RE: draft-kurtis-multihoming-longprefix comments

["J. Noel Chiappa" <jnc@ginger.lcs.mit.edu>]

    > From: "Tony Hain" <alh-ietf@tndh.net>

    >> about "provider-independent addresses", AKA "connectivity- independent
    >> addresses".
    >> This is pretty much like asking for a street address that stays the
    >> same even when you move.

    > No, it is asking for the same address to work when USPS, UPS, FedEx, the
    > pizza guy ... service providers deliver the packets.

No, it's *not*, Tony - which is not to say your point above (modulo the pizza
guy, who's an application, not a service) is not also true.

Why you are having such a hard time with this seemingly simple concept is
really starting to frustrate me (which I concede tends to make me awfully
cranky), but let's try it again.

When some host stops buying service from provider X and starts buying it from
provider Y, you wind up running a wire from that computer to *different place*
on the network - to the infrastructure of provider Y. **That host has, from
the point of view of the rest of the network, moved to a new location on the
network**.


    > Mixing the concept of service provider and connectivity is what makes it
    > so hard for the average network manager to understand why his address
    > has to change when he changes providers.

It's precisely because the service provider *provides the connectivity* that
the address has to change. That's the *service* they are providing - the
connectivity.

    > In 'the real world' the connectivity (street) is separated from the
    > service provider.

The *street* is the connectivity service - and moreover, it's one that all
"resellers" (UPS, UPS, FedEx) are allowed to use *for free*. So your analogy
breaks down here.

You have a slightly better case for this analogy in what's happening on some
cable TV systems, where you can sign up with one of multiple providers, but
you keep the same cable TV hookup. Still, even in these cases, when you switch
providers, from the point of view of the rest of the network you're moved
somewhere else (in that you're "attached" to provider Y, not provider X as
before), which is why your address has to change.

We don't have any way to assign that cable TV network a single address, *and*
ensure that incoming traffic to host Q goes over the network that host Q is
paying money to.


    > The phone system allows this (for a price), so people expect it to be
    > possible from the 'more powerful' Internet.

The way the phone system did this is they jacked up the phone system naming
layers by one, and slid a new one in underneath, one which is your real
"physical" phone number (I don't know the actual jargon terms the phone guys
use here), and the number you give everyone is now (effectively) a "virtual"
phone number.

Then they maintain a big mapping database which converts from virtual phone
numbers to actual phone numbers.

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 any rational discussion of addressing, the phrase
    >> "provider-independent addresses" ought to receive the same reception as
    >> "location-independent street address" - i.e.  something between concern
    >> (that the person needs to be institutionalized) and racous laughter (at
    >> the ludicrousness of it).

    > Only by routing gurus.

Look, the routing gurus *aren't* the people who designed a new network
architecture and put in only a single namespace. If you're pissed off, go beat
up the internetwork level architects.

    > The average network manager looks at 'the real world' where a large
    > number of services are available using a common street address, and the
    > anomaly of portable numbers in the phone system, and can't figure out
    > why the Internet is not even capable of those simple things.

If you persist in thinking that a tree sloth is a fish, you will of course be
upset that it doesn't have scales and fins.


    >> IPv6 adopted the IPv4 architecture lock, stock, and barrel, changing
    >> only the length of the address. This is touted as its great strength -
    >> in fact, it's its greatest weakness, and we see an example here.

    > The strength is that it is a model that people understand.

The model that everyone should give me a Ferrari is simple and easy to
understand. That doesn't mean it's either useful or workable.

    > Where it breaks down is that the decision leading to PA-only occurred at
    > the same time as CIDR.

Yes, and gravity and mass have no connection either.

    > a system where the multi-homing issues were pushed to the host (ie: out
    > of the DFZ routing space). Now that end site network managers are
    > getting a voice, they are pushing back and stating they don't want it in
    > the host.

Yeah, and no doubt car owners want cars that run an infinite distance on no
gas, too. I sure wouldn't mind one.


    >> *Don't* come ask for "location-indepedent street addresses".

    > People aren't asking for location-independent addresses, in fact they
    > are asking for the architectural equivalent of a street address.

Words fail me.

	Noel