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

[Shahram Davari <[e-mail]>]

Mach

Is this supported by RSVP-TE?

Best Regards,
Shahram


On Jul 15, 2010, at 6:35 PM, Mach Chen <[e-mail]> wrote:

Hi Shahram,

If the 1588-capability router does downstream (for Rx direction) and upstream (for Tx direction) label distribution respectively, it may not require its adjacent routers to upgrade.

Best regards,
Mach

--------------------------------------------------
From: "Shahram Davari" <[e-mail]>
Sent: Friday, July 16, 2010 4:37 AM
To: "Joel M. Halpern" <[e-mail]>
Cc: <[e-mail]>; <[e-mail]>; <[e-mail]>; <[e-mail]>
Subject: Re: [mpls] [PWE3] 1588 over MPLS draft

Hi Joel,

OK, do you have a better proposal?

Thx
Shahram

-----Original Message-----
From: Joel M. Halpern [mailto:[e-mail]]
Sent: Thursday, July 15, 2010 1:32 PM
To: Shahram Davari
Cc: [e-mail]; [e-mail]; [e-mail]; [e-mail]
Subject: Re: [mpls] [PWE3] 1588 over MPLS draft

I am sorry, but requiring every LSR in the infrastructure to get a
software upgrade in order to allow for the presence of 1588-supporting
devices is a MAJOR issue.  It is NOT backwards compatible.  Operators
(wether service provider or enterprise IT) do NOT like being told they
ahve to upgrade the software on all devices in their network in order to
add a capability that those devices are not engaging in.

While one can argue about the "ease" of the specific software change,
there is from an operational perspective no such thing as an easy
upgrade of any device, and there is definitely no such thing as an easy
upgrade of all the devices in the network.

Yours,
Joel

Shahram Davari wrote:
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.

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]; [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


_______________________________________________
mpls mailing list
[e-mail]
https://www.ietf.org/mailman/listinfo/mpls


_______________________________________________
mpls mailing list
[e-mail]
https://www.ietf.org/mailman/listinfo/mpls


_______________________________________________
mpls mailing list
[e-mail]
https://www.ietf.org/mailman/listinfo/mpls
_______________________________________________
mpls mailing list
[e-mail]
https://www.ietf.org/mailman/listinfo/mpls