Re: [CCAMP] WG last call draft-ietf-ccamp-layer0-types-03

Italo Busi <> Tue, 28 January 2020 01:04 UTC

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From: Italo Busi <>
To: Daniele Ceccarelli <>, "CCAMP (" <>
Thread-Topic: [CCAMP] WG last call draft-ietf-ccamp-layer0-types-03
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Date: Tue, 28 Jan 2020 01:04:04 +0000
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Subject: Re: [CCAMP] WG last call draft-ietf-ccamp-layer0-types-03
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Hi Daniele, CCAMP WG,

Please find below my WG LC comments for the layer0-types:

1)      The YANG model defines some types and identities which are needed by drafts with different maturity levels: some of which are getting ready for WG LC (e.g., wson and flexi-grid topology models ) while others are still work-in-progress (e.g., optical impairment aware topology model).

For example, the modelling of transponder and 3R capabilities is still work-in-progress:

In order not to block the progress of the other drafts which are getting ready for WG LC (e.g., wson and flexi-grid topology models), it may be worthwhile considering removing some of these definitions from the version of the draft which is sent to IESG

These definitions can be kept in the draft for the time being, to simplify progressing the work-in-progress, but  should be removed before sending this draft to IESG. A new draft for updating layer0-types could also be started to support other work which is still in-progress within CCAMP WG.

2)      I have few doubts on the layer0-node-type identity, which defines four types of nodes: flexi-grid, WSON-FOADM. WSON-ROAM and WSON-iLA

1.       I assume that a flexi-grid node is a flexi-grid ROADM (FOADM can be considered old type of equipment not supporting flexi-grid). Correct?

2.       I am not sure why iLA is only defined for WSON. I think it is also possible to have iLA used within flexi-grid topology.

3.       Considering the previous comment, I am also not sure we need different identities for WSON and flexi-grid nodes, since this information can be inferred from the topology type (WSON or flexi-grid). Therefore, I am wondering whether the node type should not just define three types (ROADM, FOADM and iLA), maybe with some constraints about the fact that FOADM can only be used by WSON topology

4.       I am not sure the ITU-T references are correct: G.694.1 defines the DWDM grids and not the layer0 node type nor the ROAM nor the FOADM. G.698.2 defines the application codes for black link interfaces and not the ILA

5.       What about the case where a TE Node is an abstraction of multiple ROADMs?

3)      As far as I know, there is no generic definition of grid type in ITU-T but only of DWDM and CWDM grids in G.694.1 and G.694.2. It would be better to reference both Recommendations for the definition of grid-type and to clarify the point within the text of the draft.

4)      As described in section 4.2 of RFC7669, there is some overlap between bandwidth and label in layer0.

RFC7689 defines the bandwidth of a WSON LSP as the bit-rate of the signal being carried, which looks like more a transponder attribute than an LSP attribute.

RFC7792 defines the bandwidth as the spectrum width (m parameter) and allows it to be used for both flexi-grid as well as legacy DWDM networks. This information is already available in the label definition. Moreover, if we consider 3R, the value of m may change along the path.

It is proposed to remove the layer0-bandwidth-type from the draft sent to IESG and to re-discuss its need as part of the modelling of transponder and 3R capabilities.

The groupings defining the path and link bandwidths, to be used to augment te-topology and te models, could be re-defined with an empty attribute or with an empty container (to allow adding additional attributes in future revisions of the model, if needed)

I have tracked these comments on github as well:

Thanks, Italo

Italo Busi
Principal Optical Transport Network Research Engineer
Huawei Technologies Co., Ltd.
Tel : +39 345 4721946
Email :

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From: Daniele Ceccarelli []
Sent: lunedì 13 gennaio 2020 14:47
To: CCAMP ( <>
Subject: [CCAMP] WG last call draft-ietf-ccamp-layer0-types-03


the IPR declaration collection has been successfully completed (and sorry once again for the issues with the list) and we can move to the next step.

This starts a 2 weeks working group last call on draft-ietf-ccamp-layer0-types-03
The last call ends on Monday January 27th. Please send you comments to the CCAMP mailing list.

All the IPR declarations from authors and contributors have been collected and can be found in the history of the document.
If interested, please volunteer to be the shepherd of the draft (authors excluded).


Daniele & Fatai