Dear Authors, et.al,
please kindly consider my comments and questions to this document:
* Introduction
o "... it is a reasonable choice to develop the unified OAM framework based
on those (CFM) concepts." I agree that for packet switching connection-oriented
networks that are based on G.800 architecture CFM, but more so Y.1731, provides
shared concepts. I think that the same cannot be said for connectionless packet
switching networks. Thus extending CFM model onto arbitrary networks without
consideration whether these are connection-oriented or connectionless is very
questionable approach, IMO;
o "...CFM, it is a reasonable choice to develop the unified OAM framework
based on those concepts" IP OAM is not based on Ethernet Service OAM model or
principles but, IMO, OAM of overlay networks more closer resemble IP OAM as
these networks are connectionless in their architecture;
o "The YANG model presented in this document is the base model and supports
IP Ping and Traceroute." If only these and similar OAM tools, e.g. LSP ping,
Loopback/Linktrace, are in scope of the document, then, I believe, the title
may say something like "YANG model of on-demand OAM tool to detect and localize
Loss of Continuity defect". Referring to ping/traceroute as "generic OAM" comes
as stretch too far;
o "...initiate a performance monitoring session can do so in the same manner
regardless of the underlying protocol or technology" I'd point to work of LMAP
WG on informational model of performance measurements in large-scale access
networks, work of ITU-T's SG15, MEF. Perhaps sentence can be stopped after "...
or a Traceroute".
o "In this document we define the YANG model for Generic OAM" Can you provide
definition or reference to the definition of the "Generic OAM"? It is
challenging to validate informational model of something that not been
sufficiently defined.
* Section 3
o "This allows users to traverse between OAM of different technologies at
ease through a uniform API set." Usually relationships between OAM layers
referred and viewed as OAM interworking. There are several examples of IETF
addressing aspects of OAM interworking. I think that interworking includes not
only scenarios of nested OAM layers but peering layers and thus is broader than
introduced in the document "nested OAM".
o Figure 1 depicts OAM of both connection-oriented and connectionless
networks. What you see common, generic in respective OAM of these networks?
* Section 4
o "In IP, the MA can be per IP Subnet ..." As there's no definition of MA in
IP, is this the definition or one of examples. Can MA in IP network be other
than per IP Subnet?
o "Under each MA, there can be two or more MEPs (Maintenance End Points)"
Firstly, since you adopt MA-centric terminology, MEP stands for Maintenance
Association End Point. Secondly, in some OAM models Down and Up MEP being
distinguished. Would your model consider that? As there's no definition of MEP
for several networks you've listed, e.g. IP, how the YANG model will abstract
something that is not defined? And thirdly, how and where MIPs are located in
IP OAM?
Thank you for your consideration of my notes and looking forward to the
interesting discussion.
Regards,
Greg
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