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From: BILLW@MATHOM.CISCO.COM (William "Chops" Westfield)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Are Commercial TCPs Berkeley Code Or Custom?
Message-ID: <12609238094.10.BILLW@mathom.cisco.com>
Date: 28 Jul 90 10:13:33 GMT
References: <32140@cup.portal.com>
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The Internet
Lines: 47


    Are most of the commercial TCP/IPs sold by companies like Wollongong,
    Excelan, and FTP software written from scratch, or is the code
    basically just modified Berkeley code?

I would expect that most of the "large computer" commercial tcps are based
on some version of the Berkeley code.  Most of the PC TCPs are probably
based on the MIT PC/IP code, although these have mutated more.


    Why is it so difficult to write a good TCP/IP?

It's not.  But it isn't easy either.  Read the Host Requirements RFC
sometime.  It's much easier to copy code from someone who has it almost
right than to start from scratch.  I once made a bunch of improvemets to
the TCP for top20, but I reached the point where it would be easier to
port berkeley code than to start from scratch to implement some new
useful features. (Even though it would have meant figuring out a way
to integrate C into an all assembler OS.  Fortunately, I got a different
job about then... :-)

    I am amazed that there are companies whose entire R&D seems to center
    around writing the TCP/IP protocol and supporting applications.  Is it
    really that difficult?

Well, entire companies have been know to support applications that DON'T
involve a network.  It is clearly more difficult if there is a network too.
People want their applications (and their networks) without having to
understand anything about the underlying technology.  Making the network
invisible is very hard.  I wish more comercial companies put effort into
it.  (There ought to be a mail system easier to install than sendmail...)


    You would think that if you started with the Berkeley stuff it
    wouldn't be that difficult to improve it, or do legal restrictions
    prevent you from using the Berkeley stuff as a base?

Berkeley TCP/IP was (is?) developed under government contract, which makes
it pretty much available.  The problem used to be the pieces of unix that
it contained.  Of course, porting the code to a non-unix environment presents
opportunities for numerous bugs to creep in.  And keeping up with the rate
of change the tcp code goes through is pretty tough too.  And if you're
talking about improvements to the applications, you have to remember that
"improvement" is in the eye of the beholder...

BillW
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