Subject: RE: IPv4 link-local (was unrelated subject line)

From: Stuart Cheshire <[email-masked]>
Date: Fri, 13 Dec 2002 16:25:21 -0800

>The real argument for IPv4 link-local cannot be to provide hosts
>with new features -- we have IPv6 for that. The only argument is
>some form of compatibility with legacy IPv4 only devices. But if
>you focus on legacy, then you don't want to deal with stuff that
>the legacy cannot handle well, e.g. having multiple addresses per
>interface, or having multiple subnets on the same link. (Or, for
>that matter, playing game with the TTL value.)

I don't know any current mainstream OS that can't handle two addresses on 
an interface.

I don't know any current mainstream OS that can't handle two subnets on 
the same physical link.

I don't know any current mainstream OS that can't set the IP TTL to 255.

The point of networking is not just to talk to other copies of your own 
product (that part is easy), but to talk to all the other products out 
there. If we only cared about Macs talking to other Macs, then IPv6LL on 
every interface would be fine, but Macs need to talk to a whole bunch of 
much simpler devices too, so that's why we need v4LL too.

Stuart Cheshire <[email-masked]>
 * Wizard Without Portfolio, Apple Computer, Inc.
 * Chairman, IETF Zeroconf
 * www.stuartcheshire.org

---

From: Keith Moore <[email-masked]>
Date: Fri, 13 Dec 2002 19:46:27 -0500

> If we only cared about Macs talking to other Macs, then IPv6LL on

if you're optimizing for simpler devices, v6LL is even simpler to 
implement than v4LL.

more generally, v6 autoconfiguration is simpler to implement than v4
DHCP.

Keith

---

From: "John C. Welch" <[email-masked]>
Date: Fri, 13 Dec 2002 19:51:35 -0500

> more generally, v6 autoconfiguration is simpler to implement than v4

You're missing a point of market reality. There is no home commercial IPv6
market. None. Period. In five years, this will not be the case. But if you
wait five years to make Ethernet start replacing Usb for things like low end
printers, then it's another two years to get stuff in hand.

IPv4 gets cheap networkable stuff out there NOW, so that upgrading to IPv6
really IS trivial.

john

-- 
John C. Welch
Consultant III
Administrative Computing
(617) 253 - 1368 work
(508) 579 - 7380 cell
bynkii2          AIM

---

From: "John C. Welch" <[email-masked]>
Date: Fri, 13 Dec 2002 19:48:53 -0500

> I don't know any current mainstream OS that can't handle two addresses on

There are too many v4 web servers using single link multihoming to take
Keith's argument seriously here.

john

-- 
John C. Welch
Consultant III
Administrative Computing
(617) 253 - 1368 work
(508) 579 - 7380 cell
bynkii2          AIM