Hi Rob,

We've posted an update to include the changes discussed below:
https://datatracker.ietf.org/doc/html/draft-ietf-lsr-ospf-reverse-metric-10

Thanks,
Ketan


On Thu, Oct 6, 2022 at 5:28 PM Ketan Talaulikar <[email protected]>
wrote:

> Hi Rob,
>
> Thanks for your review and comments/suggestions. Please check inline below
> for responses.
>
> Will update these changes (and further changes, if required) in the next
> version once we conclude.
>
> On Thu, Oct 6, 2022 at 4:20 PM Robert Wilton via Datatracker <
> [email protected]> wrote:
>
>> Robert Wilton has entered the following ballot position for
>> draft-ietf-lsr-ospf-reverse-metric-09: Discuss
>>
>> When responding, please keep the subject line intact and reply to all
>> email addresses included in the To and CC lines. (Feel free to cut this
>> introductory paragraph, however.)
>>
>>
>> Please refer to
>> https://www.ietf.org/about/groups/iesg/statements/handling-ballot-positions/
>> for more information about how to handle DISCUSS and COMMENT positions.
>>
>>
>> The document, along with other ballot positions, can be found here:
>> https://datatracker.ietf.org/doc/draft-ietf-lsr-ospf-reverse-metric/
>>
>>
>>
>> ----------------------------------------------------------------------
>> DISCUSS:
>> ----------------------------------------------------------------------
>>
>> Thanks for this document.
>>
>> I support Alvaro's discuss.  Having read Alvaro's discuss after writing my
>> ballot comments it seems to be some what closely related, but I am also
>> balloting discuss because I find the operational guidelines to be unclear.
>>
>> (1) p 8, sec 7.  Operational Guidelines
>>
>>    Implementations MUST NOT signal reverse metric to neighbors by
>>    default and MUST provide a configuration option to enable the
>>    signaling of reverse metric on specific links.  Implementations
>>    SHOULD NOT accept the RM from its neighbors by default and SHOULD
>>    provide a configuration option to enable the acceptance of the RM
>>    from neighbors on specific links.  This is to safeguard against
>>    inadvertent use of RM.
>>
>> I'm not really sure that I properly understand how this feature works
>> from a
>> manageability perspective.  Particularly for your first use case, when
>> considering that the proposal is for per link configuration for the
>> acceptance
>> of RM from neighbours.  This would seem to suggest that before you can
>> make use
>> of reverse-metric you have to already have determined the links on the
>> affected
>> devices to then configure them to accept the reverse-metrics, at which
>> point,
>> doesn't this partially defeat the use case?
>
>
> KT> If the operator is using this feature, then it needs to be enabled
> first. This is a one-time/initial config.
>
>
>> Or is the main goal to simplify
>> the coordination of changing the metric at both ends of the link at the
>> same
>> time?
>>
>
> KT> Correct. The advertisement of reverse metric is applied/triggered on
> the sending side on-need basis.
>
>
>>
>> Or is the intention that during the maintenance window the operators would
>> enable the "allow receipt of reverse-metrics" on all links within, say, an
>> area?  If so, would hierarchical device and area specific configuration
>> be more
>> appropriate?  E.g., allow it to be enabled/disbaled on individual links,
>> but
>> also allow more coarse grained configuration.
>>
>
> KT> I would expect the feature enablement (specifically the receiving
> part) to be on multiple hierarchical levels (instance/area/link). The RM
> value config for sending is on the link, but for some use cases, it would
> perhaps be also hierarchical.
>
>
>>
>> Not as an update for this document, but I am assuming that the LSR working
>> group with eventually update or augment the OSPF YANG module with standard
>> configuration to support this feature.
>>
>
> KT> Ack. Will include the same reference and text that we have discussed
> for the OSPF L2 bundles draft.
>
>
>>
>> (2) p 8, sec 7.  Operational Guidelines
>>
>>    For the use case in Section 2.1, it is RECOMMENDED that the network
>>    operator limits the period of enablement of the reverse metric
>>    mechanism to be only the duration of a network maintenance window.
>>
>> Presumably this isn't feasible when the CE is not managed by the provider?
>
>
> KT> Correct.
>
>
>>   In
>> this scenario, is the expectation that the configuration to accept
>> reverse-metrics would just be left always enabled on the CE device?
>
>
> KT> Correct.
>
>
>> Is this a
>> security concern?
>>
>
> KT> Not sure. If it was left enabled, then it was because the use case
> warranted it. We also have the log/alert recommended so this can be
> monitored/reported on the CE device.
>
> Thanks,
> Ketan
>
>
>>
>> Regards,
>> Rob
>>
>>
>>
>>
>>
>>
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