Re: [mpls] MPLS WG adoption call for draft-mirsky-mpls-p2mp-bfd

[Loa Andersson <[e-mail]>]

Carlos,

Since the a wg adoption poll I read your comments as that we are doing
progress, and that we can address the rest during the wg process,
correct?

/Loa

On 2018-11-06 00:11, Carlos Pignataro (cpignata) wrote:
> Hi Greg,
> 
> Many thanks for your response and suggestions! Please see inline.
> 
>> On Nov 2, 2018, at 6:13 AM, Greg Mirsky <[e-mail] 
>> <mailto:[e-mail]>> wrote:
>>
>> Hi Carlos,
>> thank you for your comments. Please find my notes, answers in-line 
>> tagged GIM>>.
>>
>> Regards,
>> Greg
>>
>> On Thu, Oct 25, 2018 at 8:47 PM Carlos Pignataro (cpignata) 
>> <[e-mail] <mailto:[e-mail]>> wrote:
>>
>>     Hi,
>>
>>     Cc BFD WG
>>
>>     It would be useful to understand the use case motivation or
>>     applicability of this draft, other than it can be done.
>>
>> GIM>>  The motivation can be seen in the following (from another draft 
>> that discusses OAM over G-ACh:
>>   In some
>>    environments, the overhead of extra IP/UDP encapsulations may be
>>    considered as overburden and make using more compact G-ACh
>>    encapsulation attractive.
>> Will add text in the draft.
> 
> CMP: Thank you very much. This is a good start, although it would be 
> useful to add precision into which environments specifically, and the 
> burden comparison between IP/UDP and G-ACh.
> 
>>
>>     I’m also increasingly concerned by confusing scope and definition
>>     of specifications.
>>
>>     For example:
>>
>>     https://tools.ietf.org/html/draft-mirsky-mpls-p2mp-bfd-04#section-3.2
>>
>>     3.2.  Non-IP Encapsulation of Multipoint BFD
>>
>>        Non-IP encapsulation for multipoint BFD over p2mp MPLS LSP MUST use
>>        Generic Associated Channel (G-ACh) Label (GAL) [RFC5586] at the
>>        bottom of the label stack followed by Associated Channel Header
>>        (ACH).  Channel Type field in ACH MUST be set to BFD CV [RFC6428].
>>
>>
>>     First, there’s no definition for non-IP BFD in RFC 5586 — only in
>>     RFC 5885.
>>
>> GIM>> RFC 5586 defined the use of GAL. I think that this reference is 
>> appropriate. I agree that the second reference should be to RFC 5885, 
>> not RFC 6428. Will make the change.
> 
> CMP: Thank you. However, RFC 5885 is in the context of PW VCCV — is 
> there a missing definition in the specs for BFD over G-ACh generically?
> 
>>     Second, the specification in RFC 6428 applies to MPLS Transport
>>     Profile only. NOT for MPLS, and explicitly NOT for P2MP!
>>
>>     https://tools.ietf.org/html/rfc6428#section-1
>>
>>        This document specifies the BFD extension and behavior to
>>     satisfy the
>>        CC, proactive CV monitoring, and the RDI functional
>>     requirements for
>>        both co-routed and associated bidirectional LSPs.  Supported
>>        encapsulations include Generic Associated Channel Label (GAL) /
>>        Generic Associated Channel (G-ACh), Virtual Circuit Connectivity
>>        Verification (VCCV), and UDP/IP.  Procedures for unidirectional
>>        point-to-point (P2P) and point-to-multipoint (P2MP) LSPs are for
>>        further study.
>>
>>
>>     So, no, this does not work.
>>
>>     RFC 6428 does not have scope for P2MP.
>>     And RFC 5586 does not specify anything for BFD. Instead, what
>>     needs to be cited (appropriately and expanded) is RFC 5885
>>
>> GIM>> RFC 5586 specifies the use of GAL and G-ACh and the reference is 
>> used in this context.
> 
> CMP: This is the same comment as above.
> 
>>
>>     https://tools.ietf.org/html/rfc6428#section-4
>>           RFC 5884 - BFD CC in UDP/IP/LSP
>>           RFC 5885 - BFD CC in G-ACh
>>
>> GIM>> I'd point that it is for p2p BFD CC, and p2mp BFD uses different 
>> from p2p BFD method to demultiplex BFD control packets.
> 
> 
> CMP: Apologies I did not understand this response.
> 
> CMP: Thanks again for considering the comment to improve the document.
> 
> Thanks,
> 
> Carlos.
> 
> 
>>           RFC 5085 - UDP/IP in G-ACh
>>            MPLS-TP - CC/CV in GAL/G-ACh or G-ACh
>>
>>
>>
>>     Thanks,
>>
>>     — Carlos Pignataro
>>
>>>     On Oct 13, 2018, at 4:24 PM, Greg Mirsky <[e-mail]
>>>     <mailto:[e-mail]>> wrote:
>>>
>>>     Dear WG Chairs, et al.,
>>>     as the author of the BFD for Multipoint Networks over
>>>     Point-to-Multi-Point MPLS LSP (draft-mirsky-mpls-p2mp-bfd) I
>>>     would like to ask you to consider WG adoption call of the draft.
>>>     The document addresses non-IP encapsulation of p2mp BFD over MPLS
>>>     LSP that may be useful if the overhead of IP, particularly IPv6,
>>>     encapsulation is the concern. The base specification of BFD for
>>>     Multipoint Networks is at this time in IESG LC.
>>>
>>>     Regards,
>>>     Greg
>>>     _______________________________________________
>>>     mpls mailing list
>>>     [e-mail] <mailto:[e-mail]>
>>>     https://www.ietf.org/mailman/listinfo/mpls
>>
> 
> 
> 
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-- 


Loa Andersson                        email: [e-mail]
Senior MPLS Expert
Bronze Dragon Consulting             phone: [phone]