Re: [mpls] [PWE3] 1588 over MPLS draft

[John E Drake <[e-mail]>]

> -----Original Message-----
> From: [e-mail] [mailto:[e-mail]] On
> Behalf Of Shahram Davari
> Sent: Thursday, July 15, 2010 12:52 PM
> To: Joel M. Halpern
> Cc: [e-mail]; [e-mail]; S. Davari; [e-mail]; mpls-
> [e-mail]
> Subject: Re: [mpls-tp] [mpls] [PWE3] 1588 over MPLS draft
> 
> Hi Joel,
> 
> There are 2 aspects to this puzzle:
> 
> 1) Hardware support for 1588 in a device.
> 2) Software support for 1588 in the form of allocating labels to PTP
> LSPs
> 
> A router that wants to perform 1588 time stamping must have both (1)
> and (2) functionality. While a router in the path of a PTP LSP that
> does not support (1) should support (2) and advertise labels from some
> arbitrary range for PTP LSP.
> 
> It is quite easy to upgrade a router software so that when it receives
> RSVP-TE label request to assign label from an arbitrary local range.

JD:  What happens in the case where a router's software has not been upgraded?

> 
> So I don't see any issue here.
> 
> Thanks,
> Shahram
> 
> 
> 
> -----Original Message-----
> From: Joel M. Halpern [mailto:[e-mail]]
> Sent: Thursday, July 15, 2010 12:06 PM
> To: Shahram Davari
> Cc: Mach Chen; S. Davari; Jia HE; [e-mail]; [e-mail];
> [e-mail]; [e-mail]
> Subject: Re: [mpls] [PWE3] 1588 over MPLS draft
> 
> Architecturally, as I understand the draft, the downstream neighbor of
> a
> 1588 supporting device (on the PTP carrying LSP) may not itself be a
> 1588 supporting device.  Is that correct?  If that is not correct, if
> instead the structure is that PTP supporting LSPs are established
> between adjacent enhanced devices, then I can see how some sort of a
> label range might make sense.
> 
> If however, the downstream node you refer to may be an existing LSR,
> then I do not see how you can ask an existing LSR to allocate a label
> range for a function it does not understand.
> 
> Yours,
> Joel
> 
> Shahram Davari wrote:
> > Hi Joel,
> >
> > I agree with your logic, but the idea is a bit different:
> >
> > All we need is a label range, it does not need to be globally unique
> in the network and it does
>  >not even need to be the same on the Tx and Rx direction of the same
> link. Although we need time
>  >stamping both on Rx and on Tx, but on Rx a node is in control of its
> own label and on Tx the
>  >downstream node should advertise some label range. What we don't want
> is that the downstream
>  >node to advertise random labels for each LSP carrying PTP.
> >
> > I will update the draft to mention that the label range does not
> require to be global but it can
>  >be per-platform or even per-interface.
> >
> > Thanks,
> > Shahram
> >
> > -----Original Message-----
> > From: Joel M. Halpern [mailto:[e-mail]]
> > Sent: Wednesday, July 14, 2010 8:21 PM
> > To: Mach Chen
> > Cc: Shahram Davari; S. Davari; Jia HE; [e-mail]; [e-mail];
> [e-mail]; [e-mail]
> > Subject: Re: [mpls] [PWE3] 1588 over MPLS draft
> >
> > Remember that if what is required is that the message arriving at the
> > 1588 supporting device have a certain label range, that is a purely
> > local matter.  As long as the singaling carries the indication that
> the
> > LSP is to be dedicated to 1588 traffic (a reasonable extension to the
> > signaling), the downstream switch can pick what label to assign to
> that LSP.
> >
> > If the goal is to have the outgoing label be from a specific range,
> that
> > is essentially impossible in the proposed architecture.  The proposed
> > architecture is one in which 1588 switches are peers with existing
> LSRs
> > using MPLS.  As such, in order to have a label range for outgoing
> > labels, the existing MPLS LSR would somehow have to know about this
> > reserved label range, not use those labels for other purposes, and
> > assign those labels to 1588 LSPs.  All of which is
> > non-backwards-compatible.  If the 1588 LSPs were actually
> pseudowires,
> > tunneled over LSPs, then any number of things are possible.
> >
> > Yours,
> > Joel M. Halpern
> >
> > Mach Chen wrote:
> >> Hi Shahram,
> >>
> >> I agree that the label range idea is an efficient way that could
> reduce
> >> the storage requirement of PHY chips.
> >>
> >> It's easy to require one or limited nodes to reserve a label range,
> but
> >> IMHO, it very difficut to require all nodes of a large network to do
> >> this and even worse when some labels are already used by other LSPs,
> >> unless there are some mechanisms to negotiate/advertise(e.g.,
> flooding
> >> the label range by IGP within the network) the proper label range
> hence
> >> to aviod label collision.
> >>
> >> Best regards,
> >> Mach
> >>
> >> --------------------------------------------------
> >> From: "Shahram Davari" <[e-mail]>
> >> Sent: Thursday, July 15, 2010 1:58 AM
> >> To: "Mach Chen" <[e-mail]>; "S. Davari" <[e-mail]>;
> >> "Jia HE" <[e-mail]>
> >> Cc: <[e-mail]>; <[e-mail]>; <[e-mail]>;
> >> <[e-mail]>
> >> Subject: RE: [mpls] [PWE3] 1588 over MPLS draft
> >>
> >>> Hi Mach,
> >>>
> >>> When a service provider wants to create these PTP LSPs, what is
> wrong
> >>> with allocating a range of labels for this purpose? This is purely
> a
> >>> software exercise. There are 2 million labels available to each
> node,
> >>> why can't some of them be allocated by software to PTP?
> >>>
> >>> In theory what you say is correct and should work, but in practice
> >>> there is a function called 1-step Transparent clocking that
> requires
> >>> time stamping at the PHY (immediately when the packet is received
> or
> >>> transmitted). PHY chips don't have CAM or lots of memory to store a
> >>> few thousand random labels. The label range will solve that problem
> >>> and is consistent with MPLS architecture.
> >>>
> >>> Thanks,
> >>> Shahram
> >>>
> >>> -----Original Message-----
> >>> From: Mach Chen [mailto:[e-mail]]
> >>> Sent: Wednesday, July 14, 2010 1:53 AM
> >>> To: S. Davari; Jia HE; Shahram Davari
> >>> Cc: [e-mail]; [e-mail]; [e-mail]; mpls-
> [e-mail]
> >>> Subject: Re: [mpls] [PWE3] 1588 over MPLS draft
> >>>
> >>> Hi Shahram,
> >>>
> >>> From the view of implementation, there is no more difference
> between
> >>> SHOULD
> >>> and MUST :-)
> >>> For me, the Label Range is more like a mechanim to notify related
> >>> nodes that
> >>> some LSPs are dedicated for PTP messages other than the chips
> memory
> >>> limitation, because the memory restriction is always there whatever
> >>> you use
> >>> Label Range or not.
> >>> IMHO, since the objective is to tell related MPLS nodes which LSPs
> are
> >>> PTP
> >>> LSPs, an indication in the signaling(RSVP-TE/GMPLS/LDP) is enough
> and
> >>> seems
> >>> more common. And it will avoid the strict requirement of "the
> network and
> >>> all nodes required to support the Label range".
> >>> In addition, there should be some mechanims(e.g., ISIS/OSPF
> >>> extensions) for
> >>> nodes to advertise their PTP capability hence to help PTP LSPs
> >>> computation.
> >>>
> >>> Best regards,
> >>> Mach
> >>>
> >>>
> >>> --------------------------------------------------
> >>> From: "S. Davari" <[e-mail]>
> >>> Sent: Wednesday, July 14, 2010 2:31 PM
> >>> To: "Jia HE" <[e-mail]>; "Shahram Davari"
> <[e-mail]>
> >>> Cc: <[e-mail]>; <[e-mail]>; <[e-mail]>;
> >>> <[e-mail]>
> >>> Subject: Re: [mpls] [PWE3] 1588 over MPLS draft
> >>>
> >>>> Hi Jia,
> >>>>
> >>>> Label range is a SHOULD requirements and not MUST. The reason for
> Label
> >>>> Range is
> >>>> mainly for PHY chips that don't have large memory and can't store
> a
> >>>> lot of
> >>>> Labels. Otherwise the PTP LSP is setup via signaling that
> specifies the
> >>>> LSP as
> >>>> carrying 1588.
> >>>>
> >>>> So the answer is that if a Label range is used it must be a Global
> range
> >>>> within
> >>>> a network and should not be used by any router for other
> applications.
> >>>>
> >>>> Thanks,
> >>>> Shahram
> >>>>
> >>>>
> >>>>
> >>>> ________________________________
> >>>> From: Jia HE <[e-mail]>
> >>>> To: Shahram Davari <[e-mail]>
> >>>> Cc: [e-mail]; [e-mail]; [e-mail]; mpls-
> [e-mail]
> >>>> Sent: Tue, July 13, 2010 9:50:37 PM
> >>>> Subject: Re: [mpls] [PWE3] 1588 over MPLS draft
> >>>>
> >>>>
> >>>> Hi Shahram,
> >>>>
> >>>> One question about "PTP Label Range":
> >>>>
> >>>> To my knowledge, label in MPLS network is a local  matter. For
> >>>> example, we
> >>>> may
> >>>> have per-interface or per-platform label space. Will  this
> specificed
> >>>> "PTP
> >>>> Label
> >>>> Range" conflict with the current in-use labels  for common LSPs?
> >>>>
> >>>>
> >>>> B.R.
> >>>> Jia
> >>>>
> >>>> ----- Original Message -----
> >>>>> From: Shahram    Davari
> >>>>> To: [e-mail] ; [e-mail] ; [e-mail] ;
> [e-mail]
> >>>>> Sent: Thursday, July 08, 2010 3:12 AM
> >>>>> Subject: [PWE3] 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
> >>>> ________________________________
> >>>> _______________________________________________
> >>>>> pwe3 mailing    list
> >>>>> [e-mail]
> >>>>> https://www.ietf.org/mailman/listinfo/pwe3
> >>>>>
> >>>>
> >>>
> >>>
> >>>> _______________________________________________
> >>>> mpls mailing list
> >>>> [e-mail]
> >>>> https://www.ietf.org/mailman/listinfo/mpls
> >>>>
> >>>
> >>>
> >> _______________________________________________
> >> mpls mailing list
> >> [e-mail]
> >> https://www.ietf.org/mailman/listinfo/mpls
> >
> 
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