Hi Alia,

Many thanks for your review, I will address them shortly and publish a new 
version.
Some comments inline.


Best Regards,

Stephane

From: rtgwg [mailto:rtgwg-boun...@ietf.org] On Behalf Of Alia Atlas
Sent: Thursday, June 04, 2015 23:44
To: rtgwg@ietf.org; draft-ietf-rtgwg-lfa-manageabil...@tools.ietf.org
Subject: AD Review of draft-ietf-rtgwg-lfa-manageability


As is customary, I have done my AD Review of this draft.   Thank you for a 
clearly written and well thought out draft.

I do have some minor concerns,  as below, but I am also letting this draft move 
to IETF Last Call while they are addressed.   I will need an updated draft by 
June 18, so the draft can go on the IESG telechat on June 25.

Minor comments:

0)      This draft has 6 authors.  Please prune down to 5 or assign an editor 
or two.

[SLI] Everyone listed worked hardly on the text as well as on specifications, I 
will put myself as editor to keep everyone ☺.

  1) In section 6.2.1, it says " When selecting the best alternate, the 
selection algorithm MUST
      consider all available alternates (connected or tunnel).  Especially,
      computation of PQ set ([I-D.ietf-rtgwg-remote-lfa]) SHOULD be
      performed before best alternate selection."

      Instead of "Especially" with a SHOULD - which implies that Remote LFA 
should always be run, could you change it to:  "For example with Remote LFA, 
computation of PQ set ...."?   I think the manageability concerns in this 
document are useful regardless of the fast-reroute technology and this is only 
a good example of an implementation ordering that is important.

[SLI] Fixed.

  2) In 6.2.4.1<http://6.2.4.1>: " attributes from PLR to alternate path are 
retrieved from the
      interface connected to the alternate."

      There can be multiple interfaces.  The correct behavior (union or  
evaluate once per different interface) should be clearly described.  The 
similar issue exists for the alternate path and in 6.2.4.2, but there may be 
more or less freedom about controlling which path is taken.

[SLI] I need to discuss with my co authors on that.



3) In Sec 6.2.6, "Maintain a preference system between alternates based on 
number of
      SRLG violations : more violations = less preference."   The way that I've 
seen SRLGs used as a soft restriction is by giving each SRLG a value.  Then one 
can prefer the lower sum.  This allows different consideration and valuation of 
the SRLGs.  Of course, this can fall back to each SRLG has a value of 1.   
Could you please loosen the assumption here about equally valuing the SRLGs?  
I'd prefer to see both alternatives allowed - but that is <no-hat>technical 
opinion</no-hat> whereas loosening the assumption is about not accidentally 
forcing more limited behavior and removing the ability to implement more 
sophisticated mechanisms.

[SLI] Right, here is a new text proposal which is more open:

“

When SRLG protection is computed, and implementation SHOULD permit to :

                                                <list style="symbols">

                                                <t>Exclude alternates violating 
SRLG.</t>

                                                <t>Maintain a preference system 
between alternates based on SRLG violations. How the preference system is 
implemented is out of scope of this document but here are few examples :

                                                <list style="symbols">

                                                <t>Preference based on number 
of violation. In this case : the more violation = the less preferred.</t>

                                                <t>Preference based on 
violation cost. In this case, each SRLG violation has an associated cost. The 
lower violation cost sum is preferred.</t>

                                                </list>”

The path considerations mentioned in (2) still apply.

4) In Sec 6.2.7, you might be interested in the link/node-attribute drafts that 
are being finished.

[SLI] Could you give me the pointers of drafts you are thinking about ?



5) In Sec 6.2.8: "The bandwidth criteria of the policy framework SHOULD work in 
two
   ways"  Please expand to "at least two ways" - there are other strategies as 
well that might be reasonable and no standardization reason to rule them out.

[SLI] Agree, fixed

Nits:
   a) Introduction needs to be the first section. Terminology can follow.

[SLI] Fixed

  b) Remote LFA reference needs updating to RFC 7490.  I think,  given some of 
the details in this draft,  that it should be a normative reference.

[SLI] Fixed.



Thanks for the good work,
Alia

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