🚀 go-pugleaf

davidsen@crd.ge.com (bill davidsen) writes:
>honey@citi.umich.edu (Peter Honeyman) writes:
>| william E Davidsen writes:
>| |>   Greater packet overhead, I suspect. Are you using uucp spoofing to
>| |> eliminate sending all the overhead on the wire? S111.
>| 
>| this perpetuates a myth regarding telebit uucp spoofing.  it is
>| false.  the 'g' headers are *not* stripped, they are sent from one
>| modem to the next. 
>
>  Can you expand on that? From stats I keep I see an improvement in
>performance using spoofing, so I'm not sure exactly how this "myth"
>influences my numbers. My reading of the Telebit info leads me to
>believe that the acks are locally generated, never sent between modems,
>and that parts of the headers are compressed, fiddled, and/or stripped
>such that they reduce the bits going over the wire.
>

No fiddling takes place, except when you have the modem's compression
turned on, which doesn't count.  The compression algorithm doesn't
handle the packet headers any differently than any other sequence of
bytes.

>
>  I willing to believe that Telebit might state something not true, or
>that I might misread their description, but I find it hard to believe
>that would confuse my scripts which read the data and tell me what's
>happening for transfer rates.
>

When I joined Telebit tech support, my supervisor and the senior tech
both told me spoofing stripped the headers.  Not just for uucp, but for
Kermit and X/Ymodem also.  Months later an engineer corrected me on this
point, and I've recently had the chance to examine the source code with
my own eyes.

The modem does not alter data packets in any way.  No headers are stripped.
The only headers that are altered are INITA and INITC, when the protocol
starts up.  That's how the modem forces the window size to 3.

Why did Tech Support erroneously think the modem stripped the headers from
the data packets?  Probably someone told them it did, years ago when they
were first trained on the new spoofing features.  One small slip, a phrase
worded a little too vaguely, and the myth is born.


As far as transfer rates are concerned, we're talking apples and oranges.
Telebit spoofing doesn't strip headers to make uucp run faster.  It acks
packets more quickly, allowing the packets to flow in a steady stream
without pauses.  Like Zmodem does.


-- 
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 |  Greg Andrews   |       UUCP: {amdahl,claris}!netcom!gerg        |
 |                 |   Internet: gerg@netcom.COM                    |
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