Internet Engineering Task Force (IETF) D. Kumar Request for Comments: 8533 Cisco Category: Standards Track M. Wang ISSN: 2070-1721 Q. Wu, Ed. Huawei R. Rahman S. Raghavan Cisco April 2019 A YANG Data Model for Retrieval Methods for the Management of Operations, Administration, and Maintenance (OAM) Protocols That Use Connectionless Communications Abstract This document presents a retrieval method YANG data model for connectionless Operations, Administration, and Maintenance (OAM) protocols. It provides technology-independent RPC operations for OAM protocols that use connectionless communication. The retrieval methods model herein presented can be extended to include technology- specific details. There are two key benefits of this approach: First, it leads to uniformity between OAM protocols. Second, it supports both nested OAM workflows (i.e., performing OAM functions at different or the same levels through a unified interface) as well as interactive OAM workflows (i.e., performing OAM functions at the same levels through a unified interface). Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc8533. Kumar, et al. Standards Track [Page 1] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions Used in This document . . . . . . . . . . . . . . 3 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 4 3. Overview of the Connectionless OAM Retrieval Methods Model . 4 3.1. RPC Operation Definitions . . . . . . . . . . . . . . . . 4 3.2. OAM Retrieval Methods Hierarchy . . . . . . . . . . . . . 7 4. OAM Retrieval Methods YANG Module . . . . . . . . . . . . . . 16 5. Security Considerations . . . . . . . . . . . . . . . . . . . 26 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 7.1. Normative References . . . . . . . . . . . . . . . . . . 27 7.2. Informative References . . . . . . . . . . . . . . . . . 28 Appendix A. Extending Connectionless OAM Method Module Example . 29 A.1. Example of New Retrieval Procedures Model . . . . . . . . 29 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 40 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41 Kumar, et al. Standards Track [Page 2] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 1. Introduction Operations, Administration, and Maintenance (OAM) are important networking functions that allow operators to: 1. monitor network communications (i.e., reachability verification and Continuity Check) 2. troubleshoot failures (i.e., fault verification and localization) 3. monitor service-level agreements and performance (i.e., performance management) An overview of OAM tools is presented in [RFC7276]. Ping and Traceroute [RFC4443], as well as Bidirectional Forwarding Detection (BFD) [RFC5880], are well-known fault verification and isolation tools, respectively, for IP networks [RFC792]. Over the years, different technologies have developed similar toolsets for equivalent purposes. This document presents an on-demand retrieval method YANG data model for OAM protocols that use connectionless communication. This model provides technology-independent RPC operations for OAM protocols that use connectionless communication (i.e., connectionless OAM). It is separated from the generic YANG data model for connectionless OAM [RFC8532] and can avoid mixing the models for the retrieved data from the retrieval procedures. It is expected that retrieval procedures will evolve faster than the data model [RFC8532] and will allow new procedures to be defined for retrieval of the same data defined by the generic YANG data model for connectionless OAM. 2. Conventions Used in This document The following terms are defined in [RFC6241] and are used in this document: o client o configuration data o server o state data Kumar, et al. Standards Track [Page 3] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 The following terms are defined in [RFC6020] and are used in this document: o augment o data model o data node The terminology for describing YANG data models is found in [RFC6020]. 2.1. Terminology TP - Test Point MAC - Media Access Control RPC - Remote Procedure Call RPC Operation - A specific Remote Procedure Call 2.2. Tree Diagrams Tree diagrams used in this document follow the notation defined in [RFC8340]. 3. Overview of the Connectionless OAM Retrieval Methods Model This document describes an on-demand retrieval method YANG data model for OAM protocols that use connectionless communication. This model provides technology-independent retrieval procedures (RPC operations) for connectionless OAM protocols. It provides a flexible way to retrieve the data that is defined by the "ietf-connectionless- oam.yang" module [RFC8532]. 3.1. RPC Operation Definitions The RPC model facilitates issuing commands to a Network Configuration Protocol (NETCONF) server (in this case to the device that needs to execute the OAM command) and obtaining a response. Under the "connectionless-oam-methods" module, we summarize common OAM functions and define two generic RPC operations: 'continuity- check' and 'path-discovery'. In practice, these RPC operations are activated on demand and are supported by corresponding technology- specific OAM tools [RFC7276]. For example, for the IP OAM model, the Continuity Check RPC corresponds to the IP Ping [RFC792] [RFC4443], Kumar, et al. Standards Track [Page 4] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 while the path discovery RPC operation corresponds to IP Traceroute [RFC792] [RFC4443]. Note that the RPC operation presented in this document is the base building block, which is used to derive a model for a technology- specific OAM (i.e., ICMP Ping [RFC792] [RFC4443] and Label Switched Path (LSP) Ping [RFC8029]). This base building block should be extended with corresponding technology-specific parameters. To facilitate this for future enhancements to data retrieval methods, the RPCs are captured under a separate module. The generic 'tp-address' grouping is used as data input from different RPCs described in this document. The generic 'path- discovery-data' and 'continuity-check-data' groupings defined by the "ietf-connectionless-oam.yang" module [RFC8532] are used as data outputs from different RPCs described in this document. Similar methods, including other RPCs, can retrieve the data using the same data model (i.e., the "ietf-connectionless-oam.yang" module). rpc continuity-check { if-feature cl-oam:continuity-check; description "Continuity Check RPC operation as per RFC 7276."; reference "RFC 7276: An Overview of Operations, Administration, and Maintenance (OAM) Tools"; input { uses rpc-input-parameters; .... } output { container response-info { leaf protocol-id { type identityref { base protocol-id; } mandatory true; description "Protocol used in the Continuity Check. "; } leaf protocol-id-meta-data { type identityref { base protocol-id-meta-data; } description "An optional metadata related to the protocol ID."; } leaf status-code { Kumar, et al. Standards Track [Page 5] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 type identityref{ base status-code; } mandatory true; description "Status code for Continuity Check RPC operation."; } leaf status-sub-code { type identityref{ base status-sub-code; } mandatory true; description "Status-sub-code for Continuity Check RPC operation."; } description "Status code and status-sub-code for Continuity Check RPC operation."; } uses cl-oam:continuity-check-data; } } rpc path-discovery { description "Path discovery RPC operation as per RFC 7276."; reference "RFC 7276: An Overview of Operations, Administration, and Maintenance (OAM) Tools"; input { uses rpc-input-parameters; ..... } output { list response-list { key "response-index"; description "Path discovery response list."; leaf response-index { type uint32; mandatory true; description "Response index."; } leaf protocol-id { type identityref { base protocol-id; } Kumar, et al. Standards Track [Page 6] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 mandatory true; description "Protocol used in path discovery. "; } leaf protocol-id-meta-data { type identityref { base protocol-id-meta-data; } description "An optional metadata related to the protocol ID."; } leaf status-code { type identityref{ base status-code; } mandatory true; description "Status code for path discovery RPC operation. "; } leaf status-sub-code { type identityref{ base status-sub-code; } mandatory true; description "Status-sub-code for path discovery RPC operation. "; } } uses cl-oam:path-discovery-data; } } Snippet of Data Hierarchy Related to RPC Operations 3.2. OAM Retrieval Methods Hierarchy The complete data hierarchy related to the Connectionless OAM Retrieval Methods YANG data model is presented below. module: ietf-connectionless-oam-methods rpcs: +---x continuity-check {cl-oam:continuity-check}? | +---w input | | +---w destination-tp | | | +---w tp-location-type identityref | | | +---w mac-address | | | | +---w mac-address yang:mac-address Kumar, et al. Standards Track [Page 7] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 | | | +---w ipv4-address | | | | +---w ipv4-address inet:ipv4-address | | | +---w ipv6-address | | | | +---w ipv6-address inet:ipv6-address | | | +---w tp-attribute | | | | +---w tp-attribute-type? | | | | | address-attribute-type | | | | +---w (tp-attribute-value)? | | | | +--:(ip-prefix) | | | | | +---w ip-prefix? | | | | | inet:ip-prefix | | | | +--:(bgp) | | | | | +---w bgp? | | | | | inet:ip-prefix | | | | +--:(tunnel) | | | | | +---w tunnel-interface? uint32 | | | | +--:(pw) | | | | | +---w remote-pe-address? | | | | | | inet:ip-address | | | | | +---w pw-id? uint32 | | | | +--:(vpls) | | | | | +---w route-distinguisher? | | | | | | rt:route-distinguisher | | | | | +---w sender-ve-id? uint16 | | | | | +---w receiver-ve-id? uint16 | | | | +--:(mpls-mldp) | | | | +---w (root-address)? | | | | +--:(ip-address) | | | | | +---w source-address? | | | | | | inet:ip-address | | | | | +---w group-ip-address? | | | | | inet:ip-address | | | | +--:(vpn) | | | | | +---w as-number? | | | | | inet:as-number | | | | +--:(global-id) | | | | +---w lsp-id? string | | | +---w system-info | | | +---w router-id? rt:router-id | | +---w source-interface if:interface-ref | | +---w outbound-interface if:interface-ref | | +---w vrf? | | | cl-oam:routing-instance-ref | | +---w session-type? enumeration | | +---w count? uint32 | | +---w ttl? uint8 | | +---w packet-size? uint32 | +--ro output Kumar, et al. Standards Track [Page 8] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 | +--ro response-info | | +--ro protocol-id identityref | | +--ro protocol-id-meta-data? identityref | | +--ro status-code identityref | | +--ro status-sub-code identityref | +--ro src-test-point | | +--ro ni? routing-instance-ref | | +--ro tp-location-type identityref | | +--ro mac-address | | | +--ro mac-address yang:mac-address | | +--ro ipv4-address | | | +--ro ipv4-address inet:ipv4-address | | +--ro ipv6-address | | | +--ro ipv6-address inet:ipv6-address | | +--ro tp-attribute | | | +--ro tp-attribute-type? | | | | address-attribute-type | | | +--ro (tp-attribute-value)? | | | +--:(ip-prefix) | | | | +--ro ip-prefix? | | | | inet:ip-prefix | | | +--:(bgp) | | | | +--ro bgp? | | | | inet:ip-prefix | | | +--:(tunnel) | | | | +--ro tunnel-interface? uint32 | | | +--:(pw) | | | | +--ro remote-pe-address? | | | | | inet:ip-address | | | | +--ro pw-id? uint32 | | | +--:(vpls) | | | | +--ro route-distinguisher? | | | | | rt:route-distinguisher | | | | +--ro sender-ve-id? uint16 | | | | +--ro receiver-ve-id? uint16 | | | +--:(mpls-mldp) | | | +--ro (root-address)? | | | +--:(ip-address) | | | | +--ro source-address? | | | | | inet:ip-address | | | | +--ro group-ip-address? | | | | inet:ip-address | | | +--:(vpn) | | | | +--ro as-number? | | | | inet:as-number | | | +--:(global-id) | | | +--ro lsp-id? string | | +--ro system-info Kumar, et al. Standards Track [Page 9] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 | | | +--ro router-id? rt:router-id | | +--ro egress-intf-name? if:interface-ref | +--ro dest-test-point | | +--ro ni? routing-instance-ref | | +--ro tp-location-type identityref | | +--ro mac-address | | | +--ro mac-address yang:mac-address | | +--ro ipv4-address | | | +--ro ipv4-address inet:ipv4-address | | +--ro ipv6-address | | | +--ro ipv6-address inet:ipv6-address | | +--ro tp-attribute | | | +--ro tp-attribute-type? | | | | address-attribute-type | | | +--ro (tp-attribute-value)? | | | +--:(ip-prefix) | | | | +--ro ip-prefix? | | | | inet:ip-prefix | | | +--:(bgp) | | | | +--ro bgp? | | | | inet:ip-prefix | | | +--:(tunnel) | | | | +--ro tunnel-interface? uint32 | | | +--:(pw) | | | | +--ro remote-pe-address? | | | | | inet:ip-address | | | | +--ro pw-id? uint32 | | | +--:(vpls) | | | | +--ro route-distinguisher? | | | | | rt:route-distinguisher | | | | +--ro sender-ve-id? uint16 | | | | +--ro receiver-ve-id? uint16 | | | +--:(mpls-mldp) | | | +--ro (root-address)? | | | +--:(ip-address) | | | | +--ro source-address? | | | | | inet:ip-address | | | | +--ro group-ip-address? | | | | inet:ip-address | | | +--:(vpn) | | | | +--ro as-number? | | | | inet:as-number | | | +--:(global-id) | | | +--ro lsp-id? string | | +--ro system-info | | | +--ro router-id? rt:router-id | | +--ro ingress-intf-name? if:interface-ref | +--ro sequence-number? uint64 Kumar, et al. Standards Track [Page 10] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 | +--ro hop-cnt? uint8 | +--ro session-packet-statistics | | +--ro rx-packet-count? uint32 | | +--ro tx-packet-count? uint32 | | +--ro rx-bad-packet? uint32 | | +--ro tx-packet-failed? uint32 | +--ro session-error-statistics | | +--ro packet-loss-count? uint32 | | +--ro loss-ratio? percentage | | +--ro packet-reorder-count? uint32 | | +--ro packets-out-of-seq-count? uint32 | | +--ro packets-dup-count? uint32 | +--ro session-delay-statistics | | +--ro time-unit-value? identityref | | +--ro min-delay-value? uint32 | | +--ro max-delay-value? uint32 | | +--ro average-delay-value? uint32 | +--ro session-jitter-statistics | +--ro unit-value? identityref | +--ro min-jitter-value? uint32 | +--ro max-jitter-value? uint32 | +--ro average-jitter-value? uint32 +---x path-discovery {cl-oam:path-discovery}? +---w input | +---w destination-tp | | +---w tp-location-type identityref | | +---w mac-address | | | +---w mac-address yang:mac-address | | +---w ipv4-address | | | +---w ipv4-address inet:ipv4-address | | +---w ipv6-address | | | +---w ipv6-address inet:ipv6-address | | +---w tp-attribute | | | +---w tp-attribute-type? | | | | address-attribute-type | | | +---w (tp-attribute-value)? | | | +--:(ip-prefix) | | | | +---w ip-prefix? | | | | inet:ip-prefix | | | +--:(bgp) | | | | +---w bgp? | | | | inet:ip-prefix | | | +--:(tunnel) | | | | +---w tunnel-interface? uint32 | | | +--:(pw) | | | | +---w remote-pe-address? | | | | | inet:ip-address | | | | +---w pw-id? uint32 Kumar, et al. Standards Track [Page 11] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 | | | +--:(vpls) | | | | +---w route-distinguisher? | | | | | rt:route-distinguisher | | | | +---w sender-ve-id? uint16 | | | | +---w receiver-ve-id? uint16 | | | +--:(mpls-mldp) | | | +---w (root-address)? | | | +--:(ip-address) | | | | +---w source-address? | | | | | inet:ip-address | | | | +---w group-ip-address? | | | | inet:ip-address | | | +--:(vpn) | | | | +---w as-number? | | | | inet:as-number | | | +--:(global-id) | | | +---w lsp-id? string | | +---w system-info | | +---w router-id? rt:router-id | +---w source-interface if:interface-ref | +---w outbound-interface if:interface-ref | +---w vrf? | | cl-oam:routing-instance-ref | +---w session-type? enumeration | +---w max-ttl? uint8 +--ro output +--ro response-list* [response-index] | +--ro response-index uint32 | +--ro protocol-id identityref | +--ro protocol-id-meta-data? identityref | +--ro status-code identityref | +--ro status-sub-code identityref +--ro src-test-point | +--ro ni? routing-instance-ref | +--ro tp-location-type identityref | +--ro mac-address | | +--ro mac-address yang:mac-address | +--ro ipv4-address | | +--ro ipv4-address inet:ipv4-address | +--ro ipv6-address | | +--ro ipv6-address inet:ipv6-address | +--ro tp-attribute | | +--ro tp-attribute-type? | | | address-attribute-type | | +--ro (tp-attribute-value)? | | +--:(ip-prefix) | | | +--ro ip-prefix? | | | inet:ip-prefix Kumar, et al. Standards Track [Page 12] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 | | +--:(bgp) | | | +--ro bgp? | | | inet:ip-prefix | | +--:(tunnel) | | | +--ro tunnel-interface? uint32 | | +--:(pw) | | | +--ro remote-pe-address? | | | | inet:ip-address | | | +--ro pw-id? uint32 | | +--:(vpls) | | | +--ro route-distinguisher? | | | | rt:route-distinguisher | | | +--ro sender-ve-id? uint16 | | | +--ro receiver-ve-id? uint16 | | +--:(mpls-mldp) | | +--ro (root-address)? | | +--:(ip-address) | | | +--ro source-address? | | | | inet:ip-address | | | +--ro group-ip-address? | | | inet:ip-address | | +--:(vpn) | | | +--ro as-number? | | | inet:as-number | | +--:(global-id) | | +--ro lsp-id? string | +--ro system-info | +--ro router-id? rt:router-id +--ro dest-test-point | +--ro ni? routing-instance-ref | +--ro tp-location-type identityref | +--ro mac-address | | +--ro mac-address yang:mac-address | +--ro ipv4-address | | +--ro ipv4-address inet:ipv4-address | +--ro ipv6-address | | +--ro ipv6-address inet:ipv6-address | +--ro tp-attribute | | +--ro tp-attribute-type? | | | address-attribute-type | | +--ro (tp-attribute-value)? | | +--:(ip-prefix) | | | +--ro ip-prefix? | | | inet:ip-prefix | | +--:(bgp) | | | +--ro bgp? | | | inet:ip-prefix | | +--:(tunnel) Kumar, et al. Standards Track [Page 13] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 | | | +--ro tunnel-interface? uint32 | | +--:(pw) | | | +--ro remote-pe-address? | | | | inet:ip-address | | | +--ro pw-id? uint32 | | +--:(vpls) | | | +--ro route-distinguisher? | | | | rt:route-distinguisher | | | +--ro sender-ve-id? uint16 | | | +--ro receiver-ve-id? uint16 | | +--:(mpls-mldp) | | +--ro (root-address)? | | +--:(ip-address) | | | +--ro source-address? | | | | inet:ip-address | | | +--ro group-ip-address? | | | inet:ip-address | | +--:(vpn) | | | +--ro as-number? | | | inet:as-number | | +--:(global-id) | | +--ro lsp-id? string | +--ro system-info | +--ro router-id? rt:router-id +--ro sequence-number? uint64 +--ro hop-cnt? uint8 +--ro session-packet-statistics | +--ro rx-packet-count? uint32 | +--ro tx-packet-count? uint32 | +--ro rx-bad-packet? uint32 | +--ro tx-packet-failed? uint32 +--ro session-error-statistics | +--ro packet-loss-count? uint32 | +--ro loss-ratio? percentage | +--ro packet-reorder-count? uint32 | +--ro packets-out-of-seq-count? uint32 | +--ro packets-dup-count? uint32 +--ro session-delay-statistics | +--ro time-unit-value? identityref | +--ro min-delay-value? uint32 | +--ro max-delay-value? uint32 | +--ro average-delay-value? uint32 +--ro session-jitter-statistics | +--ro unit-value? identityref | +--ro min-jitter-value? uint32 | +--ro max-jitter-value? uint32 | +--ro average-jitter-value? uint32 +--ro path-verification Kumar, et al. Standards Track [Page 14] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 | +--ro flow-info? | | string | +--ro session-path-verification-statistics | +--ro verified-count? uint32 | +--ro failed-count? uint32 +--ro path-trace-info +--ro path-trace-info-list* [index] +--ro index uint32 +--ro ni? | routing-instance-ref +--ro tp-location-type identityref +--ro mac-address | +--ro mac-address yang:mac-address +--ro ipv4-address | +--ro ipv4-address inet:ipv4-address +--ro ipv6-address | +--ro ipv6-address inet:ipv6-address +--ro tp-attribute | +--ro tp-attribute-type? | | address-attribute-type | +--ro (tp-attribute-value)? | +--:(ip-prefix) | | +--ro ip-prefix? | | inet:ip-prefix | +--:(bgp) | | +--ro bgp? | | inet:ip-prefix | +--:(tunnel) | | +--ro tunnel-interface? | | uint32 | +--:(pw) | | +--ro remote-pe-address? | | | inet:ip-address | | +--ro pw-id? | | uint32 | +--:(vpls) | | +--ro route-distinguisher? | | | rt:route-distinguisher | | +--ro sender-ve-id? | | | uint16 | | +--ro receiver-ve-id? | | uint16 | +--:(mpls-mldp) | +--ro (root-address)? | +--:(ip-address) | | +--ro source-address? | | | inet:ip-address | | +--ro group-ip-address? Kumar, et al. Standards Track [Page 15] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 | | inet:ip-address | +--:(vpn) | | +--ro as-number? | | inet:as-number | +--:(global-id) | +--ro lsp-id? | string +--ro system-info | +--ro router-id? rt:router-id +--ro timestamp-type? identityref +--ro timestamp-64bit | +--ro timestamp-sec? uint32 | +--ro timestamp-nanosec? uint32 +--ro timestamp-80bit {ptp-long-format}? | +--ro timestamp-sec? uint64 | +--ro timestamp-nanosec? uint32 +--ro ntp-timestamp-32bit | {ntp-short-format}? | +--ro timestamp-sec? uint16 | +--ro timestamp-nanosec? uint16 +--ro icmp-timestamp-32bit {icmp-timestamp}? | +--ro timestamp-millisec? uint32 +--ro ingress-intf-name? | if:interface-ref +--ro egress-intf-name? | if:interface-ref +--ro queue-depth? uint32 +--ro transit-delay? uint32 +--ro app-meta-data? uint64 Data Hierarchy of OAM Retrieval Methods 4. OAM Retrieval Methods YANG Module file "ietf-connectionless-oam-methods@2019-04-16.yang" module ietf-connectionless-oam-methods { namespace "urn:ietf:params:xml:ns:yang:ietf-connectionless-oam-methods"; prefix cloam-methods; import ietf-interfaces { prefix if; } import ietf-connectionless-oam { prefix cl-oam; } Kumar, et al. Standards Track [Page 16] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 organization "IETF LIME Working Group"; contact "WG Web: WG List: Deepak Kumar Qin Wu Srihari Raghavan Michael Wang Reshad Rahman "; description "This YANG module defines the RPC operations for connectionless OAM to be used within the IETF in a protocol-independent manner. It is assumed that each protocol maps corresponding abstracts to its native format. Each protocol may extend the YANG data model defined here to include protocol-specific extensions. Copyright (c) 2019 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info). This version of this YANG module is part of RFC 8533; see the RFC itself for full legal notices."; revision 2019-04-16 { description "Initial revision."; reference "RFC 8533: Retrieval Methods YANG Data Model for the Management of Operations, Administration, and Maintenance (OAM) Protocols That Use Connectionless Communications"; } identity protocol-id { description "This is the base identity for a generic protocol ID. The protocol registry can be found at https://www.iana.org/protocols."; } Kumar, et al. Standards Track [Page 17] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 identity protocol-id-internet { base protocol-id; description "Identity for Internet Protocols."; } identity protocol-id-proprietary { base protocol-id; description "Identity for proprietary protocols (e.g., IP SLA)."; } identity protocol-id-sfc { base protocol-id; description "Identity for Service Function Chaining."; } identity protocol-id-mpls { base protocol-id; description "The MPLS protocol."; } identity protocol-id-mpls-tp { base protocol-id; description "The MPLS-TP protocol."; } identity protocol-id-twamp { base protocol-id; description "The Two-Way Active Measurement Protocol (TWAMP) protocol."; } identity protocol-id-bier { base protocol-id; description "The Bit Index Explicit Replication (BIER) protocol."; } identity status-code { description "This is base identity for a status code."; Kumar, et al. Standards Track [Page 18] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 } identity success-reach { base status-code; description "Indicates that the destination being verified is reachable (see RFC 7276)."; reference "RFC 7276: An Overview of Operations, Administration, and Maintenance (OAM) Tools"; } identity fail-reach { base status-code; description "Indicates that the destination being verified is not reachable (see RFC 7276)."; reference "RFC 7276: An Overview of Operations, Administration, and Maintenance (OAM) Tools"; } identity success-path-verification { base status-code; description "Indicates that the path verification is performed successfully (see RFC 7276)."; reference "RFC 7276: An Overview of Operations, Administration, and Maintenance (OAM) Tools"; } identity fail-path-verification { base status-code; description "Indicates that the path verification fails (see RFC 7276)."; reference "RFC 7276: An Overview of Operations, Administration, and Maintenance (OAM) Tools"; } identity status-sub-code { description "IdentityBase status-sub-code."; } identity invalid-cc { Kumar, et al. Standards Track [Page 19] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 base status-sub-code; description "Indicates that the Continuity Check message is invalid (see RFC 7276)."; reference "RFC 7276: An Overview of Operations, Administration, and Maintenance (OAM) Tools"; } identity invalid-pd { base status-sub-code; description "Indicates that the path discovery message is invalid (see RFC 7276)."; reference "RFC 7276: An Overview of Operations, Administration, and Maintenance (OAM) Tools"; } identity protocol-id-meta-data { description "This is the base identity for metadata that corresponds to the protocol ID."; } identity protocol-internet-number { base protocol-id-meta-data; description "Internet Protocol number for standard Internet Protocols (IANA-assigned Internet Protocol numbers) to help in protocol processing. The Protocol Numbers registry can be found at https://www.iana.org/assignments/protocol-numbers."; } grouping rpc-input-parameters { container destination-tp { uses cl-oam:tp-address; description "Destination test point."; } leaf source-interface { type if:interface-ref; mandatory true; description "Source interface."; } leaf outbound-interface { Kumar, et al. Standards Track [Page 20] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 type if:interface-ref; mandatory true; description "Outbound interface."; } leaf vrf { type cl-oam:routing-instance-ref; description "Virtual Routing and Forwarding (VRF) instance."; } description "Grouping for RPC input parameters"; } rpc continuity-check { if-feature "cl-oam:continuity-check"; description "Continuity Check RPC operation as per RFC 7276."; reference "RFC 7276: An Overview of Operations, Administration, and Maintenance (OAM) Tools"; input { uses rpc-input-parameters; uses cl-oam:session-type { description "If session-type is specified, then session-type must be set to on demand"; } leaf count { type uint32 { range "0..4294967295" { description "The overall number of packets to be transmitted by the sender. The value of the count will be set to zero (0) on creation and will thereafter increase monotonically until it reaches a maximum value of 2^32-1 (4294967295 decimal), when it wraps around and starts increasing again from zero."; } } default "5"; description "Specifies the number of packets that will be sent. By default, the packet number is set to 5."; } leaf ttl { Kumar, et al. Standards Track [Page 21] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 type uint8; default "255"; description "Time to live (TTL) used to limit the lifetime of data packets transmitted in the network to prevent looping. The TTL value is decremented for every hop that the packet traverses. If the TTL is zero, the data packet will be discarded."; } leaf packet-size { type uint32 { range "64..10000"; } default "64"; description "Packet size of the Continuity Check message, in octets. By default, the packet size is set to 64 octets."; } } output { container response-info { leaf protocol-id { type identityref { base protocol-id; } mandatory true; description "Protocol used in the Continuity Check message. This could be a standard protocol (e.g., TCP/IP protocols, MPLS, etc.) or a proprietary protocol as identified by this field."; } leaf protocol-id-meta-data { type identityref { base protocol-id-meta-data; } description "An optional metadata related to the protocol ID. For example, this could be the Internet Protocol number for standard Internet Protocols used for help with protocol processing."; } leaf status-code { type identityref { base status-code; } mandatory true; description Kumar, et al. Standards Track [Page 22] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 "Status code for Continuity Check RPC operation. This could be a basic status code (e.g., destination is reachable or destination is not reachable; see RFC 7276) or some customized status code as identified by this field."; reference "RFC 7276: An Overview of Operations, Administration, and Maintenance (OAM) Tools"; } leaf status-sub-code { type identityref { base status-sub-code; } mandatory true; description "An optional status-sub-code for Continuity Check RPC operation. If the basic status code is destination reachable, this status-sub-code doesn't need to be specified. If the basic status code is destination unreachable, the status-sub-code can be used to specify the detailed reasons. This could be a basic sub-status-code (such as an invalid Continuity Check) or other error codes specific to the protocol under use for the Continuity Checks. For example, if ICMP is the protocol under use, the error codes defined in RFC 4443 can be used to specify the reasons specific to ICMP. This technology-specific status-sub-code can be defined in technology-specific models."; reference "RFC 4443: The IETF Administrative Oversight Committee (IAOC) Member Selection Guidelines and Process."; } description "Status code and status-sub-code for Continuity Check RPC operation."; } uses cl-oam:continuity-check-data; } } rpc path-discovery { if-feature "cl-oam:path-discovery"; description "Path discovery RPC operation as per RFC 7276."; reference "RFC 7276: An Overview of Operations, Administration, and Maintenance (OAM) Tools"; input { Kumar, et al. Standards Track [Page 23] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 uses rpc-input-parameters; uses cl-oam:session-type { description "If session-type is specified, then session-type must be set to on demand"; } leaf max-ttl { type uint8; default "255"; description "Maximum TTL indicates the maximum number of hops that a packet is permitted to travel before being discarded by a router. By default, the maximum TTL is set to 255."; } } output { list response-list { key "response-index"; description "Path discovery response list."; leaf response-index { type uint32; mandatory true; description "Response index."; } leaf protocol-id { type identityref { base protocol-id; } mandatory true; description "Protocol used in path discovery. This could be a standard protocol (e.g., TCP/IP protocols, MPLS, etc.) or a proprietary protocol as identified by this field."; } leaf protocol-id-meta-data { type identityref { base protocol-id-meta-data; } description "An optional metadata related to the protocol ID. For example, this could be the Internet Protocol number for standard Internet Protocols used for help with protocol processing."; } Kumar, et al. Standards Track [Page 24] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 leaf status-code { type identityref { base status-code; } mandatory true; description "Status code for Continuity Check RPC operation. This could be a basic status code (e.g., destination is reachable or destination is not reachable) or some customized status code as identified by this field."; } leaf status-sub-code { type identityref { base status-sub-code; } mandatory true; description "An optional status-sub-code for Continuity Check RPC operation. If the basic status code is destination reachable, this status-sub-code doesn't need to be specified. If the basic status code is destination unreachable, the status-sub-code can be used to specify the detailed reasons. This could be a basic sub-status-code (such as an invalid Continuity Check) or other error codes specific to the protocol under use for Continuity Checks. For example, if ICMP is the protocol under use, the error codes defined in RFC 4443 can be used to specify the reasons specific to ICMP. This technology-specific status-sub-code can be defined in technology-specific models."; reference "RFC 4443: The IETF Administrative Oversight Committee (IAOC) Member Selection Guidelines and Process."; } } uses cl-oam:path-discovery-data; } } } Kumar, et al. Standards Track [Page 25] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 5. Security Considerations The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]. The Network Configuration Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. Some of the RPC operations in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control access to these operations. These are the operations and their sensitivity/vulnerability: o continuity-check: Generates Continuity Check. o path-discovery: Generates path discovery. These operations are used to retrieve the data from the device that needs to execute the OAM command. Unauthorized source access to some sensitive information in the above data may be used for network reconnaissance or lead to denial-of-service attacks on both the local device and the network. 6. IANA Considerations This document registers a URI in the "IETF XML Registry" [RFC3688]. The following registration has been made: URI: urn:ietf:params:xml:ns:yang:ietf-connectionless-oam-methods Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. This document registers a YANG module in the "YANG Module Names" registry [RFC6020]. name: ietf-connectionless-oam-methods namespace: urn:ietf:params:xml:ns:yang:ietf-connectionless-oam-methods prefix: cloam-methods reference: RFC 8533 Kumar, et al. Standards Track [Page 26] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 7. References 7.1. Normative References [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, . [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, . [RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken, "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information", STD 77, RFC 7011, DOI 10.17487/RFC7011, September 2013, . [RFC792] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, DOI 10.17487/RFC0792, September 1981. [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . Kumar, et al. Standards Track [Page 27] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 [RFC8532] Kumar, D., Wang, M., Wu, Q., Ed., Rahman, R., and S. Raghavan, "Generic YANG Data Model for the Management of Operations, Administration, and Maintenance (OAM) Protocols That Use Connectionless Communications", RFC 8532, DOI 10.17487/RFC8532, April 2019, . 7.2. Informative References [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", STD 89, RFC 4443, DOI 10.17487/RFC4443, March 2006, . [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, . [RFC7276] Mizrahi, T., Sprecher, N., Bellagamba, E., and Y. Weingarten, "An Overview of Operations, Administration, and Maintenance (OAM) Tools", RFC 7276, DOI 10.17487/RFC7276, June 2014, . [RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N., Aldrin, S., and M. Chen, "Detecting Multiprotocol Label Switched (MPLS) Data-Plane Failures", RFC 8029, DOI 10.17487/RFC8029, March 2017, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . [RFC8407] Bierman, A., "Guidelines for Authors and Reviewers of Documents Containing YANG Data Models", BCP 216, RFC 8407, DOI 10.17487/RFC8407, October 2018, . [YANG-Push] Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen- Nygaard, E., Bierman, A., and B. Lengyel, "Subscription to YANG Datastores", Work in Progress, draft-ietf-netconf- yang-push-22, February 2019. Kumar, et al. Standards Track [Page 28] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 Appendix A. Extending Connectionless OAM Method Module Example The following is an example of extensions possible to the "ietf-connectionless-oam-methods" YANG data model defined in this document. The snippet below depicts an example of augmenting the "ietf-connectionless-oam-methods" YANG data model with ICMP ping attributes: augment "/cloam-methods:continuity-check" +"/cloam-methods:output"{ container session-rtt-statistics{ leaf min-rtt{ type uint32; description "This minimum ping round-trip-time (RTT) received."; } leaf max-rtt{ type uint32; description "This maximum ping RTT received."; } leaf avg-rtt{ type uint32; description "The current average ping RTT."; } description "This container presents the ping RTT statistics."; } } A.1. Example of New Retrieval Procedures Model As discussed in the Introduction section of this document, the new retrieval procedures can be defined for retrieval of the same data defined by the base YANG data model for connectionless OAM protocols. This appendix demonstrates how the base connectionless OAM data model can be extended to support persistent data retrieval besides on-demand retrieval procedures defined in Section 3, i.e., first retrieve a persistent-id based on the destination test point location information, and then retrieve the export details based on persistent-id. Internet Protocol Flow Information Export (IPFIX) [RFC7011] or YANG-Push [YANG-Push] are currently outlined here as data export options. Additional export options can be added in the future. Kumar, et al. Standards Track [Page 29] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 The YANG module "example-cl-oam-persistent-methods" shown below is intended as an illustration rather than a real definition of an RPC operation model for persistent data retrieval. For the sake of brevity, this module does not obey all the guidelines specified in [RFC8407]. module example-cl-oam-persistent-methods { namespace "http://example.com/cl-oam-persistent-methods"; prefix pcloam-methods; import ietf-interfaces { prefix if; } import ietf-connectionless-oam { prefix cl-oam; } import ietf-yang-types { prefix yang; } identity export-method { description "Base identity to represent a conceptual export-method."; } identity ipfix-export { base export-method; description "IPFIX-based export. Configuration provided separately."; } identity yang-push-export { base export-method; description "YANG-Push from draft-ietf-netconf-yang-push."; } identity protocol-id { description "A generic protocol identifier."; } identity status-code { description "Base status code."; } Kumar, et al. Standards Track [Page 30] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 identity success-reach { base status-code; description "Indicates that the destination being verified is reachable."; } identity fail-reach { base status-code; description "Indicates that the destination being verified is not reachable"; } identity success-path-verification { base status-code; description "Indicates that the path verification is performed successfully."; } identity fail-path-verification { base status-code; description "Indicates that the path verification fails."; } identity status-sub-code { description "Base status-sub-code."; } identity invalid-cc { base status-sub-code; description "Indicates that the Continuity Check message is invalid."; } identity invalid-pd { base status-sub-code; description "Indicates that the path discovery message is invalid."; } typedef export-method { type identityref { base export-method; Kumar, et al. Standards Track [Page 31] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 } description "Export method type."; } typedef change-type { type enumeration { enum create { description "Change due to a create."; } enum delete { description "Change due to a delete."; } enum modify { description "Change due to an update."; } } description "Different types of changes that may occur."; } rpc cc-get-persistent-id { if-feature "cl-oam:continuity-check"; description "Obtains Continuity Check persistent identification given mapping parameters as input."; input { container destination-tp { uses cl-oam:tp-address; description "Destination test point."; } uses cl-oam:session-type; leaf source-interface { type if:interface-ref; description "Source interface."; } leaf outbound-interface { type if:interface-ref; description "Outbound interface."; } leaf vrf { type cl-oam:routing-instance-ref; Kumar, et al. Standards Track [Page 32] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 description "VRF instance."; } } output { container error-code { leaf protocol-id { type identityref { base protocol-id; } mandatory true; description "Protocol used. This could be a standard protocol (e.g., TCP/IP protocols, MPLS, etc.) or a proprietary protocol as identified by this field."; } leaf protocol-id-meta-data { type uint64; description "An optional metadata related to the protocol ID. For example, this could be the Internet Protocol number for standard Internet Protocols used for help with protocol processing."; } leaf status-code { type identityref { base status-code; } mandatory true; description "Status code."; } leaf status-sub-code { type identityref { base status-sub-code; } mandatory true; description "Sub code for the Continuity Check."; } description "Status code and sub code."; } leaf cc-persistent-id { type string; description "Id to act as a cookie."; Kumar, et al. Standards Track [Page 33] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 } } } rpc cc-persistent-get-export-details { if-feature "cl-oam:continuity-check"; description "Given the persistent ID, gets the configuration options and details related to the configured data export."; input { leaf cc-persistent-id { type string; description "Persistent ID for use as a key in search."; } } output { container error-code { leaf protocol-id { type identityref { base protocol-id; } mandatory true; description "Protocol used. This could be a standard protocol (e.g., TCP/IP protocols, MPLS, etc.) or a proprietary protocol as identified by this field."; } leaf protocol-id-meta-data { type uint64; description "An optional metadata related to the protocol ID. For example, this could be the Internet Protocol number for standard Internet Protocols used for help with protocol processing."; } leaf status-code { type identityref { base status-code; } mandatory true; description "Status code."; } leaf status-sub-code { type identityref { Kumar, et al. Standards Track [Page 34] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 base status-sub-code; } mandatory true; description "Sub code for the Continuity Check."; } description "Status code and sub code."; } leaf data-export-method { type export-method; description "Type of export in use."; } choice cc-trigger { description "Necessary conditions for periodic or on-change trigger."; case periodic { description "Periodic reports."; leaf period { type yang:timeticks; description "Time interval between reports."; } leaf start-time { type yang:date-and-time; description "Timestamp from which reports were started."; } } case on-change { description "On-change trigger and not periodic."; leaf all-data-on-start { type boolean; description "Full update done on start or not."; } leaf-list excluded-change { type change-type; description "Changes that will not trigger an update."; } } } } Kumar, et al. Standards Track [Page 35] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 } rpc pd-get-persistent-id { if-feature "cl-oam:path-discovery"; description "Obtains persistent path discovery identification."; input { container destination-tp { uses cl-oam:tp-address; description "Destination test point."; } uses cl-oam:session-type; leaf source-interface { type if:interface-ref; description "Source interface."; } leaf outbound-interface { type if:interface-ref; description "Outbound interface."; } leaf vrf { type cl-oam:routing-instance-ref; description "VRF"; } } output { list response-list { key "response-index"; description "Path discovery response list."; leaf response-index { type uint32; mandatory true; description "Response index."; } leaf protocol-id { type identityref { base protocol-id; } mandatory true; description "Protocol used. This could be a standard protocol (e.g., TCP/IP protocols, MPLS, etc.) Kumar, et al. Standards Track [Page 36] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 or a proprietary protocol as identified by this field."; } leaf protocol-id-meta-data { type uint64; description "An optional metadata related to the protocol ID. For example, this could be the Internet Protocol number for standard Internet Protocols used for help with protocol processing."; } leaf status-code { type identityref { base status-code; } mandatory true; description "Status code for persistent path discovery information."; } leaf status-sub-code { type identityref { base status-sub-code; } mandatory true; description "Sub code for persistent path discovery information."; } leaf pd-persistent-id { type string; description "Id to act as a cookie."; } } } } rpc pd-persistent-get-export-details { if-feature "cl-oam:path-discovery"; description "Given the persistent ID, gets the configuration options and details related to the configured data export."; input { leaf cc-persistent-id { type string; description Kumar, et al. Standards Track [Page 37] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 "Persistent ID for use as a key in search."; } } output { list response-list { key "response-index"; description "Path discovery response list."; leaf response-index { type uint32; mandatory true; description "Response index."; } leaf protocol-id { type identityref { base protocol-id; } mandatory true; description "Protocol used. This could be a standard protocol (e.g., TCP/IP protocols, MPLS, etc.) or a proprietary protocol as identified by this field."; } leaf protocol-id-meta-data { type uint64; description "An optional metadata related to the protocol ID. For example, this could be the Internet Protocol number for standard Internet Protocols used for help with protocol processing."; } leaf status-code { type identityref { base status-code; } mandatory true; description "Status code for persistent path discovery creation."; } leaf status-sub-code { type identityref { base status-sub-code; } mandatory true; description Kumar, et al. Standards Track [Page 38] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 "Sub code for persistent path discovery creation."; } leaf data-export-method { type export-method; description "Type of export."; } choice pd-trigger { description "Necessary conditions for periodic or on-change trigger."; case periodic { description "Periodic reports."; leaf period { type yang:timeticks; description "Time interval between reports."; } leaf start-time { type yang:date-and-time; description "Timestamp from which reports are started."; } } case on-change { description "On-change trigger and not periodic."; leaf all-data-on-start { type boolean; description "Full update done on start or not."; } leaf-list excluded-change { type change-type; description "Changes that will not trigger an update."; } } } } } } } Kumar, et al. Standards Track [Page 39] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 Acknowledgements The authors of this document would like to thank Elwyn Davies, Alia Atlas, Brian E. Carpenter, Greg Mirsky, Adam Roach, Alissa Cooper, Eric Rescorla, Ben Campbell, Benoit Claise, Kathleen Moriarty, Carlos Pignataro, Benjamin Kaduk, and others for their substantive review, comments, and proposals to improve the document. Kumar, et al. Standards Track [Page 40] RFC 8533 YANG Model for CL OAM Retrieval Methods April 2019 Authors' Addresses Deepak Kumar CISCO Systems 510 McCarthy Blvd. Milpitas, CA 95035 United States of America Email: dekumar@cisco.com Michael Wang Huawei Technologies, Co., Ltd 101 Software Avenue, Yuhua District Nanjing 210012 China Email: wangzitao@huawei.com Qin Wu (editor) Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Email: bill.wu@huawei.com Reshad Rahman CISCO Systems 2000 Innovation Drive Kanata, Ontario K2K 3E8 Canada Email: rrahman@cisco.com Srihari Raghavan CISCO Systems Tril Infopark Sez, Ramanujan IT City Neville Block, 2nd floor, Old Mahabalipuram Road Chennai, Tamil Nadu 600113 India Email: srihari@cisco.com Kumar, et al. Standards Track [Page 41]