Re: [netmod] draft-wilton-netmod-interface-properties-00

[Ladislav Lhotka <[e-mail]>]

Hi Rob,

I think this is a very useful work and we will probably implement it
soon. A few comments:

- I support the proposed redesign of "iana-if-type" but I believe this
  module should in fact be declared historic. For one, the name of the
  most frequently used type, "ethernetCsmacd", is not only notoriously
  hard to remember but it is also a misnomer: these days, almost no
  Ethernet network uses CSMA/CD any more. Instead, "csma-cd" can be
  another identity that could be added to the mix of bases where
  necessary.

- Interface type identities should be defined in a distributed way and
  not in a single module as in "iana-if-type". A module defining
  configuration and state data for a particular technology should also
  define the corresponding identity or identities. This way, the choice
  of interface types will always be limited to those supported by a
  specific server.

- In Appendix B I don't understand the comment in the definition of
  container "encapsulation": what could be the abstract type and how
  would it aid extensibility?

Thanks, Lada

Robert Wilton <[e-mail]> writes:

> Hi,
>
> In the NETMOD session on Wednesday I will spend 5 minutes speaking on 
> draft-wilton-netmod-interface-properties-00, that has been created due 
> to discussions with various folks to handle interface type specific 
> configuration.
>
> The draft isn't particularly long, 21 pages, two thirds of that is just 
> examples, and it is presenting a simple idea.
>
> In particular, it is aiming at solving the problem of when statements 
> like this:
>
>       augment "/if:interfaces/if:interface" {
>         when "derived-from-or-self(if:type, 'ianaift:ethernetCsmacd') or
>               derived-from-or-self(if:type, 'ianaift:ieee8023adLag') or
>               derived-from-or-self(if:type, 'ianaift:l2vlan') or
>               derived-from-or-self(if:type, 'ianaift:ifPwType')" {
>           description "Applies to all Ethernet-like interfaces";
>         }
>
> and instead proposes this:
>
>      augment "/if:interfaces/if:interface" {
>        when "derived-from(if:type, 'ianaifp:ethernet-like')" {
>          description
>            "Applies to all interfaces that derive from the Ethernet-like
>             interface property.";
>        }
>
> The core idea being that new identities are defined to represent 
> interface properties (like ethernet-like) and the existing interface 
> types iana-if-types.yang are updated to also derive from the new 
> interface properties.
>
> This simplifies the YANG, should make interface based configuration more 
> future proof, since new interface types can also derive from the 
> appropriate interface properties.  Of course additional interface 
> properties could also be defined.
>
> I'm seeking input from the WG as to whether they like this approach, AND 
> also whether the WG drafts: draft-ietf-netmod-intf-ext-yang-05 and 
> draft-ietf-netmod-sub-intf-vlan-model-02 should be updated to make use 
> of this approach (possibly in a future bis revision to avoid delaying 
> publishing the models).
>
> Thanks,
> Rob
>
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-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67