Re: Last call for draft-ietf-tewg-interarea-mpls-te-req-01.txt

["Adrian Farrel" <adrian@olddog.co.uk>]

From Tony Li (tony.li@tony.li)

===

> I accept that full leakage of all TE information in a dynamic way 
> would almost certainly
> have a major impact on IGP scalbility.
>
> I do not accept that some carefully considered leaking of aggregated 
> TE information on a
> sparse timer basis would necessarily have such a dire impact.
>
> This is why I want the requirements draft to tell me what impact on 
> the IGP I am allowed
> to have and leave CCAMP to derive a solution that fits that 
> requirement. I don't think it
> is right to tell CCAMP what solutions it may or may not consider.

Operator hat on:

I would very much like to see it be a requirement that no information 
is leaked without specific configuration.  Further, I would very much 
like to see implementations give us reasonable granularity (and 
reasonable abstraction) in what we choose to leak.

As an example, I would like to be able to leak detailed topology 
information from my IS-IS L2 database down into an L1 area.  
I would NOT want to leak bandwidth information.  I would want
to leak an abstraction of another L1 area down into an L1 area, 
but I would definitely want that to be an abstraction, NOT the 
full database.
 
 I am not interested in perfect optimality.  I am interested in what can 
 be achieved with a limited amount of overhead.  It is very clear that 
 there cannot be any improvements without some impact on IGP 
scalability.  If nothing else, every byte in an LSA/LSP counts 
towards router memory consumption.  Thus, we have a tradeoff that
we need to make and perfect optimality is not a reasonable goal in
light of limited scalability.  Good returns can be had by leaking 
information that is topologically "close by" and abstracting distant
information.  
 If necessary, this can be supplemented by path manipulation along 
the way.
 
 Regards,
Tony