module openconfig-pcep {

    yang-version 1;

    namespace
      "http://openconfig.net/yang/pcep";

    prefix oc-pcep;

    import openconfig-extensions {
      prefix oc-ext;
    }
    import openconfig-inet-types {
      prefix oc-inet;
    }
    import openconfig-types {
      prefix oc-types;
    }
    import openconfig-keychain {
      prefix oc-keychain;
    }

    organization "OpenConfig working group";

    contact
      "OpenConfig working group
www.openconfig.net";

    description
      "This module defines configuration and operational state data
relating to Path Computation Element Protocol (PCEP) for communications
between a network element (router) acting as PCC and a PCE server,
according to RFC4655 definitions:

-PCC:  Path Computation Client; any client application requesting a
 path computation to be performed by a Path Computation Element.

-PCE:  Path Computation Element; an entity (component, application, or
 network node) that is capable of computing a network path or route
 based on a network graph and applying computational constraints.

Also according to RFC4655, a PCE can be either stateful or
stateless. In the former case, there is a strict synchronization
between the PCE and not only the network states (in term of
topology and resource information), but also the set of computed
paths and reserved resources in use in the network. Conversely,
stateless PCEs do not have to remember any computed path and each
set of request(s) is processed independently of each other. For
example, stateless PCEs may compute paths based on current TED
information, which could be out of sync with actual network state
given other recent PCE-computed paths changes.

On the other hand, RFC8051 defines for Stateful PCE two modes of
operation:

  -Passive Stateful PCE:  a PCE that uses LSP state information
   learned from PCCs to optimize path computations.  It does not
   actively update LSP state. A PCC maintains synchronization with
   the PCE.

  -Active Stateful PCE:  a PCE that may issue recommendations to
   the network. For example, an Active Stateful PCE may use the
   Delegation mechanism to update.

 LSP parameters in those PCCs that delegate control over their LSPs to
 the PCE.";

    revision "2022-02-11" {
      description "Initial revision.";
      reference
        "0.1.0";

    }

    oc-ext:openconfig-version "0.1.0";
    oc-ext:regexp-posix;
    oc-ext:catalog-organization "openconfig";
    oc-ext:origin "openconfig";

    typedef pce-mode-type {
      type enumeration {
        enum "STATELESS" {
          value 0;
          description
            "PCEP peer announce Stateless capability";
        }
        enum "STATEFUL_PASSIVE" {
          value 1;
          description
            "PCEP peer announce Stateful Passive capability";
        }
        enum "STATEFUL_ACTIVE" {
          value 2;
          description
            "PCEP peer announce Stateless Active";
        }
      }
      description
        "The type of PCEP capability supported which is advertised in the
Open message when a PCEP session is established. It could be:

 - Stateless PCEs: A PCE that do not have to remember any
   computed path and each set of request(s) is processed
   independently of each other(RFC4655).

 - Passive Stateful PCE:  a PCE that uses LSP state information
   learned from PCCs to optimize path computations, but it does
   not actively update LSP state(RFC8051). - Active Stateful
   PCE:  a PCE that may issue recommendations to the network by
   using the Delegation mechanism to update LSP parameters in
   those PCCs that delegate control over their LSPs to the PCE
   (RFC8051).";
      reference
        "RFC8051: Applicability of a Stateful Path Computation Element (PCE)";

    }

    typedef lsp-control-type {
      type enumeration {
        enum "PCE_DELEGATED" {
          value 0;
          description
            "PCC (Router) delegates control over LSP path to PCE (stateful active)";
        }
        enum "PCC_CONTROLLED" {
          value 1;
          description
            "PCC (Router) don't allow or revoke control over LSP path to
PCE (stateless)";
        }
        enum "PCC_REPORT_ONLY" {
          value 2;
          description
            "PCC (Router) only inform to a PCE whenever the state of an LSP changes,
but without delegating control (stateful passive)";
        }
      }
      description
        "The LSP path can be delegated to PCE, locally controled by PCC
or only report information state to the PCE.";
      reference
        "RFC8231: Path Computation Element Communication Protocol (PCEP)";

    }
  }  // module openconfig-pcep