Vendor-neutral YANG models

NETCONF/YANG solves the integration challenge described in Phase 0 only if vendor-neutral YANG models used to represent device configuration and state.

The most noticeable sources for vendor-neutral YANG models are IETF[1] and OpenConfig[2].

Main concerns for IETF’s YANG models are:

• When they are in drafts, different draft versions might be supported by different vendors’ solutions
• When they become standards (RFCs), it is difficult to change them, but changes often required in practice to reflect evolving technologies and solutions.

In both cases interoperability is still a challenge.

OpenConfig “is an informal working group of network operators”. OpenConfig’s initial focus is on compiling a consistent set of vendor-neutral data models (written in YANG) based on actual operational needs from use cases and requirements from multiple network operators”[3]. OpenConfig’s models cover only some scenarios of device management, but the initiative evolves relatively faster to be considered seriously. When OpenConfig models are mature enough, they are submitted as IETF drafts.

Vendor-neutral YANG models shall be chosen if available. If the model is available, but lacks some required functionality, only the lacked functionality should be implemented by a vendor specific YANG model (extension).

New transport network devices must use NETCONF and vendor-neutral YANG models. The only exclusion is devices where OF-CONFIG/OpenFlow is a primary management approach. Any deviations from the vendor-neutral models must be clearly declared[4] and must be considered only as temporary solutions. Vendors should be forced to replace the temporary solutions with vendor-neutral alternatives as soon as possible.

Network devices might have internal translation means between vendor-neutral and vendor-specific YANG models if it is required by the vendor’s implementation, but it shall not affect the externally exposed device interfaces. In other words, we should not care what happens internally in the device as long as communication between SDN controller or other management system and this device uses only vendor-neutral YANG model.