Tom:

100% agree with your comments. I2RS cares whether it is read-only or
read-write.  My work toward the revision found:

- RBNF  RBNF did not even allow you a place to r/w or r-only or permissions
(needed for security, but that's my next draft).
- The yang tree I wrote was r-w for config, but did not express the ro-only
tree.  I wanted some feedback to figure out why I had 2 write 2 trees. 
 (your telling me it is a yang short-coming).
- UML seems to be able to handle read/write variants, and I'm looking to see
if graphical tools will help the developer. 

Not shown in the reduction: 
... And I started working on BGP, ISIS, RIP.. only to find some of these
issues you mention. DCHP and NTP.   Any suggestions or help would be
gratefully accepted. 
 
I will continue to try to get more details on Yang++ and ForCES to see how
many wheels fall off.  

Sue 

-----Original Message-----
From: i2rs [mailto:[email protected]] On Behalf Of t.petch
Sent: Wednesday, April 23, 2014 12:08 PM
To: Edward Crabbe; [email protected]
Subject: Re: [i2rs] consensus on I2RS protocol and model

YANG (with NETCONF) is designed for writing configuration and reading
everything else, and does an excellent job at it.  Trouble is, for me, that
configuration doesn't mean what I think of it as; it means, in the YANG
context, what you might put in through the CLI and it excludes everything
else, such as data learnt via a protocol.

Take routing.  A static route is configuration; anything learnt, via BGP,
IS-IS, RIP etc, is not configuration (and is read only).

An interface configured automatically on a hot-plugged card is not
configuration; adding 'ospf passive' is.

And so on, for DHCP, NTP, .....

In practice, this means that the YANG model comes in twin sets, one of
read-write configuration and one of read-only not-configuration (as can be
seen in the current I-Ds that the netmod WG is producing) with no formal way
in YANG of relating the one to the other.  So if you want e.g. the routing
table, the host software has to know where to look and how to combine the
pieces to produce a coherent picture (and then you cannot edit most of it).

So if I2RS never wants to write anything to a router, YANG is fine; if I2RS
is only producing a Information Model (and ignoring whether or not data is
read-only or read-write), and not moving on to an implementation, then YANG
is fine.

Rather, as Andy Bierman said at IETF89, likely I2RS would need an extension
to YANG, a new sub-statement for all data objects, semantics not too clear
but designed to separate out the not-configuration, learnt via a protocol,
'editable-state' (and in doing so, making it read-write - but still 'config
false').

Yes, YANG allows for such extensions but it seems to me that I2RS would then
be getting YANG++ (and NETCONF++), once the necessary work has been done.

Tom Petch


----- Original Message -----
From: "Edward Crabbe" <[email protected]>
To: <[email protected]>
Sent: Friday, April 11, 2014 6:50 PM
Subject: [i2rs] consensus on I2RS protocol and model


> Dear I2RSers,
>
>
>   At the last I2RS WG meeting there was a great deal of conversation 
> regarding selection of both modeling language and underlying transport 
> protocol.  Consensus at the time was to make use of Yang and (NetConf
or
> RestConf) (unclear).
>
>   Before coming to a final consensus, we'd like to give people
adequate
> time to review source material, marshall arguments and discuss on the 
> mailing list.  To this end, we're asking that interested parties do
just
> this over the course of the next ~two weeks. Following that period, on 
> 4/28, we'll be initiating a consensus call that will last an
additional two
> weeks, with the aim of converging modeling language / protocol by
Friday,
> 5/9.
>
> The consensus call should also generate proposals for any material
changes
> required to the underlying protocols.  These proposals in turn will
form
> the basis for a later draft including gap analysis and said changes.
Those
> strongly in favor of one protocol over another should be prepared to 
> contribute to this analysis.
>
>
> best,
>
>   -ed
>


------------------------------------------------------------------------
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> i2rs mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/i2rs
>

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