]> Tongji University

4800 Cao'An Hwy Shanghai 201804 China jingxuan.n.zhang@gmail.com

Huawei Technologies

Divyashree Techno Park, Whitefield Bangalore Karnataka 560066 India dhruv.ietf@gmail.com

Sichuan University

No.24 South Section 1, Yihuan Road Chengdu 610000 China kaigao@scu.edu.cn

Deutsche Telekom

Heinrich-Hertz-Strasse 3-7 Darmstadt 64295 Germany Roland.Schott@telekom.de

Networks ALTO WG ALTO, Internet-Draft This document defines a YANG data model for Operations, Administration, and Maintenance (OAM) & Management of Application-Layer Traffic Optimization (ALTO) Protocol. The operator can use the data model to create and update ALTO information resources, manage the access control, configure server-to-server communication and server discovery, and collect statistical data. Discussion Venues Discussion of this document takes place on the ALTO Working Group mailing list (alto@ietf.org), which is archived at . Source for this draft and an issue tracker can be found at .

Introduction This document defines a YANG data model for the Operations, Administration, and Maintenance (OAM) & Management of Application-Layer Traffic Optimization (ALTO) Protocol. The basic purpose of this YANG data model is discussed in Section 16 of . The operator can use the data model to create and update ALTO information resources, manage the access control, configure server-to-server communication and server discovery, and collect statistical data. The basic structure of this YANG data model is guided by Section 16 of and . Although the scope of the YANG data model in this document mainly focuses on the support of the base ALTO protocol and the existing ALTO standard extensions (including , , , , , and {RFC9275}), the design will also be extensible for future standard extensions (e.g., ).

Requirements Language 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 BCP 14 when, and only when, they appear in all capitals, as shown here. When the words appear in lower case, they are to be interpreted with their natural language meanings.

Terminology This document uses the following acronyms:

• OAM - Operations, Administration, and Maintainance
• O&M - OAM and Management

Tree Diagrams A simplified graphical representation of the data model is used in this document. The meaning of the symbols in these diagrams is defined in .

Prefixes in Data Node Names In this document, names of data nodes and other data model objects are often used without a prefix, as long as it is clear from the context in which YANG module each name is defined. Otherwise, names are prefixed using the standard prefix associated with the corresponding YANG module, as shown in . Prefixes and corresponding YANG modules

Prefix	YANG module	Reference
yang	ietf-yang-types
inet	ietf-inet-types
tcp	ietf-tcp-server
tls	ietf-tls-server
http	ietf-http-server

Placeholders in reference Statement Note to the RFC Editor: This section is to be removed prior to publication. This draft contains placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. No other RFC Editor instructions are specified elsewhere in this document. Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements:

• DDDD --> the assigned RFC value for draft-ietf-netconf-tcp-client-server
• FFFF --> the assigned RFC value for draft-ietf-netconf-tls-client-server
• GGGG --> the assigned RFC value for draft-ietf-netconf-http-client-server
• HHHH --> the assigned RFC value for draft-ietf-netconf-netconf-client-server
• IIII --> the assigned RFC value for draft-ietf-netconf-restconf-client-server
• XXXX --> the assigned RFC value for this draft
• YYYY --> the assigned RFC value for draft-ietf-alto-performance-metrics

Design Scope and Requirements

Scope of Data Model for ALTO O&M What is in the scope of this document?

• Data model for deploy an ALTO server/client.
• Data model for operate and manage a running ALTO server/client.
• Data model for functionality/capability configuration for ALTO services.
• Data model for monitoring ALTO-related performance metrics.

What is not in the scope of this document? This document does not define any data model related to specific implementation, including:

• Data structures for how to store/deliver ALTO information resources (e.g., database schema to store a network map).
• Data structures for how to store information collected from data sources. (e.g., database schema to store topology collected from an Interface to the Routing System (I2RS) client )

Basic Requirements Based on discussions and recommendations in and , the data model provided by this document satisfies basic requirements listed in . Basic Requirements of Data Model for ALTO O&M.

Requirement	Reference
R1: The data model should support configuration for ALTO server setup.	Section 16.1 of
R2: The data model should provide logging management.	Section 16.2.1 of
R3: The data model should provide ALTO-related management information.	Section 16.2.2 of
R4: The data model should support configuration for security policy management.	Section 16.2.6 of
R5-1: The data model should support configuration for different data sources.	Section 16.2.4 of , Section 3.2 of
R5-2: The data model should support configuration for information resource generation algorithms.	Section 16.2.4 of
R5-3: The data model should support configuration for access control at information resource level.	Section 16.2.4 of
R6: The data model should provide metrics for server failures.	Section 16.2.3 of , Section 3.3 of
R7: The data model should provide performance monitoring for ALTO-specific metrics.	Section 16.2.5 of , Section 3.4 of

Additional Requirements for Extensibility R8: As the ALTO protocol is extensible, the data model for ALTO O&M should allow for augmentation to support potential future extensions.

Overview of ALTO O&M Data Model for Reference ALTO Architecture shows a reference architecture for ALTO server implementation and YANG modules that server components implement. The server manager, information resource manager and data source listeners need to implement ietf-alto.yang (see ). The performance monitor and logging and fault manager need to implement ietf-alto-stats.yang (see ). The data broker and algorithm plugins are not in the scope of the data model defined in this document. But user specified YANG modules can be applied to different algorithm plugins by augmenting the data model defined in this document (see ).

A Reference ALTO Server Architecture and YANG Modules . Algorithm Plugin: . . Data Broker . read . example-ietf-alto-alg.yang . ............... .............................. ^ | write +----------------+ Southbound ++=============++ | Data Source | API || || | Listener: | <==========> || Data Source || | ietf-alto.yang | || || +----------------+ ++=============++ ]]>

Design of ALTO O&M Data Model

Overview of ALTO O&M Data Model The ietf-alto module defined in this document provide all the basic ALTO O&M data models fitting the requirements listed in . The top-level container "alto" in the ietf-alto module contains a single "alto-server" and multiple "alto-client"s. The list "alto-client" defines a list of configurations for other applications to launch an ALTO client. They can also be used by data sources and information resource creation algorithms that are configured by an ALTO server instance. The container "alto-server" contains all the configured and operational parameters of the administrated ALTO server instance. /alto/alto-server/auth-client/client-id +--rw data-source* [source-id] | +--rw source-id string | +--rw source-type identityref | +--rw (update-policy) | | +--:(reactive) | | | +--rw (publish-mode)? | | | +--:(on-change) | | | | +--rw on-change empty | | | +--:(periodic) | | | +--rw feed-interval uint32 | | +--:(proactive) | | +--rw poll-interval uint32 | +--rw (source-params)? +--rw resource* [resource-id] +--rw resource-id resource-id +--rw resource-type identityref +--rw description? string +--rw accepted-role* | -> /alto/alto-server/role/role-name +--rw dependency* | -> /alto/alto-server/resource/resource-id +--rw (resource-params)? +--:(ird) | +--rw alto-ird-params | +--rw delegation inet:uri +--:(networkmap) | +--rw alto-networkmap-params | +--rw is-default? boolean | +--rw filtered? boolean | +---u algorithm +--:(costmap) | +--rw alto-costmap-params | +--rw filtered? boolean | +---u filter-costmap-cap | +---u algorithm +--:(endpointcost) | +--rw alto-endpointcost-params | +---u endpoint-cost-cap | +---u algorithm +--:(endpointprop) | +--rw alto-endpointprop-params | +--rw prop-types* string | +---u algorithm +--:(propmap) {propmap}? | +--rw alto-propmap-params | +---u algorithm +--:(cdni) {cdni}? | +--rw alto-cdni-params | +---u algorithm +--:(update) {incr-update}? +--rw alto-update-params +---u algorithm ]]>

Data Model for ALTO Client Operation and Management The alto-client list contains a list of client-side configurations. server-discovery-client is defined to configure how an ALTO client discover the ALTO server.

Data Model for Server-level Operation and Management The ALTO server instance contains the following configuration parameters for server-level operation and management for ALTO, which satisfies R1 - R4 in .

Data Model for ALTO Server Setup To satisfy R1 in , the ALTO server instance contains the following basic configurations for the server setup.

ALTO Server Listen Stack The "listen" contains all the configurations for the whole server listen stack across HTTP layer, TLS layer and TCP layer.

ALTO Server Discovery Setup In practice, multiple ALTO servers can be deployed for scalability. That may require communication among different ALTO servers. The YANG module defined in this document does not contain any configuration for the communication between two ALTO servers. Instead, it provides the configuration for how an ALTO server can be discovered by another ALTO server on demand. /alto-server/data-source/source-id ]]> The server-discovery node provides configuration for ALTO server discovery using different mechanisms. The initial module only defines the reverse-dns case that is used to configure DNS NAPTR records for ALTO server discovery, which is sugested by and . It configures a set of endpoints in the scope of the network domain serving this ALTO server. The node contains two leaf lists. The static list contains a list of manual configured endpoints. The dynamic list points to a list of data sources to retrieve the endpoints dynamically. As suggested by and , the IP prefixes in the scope will be translated into DNS NAPTR resource records for server discovery. Cases for other mechanisms can be augmented in the future modules.

Data Model for Logging Management To satisfy R2 in , the ALTO server instance contains the following configuration parameters for the logging management. The logging-system node provides configuration to select a logging system to capture log messages generated by the ALTO server. By default, syslog is the only supported logging system. When selecting syslog, the related configuration is delegated to the configuration file of the syslog server. A specific server implementation can extend the logging-system node to add other logging systems.

Data Model for ALTO-related Management To satisfy R3 in , the data model contains the following ALTO-related management information.

• The "cost-type" list is the registry for the cost types that can be used in the ALTO server.
• The "meta" list contains the customized meta data of the ALTO server. It will be populated into the meta field of the default Information Resource Directory (IRD).

Data Model for Security Management To satisfy R4 in , the data model leverages HTTP and TLS to provide basic security management for an ALTO server. All the related configurations are covered by the server listen stack.

Data Model for ALTO Server Configuration Management

Data Source Configuration Management To satisfy R5-1 in , the ALTO server instance contains a list of data-source entries to subscribe the data sources from which ALTO information resources are derived (See Section 16.2.4 of ). A data-source entry MUST include:

• a unique source-id for resource creation algorithms to reference,
• the source-type attribute to declare the type of the data source,
• the update-policy to specify how to get the data update from the data source,
• the source-params to specify where and how to query the data.

The update policy can be either reactive or proactive. For the reactive update, the ALTO server reactively waits the data source for pushing updates. For the proactive update, the ALTO server has to proactively fetch the data source periodically. To use the reactive update, there are two publish modes:

• If the on-change attribute presents, the data source is expected to push the update as soon as the data source changes.
• Otherwise, if the feed-interval attribute presents, the data source is expected to push the updates periodically. The value of feed-interval specifies the interval of pushing the data change updates in milliseconds. If feed-interval is zero, the data source is expected to work in the on-change mode.

To use the proactive update, the poll-interval attribute MUST present. The value of poll-interval specifies the interval of fetching the data in milliseconds. If poll-interval is zero, the ALTO server will not fetch the data source. The data-source/source-params node can be augmented for different types of data sources. This data model only includes common configuration parameters for an ALTO server to correctly interact with a data source. The implementation-specific parameters of any certain data source can be augmented in another module. An example is included in .

ALTO Information Resources Configuration Management To satisfy R5-2 and R-3, the ALTO server instance contains a list of resource entries. Each resource entry contains the configurations of an ALTO information resource (See Section 8.1 of ). The operator of the ALTO server can use this model to create, update, and remove the ALTO information resource. Each resoruce entry provides configurations defining how to create or update an ALTO information resource. Adding a new resource entry notifies the ALTO server to create a new ALTO information resource. Updating an existing resource entry notifies the ALTO server to update the generation parameters (e.g., capabilities and the creation algorithm) of an existing ALTO information resource. Removing an existing resource entry will remove the corresponding ALTO information resource. A resource entry MUST include a unique resource-id and a resource-type. It can also include an accepted-role node containing a list of role-names that is used by role-based access control for this ALTO information resource. See for details of information resource access control. For some resource-type, the resource entry MUST also include the a dependency node containing the resource-id of the dependent ALTO information resources (See Section 9.1.5 of ). For each type of ALTO information resource, the resource entry MAY also need type-specific parameters. These type-specific parameters include two categories:

1. One categories of the type-specific parameters are common for the same type of ALTO information resource. They declare the Capabilities of the ALTO information resource (See Section 9.1.3 of ).
2. The other categories of the type-specific parameters are algorithm-specific. The developer of the ALTO server can implement their own creation altorithms and augment the algorithm node to declare algorithm-specific input parameters.

Except for the ird resource, all the other types of resource entries have augmented algorithm node. The augmented algorithm node can reference data sources subscribed by the data-source entries (See ). An example of extending algorithm node for a specific type of resource is included in . The developer cannot customize the creation algorithm of the ird resource. The default ird resource will be created automatically based on all the added resource entries. The delegated ird resource will be created as a static ALTO information resource (See Section 9.2.4 of ). /alto/alto-server/role/role-name +--rw dependency* | -> /alto/alto-server/resource/resource-id +--rw (resource-params)? +--:(ird) | +--rw alto-ird-params | +--rw delegation inet:uri +--:(networkmap) | +--rw alto-networkmap-params | +--rw is-default? boolean | +--rw filtered? boolean | +---u algorithm +--:(costmap) | +--rw alto-costmap-params | +--rw filtered? boolean | +---u filter-costmap-cap | +---u algorithm +--:(endpointcost) | +--rw alto-endpointcost-params | +---u endpoint-cost-cap | +---u algorithm +--:(endpointprop) | +--rw alto-endpointprop-params | +--rw prop-types* string | +---u algorithm +--:(propmap) {propmap}? | +--rw alto-propmap-params | +---u algorithm +--:(cdni) {cdni}? | +--rw alto-cdni-params | +---u algorithm +--:(update) {incr-update}? +--rw alto-update-params +---u algorithm grouping filter-costmap-cap: +-- cost-type-names* string +-- cost-constraints? boolean +-- max-cost-types? uint32 {multi-cost}? +-- testable-cost-type-names* string {multi-cost}? +-- calendar-attributes {cost-calendar}? +-- cost-type-names* string +-- time-interval-size decimal64 +-- number-of-intervals uint32 grouping endpoint-cost-cap: +---u filter-costmap-cap grouping algorithm: +-- (algorithm) ]]>

ALTO Information Resource Access Control Management As section 15.5.2 of suggests, the module also defines authentication and authorization related configuration to employ access control at information resource level. The ALTO server returns the IRD to the ALTO client based on its authentication information. The information resource access control is supported by the following configuration: /alto/alto-server/auth-client/client-id ... ]]> It configures the role-based access control:

• auth-client declares a list of ALTO clients that can be authenticated by the internal or external authorization server. This basic model does not define any authentication approach, but the operators or future documents can augment the authentication choice for different authentication mechanisms.
• role defines a list of roles for access control. Each role contains a list of authenticated ALTO clients. Each client can be assigned to multiple roles. The role-name can be referenced by the accepted-role list of a resource. For a given authenticated ALTO client, if one of the roles containing it is allowed to access a resource, this client is allowed to access the resource.

Design of ALTO O&M Statistics Data Model The module, "ietf-alto-stats", augments the ietf-alto module to include statistics at the ALTO server and information resource level.

Model for ALTO Server Failure Monitoring To satisfy R6 in , the YANG data module defined in this document contains statistics that indicates server failures. More specifically, num-total-* and num-total-last-* provides server-level failure counters; num-res-* provides information resource-level failure counters.

Model for ALTO-specific Performance Monitoring To satisfy R7 in , the YANG data module defined in this document also contains statistics for ALTO-specific performance metrics. More specifically, this data model contains the following measurement information suggested by :

• Measurement of impact
  • Total amount and distribution of traffic
  • Application performance
• System and service performance
  • Requests and responses for each information resource
  • CPU and memory utilization
  • ALTO map updates
  • Number of PIDs
  • ALTO map sizes

Besides the measurement information suggested by , this data model also contains useful measurement information for other ALTO extensions:

• num-map-entry and num-base-obj provides measurement for number of generic ALTO entities (for and )
• num-upd-sess and num-event-* provides statistics for update sessions and events (for )

ALTO OAM YANG Module

The ietf-alto Module WG List: "; description "This YANG module defines all the configured and operational parameters of the administrated ALTO server instance. Copyright (c) 2022 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 Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices. 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 BCP 14 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here."; revision "2023-02-10" { description "Initial Version."; reference "RFC XXXX: A YANG Data Model for OAM and Management of ALTO Protocol."; } typedef resource-id { type string { length "1..64"; pattern "[0-9a-zA-Z\\-:@_]*"; } description "Format of Resource ID"; reference "Section 9.1.1 of RFC 7285."; } typedef role-name { type string; description "Name of a role for role-based access control."; } // Base identities identity resource-type { description "Base identity for type of information resource."; } identity source-type { description "Base identity for type of data source."; } identity cost-mode { description "The cost mode attribute indicates how costs should be interpreted. Specifically, the cost mode attribute indicates whether returned costs should be interpreted as numerical values or ordinal rankings."; reference "Section 6.1.2 of RFC 7285."; } identity cost-metric { description "The cost metric attribute indicates what the cost represents."; reference "Section 6.1.1 of RFC 7285."; } identity cost-source { description "Theh cost source attribute indicates the high-level type of the data source."; reference "Section 3.1 of RFC YYYY."; } // Identities for ALTO information resources identity ird { base resource-type; description "Identity for information resource directory."; } identity network-map { base resource-type; description "Identity for network map."; } identity cost-map { base resource-type; description "Identity for cost map."; } identity endpoint-cost { base resource-type; description "Identity for endpoint cost service."; } identity endpoint-prop { base resource-type; description "Identity for endpoint property service."; } identity property-map { base resource-type; description "Identity for property map."; } identity cdni { base resource-type; description "Identity for content delivery network interconnection (CDNI) advertisement service."; } identity update { base resource-type; description "Identity for update stream service."; } // Identities for cost mode identity numerical { base cost-mode; description "This mode indicates that it is safe to perform numerical operations"; } identity ordinal { base cost-mode; description "This mode indicates that the cost values in a cost map represent ranking"; } identity array { if-feature "path-vector"; base cost-mode; description "This mode indicates that every cost value in the response body of a (Filtered) Cost Map or an Endpoint Cost Service MUST be interpreted as a JSON array."; } // Identities for cost metrics identity routingcost { base cost-metric; description "This metric conveys a generic measure for the cost of routing traffic from a source to a destination."; } identity ane-path { if-feature "path-vector"; base cost-metric; description "This metric indicates that the value of such a cost type conveys an array of Abstract Network Element (ANE) names, where each ANE name uniquely represents an ANE traversed by traffic from a source to a destination."; } identity delay-ow { if-feature "performance-metrics"; base cost-metric; description "Section 4.1 of RFC YYYY"; } identity delay-rt { if-feature "performance-metrics"; base cost-metric; description "Section 4.2 of RFC YYYY"; } identity delay-variation { if-feature "performance-metrics"; base cost-metric; description "Section 4.3 of RFC YYYY"; } identity lossrate { if-feature "performance-metrics"; base cost-metric; description "Section 4.4 of RFC YYYY"; } identity hopcount { if-feature "performance-metrics"; base cost-metric; description "Section 4.5 of RFC YYYY"; } identity tput { if-feature "performance-metrics"; base cost-metric; description "Section 5.1 of RFC YYYY"; } identity bw-residual { if-feature "performance-metrics"; base cost-metric; description "Section 5.2 of RFC YYYY"; } identity bw-available { if-feature "performance-metrics"; base cost-metric; description "Section 5.3 of RFC YYYY"; } // Identities for cost sources identity nomial { if-feature "performance-metrics"; base cost-source; description "The 'nominal' category indicates that the metric value is statically configured by the underlying devices."; reference "Section 3.1 of RFC YYYY"; } identity sla { if-feature "performance-metrics"; base cost-source; description "The 'sla' category indicates that the metric value is derived from some commitment which this document refers to as service-level agreement (SLA)."; reference "Section 3.1 of RFC YYYY"; } identity estimation { if-feature "performance-metrics"; base cost-source; description "The 'estimation' category indicates that the metric value is computed through an estimation process."; reference "Section 3.1 of RFC YYYY"; } // Features feature http-listen { description "The 'http-listen' feature is only used for test depolyment. According to Sec 8.3.5 of RFC 7285, it shouldn't be used in the production depolyment."; } feature xdom-disc { description "Support cross-domain server discovery."; reference "RFC8686: Application-Layer Traffic Optimization (ALTO) Cross-Domain Server Discovery"; } feature multi-cost { description "Support multi-cost extension."; reference "RFC 8189: Multi-Cost Application-Layer Traffic Optimization (ALTO)"; } feature incr-update { description "Support incremental update extension."; reference "RFC 8895: Application-Layer Traffic Optimization (ALTO) Incremental Updates Using Server-Sent Events (SSE)"; } feature cost-calendar { description "Support cost calendar extension."; reference "RFC 8896: Application-Layer Traffic Optimization (ALTO) Cost Calendar"; } feature propmap { description "Support entity property map extension."; reference "RFC 9240: An ALTO Extension: Entity Property Maps"; } feature cdni { description "Support CDNi extension."; reference "RFC 9241: Content Delivery Network Interconnection (CDNI) Request Routing: CDNI Footprint and Capabilities Advertisement using ALTO"; } feature path-vector { description "Support path vector extension."; reference "RFC 9275: An Extension for Application-Layer Traffic Optimization (ALTO): Path Vector"; } feature performance-metrics { description "Support performance metrics extension."; reference "RFC YYYY: ALTO Performance Cost Metrics"; } // Groupings grouping filter-costmap-cap { description "This grouping defines data model for FilteredCostMapCapabilities."; reference "Sec 11.3.2.4 of RFC 7285."; leaf-list cost-type-names { type string; min-elements 1; description "Supported cost types"; } leaf cost-constraints { type boolean; description "If true, then the ALTO server allows cost constraints to be included in requests to the corresponding URI. If not present, this field MUST be interpreted as if it specified false."; } leaf max-cost-types { if-feature "multi-cost"; type uint32; default 0; description "If present with value N greater than 0, this resource understands the multi-cost extensions in this document and can return a multi-cost map with any combination of N or fewer cost types in the 'cost-type-names' list. If omitted, the default value is 0."; } leaf-list testable-cost-type-names { if-feature "multi-cost"; type string; description "If present, the resource allows constraint tests, but only on the cost type names in this array."; } container calendar-attributes { if-feature "cost-calendar"; leaf-list cost-type-names { type string; min-elements 1; description "An array of one or more elements indicating the cost type names in the IRD entry to which the values of 'time-interval-size' and 'number-of-intervals' apply."; } leaf time-interval-size { type decimal64 { fraction-digits 4; } mandatory true; description "The duration of an ALTO Calendar time interval in a unit of seconds."; } leaf number-of-intervals { type uint32 { range "1..max"; } mandatory true; description "A strictly positive integer (greater or equal to 1) that indicates the number of values of the Cost Calendar array."; } description "Configuration for CalendarAttributes."; reference "Section 4.1 of RFC 8896."; } } grouping endpoint-cost-cap { uses filter-costmap-cap; description "This grouping defines EndpointCostCapabilities as the same as FilteredCostMapCapabilities defined by the grouping filter-costmap-cap."; reference "Section 11.5.1.4 of RFC 7285"; } grouping algorithm { choice algorithm { mandatory true; description "Information resource creation algorithm to be augmented."; } description "This grouping defines base data model for information resource creation algorithm."; } grouping alto-server-grouping { description "A reuseable grouping for configuring an ALTO server without any consideration for how underlying transport sessions are established."; leaf base-uri { type inet:uri; description "The base URI for the ALTO server."; } } grouping alto-server-listen-stack-grouping { description "A reuseable grouping for configuring an ALTO server 'listen' protocol stack for a single connection."; choice transport { mandatory true; description "Selects between available transports."; case http { if-feature "http-listen"; container http { description "Configures ALTO server stack assuming that TLS-termination is handled externally."; container tcp-server-parameters { description "A wrapper around the TCP server parameters to avoid name collisions."; uses tcp:tcp-server-grouping { refine "local-port" { default "80"; description "The RESTCONF server will listen on the IANA- assigned well-known port value for 'http' (80) if no value is specified."; } } } container http-server-parameters { description "A wrapper around the HTTP server parameters to avoid name collisions."; uses http:http-server-grouping; } container alto-server-parameters { description "A wrapper around the ALTO server parameters to avoid name collisiions."; uses alto-server-grouping; } } } case https { container https { description "Configures ALTO server stack assuming that TLS-termination is handled internally."; container tcp-server-parameters { description "A wrapper around the TCP server parameters to avoid name collisions."; uses tcp:tcp-server-grouping { refine "local-port" { default "443"; description "The ALTO server will listen on the IANA- assigned well-known port value for 'https' (443) if no value is specified."; } } container tls-server-parameters { description "A wrapper around the TLS server parameters to avoid name collisions."; uses tls:tls-server-grouping; } container http-server-parameters { description "A wrapper around the HTTP server parameters to avoid name collisions."; uses http:http-server-grouping; } container alto-server-parameters { description "A wrapper around the ALTO server parameters to avoid name collisions."; uses alto-server-grouping; } } } } } } grouping alto-server-discovery-grouping { description "Grouping for configuration of how to set up server discovery for clients or other ALTO servers to discovery the URI of this ALTO server."; choice server-discovery-manner { description "Selects among available server discovery manners"; case reverse-dns { if-feature xdom-disc; description "Configure DNS NAPTR records for cross-domain ALTO server discovery using reverse DNS lookup."; container rdns-naptr-records { description "Configuration parameters for DNS NAPTR records."; leaf-list static-prefix { type inet:ip-prefix; description "Static IP prefixes in the scope."; } leaf-list dynamic-prefix-source { type leafref { path "/alto:alto/alto:alto-server/alto:data-source" + "/alto:source-id"; } description "Dynamic IP prefixes collected from data sources."; } } reference "RFC 8686: Application-Layer Traffic Optimization (ALTO) Cross-Domain Server Discovery."; } } } grouping alto-server-discovery-client-grouping { description "Grouping for configuration of how a client can discover another ALTO server."; choice server-discovery-client-manner { description "Selects among available server discovery manners."; case reverse-dns { if-feature xdom-disc; description "Use reverse DNS lookup to discover an ALTO server."; reference "RFC 8686: Application-Layer Traffic Optimization (ALTO) Cross-Domain Server Discovery."; container rdns-params { description "Configuration for reverse DNS lookup."; leaf-list dns-server { type inet:host; description "DNS server list for reverse DNS lookup."; } } } } } grouping alto-logging-system-grouping { description "Grouping for configuration of logging system used by the ALTO server."; choice logging-system { description "Selects among available logging systems."; case syslog { description "Use syslog as logging system."; container syslog-params { description "Configuration parameters for syslog."; leaf config-file { type inet:uri { pattern 'file:.*'; } default 'file:/etc/syslog.conf'; description "The file location of the syslog configuration."; } } } } } // Top-level container container alto { presence "The ALTO is enabled"; description "Parameters for the ALTO client and server."; list alto-client { key client-id; leaf client-id { type string; description "Identifier of a client that can be referenced by a data source or a resource creation algorithm to communicate with other ALTO servers."; } container server-discovery-client { uses alto-server-discovery-client-grouping; description "Configuration of how to discover another ALTO server."; } description "The ALTO client configuration."; } container alto-server { description "The ALTO server instance configuration."; container listen { description "Configure the ALTO server to listen for ALTO clients."; uses alto-server-listen-stack-grouping; } container server-discovery { description "Configure how the ALTO server to be discovered by others."; uses alto-server-discovery-grouping; } container logging-system { description "Configure logging system to capture log messages generated by the ALTO server."; uses alto-logging-system-grouping; } list cost-type { key "cost-type-name"; leaf cost-type-name { type string; description "The name to reference cost type"; } leaf cost-mode { type identityref { base cost-mode; } mandatory true; description "The referenced cost mode"; } leaf cost-metric { type identityref { base cost-metric; } mandatory true; description "The referenced cost metric"; } leaf description { type string; description "The human-readable description fo the cost-mode and cost-mode"; } container cost-context { if-feature "performance-metrics"; leaf cost-source { type identityref { base cost-source; } mandatory true; description "The referenced cost source"; } container parameters { choice parameters { description "Cases of parameters to be augmented."; } description "Additional computation parameters for the cost source."; } description "Context of how the metric is obtained."; } description "Mapping between name and referenced cost type"; } list meta { key "meta-key"; leaf meta-key { type string; description "Custom meta key"; } leaf meta-value { type string; mandatory true; description "Custom meta value"; } description "Mapping of custom meta information"; reference "Section 8.4.1 of RFC 7285."; } list auth-client { key "client-id"; leaf client-id { type string; description "Identifier to reference an ALTO client."; } choice authentication { description "Choice of authentication methods to identify this ALTO client."; } description "List of authenticated ALTO clients."; } list role { key "role-name"; leaf role-name { type role-name; description "Name of a role for access control."; } list client { key "client-id"; leaf client-id { type leafref { path "/alto:alto/alto:alto-server/alto:auth-client" + "/alto:client-id"; } description "Identifier of an ALTO client assigned to the role."; } description "List of roles for access control."; } description "List of roles for access control."; } list data-source { key "source-id"; leaf source-id { type string; description "Data source id that can be referenced by information resource creation algorithms."; } leaf source-type { type identityref { base source-type; } mandatory true; description "Identify the type of the data source."; } choice update-policy { mandatory true; case reactive { description "Configuration for the data source listener to reactively subscribe data and wait for updates published by the data source."; choice publish-mode { description "Configuration for when the data source publish an update."; case on-change { description "The data source is requested to publish an update once the data has a change."; leaf on-change { type empty; mandatory true; description "Indicate an on-change subscription."; } } case periodic { description "The data source is requested to periodically publish an update."; leaf feed-interval { type uint32; mandatory true; description "Duration of time that should occur between periodic push updates, in units of seconds."; } } } } case proactive { description "Configuration for the data source listener to proactively pull data from the data source."; leaf poll-interval { type uint32; mandatory true; description "Polling interval in seconds for proactive mode."; } } description "Policy to get updates from data sources."; } choice source-params { description "Data source specific configuration."; } description "List of subscribed data sources."; } list resource { key "resource-id"; leaf resource-id { type resource-id; description "resource-id to be defined."; } leaf resource-type { type identityref { base resource-type; } mandatory true; description "identityref to be defined."; } leaf description { type string; description "The optional description for this information resource."; } leaf-list accepted-role { type leafref { path "/alto:alto/alto:alto-server/alto:role" + "/alto:role-name"; } description "Roles allowed to access this information resource."; } leaf-list dependency { type leafref { path "/alto:alto/alto:alto-server/alto:resource" + "/alto:resource-id"; } description "A list of dependent information resources."; } choice resource-params { description "Resource-specific configuration."; case ird { when 'derived-from-or-self(resource-type, "alto:ird")'; container alto-ird-params { leaf delegation { type inet:uri; mandatory true; description "Upstream IRD to be delegated."; } description "IRD-specific configuration."; } } case networkmap { when 'derived-from-or-self(resource-type,' + '"alto:network-map")'; container alto-networkmap-params { description "(Filtered) Network Map specific configuration."; reference "Section 11.2.1 and Section 11.3.1 of RFC 7285."; leaf is-default { type boolean; description "Set whether this is the default network map."; } leaf filtered { type boolean; default false; description "Configure whether filtered network map is supported."; } uses algorithm; } } case costmap { when 'derived-from-or-self(resource-type,' + '"alto:cost-map")'; container alto-costmap-params { description "(Filtered) Cost Map specific configuration."; reference "Section 11.2.2 and Section 11.3.2 of RFC 7285."; leaf filtered { type boolean; description "Configure whether filtered cost map is supported."; } uses filter-costmap-cap; uses algorithm; } } case endpointcost { when 'derived-from-or-self(resource-type,' + '"alto:endpoint-cost")'; container alto-endpointcost-params { description "Endpoint Cost Service specific configuration."; reference "Section 11.5 of RFC 7285."; uses endpoint-cost-cap; uses algorithm; } } case endpointprop { when 'derived-from-or-self(resource-type,' + '"alto:endpoint-prop")'; container alto-endpointprop-params { description "Endpoint Cost Service specific configuration."; reference "Section 11.5 of RFC 7285."; leaf-list prop-types { type string; min-elements 1; description "Supported endpoint properties."; } uses algorithm; } } case propmap { when 'derived-from-or-self(resource-type,' + '"alto:property-map")'; if-feature "propmap"; container alto-propmap-params { uses algorithm; description "(Filtered) Entity Property Map specific configuration."; } } case cdni { when 'derived-from-or-self(resource-type, "alto:cdni")'; if-feature "cdni"; container alto-cdni-params { uses algorithm; description "CDNi specific configuration"; } } case update { when 'derived-from-or-self(resource-type,' + '"alto:update")'; if-feature "incr-update"; container alto-update-params { uses algorithm; description "Incremental Updates specific configuration"; } } } description "ALTO information resources to be defined"; } } } } ]]>

The ietf-alto-stats Module WG List: "; description "This YANG module defines all the statistics of the administrated ALTO server instance. Copyright (c) 2022 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 Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices."; revision "2023-02-10" { description "Initial Version."; reference "RFC XXXX: A YANG Data Model for Operations, Administration, and Maintenance of ALTO Protocol."; } augment "/alto:alto/alto:alto-server" { description "Top-level statistics for the whole ALTO server."; leaf num-total-req { type yang:counter32; config false; description "The total number of ALTO requests received by this ALTO server."; } leaf num-total-succ { type yang:counter32; config false; description "The total number of successful responses sent by this ALTO server."; } leaf num-total-fail { type yang:counter32; config false; description "The total number of failed responses sent by this ALTO server."; } leaf num-total-last-req { type yang:counter32; config false; description "The total number of ALTO requests received within the last 5 minutes."; } leaf num-total-last-succ { type yang:counter32; config false; description "The total number of successful responses sent by this ALTO server within the last 5 minutes."; } leaf num-total-last-fail { type yang:counter32; config false; description "The total number of failed responses sent by this ALTO server within the last 5 minutes."; } } augment "/alto:alto/alto:alto-server/alto:resource" { description "Common statistics for each information resource."; leaf num-res-upd { type yang:counter32; config false; description "The number of version updates since the information resource was created."; } leaf res-mem-size { type yang:counter32; config false; description "Memory size (Bytes) utilized by the information resource."; } leaf res-enc-size { type yang:counter32; config false; description "Size (Bytes) of JSON encoded data of the information resource."; } leaf num-res-req { type yang:counter32; config false; description "The number of ALTO requests to this information resource."; } leaf num-res-succ { type yang:counter32; config false; description "The number of successful responses for requests to this information resource."; } leaf num-res-fail { type yang:counter32; config false; description "The total number of failed responses for requests to this information resource."; } } augment "/alto:alto/alto:alto-server/alto:resource" + "/alto:resource-params/alto:networkmap" + "/alto:alto-networkmap-params" { description "Augmented statistics for network maps only."; leaf num-map-pid { type yang:counter32; config false; description "Number of PIDs contained by the network map."; } } augment "/alto:alto/alto:alto-server/alto:resource" + "/alto:resource-params/alto:propmap" + "/alto:alto-propmap-params" { description "Augmented statistics for property maps only."; leaf num-map-entry { type yang:counter32; config false; description "Number of ALTO entities contained by the property map."; } } augment "/alto:alto/alto:alto-server/alto:resource" + "/alto:resource-params/alto:cdni" + "/alto:alto-cdni-params" { description "Augmented statistics for CDNi resources only."; leaf num-base-obj { type yang:counter32; config false; description "Number of base CDNi advertisement objects contained by the CDNi resource."; } } augment "/alto:alto/alto:alto-server/alto:resource" + "/alto:resource-params/alto:update" + "/alto:alto-update-params" { description "Augmented statistics for incremental updates only."; leaf num-upd-sess { type yang:counter32; config false; description "Number of sessions connected to the incremental update service."; } leaf num-event-total { type yang:counter32; config false; description "Total number of update events sent to all the connected clients."; } leaf num-event-max { type yang:counter32; config false; description "The maximum number of update events sent to the connected clients."; } leaf num-event-min { type yang:counter32; config false; description "The minimum number of update events sent to the connected clients."; } leaf num-event-avg { type yang:counter32; config false; description "The average number of update events sent to the connected clients."; } } } ]]>

Security Considerations

The "ietf-alto" YANG Module The "ietf-alto" YANG module defines data nodes that are designed to be accessed via YANG based management protocols, such as NETCONF and RESTCONF . Both of these protocols have mandatory-to-implement secure transport layers (e.g., SSH, TLS) with mutual authentication. The Network Access Control Model (NACM) provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content. None of the readable data nodes in this YANG module are considered sensitive or vulnerable in network environments. The NACM "default-deny-all" extension has not been set for any data nodes defined in this module. None of the writable data nodes in this YANG module are considered sensitive or vulnerable in network environments. The NACM "default-deny-write" extension has not been set for any data nodes defined in this module. This module does not define any RPCs, actions, or notifications, and thus the security consideration for such is not provided here. Please be aware that this module uses groupings defined in other RFCs that define data nodes that do set the NACM "default-deny-all" and "default-deny-write" extensions.

The "ietf-alto-stats" YANG Module The "ietf-alto-stats" YANG module defines data nodes that are designed to be accessed via YANG based management protocols, such as NETCONF and RESTCONF . Both of these protocols have mandatory-to-implement secure transport layers (e.g., SSH, TLS) with mutual authentication. The Network Access Control Model (NACM) provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content. None of the readable data nodes in this YANG module are considered sensitive or vulnerable in network environments. The NACM "default-deny-all" extension has not been set for any data nodes defined in this module. None of the writable data nodes in this YANG module are considered sensitive or vulnerable in network environments. The NACM "default-deny-write" extension has not been set for any data nodes defined in this module. This module does not define any RPCs, actions, or notifications, and thus the security consideration for such is not provided here. Please be aware that this module uses groupings defined in other RFCs that define data nodes that do set the NACM "default-deny-all" and

IANA Considerations This document registers two URIs in the "IETF XML Registry" . Following the format in RFC 3688, the following registrations are requested. This document registers two YANG modules in the "YANG Module Names" registry . [RFC Editor: Please replace RFCthis with the published RFC number for this document.]

References Normative References In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. This document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas. YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS-TRACK] This document introduces a collection of common data types to be used with the YANG data modeling language. This document obsoletes RFC 6021. Applications using the Internet already have access to some topology information of Internet Service Provider (ISP) networks. For example, views to Internet routing tables at Looking Glass servers are available and can be practically downloaded to many network application clients. What is missing is knowledge of the underlying network topologies from the point of view of ISPs. In other words, what an ISP prefers in terms of traffic optimization -- and a way to distribute it. The Application-Layer Traffic Optimization (ALTO) services defined in this document provide network information (e.g., basic network location structure and preferences of network paths) with the goal of modifying network resource consumption patterns while maintaining or improving application performance. The basic information of ALTO is based on abstract maps of a network. These maps provide a simplified view, yet enough information about a network for applications to effectively utilize them. Additional services are built on top of the maps. This document describes a protocol implementing the ALTO services. Although the ALTO services would primarily be provided by ISPs, other entities, such as content service providers, could also provide ALTO services. Applications that could use the ALTO services are those that have a choice to which end points to connect. Examples of such applications are peer-to-peer (P2P) and content delivery networks. The goal of Application-Layer Traffic Optimization (ALTO) is to provide guidance to applications that have to select one or several hosts from a set of candidates capable of providing a desired resource. ALTO is realized by a client-server protocol. Before an ALTO client can ask for guidance, it needs to discover one or more ALTO servers. This document specifies a procedure for resource-consumer-initiated ALTO server discovery, which can be used if the ALTO client is embedded in the resource consumer. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. This document describes the key chain YANG data model. Key chains are commonly used for routing protocol authentication and other applications requiring symmetric keys. A key chain is a list containing one or more elements containing a Key ID, key string, send/accept lifetimes, and the associated authentication or encryption algorithm. By properly overlapping the send and accept lifetimes of multiple key chain elements, key strings and algorithms may be gracefully updated. By representing them in a YANG data model, key distribution can be automated. The Application-Layer Traffic Optimization (ALTO) protocol, specified in RFC 7285, defines several services that return various metrics describing the costs between network endpoints. This document defines a new service that allows an ALTO Client to retrieve several cost metrics in a single request for an ALTO filtered cost map and endpoint cost map. In addition, it extends the constraints to further filter those maps by allowing an ALTO Client to specify a logical combination of tests on several cost metrics. This document captures the current syntax used in YANG module tree diagrams. The purpose of this document is to provide a single location for this definition. This syntax may be updated from time to time based on the evolution of the YANG language. The goal of Application-Layer Traffic Optimization (ALTO) is to provide guidance to applications that have to select one or several hosts from a set of candidates capable of providing a desired resource. ALTO is realized by a client-server protocol. Before an ALTO client can ask for guidance, it needs to discover one or more ALTO servers that can provide suitable guidance. In some deployment scenarios, in particular if the information about the network topology is partitioned and distributed over several ALTO servers, it may be necessary to discover an ALTO server outside of the ALTO client's own network domain, in order to get appropriate guidance. This document details applicable scenarios, itemizes requirements, and specifies a procedure for ALTO cross-domain server discovery. Technically, the procedure specified in this document takes one IP address or prefix and a U-NAPTR Service Parameter (typically, "ALTO:https") as parameters. It performs DNS lookups (for NAPTR resource records in the "in-addr.arpa." or "ip6.arpa." trees) and returns one or more URIs of information resources related to that IP address or prefix. The Application-Layer Traffic Optimization (ALTO) protocol (RFC 7285) provides network-related information, called network information resources, to client applications so that clients can make informed decisions in utilizing network resources. This document presents a mechanism to allow an ALTO server to push updates to ALTO clients to achieve two benefits: (1) updates can be incremental, in that if only a small section of an information resource changes, the ALTO server can send just the changes and (2) updates can be immediate, in that the ALTO server can send updates as soon as they are available. This document is an extension to the base Application-Layer Traffic Optimization (ALTO) protocol. It extends the ALTO cost information service so that applications decide not only 'where' to connect but also 'when'. This is useful for applications that need to perform bulk data transfer and would like to schedule these transfers during an off-peak hour, for example. This extension introduces the ALTO Cost Calendar with which an ALTO Server exposes ALTO cost values in JSON arrays where each value corresponds to a given time interval. The time intervals, as well as other Calendar attributes, are specified in the Information Resources Directory and ALTO Server responses. Informative References RPSL allows a network operator to be able to specify routing policies at various levels in the Internet hierarchy; for example at the Autonomous System (AS) level. At the same time, policies can be specified with sufficient detail in RPSL so that low level router configurations can be generated from them. RPSL is extensible; new routing protocols and new protocol features can be introduced at any time. [STANDARDS-TRACK] The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs). This document obsoletes RFC 4741. [STANDARDS-TRACK] This document describes the IETF architecture for a standard, programmatic interface for state transfer in and out of the Internet routing system. It describes the high-level architecture, the building blocks of this high-level architecture, and their interfaces, with particular focus on those to be standardized as part of the Interface to the Routing System (I2RS). Many Internet applications are used to access resources such as pieces of information or server processes that are available in several equivalent replicas on different hosts. This includes, but is not limited to, peer-to-peer file sharing applications. The goal of Application-Layer Traffic Optimization (ALTO) is to provide guidance to applications that have to select one or several hosts from a set of candidates capable of providing a desired resource. This memo discusses deployment-related issues of ALTO. It addresses different use cases of ALTO such as peer-to-peer file sharing and Content Delivery Networks (CDNs) and presents corresponding examples. The document also includes recommendations for network administrators and application designers planning to deploy ALTO, such as recommendations on how to generate ALTO map information. The standardization of network configuration interfaces for use with the Network Configuration Protocol (NETCONF) or the RESTCONF protocol requires a structured and secure operating environment that promotes human usability and multi-vendor interoperability. There is a need for standard mechanisms to restrict NETCONF or RESTCONF protocol access for particular users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. This document defines such an access control model. This document obsoletes RFC 6536. Datastores are a fundamental concept binding the data models written in the YANG data modeling language to network management protocols such as the Network Configuration Protocol (NETCONF) and RESTCONF. This document defines an architectural framework for datastores based on the experience gained with the initial simpler model, addressing requirements that were not well supported in the initial model. This document updates RFC 7950. This document defines a YANG data model for Layer 3 network topologies. This document describes an HTTP-based protocol that provides a programmatic interface for accessing data defined in YANG, using the datastore concepts defined in the Network Configuration Protocol (NETCONF). This document describes a mechanism that allows subscriber applications to request a continuous and customized stream of updates from a YANG datastore. Providing such visibility into updates enables new capabilities based on the remote mirroring and monitoring of configuration and operational state. This document specifies an extension to the base Application-Layer Traffic Optimization (ALTO) Protocol that generalizes the concept of "endpoint properties", which have been tied to IP addresses so far, to entities defined by a wide set of objects. Further, these properties are presented as maps, similar to the network and cost maps in the base ALTO Protocol. While supporting the endpoints and related Endpoint Property Service defined in RFC 7285, the ALTO Protocol is extended in two major directions. First, from endpoints restricted to IP addresses to entities covering a wider and extensible set of objects; second, from properties for specific endpoints to entire entity property maps. These extensions introduce additional features that allow entities and property values to be specific to a given information resource. This is made possible by a generic and flexible design of entity and property types. The Content Delivery Networks Interconnection (CDNI) framework in RFC 6707 defines a set of protocols to interconnect CDNs to achieve multiple goals, including extending the reach of a given CDN. A CDNI Request Routing Footprint & Capabilities Advertisement interface (FCI) is needed to achieve the goals of a CDNI. RFC 8008 defines the FCI semantics and provides guidelines on the FCI protocol, but the exact protocol is not specified. This document defines a new Application-Layer Traffic Optimization (ALTO) service, called "CDNI Advertisement Service", that provides an implementation of the FCI, following the guidelines defined in RFC 8008. This document is an extension to the base Application-Layer Traffic Optimization (ALTO) protocol. It extends the ALTO cost map and ALTO property map services so that an application can decide to which endpoint(s) to connect based not only on numerical/ordinal cost values but also on fine-grained abstract information regarding the paths. This is useful for applications whose performance is impacted by specific components of a network on the end-to-end paths, e.g., they may infer that several paths share common links and prevent traffic bottlenecks by avoiding such paths. This extension introduces a new abstraction called the "Abstract Network Element" (ANE) to represent these components and encodes a network path as a vector of ANEs. Thus, it provides a more complete but still abstract graph representation of the underlying network(s) for informed traffic optimization among endpoints. Huawei Yale University Samsung Huawei Nokia Bell Labs Telefonica The cost metric is a basic concept in Application-Layer Traffic Optimization (ALTO), and different applications may use different types of cost metrics. Since the ALTO base protocol (RFC 7285) defines only a single cost metric (namely, the generic "routingcost" metric), if an application wants to issue a cost map or an endpoint cost request in order to identify a resource provider that offers better performance metrics (e.g., lower delay or loss rate), the base protocol does not define the cost metric to be used. This document addresses this issue by extending the specification to provide a variety of network performance metrics, including network delay, delay variation (a.k.a, jitter), packet loss rate, hop count, and bandwidth. There are multiple sources (e.g., estimation based on measurements or service-level agreement) to derive a performance metric. This document introduces an additional "cost-context" field to the ALTO "cost-type" field to convey the source of a performance metric. Watsen Networks Hochschule Esslingen - University of Applied Sciences This document defines three YANG 1.1 modules to support the configuration of TCP clients and TCP servers. The modules include basic parameters of a TCP connection relevant for client or server applications, as well as client configuration required for traversing proxies. The modules can be used either standalone or in conjunction with configuration of other stack protocol layers. Watsen Networks This document defines three YANG 1.1 modules: the first defines features and groupings common to both TLS clients and TLS servers, the second defines a grouping for a generic TLS client, and the third defines a grouping for a generic TLS server. Editorial Note (To be removed by RFC Editor) This draft contains placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. No other RFC Editor instructions are specified elsewhere in this document. Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements: * AAAA --> the assigned RFC value for draft-ietf-netconf-crypto- types * BBBB --> the assigned RFC value for draft-ietf-netconf-trust- anchors * CCCC --> the assigned RFC value for draft-ietf-netconf-keystore * DDDD --> the assigned RFC value for draft-ietf-netconf-tcp-client- server * FFFF --> the assigned RFC value for this draft Artwork in this document contains placeholder values for the date of publication of this draft. Please apply the following replacement: * 2022-12-12 --> the publication date of this draft The "Relation to other RFCs" section Section 1.1 contains the text "one or more YANG modules" and, later, "modules". This text is sourced from a file in a context where it is unknown how many modules a draft defines. The text is not wrong as is, but it may be improved by stating more directly how many modules are defined. The "Relation to other RFCs" section Section 1.1 contains a self- reference to this draft, along with a corresponding Informative Reference in the Appendix. The following Appendix section is to be removed prior to publication: * Appendix B. Change Log Watsen Networks This document defines two YANG modules: the first defines a minimal grouping for configuring an HTTP client, and the second defines a minimal grouping for configuring an HTTP server. It is intended that these groupings will be used to help define the configuration for simple HTTP-based protocols (not for complete web servers or browsers). Editorial Note (To be removed by RFC Editor) This draft contains placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. No other RFC Editor instructions are specified elsewhere in this document. Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements (note: not all may be present): * AAAA --> the assigned RFC value for draft-ietf-netconf-crypto- types * DDDD --> the assigned RFC value for draft-ietf-netconf-tcp-client- server * FFFF --> the assigned RFC value for draft-ietf-netconf-tls-client- server * GGGG --> the assigned RFC value for this draft Artwork in this document contains placeholder values for the date of publication of this draft. Please apply the following replacement: * 2022-12-12 --> the publication date of this draft The "Relation to other RFCs" section Section 1.1 contains the text "one or more YANG modules" and, later, "modules". This text is sourced from a file in a context where it is unknown how many modules a draft defines. The text is not wrong as is, but it may be improved by stating more directly how many modules are defined. The "Relation to other RFCs" section Section 1.1 contains a self- reference to this draft, along with a corresponding Informative Reference in the Appendix. The following Appendix section is to be removed prior to publication: * Appendix A. Change Log Watsen Networks This document defines two YANG modules, one module to configure a NETCONF client and the other module to configure a NETCONF server. Both modules support both the SSH and TLS transport protocols, and support both standard NETCONF and NETCONF Call Home connections. Editorial Note (To be removed by RFC Editor) This draft contains placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. No other RFC Editor instructions are specified elsewhere in this document. Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements (note: not all may be present): * AAAA --> the assigned RFC value for draft-ietf-netconf-crypto- types * BBBB --> the assigned RFC value for draft-ietf-netconf-trust- anchors * CCCC --> the assigned RFC value for draft-ietf-netconf-keystore * DDDD --> the assigned RFC value for draft-ietf-netconf-tcp-client- server * EEEE --> the assigned RFC value for draft-ietf-netconf-ssh-client- server * FFFF --> the assigned RFC value for draft-ietf-netconf-tls-client- server * GGGG --> the assigned RFC value for draft-ietf-netconf-http- client-server * HHHH --> the assigned RFC value for this draft Artwork in this document contains placeholder values for the date of publication of this draft. Please apply the following replacement: * 2022-12-12 --> the publication date of this draft The "Relation to other RFCs" section Section 1.1 contains the text "one or more YANG modules" and, later, "modules". This text is sourced from a file in a context where it is unknown how many modules a draft defines. The text is not wrong as is, but it may be improved by stating more directly how many modules are defined. The "Relation to other RFCs" section Section 1.1 contains a self- reference to this draft, along with a corresponding Informative Reference in the Appendix. The following Appendix section is to be removed prior to publication: * Appendix A. Change Log Watsen Networks This document defines two YANG modules, one module to configure a RESTCONF client and the other module to configure a RESTCONF server. Both modules support the TLS transport protocol with both standard RESTCONF and RESTCONF Call Home connections. Editorial Note (To be removed by RFC Editor) This draft contains placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. No other RFC Editor instructions are specified elsewhere in this document. Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements (note: not all may be present): * AAAA --> the assigned RFC value for draft-ietf-netconf-crypto- types * BBBB --> the assigned RFC value for draft-ietf-netconf-trust- anchors * CCCC --> the assigned RFC value for draft-ietf-netconf-keystore * DDDD --> the assigned RFC value for draft-ietf-netconf-tcp-client- server * EEEE --> the assigned RFC value for draft-ietf-netconf-ssh-client- server * FFFF --> the assigned RFC value for draft-ietf-netconf-tls-client- server * GGGG --> the assigned RFC value for draft-ietf-netconf-http- client-server * HHHH --> the assigned RFC value for draft-ietf-netconf-netconf- client-server * IIII --> the assigned RFC value for this draft Artwork in this document contains placeholder values for the date of publication of this draft. Please apply the following replacement: * 2022-12-12 --> the publication date of this draft The "Relation to other RFCs" section Section 1.1 contains the text "one or more YANG modules" and, later, "modules". This text is sourced from a file in a context where it is unknown how many modules a draft defines. The text is not wrong as is, but it may be improved by stating more directly how many modules are defined. The "Relation to other RFCs" section Section 1.1 contains a self- reference to this draft, along with a corresponding Informative Reference in the Appendix. The following Appendix section is to be removed prior to publication: * Appendix A. Change Log

Example: Extending the ALTO O&M Data Model Developers and operators can also extend this ALTO O&M data model to align with their own implementations. Specifically, the following nodes of the data model can be augmented:

• The server-discovery-manner choice of the server-discovery.
• The authentication choice of each auth-client.
• The data-source choice.
• The algorithm choice of the resource-params of each resource.

Example Module for Extended Server Discovery Manners The base data model defined by ietf-alto.yang only includes a reverse DNS based server discovery manner. The following example module demonstrates how additional server discovery manners can be augmented into the base data model. The case internet-routing-registry allows the ALTO server to update the server URI to the attribute of the corresponding aut-num class in IRR. The case peeringdb allows the ALTO server to update the server URI to the org object of the organization record in PeeringDB. WG List: "; description "This YANG module defines an example of the extended ALTO server discovery manners for IRR and PeeringDB. Copyright (c) 2022 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 Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices."; revision "2023-02-10" { description "Initial Version."; reference "RFC XXXX: A YANG Data Model for Operations, Administration, and Maintenance of ALTO Protocol."; } augment "/alto:alto/alto:alto-server/alto:server-discovery" + "/alto:server-discovery-manner" { description "Examples of server discovery mechanisms provided by the ALTO server."; case internet-routing-registry { description "Update descr attributes of a aut-num class in a Internet Routing Registry (IRR) database for ALTO server discovery using RPSL."; reference "RFC 2622: Routing Policy Specification Language (RPSL)."; container irr-params { description "Configuration parameters for IRR database."; leaf aut-num { type inet:as-number; description "The autonomous system (AS) to be updated."; } } } case peeringdb { description "Update metadata of a network record in PeeringDB database for ALTO server discovery using PeeringDB lookup."; container peeringdb-params { description "Configuration parameters for PeeringDB database."; leaf org-id { type uint32; description "The ID referring to the org object of the organization record in PeeringDB."; } } } } augment "/alto:alto/alto:alto-client/alto:server-discovery-client" + "/alto:server-discovery-client-manner" { description "Examples of server discovery mechanisms used by the ALTO client."; case internet-routing-registry { description "Use Internet Routing Registry (IRR) to discover an ALTO server."; reference "RFC 2622: Routing Policy Specification Language (RPSL)."; container irr-params { description "Configuration for IRR query using RPSL."; leaf whois-server { type inet:host; description "Whois server for IRR query using RPSL."; } } } case peeringdb { description "Use PeeringDB to discover an ALTO server."; container peeringdb-params { description "Configuration for PeeringDB query"; leaf peeringdb-endpoint { type inet:uri; description "Endpoint of PeeringDB API server."; } } } } } ]]>

Example Module for Extended Client Authentication Approaches The base data model defined by ietf-alto.yang does not include any choice cases for specific client authentication approaches. The following example module demonstrates how additional client authentication approaches can be augmented into the base data model. The case http-basic includes the username and password which are required by the ALTO server to authenticate an ALTO client using the HTTP basic authentication. The case oauth2 includes the URI to a third-party OAuth 2.0 based authorization server that the ALTO server can redirect to for the client authentication. WG List: "; description "This YANG module defines an example of the extended ALTO client authentication approaches for the role-based access control. Copyright (c) 2022 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 Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices."; revision "2023-02-10" { description "Initial Version."; reference "RFC XXXX: A YANG Data Model for Operations, Administration, and Maintenance of ALTO Protocol."; } augment "/alto:alto/alto:alto-server/alto:auth-client" + "/alto:authentication" { description "Example of extended ALTO client authentication approaches."; case http-basic { description "Example of the HTTP basic authentication."; container basic-auth { description "Parameters for the HTTP basic authentication."; leaf username { type string; mandatory true; description "username of the HTTP basic authentication."; } leaf password { type string; mandatory true; description "password of the HTTP basic authentication."; } } } case oauth2 { description "Example of authentication by a third-party OAuth 2.0 server."; container oauth2 { description "Parameters for authentication by a third-party OAuth 2.0 server."; leaf oauth2-server { type inet:uri; description "The URI to the authorization server."; } } } } } ]]>

Example Module for Extended Data Sources The base data model defined by ietf-alto.yang does not include any choice cases for specific data sources. The following example module demonstrates how a implementation-specific data source can be augmented into the base data model. The yang-datastore case is used to import the YANG data from a YANG model-driven datastore. It includes:

• datastore to indicate which datastore is fetched.
• target-paths to specify the list of nodes or subtrees in the datastore.
• protocol to indicate which protocol is used to access the datastore. Either restconf or netconf can be used.

WG List: "; description "This YANG module defines an example of the extended ALTO data source for YANG-based datastore. Copyright (c) 2022 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 Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices."; revision "2023-02-10" { description "Initial Version."; reference "RFC XXXX: A YANG Data Model for Operations, Administration, and Maintenance of ALTO Protocol."; } identity yang-datastore { base alto:source-type; description "Identity for data source of YANG-based datastore."; } identity protocol-type { description "Base identity for protocol type."; } identity netconf { base protocol-type; description "Identity for NETCONF protocol."; } identity restconf { base protocol-type; description "Identity for RESTCONF protocol."; } augment "/alto:alto/alto:alto-server/alto:data-source" + "/alto:source-params" { description "Example of data source for YANG datastore."; case yang-datastore { when 'derived-from-or-self(source-type, "alto-ds:yang-datastore")'; description "Example data source for local and/or remote YANG datastore."; container yang-datastore-source-params { description "YANG datastore specific configuration."; leaf datastore { type ds:datastore-ref; mandatory true; description "Identity reference of the datastore from which to get data."; } list target-paths { key name; description "XPath to subscribed YANG datastore node or subtree."; leaf name { type string; description "Identifier of the supported xpath or subtree filters."; } uses yp:selection-filter-types; } leaf protocol { type identityref { base protocol-type; } description "Protocol used to access the YANG datastore."; } container restconf { uses rcc:restconf-client-app-grouping { when 'derived-from-or-self(../protocol, "restconf")'; } description "Parameters for restconf endpoint of the YANG datastore."; } container netconf { uses ncc:netconf-client-app-grouping { when 'derived-from-or-self(../protocol, "netconf")'; } description "Parameters for netconf endpoint of the YANG datastore."; } } } } } ]]>

Example Module for Information Resource Creation Algorithm The base data model defined by ietf-alto.yang does not include any choice cases for information resource creation algorithms. But developers may augment the ietf-alto.yang data model with definitions for any custom creation algorithms for different information resources. The following example module demonstrates the parameters of a network map creation algorithm that translates an IETF layer 3 unicast topology into a network map. This example defines a creation algorithm called l3-unicast-cluster-algorithm for the network map resource. It takes two algorithm-specific parameters:

l3-unicast-topo

This parameter refers to the target path name of an operational yang-datastore data source node (See ) subscribed in the data-source list (See ). The referenced target path in the corresponding yang-datastore data source is assumed for an IETF layer 3 unicast topology defined in . The algorithm uses the topology data from this data source to compute the ALTO network map resource.

depth

This optional parameter sets the depth of the clustering algorithm. For example, if the depth sets to 1, the algorithm will generate PID for every l3-node in the topology.

The creation algorithm can be reactively called once the referenced data source updates. Therefore, the ALTO network map resource can be updated dynamically. The update of the reference data source depends on the used update-policy (See ). WG List: "; description "This YANG module defines an example of the extended ALTO information resource creation algorithm for translating an L3 unicast topology of I2RS to an ALTO network map. Copyright (c) 2022 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 Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices."; revision "2023-02-10" { description "Initial Version."; reference "RFC XXXX: A YANG Data Model for Operations, Administration, and Maintenance of ALTO Protocol."; } augment "/alto:alto/alto:alto-server/alto:resource" + "/alto:resource-params/alto:networkmap" + "/alto:alto-networkmap-params/alto:algorithm" { description "Example of network map creation algorithm."; case l3-unicast-cluster { description "Example algorithm translating an L3 unicast topology of I2RS to an ALTO network map"; container l3-unicast-cluster-algorithm { description "Parameters for l3-unicast-cluster algorithm"; leaf l3-unicast-topo { type leafref { path "/alto:alto/alto:alto-server/alto:data-source" + "/alto-ds:yang-datastore-source-params" + "/alto-ds:target-paths/alto-ds:name"; } must 'deref(.)/../..' + '/alto-ds:datastore = "ds:operational"'; mandatory true; description "The data source to an IETF layer 3 unicast topology."; } leaf depth { type uint32; description "The depth of the clustering."; } } } } } ]]>

Acknowledgements The authors thank Qiufang Ma and Qin Wu for their help with drafting the initial version of the YANG modules. Thanks also to Adrian Farrel, Qiao Xiang, Qin Wu, and Qiufang Ma for their reviews and valuable feedback.