Hi Sharam,

 

II have some initial comments and questions.  Not sure yet if I will attend
the meeting.

 

I do tend to agree that there are cases where there is a need for LSRs to
identify PTP messages. The draft is similar in some aspects to some of the
proposals made by Ron Cohen back in 2007.  The two differences I see is that
your draft proposes to use the outer label to identify PTP messages and to
use the standard PTP mappings (Annex D & F of IEEE1588), whereas in Cohen's
draft, the outer label was not used (ie., the PW instead was proposed to
distinguish the PTP LSP types) in addition to a proposal to have a direct
mapping of PTP into MPLS, although that would require a new networkProtocol
enumeration as defined in IEEE1588.

 

The draft primarily discusses the use for Transparent Clock, but it is
equally application to Boundary Clocks. Actually it should be useable for
any types of clocks defined in IEEE1588.  There are scenarios where you
might have a time synchronization chain composed of only BC-LSRs or TC-LSRs
or combination/mix. There is a need to clarify reference models as I think
these might further add requirements to the "PTP LSP" definition.

 

In section1, you say "the accuracy of the recovered clock improves".  Are
you referring to the distribution of frequency or time in this specific
paragraph?

 

In section 1, you also say "it should be possible to instead control the
delay for these messages on both directions across the node".  In theory
this is possible, but practically very difficult because of the current QoS
architecture (i.e., it is hard to control the per-hop behaviour (PBH) that
determines the scheduling treatment of packets to produce such results)

 

In section 8, can you clarify what is meant by "any PTP LSP failure will
trigger the slave to switch to the Redundant Master, even if the LSP is
protected at the MPLS layer". Why is that?

 

Thanks.

 

Michel

 

 

 

From: Shahram Davari 
Sent: Wednesday, July 07, 2010 12:12 PM
To: '[email protected]'; '[email protected]'; '[email protected]'; '[email protected]'
Subject: 1588 over MPLS draft

 

Hi All,

 

Please find attached our first draft of 1588 over MPLS. Since we have some
technical issues converting the Word format to Txt we couldn't  upload the
draft before the cut-off date. However we will present the draft in the next
IETF meeting and will upload the draft after the meeting.

 

Note that the main WG is TicToc but may require consultation with MPLS and
PWE3 WGs.

 

Thanks,

Shahram Davari

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