Re: [netmod] Y34 - root node

[Ladislav Lhotka <[e-mail]>]

> On 19 Aug 2015, at 13:25, Martin Bjorklund <[e-mail]> wrote:
> 
> Robert Wilton <[e-mail]> wrote:
>> 
>> 
>> On 18/08/2015 18:22, Andy Bierman wrote:
>>> This is how languages like SMIv2 and YANG work.
>>> A conceptual object is given a permanent "home" within the tree of
>>> object identifiers.
>>> Moving data is very expensive, since any clients working with the old
>>> data
>>> will break as soon as the data is moved.
>>> 
>>> I am not convinced the IETF can or should come up with a set of
>>> containers
>>> that covers every possible topic that can be modeled in YANG.
>> 
>> I mostly agree, but having some more structure/advice as to where to
>> place YANG modules may be helpful.  I'm thinking more along the lines
>> of broad categories rather than precise locations.
> 
> +1
> 
>>>    If someone wants to builds a YANG controller node that is managing
>>>    the configuration for a network of devices then wouldn't they want
>>>    a particular device's interface configuration to be located
>>>    somewhere like /network/device/<device-name>/interfaces/interface?
>>>    Ideally, they would be able to use the same YANG definitions that
>>>    are defined for /interfaces/ but root them relative to
>>>    /network/device/<device-name>/.
>>> 
>>> 
>>> 
>>> Yes -- some of us (like Martin) have pointed this out many times.
>>> The "device" container on an NE does not help at all wrt/
>>> aggregation on a controller. "/device" or "/" work the same for this
>>> purpose.
> 
> Actually, I would argue that / works better.  On the controller, you
> probably have a list of devices you control (this is how our NCS
> works, and how ODL works (I have been told)):
> 
>  container devices {
>    list device {
>      key name;
>      // meta-info about the device goes here, things like
>      // ip-address, port, auth info...
>      container data {
>        // all models supported by the devices are "mounted" here
>      }
>    }
>  }
> 
> So on the controller, the path to interface "eth0" on device "foo"
> would be:
> 
>  /devices/device[name='foo']/data/interfaces/interface[name='eth0']
> 
> if we also have a top-level "/device" container we'd have:
> 
>  /devices/device[name='foo']/data/device/interfaces/interface[name='eth0']
> 
>> What would the real resource location for
>> "/network/device/<device-name>/interfaces/interface" be?
> 
> I don't think there is such a thing as a "real" location.  The path is
> scoped in the system you work with; in the controller it might be as I
> illustrated above, in the device it starts with /interfaces, but in a
> controller-of-controllers it might be:
> 
>  /domains/domain[name='bar']/devices/device[name='foo']/data
>    /interfaces/interface[name='eth0']
> 
> Currently we have a proprietary way of "relocating" YANG modules, and
> ODL has its "mount", and I think Andy has some other mechanism.  Maybe
> the time has come to standardize how mount works, and maybe then also
> standardize the list of devices in a controller model.

+1

Lada

> 
> 
> /martin
> 
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Ladislav Lhotka, CZ.NIC Labs
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