Re: [Mpls-interop] MPLS-TP OAM requirements - Lock and notification of lock

[Martin Vigoureux <[e-mail]>]

Adrian, Malcolm, all,

here are my thoughts on this:

As far as I understand, strictly speaking the Lock function
does not make sense on a unidir LSP. Indeed locking is performed
at the source point and so there is no need to send any message
to perform that Lock. (the potentially needed message is to inform
the end-point(s) of the status but that is lock notification.
I'll come back to this).
Therefore Lock is only needed on a bidir entity and what is exactly
needed is the capability to request the other end point to admin lock
its direction.

Coming back to the notification, I believe the following requirement
is needed:
    The MPLS-TP OAM toolset MUST provide a functionality to enable an
    End Point of a PW, LSP or Section to inform the End Point(s) of that
    LSP, PW, or Section that the PW, LSP or Section has been
    administratively shutdown at this End Point.
But it is conditionally needed. This function is *only* needed if
locking is achieved via Lock, otherwise if it is achieved via NMS
commands we (I hope) can safely assume that:
for undir LSP there will be commands at both ends, one saying lock, the 
other saying you are notified of other end locking.
for bidir LSP there will be commands at both ends, both saying lock and 
you are notified of other end locking.

The MUST is needed because the egress must be aware of the Lock because
we expect him to then inform client MEPs that are "downstream". (see
question at the end of this e-mail).

The small problem I have is that this function is a notification
one but really tightly linked to the Lock. In other words, I do
not know where this reqs better fits (especially wrt to the conditional
issue): in Lock or in Lock Notification?
Opinions are welcomed.

Therefore I propose:

2.2.x.  Lock
The MPLS-TP OAM toolset SHOULD provide a functionality to enable an
End Point of a bidirectional PW, LSP or Section to request to its
associated End Point that it administratively shuts down the direction
of the PW, LSP or Section for which it is the head-end.

This function SHOULD be performed on-demand.

This function SHOULD be performed between the End Points of a PW, LSP
or Section.

Note that administratively shutting down corresponds to stopping user 
traffic being sent on the PW, LSP or Section.


2.2.y.  Lock Notification
The MPLS-TP OAM toolset MUST provide a function to enable End Points
of a (server) LSP or Section to notify, of its administrative locking
status, the End Points of (client) PWs or LSPs affected by this status.

This function SHOULD be performed on-demand.

This function SHOULD be performed between the End Points of a PW, LSP
or Section.
-comment:
this needs to be rephrased as the notifying end points may not be
the same nodes than the notified end points.
The general case is in fact a notification between end points of 
different e.g., LSPs while the sentence seems to say that it is between
the end-points of the same e.g., LSP.
Any suggestion welcomed.

See also my e-mail:
MPLS-TP OAM requirements - AIS/LockNotif - Can MIPs send "usolicited" 
OAM messages ?

-question:
More generally to the comment above, who should notify and who should
notify whom?
I would tend to say:
the receiving node of a locked direction, informs downstream receiving
nodes of nested LSPs. This is a Fowrward Indication and if we do
so then receiving points MUST indeed be informed of a Lock (c.f.
discussion at the beginning of the e-mail).
Should source points (locking points) do some reverse indication and
notify the source points of the LSPs that are nested in the locked LSP?
(but this maybe falls in the RDI functionality).

I guess that is all, sorry for this long e-mail.

regards,
-m


Adrian Farrel a écrit :
> Hi Malcolm,
> 
>> To address the comments from Adrian I suggest the following
>> text for sections 2.2.7 and 2.2.8:
>>
>> Note that this proposal assumes that the text related to local/remote
>> faults is moved from section 2.2.8 to section 2.2.2 as proposed in my
>> previous email.
>>
>> We probably need to discuss this text on the MEAD team call next
>> week.
>>
>> 2.2.7.  Lock
>>
>> The OAM toolset SHOULD provide a function enabling a network operator to
>> administratively shut down a PW, LSP or Section; that is, to stop user
>> traffic being sent over that PW, LSP or Section.
> 
> This is great.
> Does it mean that we do not need to add the (similar) text on CV fault 
> behavior in section 2.2.3?
> It would seem so.
> 
>> The lock function MAY be applied to a unidirectional or a bidirectional
>> PW, LSP or Section.  If the lock function is activated at the head end
>> of one direction of a bidirectional PW, LSP or Section then it SHOULD be
>> possible to cause the lock function to be activated at the head end of
>> the other direction.
>>
>> This function SHOULD be performed on-demand i.e. in response to an
>> operator command.
> 
> Or also in response to configured automatic behavior?
> 
> But this is not a protocol requirement.
> 
>> This function SHOULD be performed between End Points of PWs, LSPs
>> and Sections.
>>
>> 2.2.8 Notification of Lock
>>
>> If the lock function is supported the MPLS-TP OAM toolset MUST
>> provide a function to enable the End Point at the ingress to notify the
>> End Points at the egress that the lock function is active.  This
>> function SHOULD be performed pro-actively.
>>
>> The MPLS-TP OAM toolset MUST allow for the distinction between
>> a fault condition and an administrative locking action.
> 
> Works for me.
> 
> A
> 
> 
> 
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