Re: [Mpls-interop] MPLS-TP OAM requirements - Lock andnotificationof lock

["Malcolm Betts" <[e-mail]>]

Kam,
 
Thank you for the description of the NM aspects of Lock.  Just to
clarify one point when I stated:
I see no need to propagate the locked indication across layers.
I was think only of the direct data path.  I fully agree that management
notifications should be passed between layers as you have described.
 
I think that most of the material in you email should be in the NM
requirements document.

Malcolm Betts 
Nortel Networks 
Phone: [phone] (ESN 393) 
email: [e-mail] 

________________________________

From: Lam, Hing-Kam (Kam) [mailto:[e-mail]] 
Sent: Tuesday, May 05, 2009 1:51 AM
To: Betts, Malcolm (CAR:X632); Sprecher, Nurit (NSN - IL/Hod HaSharon);
[e-mail]; [e-mail]; Martin Vigoureux
Subject: RE: [Mpls-interop] MPLS-TP OAM requirements - Lock
andnotificationof lock



Dear all,

 

See inline below. I am addressing the issue of notification across
layers, not addressing notifying the sink (egress) points.

 

Regards,

Kam

 

> -----Original Message-----

> From: [e-mail]
[mailto:[e-mail]]

> On Behalf Of Malcolm Betts

> Sent: Monday, May 04, 2009 8:42 AM

> To: Sprecher, Nurit (NSN - IL/Hod HaSharon); [e-mail];
mpls-

> [e-mail]

> Subject: Re: [Mpls-interop] MPLS-TP OAM requirements - Lock

> andnotificationof lock

> 

> All,

> 

> I think you are making this far too complicated...  I see no need to

> propagate the locked indication across layers.

[Lam, Hing-Kam (Kam)] The bottom line is to avoid unexpected
interruption to the client services so that to reduce unnecessary alarm
being raised from the client layer.

> 

> If the operator decides to lock a LSP (for example to run a test) then

> the clients of that LSP should be taken out of service before the lock

> is applied.

[Lam, Hing-Kam (Kam)] This is a reasonable assumption and a good
practice. It will be helpful to explicitly say so in the document. The
reason is that now we are using the "LOCKED" state and "Lock" event of
the X.731 Administrative state model. There are additional state values
and events in the model. We need to be precise and accurate, in
particular if we support only a subset of the model. Otherwise it may
cause unnecessary confusion and inconsistence in the future. The
Administrative State model in X.731 defines three state values (namely:
UNLOCKED, LOCKED, and SHUTTING DOWN) and events as shown below. 

 

If you administratively lock a server, the server will enter the
"locked" state. Therefore the server will no longer be able to provide
its intended service (of supporting all its clients). The effect (i.e.
impact) on the clients is no different than a server failure. Usually
you don't want to do this. Instead, you would like to gracefully take
the server out of service, i.e. administratively shut down the server,
and by doing so the server will enter the "shutting down" state. The
"shutting down" state is a transition state. When the last user (in this
case the last client service) quit, then the server will automatically
enter the "locked" state. If we are not going to support the Shutting
Down state of the model, then you better either (1) take the clients of
the server LSP out of service before the lock is applied or (2) notify
the clients in advance, otherwise alarms will be raised against the
supported client services because of the unexpected interruption.

 

> 

> When a server LSP detects the locked notification it informs the
client

> adaptation that it is no longer receiving valid traffic.  If the
client

> has already been taken out of service then this is a "don't care".  If

> the client has not been taken out of service then it should raise an

> alarm.

> 

> 

> Malcolm Betts

> Nortel Networks

> Phone: [phone] (ESN 393)

> email: [e-mail]

> 

> -----Original Message-----

> From: [e-mail]

> [mailto:[e-mail]] On Behalf Of Sprecher, Nurit
(NSN

> - IL/Hod HaSharon)

> Sent: Monday, May 04, 2009 3:47 AM

> To: [e-mail]; [e-mail]

> Subject: Re: [Mpls-interop] MPLS-TP OAM requirements - Lock and

> notificationof lock

> 

> Huub,

> You say " this requires that a MIP has the capability to send OAM

> messages based on management command or based on an indication of a
MEP

> in a different layer. This also requires that at every MEP location

> there are also MIPs for every client entity serviced by that MEP."

> This looks more as an implementation description. What is actually

> required is that the endpoints of the client layer are informed of
this

> event.

> The way you describe it seems a little bit "against" the framework in

> which it is specified that OAM messages cannot be initiated by MIPs.

> That is why we actually say that this is an adaptation function, that

> means that the message is initiated by the MEP of the server to the
MEP

> of the client.......

> Best regards,

> NUrit

> 

> -----Original Message-----

> From: [e-mail]

> [mailto:[e-mail]] On Behalf Of ext Huub van

> Helvoort

> Sent: Monday, May 04, 2009 10:27 AM

> To: [e-mail]

> Subject: Re: [Mpls-interop] MPLS-TP OAM requirements - Lock and

> notification of lock

> 

> Hello Nurit,

> 

> You wrote:

> 

> > To continue with the othe rquestion:

> >

> >> See also my e-mail:

> >> MPLS-TP OAM requirements - AIS/LockNotif - Can MIPs send
"usolicited"

> 

> >> OAM messages ?

> >

> > The answer was no.

> >

> >> -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.

> >

> > To be more exact, the sink side of a locked LSP, PW, Section, has to

> > inform its clients.

> 

> You say " To be more exact, the sink side of a locked LSP, PW,
Section,

> has to inform its clients.",

> 

> [hvh] it should inform its client transport entities in the

> server/client relation

> 

> BUT the client is not necessarily an

> endpoint but may be an intermediate point, and it needs to notify its

> endpoints, that means that a MIP generates an OAM message.

> 

> [hvh this requires that a MIP has the capability to send OAM messages

> based on management command or based on an indication of a MEP in a

> different layer.

> This also requires that at every MEP location there are also MIPs for

> every client entity serviced by that MEP.

> 

> Long ago I discussed this point with Italo and he indicated to me that

> it is not a generation of a message by a MIP BUT it is a variation of
an

> adaptation function at the client intermediate point. Although we are

> talking here about a way to implement it, this is a conceptual issue

> that we need to agree on.

> 

> [hvh] I agree with Italo.

> 

> Also, I think we should generalize the discussion instead of talking

> every time about LSP, PW, section, etc. we should really talk about

> client/server layers to cover cases of LSP hierarchies, etc.

> 

> [hvh] then I use server/client path/trail the next time, OK?

> 

> Regards, Huub.

> 

> >> 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).

> >

> > Isn't this notification already caused by the locking at the far
end?

> > Or is the locking only applied in one direction of a bi-directional

> > path? If yes, then the notification is not required.

> >

> > Cheers, Huub.

> >

> 

> --

> ================================================================

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