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From: dorner@pequod.cso.uiuc.edu (Steve Dorner)
Newsgroups: comp.sys.mac.comm
Subject: Re: FTP Sun<-->Macintosh using SLIP (TCP/CONNECT II)
Message-ID: <1991Feb14.220440.16265@ux1.cso.uiuc.edu>
Date: 14 Feb 91 22:04:40 GMT
References: <1CE00001.65w4j6@tbomb.ice.com>
Sender: news@ux1.cso.uiuc.edu (News)
Organization: University of Illinois at U-C
Lines: 35

>First off, you must realize that TCP runs ontop of UDP on top of IP.

No.  TCP and UDP (and ICMP, for that matter) are peers, both layered on
top of IP.

>(I believe this layering is not *mandatory* but is common place).

It is mandatory, in the sense that every valid TCP packet is contained
in a valid IP packet; ditto for UDP.  It is not mandatory in the sense
that someone with strange ideas might not implement things as separate
layers.

The rest of what you say looks ok, if you everywhere replace "UDP" with "IP".

>I do not believe FTP adds any overhead in the data stream.

The overhead it adds to the data stream varies from negligible to none;
the CPU overhead on both ends of the connection can be significant if one
is doing ASCII mode transfers.

>When you start adding the overhead bytes, things get inefficent.
>Compared to ZMODEM blasting a data stream anything else will seem
>slow. BUT ZMODEM will not connect you with sumex-aim archives either!

Right; you pay for the flexibility of TCP/IP with overhead; you pay for
the efficiency of ZMODEM with very, very limited functionality.

>Again, pick the best tool for your job.

Right again.  FTP over SLIP is a silly thing to use if all you want to
do is transfer files.  If you also want to login or use mail or news, then
SLIP is the way to go.
--
Steve Dorner, U of Illinois Computing Services Office
Internet: s-dorner@uiuc.edu  UUCP: uunet!uiucuxc!uiuc.edu!s-dorner