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From: PAP4@AI.AI.MIT.EDU.UUCP
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Using SLIP to link two ethernets?
Message-ID: <201108.870516.PAP4@AI.AI.MIT.EDU>
Date: Sat, 16-May-87 21:29:40 EDT
Article-I.D.: AI.201108.870516.PAP4
Posted: Sat May 16 21:29:40 1987
Date-Received: Sun, 17-May-87 06:37:18 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
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I was wondering: why use SLIP?  There are superior protocols that have
a very useable number of implementations.  Yes, SLIP does run on just
about any asynchronous port, but if you are really serious about this
connection, there is hardware that is better suited for passing packets.

I suggest a board that has BISYNC or SDLC/HDLC.  The advantages are:

	You don't have to worry about escaping framing characters
	(the hardware does this for you)

	The CPU gets an interrupt per packet, instead of per character
	(big win on a machine with poor interrupt latency, like a VAX)

	You can run at higher speeds with synchronous modems than you
	can with asynchronous modems given the same phone line

	Packets are framed and checksummed; added reliability

It depends on your host, of course.  But most minis and mainframes
have this sort of serial interface option.  Even PC's have boards
that can do this...

With appropriate software, you can run IP encapsulated in X.25 on
an HDLC interface as well, though not everyone considers this a win.
I believe the IMPs (excuse me, PSNs) can use HDLC for HOST/PSN
communication too, when they are geographically separated.

Oh well, just thinking out loud...  Hope this helps.

-Philip