Subject: Re: RSVP-TE: specifying links in EROs

From: David Charlap <[email-masked]>
Date: Thu, 01 Dec 2005 10:25:56 -0500

Tony Li wrote:
> 
> I'm unsure of the point that you're trying to make.  The semantics of
> the ERO has been clear to numerous implementors along the way, as
> you yourself have noted.  Simply put, if the path does not traverse
> the link specified by the IP address, then it has not traversed the
> appropriate abstract node.

The prioblem is that this is not stated anywhere.  It is an unwritten
assumption.  Designing products based on unwritten assumptions is a bad 
idea.  Not everybody assumes the same thing, creating interop problems.

-- David

---

From: Tony Li <[email-masked]>
Date: Thu, 1 Dec 2005 09:36:52 -0800

> assumption.  Designing products based on unwritten assumptions is a  
> bad idea.  Not everybody assumes the same thing, creating interop  
> problems.

David,

To be sure.  All natural language specifications are subject to  
interpretation and thus possible misunderstanding.  Until the day  
that we are ready to write our specifications in denotational  
semantics (or its logically equivalent successor), we will continue  
to have semantic ambiguity.  Our approach
so far, as both an industry and as a international community, is to  
avoid such rigor due to its inherent overhead.  As a stopgap, we  
communicate with each other, again in crude natural languages, in an  
attempt to clarify documents before publication and resolve questions  
afterwards.

Regards,
Tony

p.s. When the world is ready, I propose Plotkin's operational  
semantics.  But then I'm biased...