Subject: Re: a response to "A Simple Solution for IPv6 Multihoming"

From: Dan Lanciani <[email-masked]>
Date: Wed, 22 Sep 1999 14:46:38 -0400 (EDT)

Jim Bound <[email-masked]> wrote:

|No.  It is not to any specific proposal.
|
|What is the draft name of your proposal?

It has no name.  It is merely a simple model I proposed to this list in
response to the need for portable identifiers in support of multi-homing,
session stability, etc. under the constraint that routable addresses will
likely never be portable.  I don't claim that it is the only or even the
best (or even a good) model, but I was hoping to move beyond the ``we don't
know any way to do it'' stage with an example.  You can refer to my previous
couple of postings for the details.

|In Ipv6 we don't have identifiers.

Exactly.  I proposed to add them in such a way that presents no load to the
backbone routers, requires no changes to applications or protocols above IP,
and which could probably (with a little fiddling) interoperate with nodes not
participating in the protocol.

|If anyone wants to swap the IP address and fake out the upper layers
|that is bogus but I will reiterate further if I see such an idea.

I don't want to swap IP addresses per se; I want to swap an IP address
with a different identifier drawn from a separate address space that
happens to be the same size as the routable IP address space (merely
to make the operation transparent to higher levels).  N.B. the portable
identifiers never appear in an IP header on the wire so it isn't even
really a ``swap'' so much as allowing higher levels to use the portable
identifier as a handle.

|We have permitted that with mobile IPv6 but that is because of ingress
|filtering.  Doing this in an IP stack implementation is like running
|your care with the wrong oil weight for different seasons.

Sorry, I don't understand the analogy...

				Dan Lanciani
				[email-masked]
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From: Jim Bound <[email-masked]>
Date: Thu, 23 Sep 1999 16:17:48 -0400

Hi Dan,

>couple of postings for the details.

OK I found 1 posting which I will read.

>participating in the protocol.

OK will read.

>really a ``swap'' so much as allowing higher levels to use the portable

I will respond if I don't get it.

>Sorry, I don't understand the analogy...

Last sentence had typo.  "care" should have been "car".  But...
In IPv6 mobile when you send a packet in some instances the
implementation must use an address which passes ingress filtering and is
done at the virtual network layer.  See the IPv6 mobile spec.

I am concerned when we are asked as network implementors who ship
products that we have to alter addresses in transit on an end system
(not router) that was not specifically requested by the application
layer, in the network layer (or anywhere in the virtual stack we speak
of in the kernel of an OS).  We can do it but we need to be very careful
in doing so and should look for alternatives to any models that propose
such a strategy.  I was likening it to a automobile that can use a
heavier weight oil in its engine during the summer months, but could
have negative affects to the overall engine when temperatures get really
hot like 90-100 degrees F'.  It is nitpicking but thats what I do as an
engineer.  Its like my performance ranting in IPv6 when folks want to
add a little code here and a little code here.  For example if we loose
10 milsecs for mobility, 100 milsecs for addr selection, 200 milsecs for
NUD in ND, 3000 milsecs for some transition scheme, 50000 milsecs for
IPsec, etc. etc. etc while designing the outer edges of the IPv6 core we
eventually will loose 50 seconds or more adding it all up.  I look at
IPv6 as an engineer with a Gestalt hat on and look at the big picture or
as some say get off the playing field and sit in the grandstands once in
awhile.  This will be very important to do for multihoming fixes,
renumbering, security, and changing addresses on the fly.  Which I do
see you do not propose by the way on my first read of your mail message.

One reason I rant is a business reason.  If IPv6 does not perform as
equally as fast as IPv4 it is dead.  No matter how many better
functions we put in the protocol architecture, except for IPsec and
other security which some of the market are willing to take a
performance hit on (but not all and some won't use it).  I don't agree
with this personally because I think IPv6 is so superior to IPv4 its not
even a race technically.  But I am not and cannot be a salesman or
marketeer so I go with the flow and the flow is right now IPv6 cannot
perform worse than IPv4 for anything.

thanks
/jim