),
which is itself a UN body.  Copies of it are widely available.  One
place that will be happy to sell you one is:

   Omnicom Inc.
   Suite 206, 501 Church St. NE
   Vienna, VA  22180
   703-281-1135

The current version is dated 1980; the 1984 version is imminent,
thoughthe differences won't be material until the DDN (DoD networks)
implement it which will be maybe a year; the differences are minor and
mostly extensions you won't need.  In the DDN, X25 is a host access
link protocol available as an alternate to 1822 (which is not used very
much outside the DoD).

DoD network hosts are expected to use TCP and IP, for which specs are
available from the NIC as previously stated.  Hosts using X25 to
access the DDN need to know how to encapsulate IP datagrams inside
X.25 messages; this is covered in BBN report 5476.  This follows the
guidelines originated in RFC 877 from the NIC.  It also refers to FIPS
(Federal Information Processing Standard) 100, which standardizes the
use of X25 in US Government networks (and is included in report 5476).
For the BBN report and matters relating to the DDN, you should work
through:

   Defense Communications Agency
   ATTN: DDN Program Management Office
   Code B610
   Washington DC  20305

I will be happy to field (brief) technical questions about how these
standards relate to each other on the DDN; please send mail because I
don't read this newsgroup too regularly.

Another comment on the datagram-vs-VC battle - X25 and 1822 will
really become essentially equal methods of accessing the DDN by about
fall 1986.  Although 1822 seems to present a datagram interface, in
reality the network builds virtual circuits on behalf of hosts anyway
and always has.  The hosts' control over these VCs is only indirect;
1822 implementors know about "RFNM-counting".  X25 allows hosts to
control the setup and teardown of VCs in the network explicitly, which
can result in lower network overhead if the host is smart; gateways in
particular ought to be able to take advantage of this to provide
better flow control back to specific hosts and avoid much of the
packet loss seen today (by hosts sending to gateways over long-haul
networks).  Well, I could go on but won't...

/jr