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Versions: (draft-wu-alto-te-metrics) 00 01 02 03 04

ALTO Working Group                                                 Q. Wu
Internet-Draft                                                    Huawei
Intended status: Standards Track                                 Y. Yang
Expires: December 18, 2018                               Yale University
                                                                  Y. Lee
                                                                D. Dhody
                                                                  Huawei
                                                          S. Randriamasy
                                                         Nokia Bell Labs
                                                           June 16, 2018


                     ALTO Performance Cost Metrics
                 draft-ietf-alto-performance-metrics-04

Abstract

   Cost Metric is a basic concept in Application-Layer Traffic
   Optimization (ALTO).  It is used in both the Cost Map Service and the
   Endpoint Cost Service.

   Different applications may benefit from different Cost Metrics.  For
   example, a Resource Consumer may prefer Resource Providers that offer
   a low delay delivery to the Resource Consumer.  However the base ALTO
   protocol [ALTO] has documented only one single cost metric, i.e., the
   generic "routingcost" metric (Sec. 14.2 of ALTO base specification
   [ALTO]).

   This document, proposes a set of Cost Metrics, derived and aggregated
   from routing protocols with different granularity and scope, such as
   BGP-LS,OSPF-TE and ISIS-TE, or from end-to-end traffic management
   tools.  It currently documents Network Performance Cost Metrics
   reporting on network delay, jitter, packet loss, hop count, and
   bandwidth.  These metrics may be exposed by an ALTO Server to allow
   applications to determine "where" to connect based on network
   performance criteria.  Additional Cost Metrics involving ISP specific
   considerations or other network technologies may be documented in
   further versions of this draft.

   Requirements Language The key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" in this document are to be interpreted as described in
   RFC 2119 [RFC2119].








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Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 18, 2018.

Copyright Notice

   Copyright (c) 2018 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.  Challenges on data sources and computation of ALTO
       performance metrics . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  Data sources Challenge  . . . . . . . . . . . . . . . . .   5
     2.2.  ALTO performance metrics Computation Challenges . . . . .   5
       2.2.1.  Configuration Parameters Challenge  . . . . . . . . .   5
       2.2.2.  Availability of end to end path values  Challenge . .   6
   3.  Cost Metric: POWDelay . . . . . . . . . . . . . . . . . . . .   6
   4.  Cost Metric: RTT  . . . . . . . . . . . . . . . . . . . . . .   8
   5.  Cost Metric: PDV  . . . . . . . . . . . . . . . . . . . . . .  10
   6.  Cost Metric: Hop Count  . . . . . . . . . . . . . . . . . . .  12
   7.  Cost Metric: Packet Loss  . . . . . . . . . . . . . . . . . .  14
   8.  Traffic Engineering Performance Cost Metrics  . . . . . . . .  16
     8.1.  Cost Metric: Link Maximum Reservable Bandwidth  . . . . .  17



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     8.2.  Cost Metric: Link Residue Bandwidth . . . . . . . . . . .  18
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  20
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  21
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  21
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  21
     11.2.  Informative References . . . . . . . . . . . . . . . . .  23
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  23

1.  Introduction

   Cost Metric is a basic concept in Application-Layer Traffic
   Optimization (ALTO).  It is used in both the Cost Map Service and the
   Endpoint Cost Service.  In particular, applications may benefit from
   knowing network performance measured on several Cost Metrics.  For
   example, a more delay-sensitive application may focus on latency, and
   a more bandwidth-sensitive application may focus on available
   bandwidth.

   This document introduces a set of new cost metrics, listed in
   Table 1, to support the aforementioned applications and allow them to
   determine "where" to connect based on network performance criteria.
   Hence, this document extends the base ALTO protocol [ALTO], which
   defines only a single cost metric, i.e., the generic "routingcost"
   metric (Sec. 14.2 of ALTO base specification [ALTO]).

   +----------+--------------+----------------------------------------+
   |Namespace | Property     | Reference                              |
   +----------+--------------+----------------------------------------+
   |          |  owdelay     | See Section 3,[RFC2679] Section 3.6    |
   |          |   rtt        | See Section 4,[RFC2681] Section 2.6    |
   |          |   pdv        | See Section 5,[RFC3393] Section 2.6    |
   |          | hopcount     | See Section 6,[RFC7285]                |
   |          | pktloss      | See Section 7,[RFC7680] Section 2.6    |
   |          | maxresbw     | See Section 8.1,[RFC5305] Section 3.5  |
   |          | residbw      | See Section 8.2,[RFC7810] Section 4.5  |
   +----------+--------------+----------------------------------------+
                          Table 1.

   The purpose of this draft is to list the metrics likely to be exposed
   to ALTO Clients, including those already specified in other
   standardization groups and as such it does not claim novelty on all
   the specified metrics.  Some metrics may have values produced by
   standard measurement methods such as those specified in IPPM, some
   may be ISP dependent such as those registered in ISIS or OSPF-TE.  In
   this case, this document will refer to the relevant specifications.

   An ALTO server may provide a subset of the cost metrics described in
   this document.  These cost metrics can be retrieved and aggregated



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   from routing protocols or other traffic measurement management tools
   (See Figure 1).  Note that these cost metrics are optional and not
   all them need to be exposed to applications.  For example, those that
   are subject to privacy concerns should not be provided to
   unauthorized ALTO clients.

   +--------+   +--------+  +--------+
   | Client |   | Client |  | Client |
   +----^---+   +---^----+  +---^----+
        |           |           |
        +-----------|-----------+
              NBI   |ALTO protocol
                    |
                    |
                 +--+-----+  retrieval      +---------+
                 |  ALTO  |<----------------| Routing |
                 | Server |  and aggregation|         |
                 |        |<-------------+  | Protocol|
                 +--------+              |  +---------+
                                         |
                                         |  +---------+
                                         |  |Management
                                         ---|         |
                                            |  Tool   |
                                            +---------+
                    Figure 1.End-to-End Path Cost Metrics Exposing

   When an ALTO server supports a cost metric defined in this document,
   it MUST announce this metric in its IRD.

   Additionally, future versions of this document may define network
   metric values that stem from both measurements and provider policies
   such as many metrics related to end-to-end path bandwidth.

   As for the reliability and trust in the exposed metric values,
   applications SHOULD rapidly give up using ALTO-based guidance if they
   feel the exposed information does not preserve their performance
   level or even degrades it.

   Following the ALTO base protocol, this document uses JSON to specify
   the value type of each defined metric.  See [RFC4627] for JSON data
   type specification.









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2.  Challenges on data sources and computation of ALTO performance
    metrics

2.1.  Data sources Challenge

   An ALTO server needs data sources to compute the cost metrics
   described in this document.  This document does not define the exact
   data sources.  For example, the ALTO server may use log servers or
   the OAM system as its data source [ALTO-DEPLOYMENT].  In particular,
   the cost metrics defined in this document can be computed using
   routing systems as the data sources.  Mechanisms defined in
   [RFC2681],[RFC3393],[RFC7679],[RFC7680],[RFC3630], [RFC3784],
   [RFC7471], [RFC7810], [RFC7752] and [BGP-PM] that allow an ALTO
   Server to retrieve and derive the necessary information to compute
   the metrics that we describe in this document.

   One challenge lies in the data sources originating the ALTO metric
   values.  The very important purpose of ALTO is to guide application
   traffic with provider network centric information that may be exposed
   to ALTO Clients in the form of network performance metric values.
   Not all of these metrics have values produced by standardized
   measurement methods or routing protocols.  Some of them involve
   provider-centric policy considerations.  Some of them may describe
   wireless or cellular networks.  To reliably guide users and
   applications while preserving provider privacy, ALTO performance
   metric values may also add abstraction to measurements or provide
   unitless performance scores.

2.2.  ALTO performance metrics Computation Challenges

   The metric values exposed by an ALTO server may result from
   additional processing on measurements from data sources to compute
   exposed metrics.  This may involve data processing tasks such as
   aggregating the results across multiple systems, removing outliers,
   and creating additional statistics.  There are two challenges on
   computation of ALTO performance metrics.

2.2.1.  Configuration Parameters Challenge

   Performance metrics often depend on configuration parameters.  For
   example, the value of packet loss rate depends on the measurement
   interval and varies over time.  To handle this issue, an ALTO server
   may collect data on time periods covering the previous and current
   time or only collect data on present time.  The ALTO server may
   further aggregate these data to provide an abstract and unified view
   that can be more useful to applications.  To make the ALTO client
   better understand how to use these performance data, the ALTO server




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   may provide the client with the validity period of the exposed metric
   values.

2.2.2.  Availability of end to end path values Challenge

   Applications value information relating to bandwidth availability
   where as bandwidth related metrics can often be only measured at the
   link level.  This document specifies a set of link-level bandwidth
   related values that may be exposed as such by an ALTO server.  The
   server may also expose other metrics derived from their aggregation
   and having different levels of endpoint granularity, e.g. link
   endpoints or session endpoints.  The metric specifications may also
   expose the utilized aggregation laws.

3.  Cost Metric: POWDelay

   Metric name:

      Periodic One Way Delay


   Metric Description:

      To specify spatial and temporal aggregated delay of a stream of
      packets exchanged between the specified source and destination or
      the time that the packet spends to travel from source to
      destination.  The spatial aggregation level is specified in the
      query context (e.g., PID to PID, or endpoint to endpoint).


   Method of Measurement or Calculation:

      See section 8.3 of [I-D.ietf-ippm-initial-registry] for
      Measurement Method.


   Units of Measurement:

      See section 8.4.3 of [I-D.ietf-ippm-initial-registry] for
      Measurement Unit.  The unit is expressed in milliseconds in this
      document.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.





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   Measurement Timing:

      See section 8.3.5 of [I-D.ietf-ippm-initial-registry] for
      Measurement Timing.


   Use and Applications:

      The Metric value Type is a single 'JSONNumber' type value
      containing a non-negative integer component that may be followed
      by an exponent part.  The Cost Mode is encoded as a US-ASCII
      string.

      This metric could be used as a cost metric constraint attribute
      used either together with cost metric attribute 'routingcost' or
      on its own or as a returned cost metric in the response.


 Example 1: Delay value on source-destination endpoint pairs

  POST /endpointcost/lookup HTTP/1.1
  Host: alto.example.com
  Content-Length: TBA
  Content-Type: application/alto-endpointcostparams+json
  Accept: application/alto-endpointcost+json,application/alto-error+json

 {
   "cost-type": {"cost-mode" : "numerical",
                 "cost-metric" : "powdelay"},
   "endpoints" : {
     "srcs": [ "ipv4:192.0.2.2" ],
     "dsts": [
       "ipv4:192.0.2.89",
       "ipv4:198.51.100.34",
       "ipv6:2000::1:2345:6789:abcd"
     ]
   }
 }













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   HTTP/1.1 200 OK
   Content-Length: TBA
   Content-Type: application/alto-endpointcost+json
   {
     "meta" :{
       "cost-type": {"cost-mode" : "numerical",
                     "cost-metric" : "powdelay"
        }
      },
       "endpoint-cost-map" : {
         "ipv4:192.0.2.2": {
           "ipv4:192.0.2.89"    : 10,
           "ipv4:198.51.100.34" : 20,
           "ipv6:2000::1:2345:6789:abcd"  : 30,
       }
     }
   }

4.  Cost Metric: RTT

   Metric name:

      Round Trip Delay


   Metric Description:

      To specify spatial and temporal aggregated round trip delay
      between the specified source and destination or the time that the
      packet spends to travel from source to destination and then from
      destination to source.  The spatial aggregation level is specified
      in the query context (e.g., PID to PID, or endpoint to endpoint).


   Method of Measurement or Calculation:

      See section 4.3 of [I-D.ietf-ippm-initial-registry] for
      Measurement Method.


   Units of Measurement:

      See section 4.4.3 of [I-D.ietf-ippm-initial-registry] for
      Measurement Unit.  The unit is expressed in milliseconds in this
      document.


   Measurement Point(s) with Potential Measurement Domain:



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      See section 2.1, Data sources.


   Measurement Timing:

      See section 4.3.5 of [I-D.ietf-ippm-initial-registry] for
      Measurement Timing.


   Use and Applications:

      See section 3 for use and application.


 Example 2: Round Trip Delay value on source-destination endpoint pairs

  POST /endpointcost/lookup HTTP/1.1
  Host: alto.example.com
  Content-Length: TBA
  Content-Type: application/alto-endpointcostparams+json
  Accept: application/alto-endpointcost+json,application/alto-error+json

 {
   "cost-type": {"cost-mode" : "numerical",
                 "cost-metric" : "rtt"},
   "endpoints" : {
     "srcs": [ "ipv4:192.0.2.2" ],
     "dsts": [
       "ipv4:192.0.2.89",
       "ipv4:198.51.100.34",
       "ipv6:2000::1:2345:6789:abcd"
     ]
   }
 }

















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    HTTP/1.1 200 OK
    Content-Length: TBA
    Content-Type: application/alto-endpointcost+json
    {
      "meta" :{
        "cost-type": {"cost-mode" : "numerical",
                      "cost-metric" : "rtt"
         }
       },
        "endpoint-cost-map" : {
          "ipv4:192.0.2.2": {
            "ipv4:192.0.2.89"    : 4,
            "ipv4:198.51.100.34" : 3,
            "ipv6:2000::1:2345:6789:abcd"  : 2,
        }
      }
    }


5.  Cost Metric: PDV

   Metric name:

      Packet Delay Variation


   Metric Description:

      To specify spatial and temporal aggregated jitter (packet delay
      variation) with respect to the minimum delay observed on the
      stream over the specified source and destination.  The spatial
      aggregation level is specified in the query context (e.g., PID to
      PID, or endpoint to endpoint).


   Method of Measurement or Calculation:

      See section 5.3 of [I-D.ietf-ippm-initial-registry] for
      Measurement Method.


   Units of Measurement:

      See section 5.4.4 of [I-D.ietf-ippm-initial-registry] for
      Measurement Unit.  The unit is expressed in milliseconds in this
      document.





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   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 5.3.5 of [I-D.ietf-ippm-initial-registry] for
      Measurement Timing.


   Use and Applications:

      See section 3 for use and application.


  Example 3: Delay jitter value on source-destination endpoint pairs

  POST /endpointcost/lookup HTTP/1.1
  Host: alto.example.com
  Content-Length: TBA
  Content-Type: application/alto-endpointcostparams+json
  Accept: application/alto-endpointcost+json,application/alto-error+json

  {
    "cost-type": {"cost-mode" : "numerical",
     "cost-metric" : "delayjitter"},
    "endpoints" : {
      "srcs": [ "ipv4:192.0.2.2" ],
      "dsts": [
        "ipv4:192.0.2.89",
        "ipv4:198.51.100.34",
        "ipv6:2000::1:2345:6789:abcd"
      ]
    }
  }















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  Example 3: Delay jitter value on source-destination endpoint pairs

  POST /endpointcost/lookup HTTP/1.1
  Host: alto.example.com
  Content-Length: TBA
  Content-Type: application/alto-endpointcostparams+json
  Accept: application/alto-endpointcost+json,application/alto-error+json

  {
    "cost-type": {"cost-mode" : "numerical",
     "cost-metric" : "delayjitter"},
    "endpoints" : {
      "srcs": [ "ipv4:192.0.2.2" ],
      "dsts": [
        "ipv4:192.0.2.89",
        "ipv4:198.51.100.34",
        "ipv6:2000::1:2345:6789:abcd"
      ]
    }
  }
  HTTP/1.1 200 OK
   Content-Length: TBA
   Content-Type: application/alto-endpointcost+json
  {
    "meta": {
             "cost type": {
             "cost-mode": "numerical",
             "cost-metric":"delayjitter"
      }
     },
    "endpoint-cost-map": {
             "ipv4:192.0.2.2": {
             "ipv4:192.0.2.89"    : 0
             "ipv4:198.51.100.34" : 1
             "ipv6:2000::1:2345:6789:abcd"  : 5
           }
        }
     }

6.  Cost Metric: Hop Count

   The metric hopcount is mentioned in [ALTO] as an example.  This
   section further clarifies its properties.

   Metric name:

      Hop count




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   Metric Description:

      To specify the number of hops in the path between the source
      endpoint and the destination endpoint.  The hop count is a basic
      measurement of distance in a network and can be exposed as Router
      Hops, IP hops in direct relation to the routing protocols
      originating this information.  It might also result from the
      aggregation of such information.

   Method of Measurement or Calculation:

      The hop count can and calculated based on the number of routers
      from the source endpoint through which data must pass to reach the
      destination endpoint.


   Units of Measurement:

      The unit is integer number.


   Measurement Point(s) with Potential Measurement Domain:

      The hop count can be measured at the source endpoint by
      traceroute.


   Measurement Timing:

      Upon need, the traceroute can use UDP probe message or other
      implementations that use ICMP and TCP to discover the hop counts
      along the path from source endpoint to destination endpoint.


   Use and Applications:

      See section 3 for use and application.














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  Example 4: hopcount value on source-destination endpoint pairs

  POST /endpointcost/lookup HTTP/1.1
  Host: alto.example.com
  Content-Length: TBA
  Content-Type: application/alto-endpointcostparams+json
  Accept: application/alto-endpointcost+json,application/alto-error+json

    {
      "cost-type": {"cost-mode" : "numerical",
       "cost-metric" : "hopcount"},
      "endpoints" : {
        "srcs": [ "ipv4:192.0.2.2" ],
        "dsts": [
          "ipv4:192.0.2.89",
          "ipv4:198.51.100.34",
          "ipv6:2000::1:2345:6789:abcd"
        ]
      }
    }

   HTTP/1.1 200 OK
   Content-Length: TBA
   Content-Type: application/alto-endpointcost+json
   {
       "meta": {
                  "cost type": {
                "cost-mode": "numerical",
                "cost-metric":"hopcount"}
          }
       },
      "endpoint-cost-map": {
              "ipv4:192.0.2.2": {
              "ipv4:192.0.2.89"   : 5,
              "ipv4:198.51.100.34": 3,
              "ipv6:2000::1:2345:6789:abcd" : 2,
                                }
                }
    }

7.  Cost Metric: Packet Loss

   Metric name:

      Packet loss


   Metric Description:



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      To specify spatial and temporal aggregated packet loss over the
      specified source and destination.  The spatial aggregation level
      is specified in the query context (e.g., PID to PID, or endpoint
      to endpoint).


   Method of Measurement or Calculation:

      See section 2.6 of [RFC7680] for Measurement Method.


   Units of Measurement:

      The unit is percentile.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 2 and section3 of [RFC7680] for Measurement Timing.


   Use and Applications:

      See section 3 for use and application.






















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  Example 5: pktloss value on source-destination endpoint pairs

  POST /endpointcost/lookup HTTP/1.1
  Host: alto.example.com
  Content-Length: TBA
  Content-Type: application/alto-endpointcostparams+json
  Accept: application/alto-endpointcost+json,application/alto-error+json

    {
      "cost-type": {"cost-mode" : "numerical",
       "cost-metric" : "pktloss"},
      "endpoints" : {
        "srcs": [ "ipv4:192.0.2.2" ],
        "dsts": [
          "ipv4:192.0.2.89",
          "ipv4:198.51.100.34",
          "ipv6:2000::1:2345:6789:abcd"
        ]
      }
    }

   HTTP/1.1 200 OK
   Content-Length: TBA
   Content-Type: application/alto-endpointcost+json
   {
       "meta": {
                  "cost type": {
                "cost-mode": "numerical",
                "cost-metric":"pktloss"}
          }
       },
      "endpoint-cost-map": {
              "ipv4:192.0.2.2": {
              "ipv4:192.0.2.89"   : 0,
              "ipv4:198.51.100.34": 0,
              "ipv6:2000::1:2345:6789:abcd" : 0,
                                }
                }
    }

8.  Traffic Engineering Performance Cost Metrics

   This section introduces ALTO network performance metrics that may be
   aggregated from network metrics measured on links and specified in
   other documents.  In particular, the bandwidth related metrics
   specified in this section are only available through link level
   measurements.  For some of these metrics, the ALTO Server may further
   expose aggregated values while specifying the aggregation laws.



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8.1.  Cost Metric: Link Maximum Reservable Bandwidth

   Metric name:

      Maximum Reservable Bandwidth


   Metric Description:

      To specify spatial and temporal maximum reservable bandwidth over
      the specified source and destination.  The value is corresponding
      to the maximum bandwidth that can be reserved (motivated from RFC
      3630 Sec. 2.5.7.).  The spatial aggregation unit is specified in
      the query context (e.g., PID to PID, or endpoint to endpoint).


   Method of Measurement or Calculation:

      Maximum Reserveable Bandwidth is the bandwidth measured between
      two directly connected IS-IS neighbors or OSPF neighbors, See
      section 3.5 of [RFC5305] for Measurement Method.


   Units of Measurement:

      The unit of measurement is byte per seconds.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 3.5 of [RFC5305] and section 5 of [RFC7810] for
      Measurement Timing.


   Use and Applications:

      See section 3 for use and application.









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  Example 6: maxresbw value on source-destination endpoint pairs

  POST/ endpointcost/lookup HTTP/1.1
  Host: alto.example.com
  Content-Length: TBA
  Content-Type: application/alto-endpointcostparams+json
  Accept: application/alto-endpointcost+json,application/alto-error+json

    {
      "cost-type" { "cost-mode":  "numerical",
      "cost-metric":  "maxresbw"},
      "endpoints":  {
        "srcs": [ "ipv4 : 192.0.2.2" ],
        "dsts": [
          "ipv4:192.0.2.89",
          "ipv4:198.51.100.34",
          "ipv6:2000::1:2345:6789:abcd"
        ]
      }
    }

   HTTP/1.1 200 OK
   Content-Length: TBA
   Content-Type: application/alto-endpointcost+json
   {
       "meta": {
              "cost-type": {
              "cost-mode": "numerical",
              "cost-metric": "maxresbw"
              }
       },
     " endpoint-cost-map": {
             "ipv4:192.0.2.2" {
             "ipv4:192.0.2.89" :    0,
             "ipv4:198.51.100.34": 2000,
             "ipv6:2000::1:2345:6789:abcd":  5000,
                               }
              }
   }

8.2.  Cost Metric: Link Residue Bandwidth

   Metric name:

      Residue Bandwidth


   Metric Description:



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      To specify spatial and temporal residual bandwidth over the
      specified source and destination.  The value is calculated by
      subtracting tunnel reservations from Maximum Bandwidth (motivated
      from [RFC7810], Sec.4.5.).  The spatial aggregation unit is
      specified in the query context (e.g., PID to PID, or endpoint to
      endpoint).


   Method of Measurement or Calculation:

      Residue Bandwidth is the Unidirectional Residue bandwidth measured
      between two directly connected IS-IS neighbors or OSPF neighbors,
      See section 4.5 of [RFC7810] for Measurement Method.


   Units of Measurement:

      The unit of measurement is byte per seconds.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 5 of [RFC7810] for Measurement Timing.


   Use and Applications:

      See section 3 for use and application.


















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  Example 7: residuebw value on source-destination endpoint pairs

  POST/ endpointcost/lookup HTTP/1.1
  Host: alto.example.com
  Content-Length: TBA
  Content-Type: application/alto-endpointcostparams+json
  Accept: application/alto-endpointcost+json,application/alto-error+json

    {
     "cost-type": { "cost-mode":  "numerical",
     "cost-metric":  "residubw"},
     "endpoints":  {
       "srcs": [ "ipv4 : 192.0.2.2" ],
       "dsts": [
         "ipv4:192.0.2.89",
         "ipv4:198.51.100.34",
         "ipv6:2000::1:2345:6789:abcd"
       ]
     }
  }

   HTTP/1.1 200 OK
   Content-Length: TBA
   Content-Type: application/alto-endpointcost+json
   {
      "meta": {
             "cost-type" {
             "cost-mode": "numerical",
             "cost-metric": "residubw"
           }
       },
   "endpoint-cost-map" {
            "ipv4:192.0.2.2" {
            "ipv4:192.0.2.89" :    0,
            "ipv4:198.51.100.34": 2000,
            "ipv6:2000::1:2345:6789:abcd":  5000,
                          }
           }
   }

9.  Security Considerations

   The properties defined in this document present no security
   considerations beyond those in Section 15 of the base ALTO
   specification [ALTO].

   However concerns addressed in Sections "15.1 Authenticity and
   Integrity of ALTO Information", "15.2 Potential Undesirable Guidance



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   from Authenticated ALTO Information" and "15.3 Confidentiality of
   ALTO Information" remain of utmost importance.  Indeed, TE
   performance is a highly sensitive ISP information, therefore, sharing
   TE metric values in numerical mode requires full mutual confidence
   between the entities managing the ALTO Server and Client.  Numerical
   TE performance information will most likely be distributed by ALTO
   Servers to Clients under strict and formal mutual trust agreements.
   On the other hand, ALTO Clients must be cognizant on the risks
   attached to such information that they would have acquired outside
   formal conditions of mutual trust.

10.  IANA Considerations

   IANA has created and now maintains the "ALTO Cost Metric Registry",
   listed in Section 14.2, Table 3 of [RFC7285].  This registry is
   located at <http://www.iana.org/assignments/alto-protocol/alto-
   protocol.xhtml#cost-metrics>.  This document requests to add the
   following entries to "ALTO Cost Meric Registry".

+----------+------------+----------------------------------------------+
|Namespace | Property   | Reference                                    |
+----------+------------+----------------------------------------------+
|          |  owdelay   | [thisdraft] Section 3,[RFC2679] Section 3.6  |
|          |   rtt      | [thisdraft] Section 4,[RFC2681],Section 2.6  |
|          |   pdv      | [thisdraft] Section 5,[RFC3393],Section 2.6  |
|          | hopcount   | [thisdraft] Section 6,[RFC7285]              |
|          | pktloss    | [thisdraft] Section 7,[RFC7680],Section 2.6  |
|          | maxresbw   | [thisdraft] Section 8.1,[RFC5305],Section 3.5|
|          | residbw    | [thisdraft] Section 8.2,[RFC7810],Section 4.5|
+----------+------------+----------------------------------------------+

11.  References

11.1.  Normative References

   [I-D.ietf-idr-te-pm-bgp]
              Ginsberg, L., Previdi, S., Wu, Q., Tantsura, J., and C.
              Filsfils, "BGP-LS Advertisement of IGP Traffic Engineering
              Performance Metric Extensions", draft-ietf-idr-te-pm-
              bgp-10 (work in progress), March 2018.

   [I-D.ietf-ippm-initial-registry]
              Morton, A., Bagnulo, M., Eardley, P., and K. D'Souza,
              "Initial Performance Metric Registry Entries", draft-ietf-
              ippm-initial-registry-06 (work in progress), March 2018.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", March 1997.



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   [RFC2679]  Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
              Delay Metric for IPPM", RFC 2679, DOI 10.17487/RFC2679,
              September 1999, <https://www.rfc-editor.org/info/rfc2679>.

   [RFC2681]  Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
              Delay Metric for IPPM", RFC 2681, DOI 10.17487/RFC2681,
              September 1999, <https://www.rfc-editor.org/info/rfc2681>.

   [RFC3393]  Demichelis, C. and P. Chimento, "IP Packet Delay Variation
              Metric for IP Performance Metrics (IPPM)", RFC 3393,
              DOI 10.17487/RFC3393, November 2002,
              <https://www.rfc-editor.org/info/rfc3393>.

   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627,
              DOI 10.17487/RFC4627, July 2006,
              <https://www.rfc-editor.org/info/rfc4627>.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <https://www.rfc-editor.org/info/rfc5234>.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, DOI 10.17487/RFC5305, October
              2008, <https://www.rfc-editor.org/info/rfc5305>.

   [RFC7285]  Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
              Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
              "Application-Layer Traffic Optimization (ALTO) Protocol",
              RFC 7285, DOI 10.17487/RFC7285, September 2014,
              <https://www.rfc-editor.org/info/rfc7285>.

   [RFC7471]  Giacalone, S., Ward, D., Drake, J., Atlas, A., and S.
              Previdi, "OSPF Traffic Engineering (TE) Metric
              Extensions", RFC 7471, DOI 10.17487/RFC7471, March 2015,
              <https://www.rfc-editor.org/info/rfc7471>.

   [RFC7679]  Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton,
              Ed., "A One-Way Delay Metric for IP Performance Metrics
              (IPPM)", STD 81, RFC 7679, DOI 10.17487/RFC7679, January
              2016, <https://www.rfc-editor.org/info/rfc7679>.

   [RFC7680]  Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton,
              Ed., "A One-Way Loss Metric for IP Performance Metrics
              (IPPM)", STD 82, RFC 7680, DOI 10.17487/RFC7680, January
              2016, <https://www.rfc-editor.org/info/rfc7680>.




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   [RFC7752]  Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
              S. Ray, "North-Bound Distribution of Link-State and
              Traffic Engineering (TE) Information Using BGP", RFC 7752,
              DOI 10.17487/RFC7752, March 2016,
              <https://www.rfc-editor.org/info/rfc7752>.

   [RFC7810]  Previdi, S., Ed., Giacalone, S., Ward, D., Drake, J., and
              Q. Wu, "IS-IS Traffic Engineering (TE) Metric Extensions",
              RFC 7810, DOI 10.17487/RFC7810, May 2016,
              <https://www.rfc-editor.org/info/rfc7810>.

11.2.  Informative References

   [I-D.ietf-alto-deployments]
              Stiemerling, M., Kiesel, S., Scharf, M., Seidel, H., and
              S. Previdi, "ALTO Deployment Considerations", draft-ietf-
              alto-deployments-16 (work in progress), July 2016.

   [RFC6390]  Clark, A. and B. Claise, "Framework for Performance Metric
              Development", RFC 6390, July 2011.

Authors' Addresses

   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: bill.wu@huawei.com


   Y. Richard Yang
   Yale University
   51 Prospect St
   New Haven, CT  06520
   USA

   Email: yry@cs.yale.edu


   Young Lee
   Huawei
   1700 Alma Drive, Suite 500
   Plano, TX  75075
   USA

   Email: leeyoung@huawei.com



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   Dhruv Dhody
   Huawei
   Leela Palace
   Bangalore, Karnataka  560008
   INDIA

   Email: dhruv.ietf@gmail.com


   Sabine Randriamasy
   Nokia Bell Labs
   Route de Villejust
   Nozay  91460
   FRANCE

   Email: sabine.randriamasy@nokia-bell-labs.com



































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