Subject: GSE

From: Iljitsch van Beijnum <[email-masked]>
Date: Fri, 1 Nov 2002 12:17:42 +0100 (CET)

There has been some talk about GSE in the past few days. Before anyone
gets too excited about this, let me point out some of the numerous
prolems with this approach:

- GSE doesn't provide any failover mechanisms but depends on tunnels to
  repair dead customer<->ISP links. This could be done just as easily
  with regular PA space.
- It is very unclear how GSE is supposed to work in a single host
  environment. Do hosts that don't sit behind a GSE-capable border
  router the GSE processing themselves or is this done by the ISP?
- It needs changes to transport protocols and possibly to intra-site
  routing and address discovery.
- The flat part of the identifier space makes locator discovery hard.

That being said, I think GSE could be a subset of a more general
approach. If you're going to map identifiers to locators one form of
these identifiers could have the first 48 bits set to 0, if the
identifier to locator discovery service is willing to go the extra mile
and provide mappings for individual 128 bit identifiers. Or you could
have 127 bit hashes as required by HIP. Or use an IPv4 or OSI NET
identifier with an IPv6 locator...

Being agnostic about the structure of the identifier is a good thing for
future extensibility. However, using identifiers with regular IPv6
unicast semantics will make the transition a lot easier as it allows
interoperability between multihoming-aware and non-multihoming aware
systems and/or providing the multihoming support in separate boxes.

---

From: Iljitsch van Beijnum <[email-masked]>
Date: Fri, 1 Nov 2002 14:02:45 +0100 (CET)

On Fri, 1 Nov 2002, Iljitsch van Beijnum wrote:

> unicast semantics will make the transition a lot easier

Question: would it be a desireable or even required property of an
identifier to be identifiable as such by all?

Obviously, the destination site or host would know whether one of its
addresses is an identifier or a locator. But would it be important for
others to be able to make this distinction? It might be good to avoid
trying to map a locator to a new locator. On the other hand, this means
identifiers have to come from a separate block of IPv6 address space
(assuming they look like IPv6 unicast addresses). This isn't (very)
compatible with an extra address negotiation solution or with
interoperation with non-multihoming aware systems.

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From: Masataka Ohta <[email-masked]>
Date: Fri, 1 Nov 2002 22:44:35 +0859 ()

Iljitsch;

> There has been some talk about GSE in the past few days.

Hugh? Really?

> Before anyone

GSE is an approach with intelligent routers and hopeless that please
refrain from wasting bandwith on it.

> approach.

Wrong. Any approach containing GSE as a subset is worse than GSE.

> However, using identifiers with regular IPv6

Transition from what? IPv4? OSI? Or?

Our 8+8 code interoperates with leagacy v6 one, but does it make
any sense?

							Masataka Ohta

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From: RJ Atkinson <[email-masked]>
Date: Fri, 1 Nov 2002 08:57:54 -0500

I think that Iljitsch's note is a fine reminder that different folks
have very different understandings of what the term "GSE" means.  A
point by point refutation seems pointless since it is clear he has
a different definition of the term than some other folks on this list.

Rather than have the group continue to wedge by using different 
definitions
for that term, it would be helpful if folks avoided that term, and 
instead
talked a bit more precisely about *their* intended meaning.

For my part, I agree with tli, jnc, and others that the best 
architectural
approach to supporting multi-homing while not hosing the operational 
routers
in the DFZ is to separate host identity from routing goop.

Ran
[email-masked]

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From: RJ Atkinson <[email-masked]>
Date: Fri, 1 Nov 2002 09:05:23 -0500

A reasonable approach is to say that the low order 64 bits of an IPv6
unicast address identify a host within a subnet and that the high-order
64-bits of an IPv6 unicast address identify the subnet itself.

This would both support tli's proposal and not be wildly inconsistent
with existing IPv6 specs.

Ran

On Friday, Nov 1, 2002, at 08:02 America/Montreal, Iljitsch van Beijnum

---

From: Iljitsch van Beijnum <[email-masked]>
Date: Fri, 1 Nov 2002 15:12:24 +0100 (CET)

> a different definition of the term than some other folks on this list.

I based my comments on "GSE - An Alternate Addressing Architecture for
IPv6" <draft-ipng-gseaddr-00.txt>, available at:
http://arneill-py.sacramento.ca.us/ipv6mh/draft-ipng-gseaddr-00.txt

---

From: "Robert J. Rockell" <[email-masked]>
Date: Fri, 1 Nov 2002 09:44:44 -0500 (EST)

->For my part, I agree with tli, jnc, and others that the best
->architectural
->approach to supporting multi-homing while not hosing the operational
->routers
->in the DFZ is to separate host identity from routing goop.

Agree fully.

->
->Ran
->[email-masked]
->
->

---

From: Iljitsch van Beijnum <[email-masked]>
Date: Fri, 1 Nov 2002 18:13:39 +0100 (CET)

> Wrong. Any approach containing GSE as a subset is worse than GSE.

With a solution that can work with any kind of structure for the
identifier it would be easy to implement GSE for those who still want
it, without betting all our cards on one horse or a cliche of similar
sentiment.

> Transition from what? IPv4? OSI? Or?

Transition from existing v6.

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From: Masataka Ohta <[email-masked]>
Date: Sat, 2 Nov 2002 10:43:26 +0859 ()

Iljitsch;

> it,

Wrong.

GSE is impossible to implement, not because of its structure for
the identifier but because of its ignorance of the end to end
principle.

> without betting all our cards on one horse or a cliche of similar
> sentiment.

GSE was a dead horse from the beginning.

It has been harmful for healthy horses.

> Transition from existing v6.

An interesting theory.

							Masataka Ohta

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From: Masataka Ohta <[email-masked]>
Date: Sat, 2 Nov 2002 10:38:11 +0859 ()

Ran;

> have very different understandings of what the term "GSE" means.

GSE is defined clearly with no different understandings except
for that you just invented.

Thank you for your creativity.

> in the DFZ is to separate host identity from routing goop.

There are several such proposals found in big internet mailing
list.

Call them 8+8 or 6+2+8 but not GSE.

Also, say "locator", not "routing goop".

As for GSE, it appeared much later but is hopeless.

GSE, for example, leaves dependency betwen identifier and locators.

							Masataka Ohta