Acee
Tweaking the subject line slightly since this is a more generic point.
My point about
refine "version/ospfv2/ospfv2" {
must "derived-from-or-self( "
+ "../../../../../../../../../../"
+ "rt:type, 'ospf:ospfv2')" {
description "OSPFv2 LSA.";
was more about the difficulty of validating these conditionals in YANG.
It could be worse e.g.
augment "/nw:networks/nw:network/nt:link/tet:te/"
+ "tet:te-link-attributes/"
+ "tet:max-resv-link-bandwidth/"
+ "tet:te-bandwidth/tet:technology" {
when "../../../../../../nw:network-types/tet:te-topology/"
+ "otntopo:otn-topology" {
occurring 100 or so times in an I-D. Tools can check the syntax, they
can (almost) never check the semantics. It takes something more
intelligent, more knowledgeable than a tool to spot that e.g.
RFC 5178 - OSPFv3 Graceful Restart";
is wrong and I think the same of complicated YANG expressions.
If complicated expressions occur once, I could check them; 100 times, no
way. Every other language (almost) I have used allows me to say
must "derived-from-or-self( "
+ "../../../../../../../../../../"
+ "rt:type, 'ospf:ospfv2')" {
is equivalent to
ospfv2 {type boolean}
so I need check the complicated expression once, subsequent uses being
just
ospfv2
which is then obviously right or wrong.
You only have any one 'complicated' expression occurring half a dozen
times or so, but then there are a number of them, conditional on OSPF
version, LSA type and so on. If one instance of one expression was
syntactically valid but not quite right, perhaps missing 'or-self' or
/.. or some such, would anyone ever notice?
I see this as the biggest single defect in YANG that has only become
apparent with the use it is put to in the Routing Area; and it is YANG
that needs to change (IMHO).
Tom Petch
----- Original Message -----
From: "Acee Lindem (acee)" <[email protected]>
To: "tom petch" <[email protected]>; "Jeff Tantsura"
<[email protected]>; <[email protected]>
Sent: Thursday, August 23, 2018 12:23 AM
Subject: Re: [Lsr] LSR Working Last Call for draft-ietf-ospf-yang
> Hi Tom,
>
> Thanks much Tom - I agree with your comments. See one inline.
>
> I will likely work on these prior to the end of the WG last call
period.
>
> On 8/22/18, 11:41 AM, "tom petch" <[email protected]> wrote:
>
> ---- Original Message -----
> From: "Jeff Tantsura" <[email protected]>
> Sent: Friday, August 17, 2018 9:14 PM
>
> Acee,
>
> The draft is in good shape, support.
>
> <tp>
>
> Mmm that sounds like a good challenge. I had a quick look and
noticed:
>
> - NMDA gets discussed in s.2.1; I like to see support for it
mentioned
> earlier, in Abstract and Introduction, something I have seen the
IESG
> request recently
>
> - there is no explanation of the legend used in the tree diagrams;
if
> appropriate, this can be fixed with an Informative Reference to
RFC8340
>
> - s.2.4 NSR needs expanding IMHO
>
> - s.2.4 I would like a list of features, all 20 of them, not just
> "such as NSR, max-LSA, etc"
> so I don't have to reverse engineer the YANG module to find them;
as and
> when new features come along, I expect there will be a delay
before they
> make it into YANG so a clear list for those supported by this
module
> would be useful
>
> - sometimes it is 'link state database ', sometimes 'Link State
> Database', sometimes 'Link State database'; I would like
consistency
> (and prefer the capitalised version)
>
> I agree.
>
> - the YANG module as
> version 1.1
> but RFC7950 is not mentioned or referenced; odd
>
> - the YANG module has
> RFC 5178 - OSPFv3 Graceful Restart";
> which I think should be RFC 5187
>
> Yup.
>
> - the YANG module has
> "RFC XXXX - YANG Data Model for Bidirectional Forwarding Detection
> (BFD)";
> "RFC XXXX: A YANG Data Model for OSPF.";
> "RFC XXXX - SPF Back-off algorithm for link state IGPs"; RFC8405
> reference "draft-ietf-bfd-yang-xx.txt:
>
> I suggest using a larger namespace than 'XXXX'; perhaps 'XXXX' and
> 'YYYY' (since "RFC XXXX - SPF Back-off algorithm for link state
IGPs"
> is in fact RFC8405 and is already in the Normative References)
along
> with a note to the RFC Editor telling them what 'YYYY' and 'XXXX'
should
> be replaced with.
>
> reviewing the technical bits is going to be a challenge; I
struggle to
> interpret such as
> when "derived-from("
> +
"../../../../../areas/area[area-id=current()/../area-id]/"
> + "area-type, 'stub-nssa-area')" {
> or
> refine "version/ospfv2/ospfv2" {
> must "derived-from-or-self( "
> + "../../../../../../../../../../"
> + "rt:type, 'ospf:ospfv2')" {
> description "OSPFv2 LSA.";
>
> I note the use of "derived-from-or-self " as opposed to
"derived-from "
> but it will take me longer to work out if the usage is
appropriate.
>
> In cases where the leaf should take on a specific identity rather than
the general identity, It should simply be derived-from(). I'll revisit
these.
>
> Thanks,
> Acee
>
> Tom Petch
>
> Cheers,
>
> Jeff
>
>
>
> From: Lsr <[email protected]> on behalf of "Acee Lindem (acee)"
> <[email protected]>
> Date: Friday, August 17, 2018 at 13:09
> To: "[email protected]" <[email protected]>
> Subject: [Lsr] LSR Working Last Call for draft-ietf-ospf-yang
>
>
>
> This begins an LSR WG last call for the subject draft. Please send
your
>
> comments to this list prior to 12:00 AM GMT, September 8th, 2018.
>
>
>
> Given the size of the model and the US Labor Day Holiday, we’re
allowing
> a full 3 weeks.
>
>
>
> For your convenience, here is a URL:
>
>
>
> https://datatracker.ietf.org/doc/draft-ietf-ospf-yang/
>
>
>
> Note there is one obsolete reference left as an exercise for the
> reviewers. Note that the document has already been through a
couple YANG
> doctor reviews.
>
>
>
> Thanks,
> Acee
>
> _______________________________________________ Lsr mailing list
> [email protected] https://www.ietf.org/mailman/listinfo/lsr
>
>
>
>
> ------------------------------------------------------------------
------
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>
>
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>
>
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