Subject: [Netconf] LL review of draft-ietf-netconf-with-defaults-05

From: Ladislav Lhotka <[email-masked]>
Date: Sun, 21 Mar 2010 10:35:17 -0700

Hi,

here are my comments to the with-defaults draft:

In general, this capability is quite important and the document does a
decent job in specifying the necessary functionality given the
limitation that it has to remain neutral with respect to the possible
implementations of defaults. As a side note, the YANG module in Sec. 3
is a nice testimony to the flexibility and readability of YANG.

Specific comments:

Sec. 1.1:
definition of "default data": "MAY or MAY NOT" - "MAY NOT" is not among
the RFC 2119 keywords, I think it is better to write it all lowercase.

Sec. 2.6:
It should be clearly stated here that the new element <with-defaults>
belongs to the XML namespace with URI
urn:ietf:params:netconf:capability:with-defaults:1.0. I would even
recommend to write this element in the text always with the prefix, i.e.
<nwd:with-defaults>.

It should be explained in more detail how with-defaults modifies the
existing operations. For instance, in the context of the example: What
will be returned if with-defaults is set to "trim" (or "explicit") and
the get-config filter is either
    <interfaces xmlns="http://example.com/interfaces/1.2">
        <interface>
            <mtu/>
        </interface>
    </interfaces>
 or
    <interfaces xmlns="http://example.com/interfaces/1.2">
        <interface>
            <mtu>1500</mtu>
        </interface>
    </interfaces>
Will the reply in either case contain the mtu node with the default
value or not?

The example also indicates a problem that may need to be addressed in
RFC 4741bis: In standard XML, whitespace in the element text is not
normalized, so is <with-defaults xmlns="...">report-all</with-defaults>
and
<with-defaults xmlns="...">
  report-all
</with-defaults>
really the same thing? 

Sec. 7, Normative references:
XML 1.0 spec is now in its fifth edition from 26 November 2008. Is there
any reason for not using this latest edition?

Lada

-- 
Ladislav Lhotka, CESNET
PGP Key ID: E74E8C0C