Stewart,

Since you brought the link up scenario ....


>  keeping the link out of service until a quiet time

How would a router know when there is a "quiet time" *network wide* which
would not cause disruption for the sensitive applications when the link is
flooded again ?

Or do you mean that such quiet time is a preconfigure window on the router
by operator (say to match local after hours times) ?

Or you mean that link up would always require operator's action ?

Thx,
R.


On Thu, Sep 21, 2017 at 10:21 AM, Stewart Bryant <[email protected]>
wrote:

>
> The draft states that
>
> " The proposed mechanism is limited to the link down event in order to
> keep the mechanism simple."
>
> Since a link that goes down will normally also come up again, the draft
> ought to provide some guidance to the operator on how they should handle
> that situation. Applications that care about the disruption caused by
> microloops presumably have no care as to whether they are cause by link up
> or link down, and so would prefer a complete elimination of that
> disruption. However I accept that complete elimination has wider network
> impact and that this approach which is really microloop mitigation has
> utility.
>
> The advice might be as simple as keeping the link out of service until a
> quiet time, or the loss of connectivity has moved to the network to a state
> of fragility such that disruption is acceptable.
>
> - Stewart
>
>
>
> On 20/09/2017 19:44, The IESG wrote:
>
>> The IESG has received a request from the Routing Area Working Group WG
>> (rtgwg) to consider the following document: - 'Micro-loop prevention by
>> introducing a local convergence delay'
>>    <draft-ietf-rtgwg-uloop-delay-06.txt> as Proposed Standard
>>
>> The IESG plans to make a decision in the next few weeks, and solicits
>> final
>> comments on this action. Please send substantive comments to the
>> [email protected] mailing lists by 2017-10-04. Exceptionally, comments may be
>> sent to [email protected] instead. In either case, please retain the
>> beginning of
>> the Subject line to allow automated sorting.
>>
>> Abstract
>>
>>
>>     This document describes a mechanism for link-state routing protocols
>>     to prevent local transient forwarding loops in case of link failure.
>>     This mechanism proposes a two-step convergence by introducing a delay
>>     between the convergence of the node adjacent to the topology change
>>     and the network wide convergence.
>>
>>     As this mechanism delays the IGP convergence it may only be used for
>>     planned maintenance or when fast reroute protects the traffic between
>>     the link failure time and the IGP convergence.
>>
>>     The proposed mechanism is limited to the link down event in order to
>>     keep the mechanism simple.
>>
>>     Simulations using real network topologies have been performed and
>>     show that local loops are a significant portion (>50%) of the total
>>     forwarding loops.
>>
>>
>>
>>
>>
>> The file can be obtained via
>> https://datatracker.ietf.org/doc/draft-ietf-rtgwg-uloop-delay/
>>
>> IESG discussion can be tracked via
>> https://datatracker.ietf.org/doc/draft-ietf-rtgwg-uloop-delay/ballot/
>>
>> The following IPR Declarations may be related to this I-D:
>>
>>     https://datatracker.ietf.org/ipr/2565/
>>
>>
>>
>>
>>
>>
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>
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