Andy Bierman <a...@yumaworks.com> wrote:
> On Wed, Jan 11, 2017 at 9:21 AM, Ladislav Lhotka <lho...@nic.cz> wrote:
>
> >
> > > On 11 Jan 2017, at 17:56, Andy Bierman <a...@yumaworks.com> wrote:
> > >
> > > Hi,
> > >
> > >
> > > On Wed, Jan 11, 2017 at 7:12 AM, Robert Wilton <rwil...@cisco.com>
> > wrote:
> > >
> > >
> > > On 11/01/2017 09:22, Martin Bjorklund wrote:
> > > Andy Bierman <a...@yumaworks.com> wrote:
> > > On Tue, Jan 10, 2017 at 1:20 PM, Kent Watsen <kwat...@juniper.net>
> > wrote:
> > >
> > > I think it is better to have a human decide what is in the module
> > > instead of relying on a pyang plugin to generate some additional module
> > > that follows some simplistic pattern.
> > > It may be simple, but I’m thinking that’s only because it’s not tricky
> > ;)
> > >
> > >
> > > The client and server developers still need to know about this
> > > auto-generated module
> > > and implement it. Operators might have to know about it to use it.
> > > My idea is not to auto generate models on the fly.
> > >
> > > My aim is to allow folks to start writing models in the desired long
> > term format (i.e. combined config and state tree) with the model designer
> > being able to assume the existence of the operational state datastore.
> > >
> > >
> > >
> > > I am not convinced this "new format" has solved anything.
> > > Don't you need separate description-stmts in every node for each
> > > datastore? What does the value mean if pre-configured? configured?
> > > operational? Will the auto-generated objects be exactly correct
> > > and never need any alterations or additional text?
> > > They still need to be used by developers and YANG tools.
> >
> > Right, this is one problem of this "deduplication": even if two nodes -
> > one config and the other state - have the same name or even type (which is
> > not always the case, as we know), their semantics is often different. An IP
> > address in configuration means a manually configured address whereas in
> > state it may come from any source. So writing sensible descriptions will
> > become tricky.
> >
> > >
> > > Is is that realistic to force the config structure and operational
> > structure
> > > to be the same? Seems it is quite common to monitor data structures
> > > with additional keys or different keys. This is completely unsupported
> > > so separate /foo and /foo-state trees will still exist.
> >
> > I agree.
> >
> > Lada
> >
> > >
> > > IMO this combination of trees needs to be proven.
> > > Take ietf-interfaces and show how much better it will work
> > > if the /interfaces and /interfaces-state trees were combined.
> > >
> > >
> > > Andy
> > >
> > >
> > > The tooling would be there to statically generate the extra foo-state
> > config false node modules for servers that don't support the operational
> > state datastore. This could be done once, and the extra foo-state modules
> > committed to the github YANG respository in the same way that models are
> > extracted from IETF RFCs today.
> > >
> > > The aim here is that the single model being produced by IETF would be
> > usable both by new client/servers that support an operational state
> > datastore, and also by existing NETCONF client/servers that don't implement
> > an operational state datastore.
> > >
> > > I'm not proposing that as a long term solution, but as a path to make it
> > easier for folk to migrate, and to not slow down the model writing effort.
> > Otherwise, it may be hard to get a protocol model writer to design the YANG
> > model in a way that is not fully usable on any current devices.
> > >
> > > As an illustration, an RFC published combined ietf-interfaces model may
> > look like this:
> > >
> >
>
>
> OK -- let me see if I understand the value of combining ietf-interfaces.
>
>
> Here is the starting tree:
>
>
> +--rw interfaces
> | +--rw interface* [name]
> | +--rw name string
> | +--rw description? string
> | +--rw type identityref
> | +--rw enabled? boolean
> | +--rw link-up-down-trap-enable? enumeration
> +--ro interfaces-state
> +--ro interface* [name]
> +--ro name string
> +--ro type identityref
> +--ro admin-status enumeration
> +--ro oper-status enumeration
> +--ro last-change? yang:date-and-time
> +--ro if-index int32
> +--ro phys-address? yang:phys-address
> +--ro higher-layer-if* interface-state-ref
> +--ro lower-layer-if* interface-state-ref
> +--ro speed? yang:gauge64
> +--ro statistics
> +--ro discontinuity-time yang:date-and-time
> +--ro in-octets? yang:counter64
> +--ro in-unicast-pkts? yang:counter64
> +--ro in-broadcast-pkts? yang:counter64
> +--ro in-multicast-pkts? yang:counter64
> +--ro in-discards? yang:counter32
> +--ro in-errors? yang:counter32
> +--ro in-unknown-protos? yang:counter32
>
> +--ro out-octets? yang:counter64
> +--ro out-unicast-pkts? yang:counter64
> +--ro out-broadcast-pkts? yang:counter64
> +--ro out-multicast-pkts? yang:counter64
> +--ro out-discards? yang:counter32
> +--ro out-errors? yang:counter32
>
>
>
> So these are the objects that would no longer be duplicated:
>
> - name
> - type
>
> Neither one is supposed to have a different value in operational state vs
> configuration.
>
> - enabled
> - link-up-down-trap-enable
>
> These 2 could be different in operational state I suppose.
> An RPC can provide the operational value without changing the YANG module
>
> rpc get-oper-value {
> input {
> leaf node {
> type instance-identifier;
> description "the config=true node to check";
> }
> }
> output {
> anydata value {
> description
> "contains 1 child node matching the input 'node' parameter.
> The value of the node is the current operational value."
> }
> }
> }
This is essentially what we propose, except that we have generalized
it so that more than one value can be retreived: <get-state> or
<get-data> which takes a filter just like <get>.
> <rpc>
> <get-oper-value>
> <node>/if:interfaces/if:interface[if:name='eth0']/enabled</node>
> </get-oper-value>
> </rpc>
>
>
> <rpc-reply>
> <value>
> <if:enabled>false</if:enabled>
> </value>
> </rpc-reply>
>
> I don't need to change the YANG module at all to support operational state.
Correct. Old modules will continue to work. Clients that <get-state>
both /interfaces and /interfaces-state will receive some duplicate
data.
However, the new model allows for combined trees to be defined.
/martin
>
>
> Andy
>
>
>
> > > module: ietf-interfaces-combined
> > > +--rw interfaces
> > > +--rw interface* [name]
> > > +--rw name string
> > > +--rw description? string
> > > +--rw type identityref
> > > +--rw enabled? boolean
> > > +--rw link-up-down-trap-enable? enumeration {if-mib}?
> > > +--ro oper-status enumeration
> > > +--ro last-change? yang:date-and-time
> > > +--ro if-index int32 {if-mib}?
> > > +--ro phys-address? yang:phys-address
> > > +--ro higher-layer-if* interface-ref
> > > +--ro lower-layer-if* interface-ref
> > > +--ro speed? yang:gauge64
> > > +--ro statistics
> > > +--ro discontinuity-time yang:date-and-time
> > > +--ro in-octets? yang:counter64
> > > +--ro in-unicast-pkts? yang:counter64
> > > +--ro in-broadcast-pkts? yang:counter64
> > > +--ro in-multicast-pkts? yang:counter64
> > > +--ro in-discards? yang:counter32
> > > +--ro in-errors? yang:counter32
> > > +--ro in-unknown-protos? yang:counter32
> > > +--ro out-octets? yang:counter64
> > > +--ro out-unicast-pkts? yang:counter64
> > > +--ro out-broadcast-pkts? yang:counter64
> > > +--ro out-multicast-pkts? yang:counter64
> > > +--ro out-discards? yang:counter32
> > > +--ro out-errors? yang:counter32
> > >
> > > The extra generated model would look like this:
> > >
> > > module: ietf-interfaces-combined-state
> > > +--ro interfaces-state
> > > +--ro interface* [name]
> > > +--ro name string
> > > +--ro description? string
> > > +--ro type identityref
> > > +--ro enabled? boolean
> > > +--ro link-up-down-trap-enable? enumeration {if:if-mib}?
> > > +--ro oper-status enumeration
> > > +--ro last-change? yang:date-and-time
> > > +--ro if-index int32 {if:if-mib}?
> > > +--ro phys-address? yang:phys-address
> > > +--ro higher-layer-if* if:interface-ref
> > > +--ro lower-layer-if* if:interface-ref
> > > +--ro speed? yang:gauge64
> > > +--ro statistics
> > > +--ro discontinuity-time yang:date-and-time
> > > +--ro in-octets? yang:counter64
> > > +--ro in-unicast-pkts? yang:counter64
> > > +--ro in-broadcast-pkts? yang:counter64
> > > +--ro in-multicast-pkts? yang:counter64
> > > +--ro in-discards? yang:counter32
> > > +--ro in-errors? yang:counter32
> > > +--ro in-unknown-protos? yang:counter32
> > > +--ro out-octets? yang:counter64
> > > +--ro out-unicast-pkts? yang:counter64
> > > +--ro out-broadcast-pkts? yang:counter64
> > > +--ro out-multicast-pkts? yang:counter64
> > > +--ro out-discards? yang:counter32
> > > +--ro out-errors? yang:counter32
> > >
> > > Servers that support operational-state would just implement
> > ietf-interfaces-combined
> > >
> > > Servers that don't support operational-state could implement
> > ietf-interfaces-combined and ietf-interfaces-combined-state, probably not
> > implementing the duplicate config false leaves under the interfaces config
> > tree. Deviations could also be auto-generated to remove the config false
> > leaves from the config tree so that they are only in the state tree.
> > >
> > > Of course, Clients may need to support both schemes depending on what
> > types of devices they are interacting with.
> > >
> > > Finally, I've illustrated this using ietf-interfaces, but I'm not
> > actually proposing immediately changing that model. I was more thinking
> > about IETF protocols that in the process of working on their YANG models.
> > >
> > > Rob
> > >
> > >
> > > Exactly. I agree that this is a real hack. Implementations can use
> > > whatever transformation tricks they want in order to comply with
> > > different standards, but the standard modules should be very clear.
> > >
> > >
> > >
> > >
> > >
> > >
> > > /martin
> > > _______________________________________________
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> > > netmod@ietf.org
> > > https://www.ietf.org/mailman/listinfo/netmod
> > >
> > >
> > > _______________________________________________
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> >
> > --
> > Ladislav Lhotka, CZ.NIC Labs
> > PGP Key ID: 0xB8F92B08A9F76C67
> >
> >
> >
> >
> >
> >
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