Subject: RE: draft-kurtis-multihoming-longprefix comments

From: "Tony Li" <[email-masked]>
Date: Tue, 7 Jan 2003 17:28:53 -0800

|   The 
|   forced address
|   change approach simplifies routing by moving the complexity to the
|   endpoints.

You say that like it's a bad thing.  Please remember that in the world
where every home has a different provider all using their unchangeable
addresses, we end up with host routing.  And we're NOT going there.

Ya know, geographic addressing works because three space forces you
into geographic connectivity.  If there was a rift in three space as 
often as there is in cyberville, we wouldn't be doing geographic addressing
there either.  You just couldn't get there from here.

|   Which is easier, 
|   building a
|   routing system that scales to several billion entries, or 
|   silicon that
|   is good at counting? 

Anything that scales to several billion anythings is currently not
in the reach of silicon.  They are the same: both intractable.

|   I understand how they did it (my desk phone has a Bellevue 
|   & San Jose
|   number), the point was that is the type of service Joe 
|   Sixpack expects,
|   yet it doesn't scale in the routing system.

If you understand that it doesn't scale, then why are you advocating
it?

|   > To do the equivalent in the Internet, we'd have to allow 
|   > people to emit packets with a "virtual" address in them 
|   > (let's call them Effective Internet Demultiplexors, or EID's, 
|   > for short), and then some router would have to do the mapping 
|   > and stick on the actual address.
|   > 
|   > I have in the distant past proposed doing exactly that, but 
|   > people didn't like the idea.
|   
|   In an abstract sense, 8+8 (maybe 16+16) does the same thing.

Yes, they both do.  People still don't like 'em cause they're 
"not the IP way."

|   I am not picking on anyone, just trying to point out that 
|   the average
|   network manager doesn't really have a clue how complex this is, and
|   wouldn't laugh at the concept of addresses that are 
|   consistent across
|   provider changes.

We are first trying to achieve consensus amongst those who should
know a sensible architecture.  If we can say "here's how it will be"
then selling Joe sixpack on it is much easier.  If we continue
having to have this same discussion with you for another decade,
we will not move one iota from where we are today.

|   The point is we did not solve the problem, we just moved it. 

We have no choice but to move it.  Multihoming cannot be solved
soley by routing without architectural change in a scalable manner.

|   If the address were independent of 
|   delivery and
|   the remote routing mechanism only dealt with cities, Joe's 
|   would have to
|   bring it to Seattle to figure out what to do with it.

And that would be a fine abstraction if that had anything to
do with reality.  Unfortunately, geographic addressing has
about as much to do with topological connectivity as common
last names have to do with street addresses.

Tony

---

From: "Tony Hain" <[email-masked]>
Date: Tue, 7 Jan 2003 18:13:38 -0800

Tony Li wrote:
> You say that like it's a bad thing.  

Not intentionally. It was just a statement that the complexity has been
moved, not removed.

> ...

I bring it up because it is not significantly different than other
mapping schemes that have been proposed. We know it doesn't scale, and
it is only done once at call setup rather than per packet.

> ...

If by 'IP way' you mean that it is a change to the expectations apps
have of the underlying architecture, then I have to agree. It is not
clear to me that 16+16 is visible to apps, so maybe that doesn't apply.

> ...

You seem to think I am being obstructionist. I am not.

> last names have to do with street addresses.

And when I am in Japan connecting to home, topological detail of Seattle
has absolutely nothing to do with which service provider I hand packets
to. The fact the destination is Seattle rather than San Francisco might
have something to do with a trans-pacific cable choice, but the cable &
dsl providers are present in both so PA doesn't really help with TE
there. Once the radius is reduced to 1000km, the number of possibilities
increases dramatically, but outside that range there are really very few
choices. Why should all DFZ routers outside that range know the details?

Tony