[mpls] Re: Opsdir last call review of draft-ietf-mpls-inband-pm-encapsulation-14

[[e-mail]]

Hi Daniele,


A new version -15 of this document has been posted to address your comments. Link as below.
https://datatracker.ietf.org/doc/html/draft-ietf-mpls-inband-pm-encapsulation-15 

Best Regards,
Xiao Min

Original


From: 肖敏10093570
To: DanieleCeccarelli(dceccare) <[e-mail]>;
Cc: [e-mail] <[e-mail]>;[e-mail] <[e-mail]>;[e-mail] <[e-mail]>;[e-mail] <[e-mail]>;
Date: 2024年08月26日 18:04
Subject: Re: Opsdir last call review of draft-ietf-mpls-inband-pm-encapsulation-14



Hi Daniele,


Thank you for the prompt reply.
Please see inline.






From: DanieleCeccarelli(dceccare) <[e-mail]>
To: 肖敏10093570;
Cc: [e-mail] <[e-mail]>;[e-mail] <[e-mail]>;[e-mail] <[e-mail]>;[e-mail] <[e-mail]>;
Date: 2024年08月26日 17:27
Subject: RE: Opsdir last call review of draft-ietf-mpls-inband-pm-encapsulation-14



Hi Xiao Min,
 
Please find some more comments in line.
 
Thanks
Daniele  
 

From: [e-mail] <[e-mail]> 
 Sent: Monday, August 26, 2024 10:58 AM
 To: Daniele Ceccarelli (dceccare) <[e-mail]>
 Cc: [e-mail]; [e-mail]; [e-mail]; [e-mail]
 Subject: Re: Opsdir last call review of draft-ietf-mpls-inband-pm-encapsulation-14


 
Hi Daniele,

 Thanks for your review and thoughtful comments.
Please see inline.

Original

From: DanieleCeccarelliviaDatatracker <[e-mail]>



To: [e-mail] <[e-mail]>;



Cc: [e-mail] <[e-mail]>;[e-mail] <[e-mail]>;[e-mail] <[e-mail]>;



Date: 2024年08月23日 20:34



Subject: Opsdir last call review of draft-ietf-mpls-inband-pm-encapsulation-14




Reviewer: Daniele Ceccarelli
 Review result: Has Issues
 
 General comments:
 The intro says: "Considering the MPLS performance measurement with the
 Alternate-Marking method can also be achieved by MNA encapsulation, it is
 agreed that this document will be made Historic once the MNA solution of
 performance measurement with the Alternate-Marking method is published as an
 RFC." The first reaction to this statement is: how long will it take for the
 MNA encapsulation to be delivered? If we already know that this will be
 obsoleted by the MNA encapsulation, is it worth publishing it?
[XM]>>> At the request of the MPLS WG chairs, the text you quoted was added to version -11 of this document. After that, this document passed WGLC and there was unanimous consensus to publish it as an RFC. Considering there are existing interoperable implementations of this document, while the MNA solution of performance measurement with alternate marking method is still at the early stage without WG draft and known implementation, it's worth publishing this document.
[[DC]] Ok. Sounds a pretty strange approach to me, but it’s up to the chairs to decide. Probably a temporary solution waiting for something to happen might be labelled as “experimental”, but again, up to the chairs to decide.
[XM-2]>>> During the WGLC of this document, there was discussion about whether this document should be "standards track" or "experimental", it's agreed it should be "standards track".


Detailed comments below:
 - Section 3: I was expecting a bit of intro/explanation here. The section
 starts saying that the encapsulation has this format. Boom. Is it something
 that already exists? If so where has it been defined? If not could we say
 something like" this document defines a new encapsulation as shown in figure
below..." 
[XM]>>> That's defined in this document first. Propose to change the text as below.
OLD
Flow-based MPLS performance measurement encapsulation with alternate marking method has the following format:
NEW
This document defines the Flow-based MPLS performance measurement encapsulation with alternate marking method, as shown in figure below.
[[DC]] sounds good.
 
- Section 3 suggest rephrasing. 
OLD
 The Traffic Class (TC) and Time To Live (TTL) [RFC3032] for the XL
    and FLI MUST use the same field values as the label immediately
    preceding the XL. unless it is known that the XL will not be exposed
    as the top label at any point along the LSP.
 NEW
  The Traffic Class (TC) and Time To Live (TTL) fields of the XL
    and FLI MUST use the same values of the label immediately
    preceding the XL, unless it is known that the XL will not be exposed
   as the top label at any point along the LSP.
Is the "unless..." really necessary? Can't this be always the case?
[XM]>>> Yes, this can always be the case. Will use the text you suggested and delete the "unless...".
 
- Section 3: "The BoS bit for the FL
   depends on whether the FL is placed at the bottom of the MPLS label
    stack, i.e., the BoS bit for the FL is set only when the FL is placed
    at the bottom of the MPLS label stack.
Isn't this always the case?
[XM]>>> No, Figure 2 provides an example the FL is not placed at the bottom of the MPLS label stack.
[[DC]] I’m not saying that the FL is always at the bottom of the stack, I’m saying that the BoS bit for the FL is set when the FL is at the bottom of the stack. What I’m trying to say is that it’s not something newly defined here but expected behavior.
[XM-2]>>> Aha, I see your point. :-) I see the value of this sentence is to emphasize that the definition of the BoS bit is not changed by this document in any way.
 
- Section 3: To achieve the purpose
    of coloring the MPLS traffic, and to distinguish between hop-by-hop
    measurement and edge-to-edge measurement, the TC for the FL is
    defined as follows:
 The TC is a single field 3 bits long and here it's used as 3 independent flags.
I'm not sure if this is possible, but if it is it must at least be explained. 
[XM]>>> This is possible and it's already been implemented. Propose to add below new text to the end of the TC definition.
NEW
Considering the FL is not used as a forwarding label, the repurposing of the TC for the FL is feasible and viable.
[[DC]] I’m not an expert here, if you say that it’s possible to change the role/definition of label fields in non-forwarding labels I trust you.
[XM-2]>>> Thank you for your trust.

Regards,
Xiao Min
 
- Examples section highly appreciated 
- Section 4,5 and 6 clear
[XM]>>> Thank you.
 
Cheers,
Xiao Min