A YANG model for Power Management

Network sustainability is a key issue facing the industry. Networks consume significant amounts of power at a time when the cost of power is rising and sensitivity about sustainability is very high. As an industry, we need to find ways to optimize the power efficiency of our networks both at a micro and macro level. We have observed that traffic levels fluctuate and when traffic ebbs there is much more capacity than is needed. Powering off portions of network elements could save a significant amount of power, but to scale and be practical, this must be automated. The natural mechanism for enabling automation would be a Yet Another Next Generation (YANG) interface, so this document proposes a YANG model for power management. already provides a model for server hardware management, but does not naturally extend to routers and other network elements. That gap is currently being addressed by and . This document extends the work presented there to include power management. This initial draft only provides a tree representation. When there is rough consensus on the tree represetnation, the details of the model will be fleshed out.

The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “NOT RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in BCP14 when, and only when, they appear in all capitals, as shown here.

The models mentioned above already model a router or network element as a set of components. The details of those components are left to the specific implementation and can be at any level of specificity. Thanks to this flexibility, it is necessary and sufficient that we characterize power management relative to components. The elements defined below allow management entities to understand how much power each component is using and whether the component can be placed into a ‘power-save’ mode where it would consume less power. Another element allows the management plane to put the component into power-save mode.

Name: used-power Node Type: leaf Data Type: uint32 Description: Power drawn by the component, in watts. This node is applied to components in the model. If an accurate dynamic power measurement is not available, then static power estimates are acceptable.

Name: power-save-capable Node Type: leaf Data Type: boolean Description: True if the component can be put into power-save mode.

Node: power-save Node Type: leaf Data Type: Boolean Description: True if the component is in power-save mode. Access: Read/write

Most inventory models have a hierarchy of components. This hierarchy reflects the physical structure of the system (e.g., a line card can physically contain a port). With regard to physical containment, components maintain a one-to-many relationship. That is, Component A can contain many other components, including Component B. However, component B can be contain by only one component (i.e., Component A.) However, legacy inventory models do not reflect functional dependencies. Specifically, they do not indicate which components obtain services from, and therefore depend, components other than their container. Because funtional dependencies are relavant to power management, they are included in the proposed model. With regard to functional dependencies, components maintain a many-to-many relationship. That is, a component can reuire on many components and be required by many other components. Functional dependencies may be updated dynamically.

This container holds a list of components that the component uses. For example, a linecard uses a set of switch cards, so the switch cards would be required components. If the bandwidth used by the linecard changes, then the set of switch cards that are required may change dynamically. Node: required-components Node Type: list Description: A list of other components that are required for this component to operate.

This container holds a list of components that are used by this component. For example, a switch card is used by a set of line cards, so the line cards would be dependent components. This list can also change dynamically. Node: dependent-components Node Type: list Description: A list of other components that are used by this component.

../uuid +--ro dependent-components* -> ../uuid ]]>

YANG provides information about and configuration capabilities to the network management plane. Other mechanisms already exist that help secure these interactions. This document extends the scope of what can be controlled by the management plane, but creates no new access paths.

This document makes no requests for IANA.