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From: brescia@CCV.BBN.COM.UUCP
Newsgroups: mod.protocols.tcp-ip
Subject: Re: Proteon vs Arpanet query
Message-ID: <8702192132.AA28149@ucbvax.Berkeley.EDU>
Date: Thu, 19-Feb-87 14:16:01 EST
Article-I.D.: ucbvax.8702192132.AA28149
Posted: Thu Feb 19 14:16:01 1987
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First, let me apologize to the whole list for sending out the previous
message.  It slipped through my fingers while trying to reply.  (An apology is
a bad thing to begin a letter with.)

Bob,
There are two main ways to connect to a PSN at 'level 1', the electrical level.
There is 1822 DH, which is good up to about 1000 feet, and there is 'modem'
which may be RS232, V.35, RS422, and possibly others.

If the arpanet PSN is not in your building, and you cannot get one installed
in your building, you will need some sort of modem connection.  As H.Weiss
pointed out, you could use ECU's to turn the modem line into a DH connection
at your end and at the PSN, but ECU's are impossible for DDN to monitor and
the modem line is also hidden from monitoring also.  

The PSN modem connections are based on HDLC, and can use HDH or X.25 ("DDN
Standard X.25").  You want to see if Proteon will support either of those
protocols.  

Disclaimer:
This is a statement from a PSN user; I run gateways, not PSNs.  I do not
speak for DDN or the PSN support group.

    Mike