[5339] in North American Network Operators' Group

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Re: Cisco's AIP vs HSSI

daemon@ATHENA.MIT.EDU (Avi Freedman)
Tue Oct 15 15:00:58 1996

From: Avi Freedman <freedman@netaxs.com>
To: kwe@6SigmaNets.com (Kent W. England)
Date: Tue, 15 Oct 1996 14:15:37 -0400 (EDT)
Cc: freedman@netaxs.com, bmanning@isi.edu, nanog@merit.edu
In-Reply-To: <3.0b36.32.19961015100317.006def8c@mail.cts.com> from "Kent W. England" at Oct 15, 96 10:06:17 am

> While this is certainly true, HDLC is a point-to-point protocol
> and not a network protocol, like frame relay, SMDS or ATM. And
> HDLC itself isn't quite enough, IMHO, you really need PPP.

We run PPP on all non-frame-or-smds and less-than-DS3 links so that
the customer (or ourselves, if it came to it) could switch to non-
Cisco gear instantly.

But we usually leave most cisco-cisco high-speed links at HDLC.
My impression is that HDLC was the same efficiency - or moderately
more so - than PPP.

For what do feel that one *really* needs PPP?

Or, to put it another way, maybe we're talking about different things.
I'm talking about the HDLC *point-to-point* *network* protocol, as 
implemented by Cisco, not HDLC the low-low-level point-to-point protocol.

> And the efficiency lost to ATM is not 40% as often claimed on this
> list, but rather it is 12% less efficient than PPP for TCP. 
> 10% is the cell header overhead and 2% is due to modulo 48 padding, 
> given actual traffic at FIX West as measured by kc at NLANR.

Quite believable.

> --Kent
> 
> We return to our regularly scheduled ATM tweaking program now in 
> progress.
> :-)

:)

Avi


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