Subject: RE: last thought on complex aggregation

From: "Natale, Jonathan" <[email-masked]>
Date: Thu, 17 Oct 2002 14:43:56 -0400

Jeff,

Since there are no implementations that do complex aggregation, then your
scenario will probably never happen.  Removing complex aggregation from the
spec is so that nobody takes the trouble of coding it.  So far, the lone
implementer (that I am aware of) was QoSnetics/Qbot/Router tester; they
wrote a test (expecting the complex type of aggregation) which failed for
all known (by me at least) "real" implementations (note that they mis-read
RFC1771/Draft-10, which indicated that simple aggregation is sufficient
also).  Nobody "fixed" their code based on this test, or we would not be
having this conversation.

Also, what would happen in a real network with this type of aggregation???
--We don't know.  I think that is the main point.

:-)

-----Original Message-----
From: Jeffrey Haas [mailto:[email-masked]] 
Sent: Thursday, October 17, 2002 1:45 PM
To: [email-masked]
Subject: last thought on complex aggregation

I finally remembered what was bothering me about removing complex
aggregation from the spec.

If it is removed, people who do conformance tests and some implementations
may take this to mean "it shall be illegal to have an AS_PATH that contains
a SEQUENCE of a particular type after a SET".

This would make a perfectly ok AS_PATH into one that isn't legal, even if no
implementation currently generates it.

-- 
Jeff Haas 
NextHop Technologies

---

From: Jeffrey Haas <[email-masked]>
Date: Thu, 17 Oct 2002 14:49:19 -0400

On Thu, Oct 17, 2002 at 02:43:56PM -0400, Natale, Jonathan wrote:
> Nobody "fixed" their code based on this test, or we would not be

IMO, that particular test should have been "can a router accept
a packet of this form (complexly aggregated) and still work"?

> --We don't know.  I think that is the main point.

IMO, things would work fine so long as people could accept packets of 
that form.

-- 
Jeff Haas 
NextHop Technologies

---

From: "John G. Scudder" <[email-masked]>
Date: Thu, 17 Oct 2002 14:59:10 -0400

I have the same opinion about removing "complex aggregation" as Jeff 
-- I'm not thrilled but on the other hand I see no serious harm that 
will be caused by doing so.

I am assuming that people will follow the "be liberal in what you 
accept" dictum and accept any reasonable AS path.  IMO an 
implementation that rejects an AS path of the form 
(sequence)(set)(sequence) simply because the RFC doesn't spell out 
how to form one, is an implementation which is trying to be too 
clever by half.

In other words, as long as the spec doesn't explicitly make such AS 
paths illegal, I don't think any permanent harm will have been done.

--John

---

From: Jeffrey Haas <[email-masked]>
Date: Thu, 17 Oct 2002 15:03:52 -0400

> paths illegal, I don't think any permanent harm will have been done.

Amen.

-- 
Jeff Haas 
NextHop Technologies

---

From: Yakov Rekhter <[email-masked]>
Date: Thu, 17 Oct 2002 16:40:02 -0700

Jeff,

> > paths illegal, I don't think any permanent harm will have been done.

With this in mind let's consider this issue closed (section on
complex path aggregation will be removed).

yakov.