[Lsr] When to augment LSR base YANG modules...

[Christian Hopps <[e-mail]>]

The base YANG modules for IS-IS and OSPF both include operational state to describe TLV data. During the discussion about OSPFv3's version of this data, I brought up the issue of when and how the base modules should be augmented to add new TLV types to the model, suggesting it be done inline and with the RFC that adds the new feature/functionality to the protocol.

I'll go farther here and say this should apply to all the YANG required for management of the new feature, and it should all be added inline with the feature (i.e., in the same draft). In other words new features/functionality should include the YANG augment required to manage said features/functionality.

This has been suggested/tried previously with SNMP with varying (low) levels of success. The difference here is 1) YANG additions (a new module perhaps just augmenting the base) is easy, whereas SNMP wasn't. Additionally, operators weren't using SNMP to fully manage functionality (e.g., not doing configuration) so a requirement for extra work was harder to justify. Operators *do* want to fully manage their networks/servers with YANG though.

The argument against this during the meeting was that it would create many small modules. I don't find this compelling (i.e., "so"? :)

Assume I'm an operator -- the actual consumer of this management stuff:

  - If I'm going to use this new feature X, I need to be able to manage it. So I need it YANG for it. Not only do I need any new TLV data in the operational state, but I need the configuration and any other operational state right along with it. Otherwise each vendor has to add new YANG to their vendor modules, or the feature is useless to me. I can't use something if I can't turn it on.

  - I don't care about having many smaller modules that augment the base module -- at all. Quite the opposite actually, when new functionality is accompanied by it's own module it provides me a simple way to see if that functionality is present as the module will be present in the YANG capabilities announced by the device.

I'd be interested in hearing reasons we (as a WG) shouldn't just expect a YANG module (even if it's small) to be included with drafts that add new functionality.

Thanks,
Chris.