Hi Deborah, Alvaro, 

Bruno has posted -08 version addressing Alvaro's default timer value request. 
Can you clear your DISCUSSES? 

https://datatracker.ietf.org/doc/draft-ietf-rtgwg-backoff-algo/

Thanks,
Acee 

On 2/24/18, 8:52 PM, "Acee Lindem (acee)" <[email protected]> wrote:

    Hi Deborah, 
    
    On 2/24/18, 4:07 PM, "BRUNGARD, DEBORAH A" <[email protected]> wrote:
    
        Hi Acee,
        
        Sorry for not responding earlier, I had an unexpected disruption to my 
schedule these last days.
        
        I was concerned as the document itself says "Optionally, 
implementations may also offer alternative algorithms." So it is not clear if 
it is the algorithm or the parameters which are intended PS.
    
    This is the reality that IGP implementations that have been using their 
proprietary SPF backoff algorithms for decades are not going to move to the 
standard mechanisms as their default overnight. 
        
        And especially concerning is section 7 on partial deployment. It states 
the algorithm is only effective if it is deployed on all routers, and partial 
deployment will increase the frequency and duration of micro-loops. It does go 
on to say operators have progressively replaced an implementation of a given 
algorithm by a different one.
        
        If this is to be PS, then you need to provide guidance on how an 
operator is to do the upgrade to this new algorithm on a network. I understand 
there are prototype implementations, but I'm concerned on field grade 
deployments in existing networks.
    
    The IETF can't just mandate that vendors implement the new standard SPF 
backoff algorithm, make it the default SPF Backoff, or that operators deploy 
it. I believe we have provided ample guidance by indicating that the full 
benefit is only obtained when the same algorithm is deployed over the IGP 
domain (or at least an area). The standardization of the SPF Backoff algorithm 
is the start of the journey, not the destination. 
    
        
        Thanks,
        Deborah
        
        -----Original Message-----
        From: Acee Lindem (acee) [mailto:[email protected]] 
        Sent: Wednesday, February 21, 2018 7:53 PM
        To: BRUNGARD, DEBORAH A <[email protected]>; The IESG <[email protected]>
        Cc: [email protected]; Uma Chunduri 
<[email protected]>; [email protected]; [email protected]
        Subject: Re: Deborah Brungard's Discuss on 
draft-ietf-rtgwg-backoff-algo-07: (with DISCUSS)
        
        Hi Deborah, 
        
        
        
        Given that the goal of RFC 6976 was much more ambitious and the 
mechanisms are much more complex, I don't think this draft should be put in the 
same category. 
        
        
        
        What we have done is precisely specify a standard algorithm for IGP SPF 
back-off. When deployed, this standard algorithm will greatly improve (but not 
eliminate) micro-loops in IGP routing domains currently utilizing disparate SPF 
back-off algorithms. The problem statement draft best articulates the impact of 
differing SPF back-off algorithms: 
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.ietf.org_id_draft-2Dietf-2Drtgwg-2Dspf-2Duloop-2Dpb-2Dstatement-2D06.txt&d=DwIGaQ&c=LFYZ-o9_HUMeMTSQicvjIg&r=6UhGpW9lwi9dM7jYlxXD8w&m=lB8O9Nd8E9rpRoJj0YX-mV3Tpp8iWGOSIp_fkDPkMuA&s=Vtva23qDNV_XHrGXH4C87wmfZuLcxGEDJAXqVihSSPw&e=
 . Finally, there have been several prototype implementations validating the 
algorithm specification's completeness and clarity. 
        
        
        
        Thanks,
        
        Acee
        
        
        
            Deborah Brungard has entered the following ballot position for
        
            draft-ietf-rtgwg-backoff-algo-07: Discuss
        
            
        
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----------------------------------------------------------------------
        
            DISCUSS:
        
            
----------------------------------------------------------------------
        
            
        
            While I agree with Alvaro's concerns, my concern is the 
appropriateness of this document as PS.
        
            This document should have a similar status as RFC6976 
(Informational) which also provided a
        
            mechanism that prevented transient loops saying "the mechanisms 
described in this
        
            document are purely illustrative of the general approach and do not 
constitute a protocol
        
            specification". Especially as this document compares itself to 
RFC6976, saying RFC6976 is a
        
            "full solution".
        
            
        
            With a change of status to Informational, this document would be 
better
        
            scoped as providing guidance vs. a specification.
        
            
        
            
        
            
        
            
        
            
        
        
        
        
    
    

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