Re: [mpls] Linear Protection MIB

Hi Daniel,

Thanks for your suggestion and comments.

Please find the comments inline.

On Sun, Jan 29, 2012 at 1:39 PM, Daniel Cohn <DanielC@orckit.com> wrote:

> Hi authors, ****
>
> ** **
>
> Thanks for sending this draft to the working group. Please see a couple of
> suggestions below.****
>
> ** **
>
> **-          **I think you should add an object to configure the hold-off
> timer (see RFC 6378, section 3.1). Something like:****
>
> ** **
>
> mplsLpsConfigHoldOff   OBJECT-TYPE****
>
>     SYNTAX     Integer32 (0..10000)****
>
>     MAX-ACCESS read-create****
>
>     STATUS     current****
>
>     DESCRIPTION                                                     ****
>
>          "The hold-off time in milliseconds. Represents the time ****
>
>          between SF/SD condition detection and the declaration of ****
>
>          an SF/SD request to the protection switching logic. ****
>
>          It is intended to avoid unnecessary switching when a lower-****
>
>          layer protection mechanism is in place. ****
>
>          Can be configured in steps of 100"****
>
>     DEFVAL { 0 }****
>
> **
>
<smiler>

The hold-off timer is a property of server layer not the protection
switching group.
As per the RFC definition, when the server layer detects a SF condition the
server layer should not immediately trigger the recovery,
rather it should wait for the hold-off timer value. So IMO the Hold-off
timer should be a property of server layer not the protection
group.

The section 4.9 of RFC states as follows.

"    A hold-off timer is required to coordinate recovery timing in

   multiple layers or across nested recovery domains.  Setting this
   configurable timer involves a trade-off between rapid recovery and
   the creation of a race condition where multiple layers respond to the
   same fault, potentially allocating resources in an inefficient
   manner. *Thus, the detection of a defect condition in the MPLS-TP*

*   layer should not immediately trigger the recovery process if the
   hold-off timer is configured as a value other than zero.*

</smiler>

>  **
>
> **-          **I think mplsLpsConfigSdThreshold should be defined in the
> LSP MIB and not here. The reason for this is that the SD threshold should
> also used to generate an SD defect, regardless of whether protection is
> defined or not.****
>
>
>
<smiler>

 The value stored in this object won't be used to generate the SD defect.
 Instead this value will be used for triggering the recovery.
 As mentioned in the description section of this object in the draft, when
the MPLS OAM detects a  signal degrade with greater than
 or equal to this threshold value, the SD event will be given to
this protection domain as a local input.
 The idea is to keep these two threshold (threshold to generate the SD and
threshold to trigger the recovery) separately.

  Please let us know about your views.

</smiler>

>                                              ****
>
> Let me know what you think. ****
>
> ** **
>
> Regards,****
>
> ** **
>
> Daniel   ****
>
> ** **
>
> *From:* mpls-bounces@ietf.org [mailto:mpls-bounces@ietf.org] *On Behalf
> Of *Vishwas Manral
>
> *Sent:* Thursday, January 26, 2012 11:35 PM
> *To:* mpls@ietf.org
> *Subject:* [mpls] Linear Protection MIB****
>
> ** **
>
> Hi folks,
>
>
> We recently posted the draft
> http://datatracker.ietf.org/doc/draft-smiler-mpls-tp-linear-protection-mib/?include_text=1on MPLS-TP linear protection MIB support.
>
> Please have a look and send us any comments you may have.
>
> Thanks,
> Vishwas
>
> ****
>
>
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