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

[[e-mail]]

Hi Sharam,
The label should not be per-platform or per-interface, but more general 
concept, context specific label space, see RFC5331 for detail.

BR
Lizhong
 
> ------------------------------
> 
> Message: 3
> Date: Thu, 15 Jul 2010 10:46:22 -0700
> From: "Shahram Davari" <[e-mail]>
> Subject: Re: [PWE3] [mpls]  1588 over MPLS draft
> To: "Joel M. Halpern" <[e-mail]>,   "Mach Chen"
>    <[e-mail]>
> Cc: "[e-mail]" <[e-mail]>, "[e-mail]"
>    <[e-mail]>,   "[e-mail]" <[e-mail]>,
>    "[e-mail]" <[e-mail]>,   "S. Davari" <[e-mail]>
> Message-ID:
>    <[e-mail].
> broadcom.com>
> 
> Content-Type: text/plain; charset=utf-8
> 
> 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]; [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]; [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
> >>>>
> >>>
> >>>
> >>
> >>

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