Legacy systems always have some ugly limitations that people have to work
around.
Look at the Intel x86 processor architecture with the evolution of segmented
addressing
compared to the 68000, SPARC or PowerPC which people claimed would clearly
replace the ugly x86 because of the more modern, clean, massive virtual memory
address architecture and clean RISC instruction set decoding...
....when is the wide-spread replacement for the x86/Pentium scheduled ?
When is the year of the C(_at_)t ?
http://www.ddj.com/articles/1993/9310/
http://maccentral.macworld.com/news/0208/25.jaguar.php
Jim Fleming
2002:[IPv4]:000X:03DB:...IPv8 is closer than you think...
http://www.iana.org/assignments/ipv4-address-space
http://www.ntia.doc.gov/ntiahome/domainname/130dftmail/unir.txt
----- Original Message -----
From: "Jason Gao" <jag(_at_)kinet(_dot_)com(_dot_)cn>
To: "vinton g. cerf" <vinton(_dot_)g(_dot_)cerf(_at_)wcom(_dot_)com>; "Fred
Baker" <fred(_at_)cisco(_dot_)com>
Cc: <ietf(_at_)ietf(_dot_)org>
Sent: Friday, September 06, 2002 12:15 AM
Subject: Re: Fuzzy-layering and its suggestion
Thanks for the comment!
I didn't mean to blaim that TCP and IP is not 'clear' ( I should have used
the word 'stern', or some other word not so
commendatory as 'clear') layered. What I really wanted to say is that I prefer
the choice, because I think it is a positive example
of fuzzy-layering.
Thanks for the comment again!
----- Original Message -----
From: "vinton g. cerf" <vinton(_dot_)g(_dot_)cerf(_at_)wcom(_dot_)com>
To: "Jason Gao" <jag(_at_)kinet(_dot_)com(_dot_)cn>; "Fred Baker"
<fred(_at_)cisco(_dot_)com>
Cc: <ietf(_at_)IETF(_dot_)ORG>
Sent: Friday, September 06, 2002 12:30 PM
Subject: Re: Fuzzy-layering and its suggestion
this was a choice made long ago to increase by a small amount the
efficiency of the representation of the two layers. Keep in
mind that IP was split off of TCP in version 3 of the protocol. They were
originally combined.
vint cerf
At 09:00 AM 9/6/2002 +0800, Jason Gao wrote:
Well, I should have cited another instance. What the TCP checksum protects
includes the pseudu-header which contains the source
and the destination IP address. Transport address in TCP (and SCTP) contains IP
address. Clearly the IP address is not stored in the
transport layer header. IMHO it is not an instance of clear layering.
Vint Cerf
SVP Architecture & Technology
WorldCom
22001 Loudoun County Parkway, F2-4115
Ashburn, VA 20147
703 886 1690 (v806 1690)
703 886 0047 fax