I-D Action:draft-azinger-scalable-addressing-00.txt

[Brian E Carpenter]

Carlos,

On 2010-09-30 09:38, Carlos Morgado wrote:
> On Sep 29, 2010, at 7:38 PM, Tony Li wrote:
> 
>> On Sep 29, 2010, at 3:05 AM, Carlos Morgado wrote:
>>
>>> A decent ISP will have maybe 3 or 4 upstreams. On the all-PA scenario this means 3 or 4 prefixes to manage through the network.
>>
>> What we proposed was that ISPs get PI.
>>
>>
>>> I haven't seen any discussion about what this means to end users, do they get 4 prefixes on their home gateways ? This, as far as I know, isn't being covered in CPE development. In fact, the mass deployable equipments I know barely work with autoconfiguration of a single prefix let alone multiple prefixes. 
>>
>> If the end site is multi-homed, yes, exactly, there would be 4 prefixes.
>>
>> This is the architectural change that we need to make if we want to have scalable multi-homing.
>>
> 
> I meant end users of the ISP which you said above would get PI so problem solved there.
> On the end site scenario I'm pretty sure they just a) go with NAT b) push one of the prefixes upstream everywhere c) most likely both.

It all depends on the site. Roughly, I see three categories (ignoring
mobile customers for the moment).

1. Domestic or small office. They will do whatever their off-the-shelf
CPE does. But I expect the vast majority will, as today, have a single
ISP and will use whatever prefix the ISP gives them each time they reconnect
the CPE. PA for them, but they won't even know it. Running as pure clients,
or p2p nodes, they don't face any particular problem with PA.

Here we are talking about hundreds of millions to a couple
of billion customers world-wide. PI is unthinkable, but not needed.

2. Medium size businesses. They may be motivated to multihome, and
they probably run their own servers as well as pure clients. These are
the tricky ones, because the problems you and spz have described arise,
and there are a few million such businesses in the world. If they all
generate their own BGP4 announcement we are in serious trouble. Any RIR
policy that drives in this direction spells doom.

3. Large to very large businesses. There isn't much doubt they will
have problems with any solution except PI, but as long as there are
only a limited number of them (100,000 world-wide?) we can presumably
carry their prefixes.

Mobile customers will end up looking very like wired domestic customers,
under their carrier's PA prefix, although the reasons are different.
Here we are also talking about hundreds of millions to several billion
customers, so no PI please.

There is a problem if a domestic style customer has both a fixed and
mobile connection simultaneously. They are just going to have to
use two prefixes, but if they are pure clients this shouldn't be
too big a problem.

    Brian