Tony, The idea is that this encapsulation is used in scenarios where the MPLS cloud is PTP-aware. MPLS LSRs act as boundary (or transparent) clocks and ensure that time delivery is will not be affected by queuing and forwarding delays.
I think the question in these scenarios should be the other way round: why should PTP messages sent between two PTP aware LSRs be encapsulated in Ethernet and/or IP? Beyond bandwidth efficiency, addition of superfluous layers adds complications and implementation assumptions. I think it is similar to the reason why OAM messages between two LSRs are not encapsulated in Ethernet/IP. Does this make sense? Best, Ron On Sat, Jul 10, 2010 at 8:53 AM, Tony Li <[email protected]> wrote: > > Thanks Ron. > > Please pardon my ignorance, but what's the benefit of this over doing an > EthernetPW? > > Tony > > > On Jul 9, 2010, at 10:27 PM, Ron Cohen wrote: > > > Hi Tony, > > > > PTP is designed to be extended over multiple transports. Some transports > are included in IEEE1588-2008 Annex-s, while the idea was that others (such > as MPLS) will be developed by the expert standardization bodies. > > > > I wrote a proposal a while ago for direct PTP over MPLS mapping. It is > still available here http://tools.ietf.org/html/draft-ronc-ptp-mpls-00 . > At least part of it still makes sense. > > > > Best, > > Ron > > > > On Fri, Jul 9, 2010 at 10:41 PM, Tony Li <[email protected]> wrote: > > > > And, how can the encapsulation be anything other than EthernetPW? > > > > Tony > > > > > > On Jul 9, 2010, at 12:38 PM, <[email protected]> wrote: > > > > > Hi Yaakov, > > > > > > when you say encapsulation what is the intention e.g. at the interface? > > > > > > Mike > > > ________________________________ > > > From: [email protected] [[email protected]] On Behalf Of > Yaakov Stein [[email protected]] > > > Sent: 09 July 2010 05:06 > > > To: [email protected]; [email protected]; > [email protected] > > > Subject: Re: [TICTOC] FW: 1588 over MPLS draft > > > > > > Sebastien > > > > > > Yes, developing an MPLS encapsulation for 1588 is high on TICTOC's list > of things to accomplish. > > > > > > Y(J)S > > > > > > From: [email protected] [mailto:[email protected]] On > Behalf Of [email protected] > > > Sent: Thursday, July 08, 2010 18:37 > > > To: [email protected]; [email protected] > > > Subject: Re: [TICTOC] FW: 1588 over MPLS draft > > > > > > Hi, > > > > > > After reading this interesting draft, I would have some questions for > clarification (sorry, I will not attend to the Maastricht meeting). > > > > > > My first general question is related to the objective of TICTOC > regarding this topic: is it planned that TICTOC would develop a specific > mechanism for transporting PTP over MPLS as the one proposed in this > document? If so, is it oriented to telecoms applications, or to other types > of applications? > > > > > > My second question would be to better understand why there is a need > for transporting PTP over MPLS. It is still unclear to me. FYI, similar > discussions happened in June in ITU-T Q13/15 during the last Geneva meeting. > > > > > > My understanding of the context of this draft is that the network > between a PTP master and a PTP slave experiences full timing support for > PTP, such as TC in every node (or possibly BC, that is also slightly evoked > in the document?). In this context, it can be questioned if the PTP timing > delivery is really done "end-to-end", since every node has to process the > PTP messages. Therefore, is it really appropriate in this case to put the > PTP messages into a tunneling transport, such as MPLS? > > > > > > It looks more logical to me in this situation to transport the PTP > timing flows outside MPLS (e.g. simply over UDP/IP) on a hop-by-hop basis > (e.g. each node delivers its timing to the next one). > > > But maybe I misunderstood or missed something... > > > > > > Any thoughts? > > > > > > Thanks. > > > > > > BR, > > > > > > Sébastien > > > ________________________________ > > > De : [email protected] [mailto:[email protected]] De la > part de Shahram Davari > > > Envoyé : mercredi 7 juillet 2010 21:36 > > > À : [email protected] > > > Objet : [TICTOC] FW: 1588 over MPLS draft > > > > > > > > > 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 > > > _______________________________________________ > > > TICTOC mailing list > > > [email protected] > > > https://www.ietf.org/mailman/listinfo/tictoc > > > > _______________________________________________ > > TICTOC mailing list > > [email protected] > > https://www.ietf.org/mailman/listinfo/tictoc > > > >
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