Subject: Re: Bash IETF, not RIRs

From: Iljitsch van Beijnum <[email-masked]>
Date: Tue, 11 Nov 2003 16:50:49 -0600

On 13-okt-03, at 5:23, Iljitsch van Beijnum wrote:

> Back to your idea of having a full routing table in each host. We've 
> talked about this and things haven't changed in the mean time. Without 
> aggregation, this makes sense, as a host then knows what's reachable 
> and what isn't, and maybe even gets to determine which path to a 
> certain destination is shorter. But all this very useful information 
> is hidden behind aggregation. For instance, if you want to determine 
> whether you want to reach me through my 3ffe:2500:310::/48 or my 
> 2001:888:1dde::/48 prefix, you're not going to be able to see whether 
> those are reachable, as the /48s aren't going to be in the global 
> routing table, just 3ffe:2500::/32 and 2001:888::/32.

---

From: Masataka Ohta <[email-masked]>
Date: Wed, 12 Nov 2003 09:01:03 +0900

Iljitsch;

>> talked about this and things haven't changed in the mean time.

Read the draft before talking or things won't change in your mind.

   With regard to multihoming, when an end system want to communicate
   with a multihomed end system, the end system must be able to select
   most appropriate (based on the local information) destination address
   of the multihomed end system.

   However, some think it of course to separate routers and nodes and
   let hosts not have routing information (which means the current IPv6
   architecture is broken) and, worse, let most routers use default
   routes.

   With detailed route information, end systems can use the information
   as a hint to select the best destination address.  However, with
   default route, end systems have no idea on what is the best address
   and must blindly try all the possibilities at random.

>> Without 

If routing system tells you that some address is not reachable,
which is impossible with a default route, the address is not
reachable.

But, don't expect routing system offer more accuracy.

Aggregation is not essential.

Even if you use host routes, exsiting of a host route does not
guarantee that the host is reachable. It may be just a result of
misconfiguration.

Routing systems give hint to help hosts make efficient decisions.

Note also that this is not the only reason to have full routing table.

The fundamental reason is because it is end to end.

							Masataka Ohta

---

From: "marcelo bagnulo" <[email-masked]>
Date: Wed, 12 Nov 2003 08:48:32 -0600

> Aggregation is not essential.

I guess this is not really what you mean. aggregation is essential to
provide scalability of the routing system, as your draft about ISP
multi-homing explains (sort of)

> Routing systems give hint to help hosts make efficient decisions.

Well i guess that the question then is it is worth it...
If the table is very aggregated, you don't really have much information
If it is not, the amount of information is huge and it is very expensive for
a host to store it
And all this effort, just for a hint.
You will need another mechanism that actually detects and define which
address to use, so why don't you just use it in the first place?

Regards, marcelo

---

From: Masataka Ohta <[email-masked]>
Date: Thu, 13 Nov 2003 00:11:15 +0900

marcelo;

> multi-homing explains (sort of)

Aggregation is not essential cause of the concern of Iljitsch.

> If the table is very aggregated, you don't really have much information

If the table have only a single entry, yes.

> If it is not, the amount of information is huge and it is very expensive for

My presentation yesterday quantatatively showed you are totally wrong.

							Masataka Ohta