Subject: Re: IPv4 vs MAC

From: "Jose Manuel Arronte Garcia" <[email-masked]>
Date: Thu, 26 Jul 2001 18:52:50 -0500

Thank you all for your accurate comments...

> 1. the Internet has may different lower layers;
>    not everything in the Internet uses a MAC address

I am aware not everything uses a MAC address, Yes, as K. Hamzed said, for
example, WAN links don't use them...

>
> 2. MAC addresses are not routable.  there's no way for me to find
>    out how to route a packet to your Ethernet even if I have your
>    MAC address
>

I may have not expressed correctly, what I meant is:

If the used 48-bit addresses in lower layer protocols, why they did not use
48-bit routing-enabled addressing for the Internetwork layer? Not just use
the very same addresses as I may have implied (I DO NOT mean that). After
all, they were using 48-bit addresses already.

Thanks.

Saludos.
Regards.
_________________________________________
José Manuel Arronte García
Supervisor de Soporte Técnico Helpdesk

Meg@Red Veracruz
Telecomunicaciones y Entretenimiento SA
Av. S. Díaz Mirón 2625-A
Fracc. Moderno
Veracruz Ver. MÉXICO

http://www.megacable.com.mx
http://www.megared.net.mx

---

From: [email-masked]
Date: Fri, 27 Jul 2001 00:54:19 -0400

> all, they were using 48-bit addresses already.

First off, 32 was probably chosen because it was a number of octets(*)
that fit nicely into a register.  Dealing with 48 gets more interesting.

Secondly, at the time, a 9600 baud leased line was a *high speed* link,
and 56KB was "long haul backbone link".  The added 4 bytes/packet would
be noticable at that speed.

Third, they were doing a new design, and the old one (NCP) had a 256
host limit.   I wasn't there, but I bet '4 billion will be PLENTY' was a
common sentiment - and understanding the amount of address space wasted
by subnetting and the eventual need for CIDR so routing tables could be
aggregated were still a decade down the road.

				Valdis Kletnieks
				Operating Systems Analyst
				Virginia Tech

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From: "Jim Fleming" <[email-masked]>
Date: Fri, 27 Jul 2001 02:39:00 -0500

----- Original Message -----
From: <[email-masked]>
> be noticable at that speed.

In my opinion, adding any useless bits or bytes in the IP headers is not a
good thing.
With IPv16, we move the 4 bit version number out, as an implied constant. If
one
is connected, they assume that version. It makes no sense to waste 4 bits in
each
packet for a constant version number.

In the same 20 byte foot-print, various trade-offs yield more space for
address bits.
IPv4 is clearly very wasteful.

IPv4 - 40%
IPv8 - 59%
IPv16 - 80%

Jim Fleming
http://www.unir.com/images/architech.gif
http://www.unir.com/images/address.gif
http://www.unir.com/images/headers.gif
http://www.ntia.doc.gov/ntiahome/domainname/130dftmail/unir.txt
http://msdn.microsoft.com/downloads/sdks/platform/tpipv6/start.asp
http://www.ietf.org/mail-archive/ietf/Current/msg12213.html
http://www.ietf.org/mail-archive/ietf/Current/msg12223.html

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From: Robert Elz <[email-masked]>
Date: Fri, 27 Jul 2001 15:40:53 +0700

Date:        Fri, 27 Jul 2001 00:54:19 -0400
    From:        [email-masked]
    Message-ID:  <[email-masked]>

  | First off, 32 was ...
  | Secondly, at the time, a 9600 baud leased line ...
  | Third, they were doing a new design, and the old one (NCP) had a 256
  | host limit.   I wasn't there, but I bet '4 billion will be PLENTY' ...

And of course, when IP was designed, 48 bit MAC addresses didn't exist
yet, so using them (even as any kind of hint as to how big addresses might
want to be) would have been an interesting achievement.

Does no-one else still recall the world before ARP, where MAC addresses
(ie: the old 16 bit things that 3Mbit ethernet used) were embedded in the
bottom 16 bits of your class B address (no-one had anything smaller than
that of course...)

kre

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From: "Jim Fleming" <[email-masked]>
Date: Fri, 27 Jul 2001 05:05:50 -0500

----- Original Message ----- 
From: "Robert Elz" <[email-masked]>
> bottom 16 bits of your class B address (no-one had anything smaller than

http://www1.ietf.org/mail-archive/ietf/Current/msg12458.html
RFC-2001-06-24-000 - 2001 A Space Odyssey

http://www.networksorcery.com/enp/rfc/rfc25.txt
"Because it may be desirable to reserve one or more link numbers for
instrumentation purposes, and because 256 link numbers are many more
than are needed, we suggest that no link number over 63 be used.  At
UCLA, we will implement our tables to take advantage of this limitation.
We also note that 32 may be even more realistic, but 64 is certainly
sufficient."
-------------

Jim Fleming
http://www.DOT-Arizona.com
http://www.DOT.Arizona
http://www.dot-arizona.com/IPv8/IPv4/

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From: "Balaji H. Kasal" <[email-masked]>
Date: Fri, 27 Jul 2001 17:02:04 +0530 (IST)

> packet for a constant version number.

why we are going from IPv6 to IPv16? 
Is there noway to modify our original alogrithums to take care? (I think
this surely creat problems in future!)

Worm Regards,
--balaji

-- 
--balaji

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From: "Jim Fleming" <[email-masked]>
Date: Fri, 27 Jul 2001 06:52:12 -0500

----- Original Message ----- 
From: "Balaji H. Kasal" <[email-masked]>
> this surely creat problems in future!)

You might want to start with IPv8.

Jim Fleming

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From: Lloyd Wood <[email-masked]>
Date: Fri, 27 Jul 2001 13:23:23 +0100 (BST)

> Secondly, at the time, a 9600 baud leased line was a *high speed* link,

9600 bps, dammit.

> and 56KB was "long haul backbone link".  

56 kbps, dammit.

L.

a baud is a symbol per second, NOT a bit per second.

<[email-masked]>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>

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From: John Stracke <[email-masked]>
Date: Fri, 27 Jul 2001 12:49:22 -0400

>why we are going from IPv6 to IPv16? 
We aren't.

-- 
/=================================================================\
|John Stracke    | http://www.ecal.com |My opinions are my own.   |
|Chief Scientist |================================================|
|eCal Corp.      |It's not an optical illusion, it just looks like|
[email-masked]|one.                                            |
\=================================================================/

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From: Steve Feldman <[email-masked]>
Date: Fri, 27 Jul 2001 11:29:04 -0700

> bottom 16 bits of your class B address (no-one had anything smaller than

Oh my, I remember writing drivers for those beasts
back in my UC Berkeley days.  (We had a class A!)

And wondering how to deal with those new-fangled 48 bit
MAC adddresses in 10 Megabit Ethernet.  I think I
started off just taking the low 16 bits, which worked
fine when there were only 100 or so Ethernet interfaces
in existence.  (The first ARP RFC didn't come out until
after I graduated.)

As I recall, Xerox's XNS protocol used the entire MAC address
as the protocol address, which made translation easy but
routing difficult.

I feel old...

	Steve

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From: "Jim Fleming" <[email-masked]>
Date: Fri, 27 Jul 2001 14:31:15 -0500

----- Original Message ----- 
From: "John Stracke" <[email-masked]>
To: <[email-masked]>
Sent: Friday, July 27, 2001 11:49 AM
Subject: Re: IPv4 vs MAC

> >why we are going from IPv6 to IPv16? 

IPv8 Addressing and IPv16 Addressing are compatible.

Jim Fleming

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From: "Jim Fleming" <[email-masked]>
Date: Fri, 27 Jul 2001 14:31:51 -0500

----- Original Message -----
From: "Steve Feldman" <[email-masked]>
To: "Robert Elz" <[email-masked]>
Cc: <[email-masked]>
Sent: Friday, July 27, 2001 1:29 PM
Subject: Re: IPv4 vs MAC

> as the protocol address, which made translation easy but

Keep in mind that the entire ARP, MAC empire on the Ethernet
takes a "broadcast" medium and turns it into a "point-to-point circuit"
medium. This allows the 48 bit addresses to be used for "local"
send-receive end-points for the next layer up, IP protocol which
looks to many people to be a "broadcast" (NON-point-to-point)
protocol.....but it's next layer up, TCP....turns the whole thing
back into a NON-broadcast Poinit-toPoint Circuit focus......

In summary....we have Ethernet, which people think is a "send-to-all"
"receive-from-all" technology, but that is negated in order to create
an *illusion* of an IP send-to-all, receive-from-all layer [which we
all know it is not], and then on top of all this, reliable TCP circuits
are created....and for performance, people end up trying to stuff it
all through "circuit-mentality" ATM....which many people view as
*bad*(tm).....because they want to believe the Internet is NOT
circuit-based but packet-based....

packet-based Ethernet ---> circuit-based via MAC, ARP, etc.
packet-based IPv4 ----> circuit-based via TCP

Jim Fleming