openconfig-routing-policy

Organization:

OpenConfig working group

Module:

openconfig-routing-policy

Version:

2022-05-24

File:

openconfig-routing-policy.yang

Abstract:

This module describes a YANG model for routing policy configuration. It is a limited subset of all of the policy configuration p...

Contact:

OpenConfig working group
netopenconfig@googlegroups.com

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YANG Catalog

Description:

This module describes a YANG model for routing policy
configuration. It is a limited subset of all of the policy
configuration parameters available in the variety of vendor
implementations, but supports widely used constructs for managing
how routes are imported, exported, and modified across different
routing protocols. This module is intended to be used in
conjunction with routing protocol configuration models (e.g.,
BGP) defined in other modules.

Route policy expression:

Policies are expressed as a set of top-level policy definitions,
each of which consists of a sequence of policy statements. Policy
statements consist of simple condition-action tuples. Conditions
may include mutiple match or comparison operations, and similarly
actions may be multitude of changes to route attributes or a
final disposition of accepting or rejecting the route.

Route policy evaluation:

Policy definitions are referenced in routing protocol
configurations using import and export configuration statements.
The arguments are members of an ordered list of named policy
definitions which comprise a policy chain, and optionally, an
explicit default policy action (i.e., reject or accept).

Evaluation of each policy definition proceeds by evaluating its
corresponding individual policy statements in order. When a
condition statement in a policy statement is satisfied, the
corresponding action statement is executed. If the action
statement has either accept-route or reject-route actions, policy
evaluation of the current policy definition stops, and no further
policy definitions in the chain are evaluated.

If the condition is not satisfied, then evaluation proceeds to
the next policy statement. If none of the policy statement
conditions are satisfied, then evaluation of the current policy
definition stops, and the next policy definition in the chain is
evaluated. When the end of the policy chain is reached, the
default route disposition action is performed (i.e., reject-route
unless an an alternate default action is specified for the
chain).

Policy 'subroutines' (or nested policies) are supported by
allowing policy statement conditions to reference another policy
definition which applies conditions and actions from the
referenced policy before returning to the calling policy
statement and resuming evaluation. If the called policy
results in an accept-route (either explicit or by default), then
the subroutine returns an effective true value to the calling
policy. Similarly, a reject-route action returns false. If the
subroutine returns true, the calling policy continues to evaluate
the remaining conditions (using a modified route if the
subroutine performed any changes to the route).