Subject: [CCAMP] Adding composite labels to flexi-grid

From: "Adrian Farrel" <[email-masked]>
Date: Tue, 17 Jun 2014 13:55:26 +0100

Hi,

Ramon and I have worked up some text to go in
draft-ietf-ccamp-flexigrid-lambda-label to describe composite labels.

There is not a huge amount to say *in*this*document* partly because we have lots
of running code about how to do VCAT in a number of technologies, and partly
because this document describes the label format, not the signaling, routing, or
usage.

Would like your comments and plan to post before the Toronto cut-off. We can
return to the debate in Toronto if it needs f2f time.

BTW, as an aside, this is deliberately not intended to discuss the "super
channel". At this stage, super-channel is not something that the ITU-T
recognises as a data plane concept (although I know a number of companies are
interested in this and will work in that area). Iftekhar has a strong interest
in describing GMPLS labels and processing for super channels, and has indicated
that he is willing to be an anchor for this work in the IETF.

Thanks,
Adrian

====

New section

2.1.  Virtual Concatenation

   It is possible to construct an end-to-end connection by
   "concatenating" more than one flexi-grid slot.  The mechanism used is
   similar to virtual concatenation (VCAT) familiar in time-division
   multiplexing (TDM) and optical transport networks (OTN).  The
   concatenated slots could potentially be contiguous or non-contiguous
   (as allowed by the definitions of the data plane) and could be
   signaled as a single LSP or constructed from a group of LSPs.  For
   more details, refer to Section 4.3.

===

New section

4.3.  Virtual Concatenation

   Virtual concatenation is already supported in GMPLS for TDM and OTN
   [RFC4606], [RFC6344], [RFC7139].  The mechanism used for flexigrid is
   similar.

   To signal an LSP that uses multiple flexi-grid slots a "compound
   label" is constructed.  That is, the LABEL object is constructed from
   a concatenation of the 64-bit Flexi-Grid Labels shown in Figure 1.
   The number of elements in the label can be determined from the length
   of the LABEL object.  The resulting LABEL object is shown in Figure
   2 including the object header that is not normally shown in
   diagrammatic representations of RSVP-TE objects.  Note that r is the
   count of component labels, and this is backward compatible with the
   label shown in Figure 1 where the value of r is 1.

   The order of component labels MUST be presented in increasing order
   of the value n.  Implementations MUST NOT infer anything about the
   encoding of a signal into the set of slots represented by a compound
   label from the label itself.  Information about the encoding MAY be
   handled in other fields in signaling messages or through an out of
   band system, but such considerations are out of the scope of this
   document.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Object Length (4 + 8r)      | Class-Num (16)|  C-Type (2)   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Grid | C.S.  |    Identifier   |              n                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              m                |          Reserved             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Grid | C.S.  |    Identifier   |              n                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              m                |          Reserved             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 2 : A Compound Label for Virtual Concatenation

   Note that specific rules must be applied as follows:

   - Grid MUST show "ITU-T Flex" value 3 in each component label.
   - C.S. MUST have the same value in each component label.
   - Identifier in each component label may identify different physical
     equipment.
   - Values of n and m in each component label define the slots that
     are concatenated.

   At the time of writing [G.694.1] only supports the concatenation of
   adjacent slots (i.e., without intervening unused slots that could be
   used for other purposes) of identical width (same value of m), and
   the component slots must be in increasing order of frequency (i.e.,
   increasing order of the value n).  The mechanism defined here MUST 
   NOT be used for other forms of concatenation unless and until those
   forms of concatenation are defined and documented in Recommendations
   published by the ITU-T.

   Note further that while the mechanism described here naturally means
   that all component channels are corouted, a composite channel can
   also be achieved by constructing individual LSPs from single flexi-
   grid slots and managing those LSPs as a Virtual Concatenation Group
   (VCG).  A mechanism for achieving this for TDM is described in
   [RFC6344], but is out of scope for discussion in this document
   because the labels used are normal, single slot labels and require no
   additional definitions.

---

From: [email-masked]
Date: Thu, 19 Jun 2014 06:11:06 -0400

Hi Adrian, 

I have some concerns about using the term VCAT in the context of a media 
channel. The media is flat and has no structure so if the "concatenated" 
media channels are adjacent, we have a larger media channel. If (as I 
think you intend) the media channels are not adjacent then you have a set 
of media channels.

Another way of looking at this (and please don't over extend the analogy) 
is water and pipe. The water is the optical signal and the media channel 
is the pipe. This draft is addressing the management of pipes. 

The concept of VCAT only applies to digital streams, it cannot be applied 
to the media layer layer.

This concept of a group (or set) of media channels may be useful in the 
future after SG15 have completed the work on OTN B100G where the 
possibility of inverse multiplexing a 400G OTN digital stream into two (or 
four) digital streams which are then modulated onto two (or four) optical 
signals that use two (or four) independent media channels is under 
consideration and managing these independent media channels as a set would 
be useful. However, this is still under discussion in SG15.

Regards,

Malcolm

"Adrian Farrel" <[email-masked]> 
Sent by: "CCAMP" <[email-masked]>
17/06/2014 08:55 AM
Please respond to
[email-masked]

To
<[email-masked]>, 
cc

Subject
[CCAMP] Adding composite labels to flexi-grid

Hi,

There is not a huge amount to say *in*this*document* partly because we 
have lots
of running code about how to do VCAT in a number of technologies, and 
partly
because this document describes the label format, not the signaling, 
routing, or
usage.

Would like your comments and plan to post before the Toronto cut-off. We 
can
return to the debate in Toronto if it needs f2f time.

BTW, as an aside, this is deliberately not intended to discuss the "super
channel". At this stage, super-channel is not something that the ITU-T
recognises as a data plane concept (although I know a number of companies 
are
interested in this and will work in that area). Iftekhar has a strong 
interest
in describing GMPLS labels and processing for super channels, and has 
indicated
that he is willing to be an anchor for this work in the IETF.

Thanks,
Adrian

====

New section

===

New section

    0                   1                   2                   3

_______________________________________________
CCAMP mailing list
[email-masked]
https://www.ietf.org/mailman/listinfo/ccamp

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ZTE Information Security Notice: The information contained in this mail (and any attachment transmitted herewith) is privileged and confidential and is intended for the exclusive use of the addressee(s).  If you are not an intended recipient, any disclosure, reproduction, distribution or other dissemination or use of the information contained is strictly prohibited.  If you have received this mail in error, please delete it and notify us immediately.

---

From: "Adrian Farrel" <[email-masked]>
Date: Mon, 23 Jun 2014 13:56:18 +0100

Hi Malcolm,
 
Thanks for this.
 
In terms of over-extended analogies, maybe there is a tendency to over-extend
the meaning of the term/concept VCAT.
 
I disagree that the result of adjacent concatenated media channels is a larger
media channel. There is a distinction between building a larger (if you like,
wider) channel either simply through a larger value of m or through the
so-called "super channel", and constructing a set of media channels as you
describe it.
 
You say "The concept of VCAT only applies to digital streams, it cannot be
applied to the media layer layer" and i think this is taking the architecture
too far into the implementation. But also that this is not an important part of
the discussion.
 
So, to take your analogy, the sender of water has a big tank with a flow that
goes here to there. The "composite label" describes a set of parallel pipes. How
the water is distributed across those pipes is not in scope for this document.
 
I think we can address your concerns by renaming Section 2.1 to "Composite
Labels" and tweaking the text. Thus...
 
2.1.  Composite Labels
 
   It is possible to construct an end-to-end connection by
   "concatenating" more than one flexi-grid slot.  The mechanism used in
   GMPLS is similar to that used to support virtual concatenation (VCAT)
   familiar in time-division multiplexing (TDM) and optical transport
   networks (OTN).  The concatenated slots could potentially be 
   contiguous or non-contiguous (as allowed by the definitions of the
   data plane) and could be signaled as a single LSP or constructed from
   a group of LSPs.  For more details, refer to Section 4.3.
 
This specifically does not say that the "concatenated" construction is VCAT. And
it states that the similarity is in GMPLS. Furthermore, it delegates the
applicability to the definition of the data plane.
 
Similarly, Section 4.3 can be renamed "Composite Labels". The only other change
in that Section I believe is needed to address your concerns is to remove
mention of VCG from the final paragraph. Thus:
 
   Note further that while the mechanism described here naturally means
   that all component channels are corouted, a composite channel can
   also be achieved by constructing individual LSPs from single flexi-
   grid slots and managing those LSPs as a group.  A mechanism for 
   achieving this for TDM is described in [RFC6344], but is out of scope
   for discussion in this document because the labels used are normal,
   single slot labels and require no additional definitions.
 
Cheers,
Adrian
 
From: [email-masked] [mailto:[email-masked]] 
Sent: 19 June 2014 11:11
To: [email-masked]
Cc: [email-masked]; CCAMP
Subject: Re: [CCAMP] Adding composite labels to flexi-grid
 
Hi Adrian, 

I have some concerns about using the term VCAT in the context of a media
channel. The media is flat and has no structure so if the "concatenated" media
channels are adjacent, we have a larger media channel. If (as I think you
intend) the media channels are not adjacent then you have a set of media
channels. 

Another way of looking at this (and please don't over extend the analogy) is
water and pipe. The water is the optical signal and the media channel is the
pipe. This draft is addressing the management of pipes. 

The concept of VCAT only applies to digital streams, it cannot be applied to the
media layer layer. 

This concept of a group (or set) of media channels may be useful in the future
after SG15 have completed the work on OTN B100G where the possibility of inverse
multiplexing a 400G OTN digital stream into two (or four) digital streams which
are then modulated onto two (or four) optical signals that use two (or four)
independent media channels is under consideration and managing these independent
media channels as a set would be useful. However, this is still under discussion
in SG15. 

Regards, 

Malcolm 

Please respond to
[email-masked]

To
<[email-masked]>, 

cc

Subject

Hi,

Thanks,
Adrian

====

New section

===

New section

   0                   1                   2                   3

_______________________________________________
CCAMP mailing list
[email-masked]
 <https://www.ietf.org/mailman/listinfo/ccamp>
https://www.ietf.org/mailman/listinfo/ccamp

--------------------------------------------------------
ZTE Information Security Notice: The information contained in this mail (and any
attachment transmitted herewith) is privileged and confidential and is intended
for the exclusive use of the addressee(s).  If you are not an intended
recipient, any disclosure, reproduction, distribution or other dissemination or
use of the information contained is strictly prohibited.  If you have received
this mail in error, please delete it and notify us immediately.

---

From: "Varma, Eve L (Eve)" <[email-masked]>
Date: Mon, 23 Jun 2014 13:20:59 +0000

Hi Adrian,

I think the intended point is that since each network media channel has an effective frequency slot with a nominal central frequency and slot width, while you might think of making a wider slot as allocating extra increments (e.g., 12.5GHz or 50GHz at a time), it is still one slot with a greater width. But since this is talking about the channel and not the signal, this isn't concatenation, it is just wider effective frequency slots for the channel (and non-contiguous network media channels are simply different network media channels).

As Malcolm indicated below, if the intention is, for example, to support carrying a B100G signal over multiple different (non-contiguous) network media channels, that would be inverse muxing vs. concatenation.

Best regards,
Eve
From: CCAMP [mailto:[email-masked]] On Behalf Of Adrian Farrel
Sent: Monday, June 23, 2014 8:56 AM
To: [email-masked]
Cc: [email-masked]
Subject: Re: [CCAMP] Adding composite labels to flexi-grid

Hi Malcolm,

Thanks for this.

In terms of over-extended analogies, maybe there is a tendency to over-extend the meaning of the term/concept VCAT.

I disagree that the result of adjacent concatenated media channels is a larger media channel. There is a distinction between building a larger (if you like, wider) channel either simply through a larger value of m or through the so-called "super channel", and constructing a set of media channels as you describe it.

You say "The concept of VCAT only applies to digital streams, it cannot be applied to the media layer layer" and i think this is taking the architecture too far into the implementation. But also that this is not an important part of the discussion.

So, to take your analogy, the sender of water has a big tank with a flow that goes here to there. The "composite label" describes a set of parallel pipes. How the water is distributed across those pipes is not in scope for this document.

I think we can address your concerns by renaming Section 2.1 to "Composite Labels" and tweaking the text. Thus...

2.1.  Composite Labels

This specifically does not say that the "concatenated" construction is VCAT. And it states that the similarity is in GMPLS. Furthermore, it delegates the applicability to the definition of the data plane.

Similarly, Section 4.3 can be renamed "Composite Labels". The only other change in that Section I believe is needed to address your concerns is to remove mention of VCG from the final paragraph. Thus:

Cheers,
Adrian

From: [email-masked]<mailto:[email-masked]> [mailto:[email-masked]]
Sent: 19 June 2014 11:11
To: [email-masked]<mailto:[email-masked]>
Cc: [email-masked]<mailto:[email-masked]>; CCAMP
Subject: Re: [CCAMP] Adding composite labels to flexi-grid

Hi Adrian,

I have some concerns about using the term VCAT in the context of a media channel. The media is flat and has no structure so if the "concatenated" media channels are adjacent, we have a larger media channel. If (as I think you intend) the media channels are not adjacent then you have a set of media channels.

Another way of looking at this (and please don't over extend the analogy) is water and pipe. The water is the optical signal and the media channel is the pipe. This draft is addressing the management of pipes.

The concept of VCAT only applies to digital streams, it cannot be applied to the media layer layer.

This concept of a group (or set) of media channels may be useful in the future after SG15 have completed the work on OTN B100G where the possibility of inverse multiplexing a 400G OTN digital stream into two (or four) digital streams which are then modulated onto two (or four) optical signals that use two (or four) independent media channels is under consideration and managing these independent media channels as a set would be useful. However, this is still under discussion in SG15.

Regards,

Malcolm

"Adrian Farrel" <[email-masked]<mailto:[email-masked]>>
Sent by: "CCAMP" <[email-masked]<mailto:[email-masked]>>

17/06/2014 08:55 AM
Please respond to
[email-masked]<mailto:[email-masked]>

To

<[email-masked]<mailto:[email-masked]>>,

cc

Subject

Hi,

Thanks,
Adrian

====

New section

===

New section

   0                   1                   2                   3

_______________________________________________
CCAMP mailing list
[email-masked]<mailto:[email-masked]>
https://www.ietf.org/mailman/listinfo/ccamp

---

From: "Adrian Farrel" <[email-masked]>
Date: Mon, 23 Jun 2014 19:11:38 +0100

Ah, Eve, thanks.
 
Inverse mux is a useful term. You can inverse mux over a set of channels that
may or may not be contiguous.
 
Adrian
 
From: Varma, Eve L (Eve) [mailto:[email-masked]] 
Sent: 23 June 2014 14:21
To: [email-masked]; [email-masked]
Cc: [email-masked]
Subject: RE: [CCAMP] Adding composite labels to flexi-grid
 
Hi Adrian,
 
I think the intended point is that since each network media channel has an
effective frequency slot with a nominal central frequency and slot width, while
you might think of making a wider slot as allocating extra increments (e.g.,
12.5GHz or 50GHz at a time), it is still one slot with a greater width. But
since this is talking about the channel and not the signal, this isn't
concatenation, it is just wider effective frequency slots for the channel (and
non-contiguous network media channels are simply different network media
channels).
 
As Malcolm indicated below, if the intention is, for example, to support
carrying a B100G signal over multiple different (non-contiguous) network media
channels, that would be inverse muxing vs. concatenation. 
 
Best regards,
Eve
 
Hi Malcolm,
 
Thanks for this.

 

 
2.1.  Composite Labels

 

Cheers,
Adrian

Hi Adrian, 

Regards, 

Malcolm 

Please respond to
[email-masked]

To
<[email-masked]>, 

cc

Subject

Hi,

Thanks,
Adrian

====

New section

===

New section

   0                   1                   2                   3