Subject: [mpls-tp] draft mpls-tp-loss-delay-02

From: D'Alessandro Alessandro Gerardo <[email-masked]>
Date: Mon, 26 Jul 2010 18:30:24 +0200

Dear all,
said that the draft proposal is interesting, I have the following concerns and questions for clarifications about the draft mpls-tp-loss-delay:

 1.  do we really need support for both 32bit and 64bit packet counters for Loss measurement (LM) in PTN equipment?
 2.  do we really need support for multiple timestamp formats (NTP and 1588 PTP) in PTN equipment? This also implies a negotiation procedure
All these options add complexity to the implementation and have as side effects rising potential interworking issues/complexity, increasing operational costs, etc.

 1.  the concepts of "query rate exceeded" and "temporary resource exhaustion" are concepts that do not fit with a transport profile
in a transport network, when a certain level of performance are required, they must be guaranteed and I don't see the possibility for the equipment to change the configured parameters

 1.  par 4.1.7: the concept of "LM packet misordering" is introduced: do you see this risk in a TP network?
Could you explain a bit more the scenarios when this can occur?

 1.  par. 4.1.5: I found the following "if a temporary error condition is indicated, LM operation may be restarted automatically"
I would suggest to explain a bit more this situation and at the same time to preserve the "transport" approach that is leaving the operator the control of the issue

My feeling is that this proposal well addresses the need of MPLS routers but it doesn't clearly highlight the MPLS-TP router behavior. Why don't rename it as "mpls-loss-delay" (without -tp) and start a new document, based on the previous one, where to clearly describe the configuration and options an MPLS-TP router have to support excluding all options/configurations/behaviors that does not pertain to the transport world.

This will result in less complex implementations, greater interworking, cheaper equipment and OPEX...

Best regards,
Alessandro

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Telecom Italia
Alessandro D'Alessandro
Transport & OPB Innovation
Via Reiss Romoli, 274 - 10148 Torino
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