Hi Stephane,

You asked the right questions. But I don't think I can give better/precise 
answers than the reply we already got.

Any ways, let me try -

> Why do you say that the gain is very minimal ?

(..per base draft, in real SP topologies) 9 out of 14 topologies showed very 
minimal gain with rLFA NP
and the remaining 5 topologies with limited improved coverage. Given the PQ 
explosion in certain topologies
to as many as more than half the number of nodes in the network, I don't think 
this gain is, in any way matching the
complexity of the proposal/performance impact at times in the network ..

>The gain is major, and it's not just a question of numbers ...

I don't think so. I think you have to explain why and how you think it's a 
major gain.

>.. NP coverage may be quite good depending of topology, it's not guaranteed

It's always good to be optimistic but number are speaking the other way.

> Would be also interested in why do you think the solution is complex ?

It's pumping complexity in the code base not only in terms of maintainability 
with
competing and interfering solution space  on the table from MRT to other 
technologies but
also due to the the heuristics proposed (are indeed fragile as indicated). 
Secondly, IMO,
though it's not mandatory to collect path characteristics (you also expect not 
only PQs but also
all the nodes to upgrade and advertise node admin tags to get these ?)  from PQ 
to destination,
overall it is bit of over engineering . This got to be simplified at minimum.
Probably this can be discussed later.
--
Uma C.

From: Alia Atlas [mailto:[email protected]]
Sent: Saturday, March 15, 2014 5:57 AM
To: Stephane Litkowski
Cc: Uma Chunduri; Alvaro Retana (aretana); [email protected]; 
[email protected]
Subject: Re: WG Adoption Call for draft-psarkar-rtgwg-rlfa-node-protection

Stephane,

A solution that requires or desires different heuristics depending upon the 
network topology is complex and somewhat fragile.

I also feel that we are in the realm of attempted partial solutions, each more 
complex than the previous one.  SPRING has the hope of making the rLFA approach 
simpler and without a concern for the computational load during convergence 
time (or alternately for the time that is unprotected),

That said, I know this is the path that you are all going down and that you see 
the trade-offs as acceptable.

Regards,
Alia


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