CDNI Capacity Capability Advertisement Extensions

2.1.1. Telemetry Source Object

The Telemetry Source Object is built of an associated type, a list of exposed metrics, and type-specific configuration data.¶

• Property: id¶

  • Description: An identifier of a telemetry source. The ID string assigned to this Telemetry Source MUST be unique across all Telemetry Source objects in the advertisement. The ID string SHOULD remain consistent for the same source reference across advertisements.¶

  • Type: String.¶

  • Mandatory-to-Specify: Yes.¶

• Property: type¶

  • Description: A valid telemetry source type. See Section 2.1.1.1.¶

  • Type: String.¶

  • Mandatory-to-Specify: Yes.¶

• Property: metrics¶

  • Description: The metrics exposed by this source.¶

  • Type: A JSON array of Telemetry Source Metric objects (see Section 2.1.1.2).¶

  • Mandatory-to-Specify: Yes.¶

• Property: configuration¶

  • Description: a source-specific representation of the Telemetry source configuration. For the generic source type, this configuration format is defined out-of-band. For other types, the configuration format will be specified in a yet to be defined Telemetry Interface specification. The goal of this element is to allow for forward compatibility with a formal Telemetry interface.¶

  • Type: A JSON object, the structure of which is specific to the Telemetry source and outside the scope of this document.¶

  • Mandatory-to-Specify: No.¶

2.1.2. Telemetry Capability Object Serialization

The following shows an example of Telemetry Capability including two metrics for a source, that is scoped to a footprint.¶

"capabilities": [
  {
    "capability-type": "FCI.Telemetry",
    "capability-value": {
      "sources": [
        {
          "id": "capacity_metrics_region1",
          "type": "generic",
          "metrics": [
            {
              "name": "egress_5m",
              "time-granularity": 300,
              "data-percentile": 50,
              "latency": 1500
            },
            {
              "name": "requests_5m",
               ...
            }
          ]
        }
      ]
    },
    "footprints": [
      <footprint objects>
    ]
  }
]

2.2.1. CapacityLimit Object

A CapacityLimit object is used to represent traffic limits for delegation from the uCDN towards the dCDN. The limit object is scoped to the footprint associated with the FCI capability advertisement encompassing this object. Limits will be considered using a logical "AND": a uCDN will need to ensure that all limits are considered rather than choosing only the most specific.¶

• Property: limit-type¶

  • Description: The units of maximum-hard and maximum-soft.¶

  • Type: String. One of the values listed in Section 2.2.1.1.¶

  • Mandatory-to-Specify: Yes.¶

• Property: id¶

  • Description: Specifies an identifier associated with a limit. This MAY be used as a relational identifier to a specific CapacityLimit Object. If specified, this identifier MUST be unique among specified identifiers associated with any other CapacityLimit objects in the advertisement.¶

  • Type: String.¶

  • Mandatory-to-Specify: No.¶

• Property: maximum-hard¶

  • Description: The maximum unit of capacity that is available for use.¶

  • Type: Integer.¶

  • Mandatory-to-Specify: Yes.¶

• Property: maximum-soft¶

  • Description: A soft limit at which an upstream SHOULD reduce traffic before hitting the hard limit. This value SHOULD be less than the value of maximum-hard. If this value is not specified, it is equal to the value of maximum-hard.¶

  • Type: Integer.¶

  • Mandatory-to-Specify: No.¶

• Property: current¶

  • Description: Specifies the current usage value of the limit. It is NOT RECOMMENDED to specify the current usage value inline with the FCI.CapacityLimits advertisements as it will reduce the ability to cache the response, but this mechanism exists for simple use cases where an external telemetry source cannot be feasibly implemented. The intended method for providing telemetry data is to reference a Telemetry Source object Section 2.2.1.2 to poll for the current usage.¶

  • Type: Integer.¶

  • Mandatory-to-Specify: No.¶

• Property: telemetry-source¶

  • Description: Mapping of each particular limit to a specific metric with relevant real-time data provided by a telemetry source.¶

  • Type: CapacityLimitTelemetrySource object (see Section 2.2.1.2).¶

  • Mandatory-to-Specify: No.¶

2.2.2. CapacityLimit Object Serialization

The following shows an example of an FCI.CapacityLimits object.¶

"capabilities":[
  {
    "capability-type":"FCI.CapacityLimits",
    "capability-value":{
      "limits":[
        {
          "id":"capacity_limit_region1",
          "limit-type":"egress",
          "maximum-hard":50000000000,
          "maximum-soft":25000000000,
          "telemetry-source":{
            "id":"capacity_metrics_region1",
            "metric":"egress_5m"
          }
        }
      ]
    },
    "footprints":[
      "<footprint objects>"
    ]
  }
]

3.1.1. CDNI FCI Telemetry Payload Type

• Purpose: The purpose of this Payload Type is to list the supported telemetry sources and the metrics made available by each source.¶

• Interface: FCI.¶

• Encoding: See section Section 2.1.¶

3.1.2. CDNI FCI Capacity Limits Payload Type

• Purpose: The purpose of this Payload Type is to define Capacity Limits based on a utilization metrics corresponding to telemetry sources provided by the dCDN.¶

• Interface: FCI.¶

• Encoding: See section Section 2.2.¶