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Versions: 00 01 03 04 05 06 07 08 09 draft-ietf-alto-performance-metrics

ALTO Working Group                                                 Q. Wu
Internet-Draft                                                    Huawei
Intended status: Standards Track                                 Y. Yang
Expires: March 2, 2017                                   Yale University
                                                                  Y. Lee
                                                                D. Dhody
                                                                  Huawei
                                                          S. Randriamasy
                                                         Nokia Bell Labs
                                                         August 29, 2016


                     ALTO Performance Cost Metrics
                      draft-wu-alto-te-metrics-09

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.  Future extensions to ALTO may also use Cost
   Metric.

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

   In this document, we 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 tool.  We currently document 11 new Performance Metric to
   measure network delay, jitter, packet loss, hop count, and bandwidth.
   The metrics documented in this document provide a relatively
   comprehensive set of Cost Metrics for ALTO and allow applications to
   determine "where" to connect based on end to end network performance
   criteria.  Additional Cost Metrics such as financial cost metrics may
   be documented in other documents.

   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 http://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 March 2, 2017.

Copyright Notice

   Copyright (c) 2016 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
   (http://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.  Data sources, computation of defined cost metrics . . . . . .   5
     2.1.  Data sources  . . . . . . . . . . . . . . . . . . . . . .   5
     2.2.  Computation of metrics  . . . . . . . . . . . . . . . . .   5
   3.  Cost Metric: OWDelay  . . . . . . . . . . . . . . . . . . . .   6
   4.  Cost Metric: PDV  . . . . . . . . . . . . . . . . . . . . . .   8
   5.  Cost Metric: Packet Loss  . . . . . . . . . . . . . . . . . .   9
   6.  Cost Metric: Hop Count  . . . . . . . . . . . . . . . . . . .  11
   7.  Cost Metric: Bandwidth  . . . . . . . . . . . . . . . . . . .  13
   8.  Cost Metric: Maximum Bandwidth  . . . . . . . . . . . . . . .  14
   9.  Cost Metric: Maximum Reservable Bandwidth . . . . . . . . . .  16
   10. Cost Metric: RTT  . . . . . . . . . . . . . . . . . . . . . .  18
   11. Cost Metric: Residue Bandwidth  . . . . . . . . . . . . . . .  20
   12. Cost Metric: Available Bandwidth  . . . . . . . . . . . . . .  22



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   13. Cost Metric: Utilized Bandwidth . . . . . . . . . . . . . . .  24
   14. Security Considerations . . . . . . . . . . . . . . . . . . .  26
   15. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  27
   16. References  . . . . . . . . . . . . . . . . . . . . . . . . .  27
     16.1.  Normative References . . . . . . . . . . . . . . . . . .  27
     16.2.  Informative References . . . . . . . . . . . . . . . . .  28
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  29

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.

   The objective of this document is to introduce 11 new performance
   cost metrics, listed in Table 1, to support the aforementioned
   applications and allow applications to determine "where" to connect
   based on end to end 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      | [RFCxxxx], Section 3   |
      |           |  pdv         | [RFCxxxx], Section 4   |
      |           | pktloss      | [RFCxxxx], Section 5   |
      |           | hopcount     | [RFCxxxx], Section 6   |
      |           | bandwidth    | [RFCxxxx], Section 7   |
      |           | maxbw        | [RFCxxxx], Section 8   |
      |           | maxresbw     | [RFCxxxx], Section 9   |
      |           |  rtt         | [RFCxxxx], Section 10  |
      |           | residbw      | [RFCxxxx], Section 11  |
      |           | availbw      | [RFCxxxx], Section 12  |
      |           | utilbw       | [RFCxxxx], Section 13  |
      +-----------+--------------+------------------------+
                          Table 1.

   An ALTO server may provide a subset of the cost metrics documented in
   this document.  These cost metrics can be retrieved and aggregated
   from routing protocol or other traffic measurement management tool
   (See Figure 1).  Note that these cost metrics are optional metrics
   and Not all these cost metrics need to be exposed to the application.



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   If some of these cost metrics have privacy concern, the alto server
   should not provide them to the client.

   +--------+   +--------+  +--------+
   | Client |   | Client |  | Client |
   +----^---+   +---^----+  +---^----+
        |           |           |
        +-----------|-----------+
              NBI   |ALTO protocol
                    |
                    |
                 +--+-----+  retrieve       +---------+
                 |  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,
   the server SHOULD announce the metric in its IRD.

   The definitions of a set of cost metrics can allow us to extend the
   ALTO base protocol (e.g., allowing output and constraints use
   different cost metrics), but such extensions are not in the scope of
   this document.

   One challenge in describing the metrics is that 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, ALTO server may collect data on time
   periods covering the past, present or only collect data on present
   time.  The ALTO may further aggregate these data to provide an
   abstract and unified view that can be more useful to applications.
   To make the ALTO client understand whether the performance data is
   past data or present data, the ALTO server needs to expose to the
   client the validity period of each performance metric.

   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.  Data sources, computation of defined cost metrics

   The cost metrics described in this document are similar, in that they
   may use similar data sources and have similar issues in their
   calculation.  Hence, instead of specifying such issues for each
   metric individually, we specify the common issue in this section.

2.1.  Data sources

   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
   [RFC3630], [RFC3784], [OSPF-TE], [ISIS-TE], [BGP-LS] and [BGP-PM]
   that allow an ALTO Server to retrieve and derive the necessary
   information to compute the metrics that we described in this
   document.

2.2.  Computation of metrics

   An ALTO server processes measurements from data sources to compute
   exposed metrics.  It may need performance data processing tasks such
   as aggregating the results across multiple systems, removing
   outliers, and creating additional statistics.

   One specific challenge in deriving the metrics in this document is
   that these performance metrics depend on some configuration
   parameters.  For example, the value of packet loss rate depends on
   the measurement interval and varies over time.  If the ALTO server
   uses aforementioned routing protocol based mechanisms as data
   sources, then the measurement interval may be preconfigured by the
   routing protocol.  For example, Section 5 of [ISIS-TE] defines a
   default measurement interval of 30 seconds.  This document uses the
   term Measurement Interval to refer to the measurement interval used
   by the data sources.  In the [ISIS-TE] case, it is a measurement
   interval set by routing protocol.  The Measurement Interval(s) of the
   data sources can be different from the interval that this document
   derives the metric, e.g., the interval used by this document is
   multiple of measurement interval of the data sources.  Hence, an ALTO
   server needs to resolve the mismatch, when it happens.

   Another issue of converting from data source measurements to ALTO
   exposed metric values is that the measurement results that the ALTO
   Server retrieves may be defined for only links, and hence, the server
   will need to compose the link metrics to obtain path metrics used in
   services such as the Cost Map Service.  In this definition, we define



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   the metrics to be independent of link or path, considering that
   future ALTO extensions may define link-based services, and hence the
   defined metrics should still be usable.

3.  Cost Metric: OWDelay

   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 unit is specified in the
      query context (e.g., PID to PID, or endpoint to endpoint); and the
      temporal unit is specified as the measurement interval in the
      query context.


   Method of Measurement or Calculation:

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


   Units of Measurement:

      See section 7.4.4 of [I-D.ietf-ippm-initial-registry] for
      Measurement Unit.  The unit is expressed in seconds.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

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


   Use and Applications:





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

      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" : "delay"},
   "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" : "delay"
      }
    },
     "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,
     }
   }
 }




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4.  Cost Metric: PDV

   Metric name:

      Pakcet 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 unit is specified in the query context (e.g., PID to
      PID, or endpoint to endpoint); and the temporal unit is specified
      as the measurement interval in the query context.


   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 seconds.


   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.


   Measurement Timing:Use and Applications:

      See section 3 for use and application.








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  Example 2: Delayjitter 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
           }
        }
     }

5.  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 unit is
      specified in the query context (e.g., PID to PID, or endpoint to
      endpoint); and the temporal unit is specified as the measurement
      interval in the query context.


   Method of Measurement or Calculation:

      See section 2.2, Computation of metrics.


   Units of Measurement:

      The unit is percentile.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 2.1, second paragraph for Measurement Timing.


   Use and Applications:

      See section 3 for use and application.





















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  Example 3: 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": 1,
             "ipv6:2000::1:2345:6789:abcd" : 2,
                               }
               }
   }

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 or other hops in direct relation to the routing
      prtocols originating this information. it might also result from
      the aggregation of such information.

   Method of Measurement or Calculation:

      See section 2.2, Computation of metrics.


   Units of Measurement:

      The unit is integer number.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 2.1, second paragraph for Measurement Timing.


   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: Bandwidth

   Metric name:

      Bandwidth


   Metric Description:





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      To specify spatial and temporal aggregated bandwidth over the
      specified source and destination.  The spatial aggregation unit is
      specified in the query context (e.g., PID to PID, or endhost to
      endhost); and the temporal unit is specified as the measurement
      interval in the query context.

      This is just a definition of a class of cost metric 'bandwidth'.
      The use of this cost metric is always in conjunction with what it
      represents, which could be Max Bandwidth (maxbw), Residual
      Bandwidth (residuebw) etc.


   Method of Measurement or Calculation:

      See section 2.2, Computation of metrics.


   Units of Measurement:

      The units are bytes per second.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 2.1, second paragraph for Measurement Timing.


   Use and Applications:

      See section 3 for use and application.


8.  Cost Metric: Maximum Bandwidth

   Metric name:

      Maximum Bandwidth


   Metric Description:

      To specify spatial and temporal maximum bandwidth over the
      specified source and destination.  The values correspond to the



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      maximum bandwidth that can be used (motivated from RFC 3630 Sec.
      2.5.6.).  The spatial aggregation unit is specified in the query
      context (e.g., PID to PID, or endhost to endhost); and the
      temporal unit is specified as the measurement interval in the
      query context.


   Method of Measurement or Calculation:

      See section 2.2, Computation of metrics.


   Units of Measurement:

      See definition for the Bandwidth Cost Metric.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 2.1, second paragraph for Measurement Timing.


   Use and Applications:

      See section 3 for use and application.





















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  Example 5: maxbw 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":  "maxbw"},
     "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": "maxbw"
             }
      },
  "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.  Cost Metric: Maximum Reservable Bandwidth

   Metric name:

      Maximum Reservable Bandwidth


   Metric Description:



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      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); and
      the temporal unit is specified as the measurement interval in the
      query context.


   Method of Measurement or Calculation:

      See section 2.2, Computation of metrics.


   Units of Measurement:

      See definition of the Bandwidth Cost Metric.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 2.1, second paragraph 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,
                              }
             }
  }

10.  Cost Metric: RTT

   Metric name:

      Round Trip Delay


   Metric Description:




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      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 unit is specified
      in the query context (e.g., PID to PID, or endpoint to endpoint);
      and the temporal unit is specified as the measurement interval in
      the query context.


   Method of Measurement or Calculation:

      See section 2.2, Computation of metrics.


   Units of Measurement:

      See definition for the bandwidth Cost Metric.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 2.1, second paragraph for Measurement Timing.


   Use and Applications:

      See section 3 for use and application.



















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 Example 7: 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"
     ]
   }
 }

 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,
     }
   }
 }


11.  Cost Metric: 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); and the temporal unit is specified as the measurement
      interval in the query context.


   Method of Measurement or Calculation:

      See section 2.2, Computation of metrics.


   Units of Measurement:

      See definition of the general Bandwidth.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 2.1, second paragraph for Measurement Timing.


   Use and Applications:

      See section 3 for use and application.



















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  Example 8: 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,
                         }
          }
  }

12.  Cost Metric: Available Bandwidth

   Metric name:

      Available Bandwidth


   Metric Description:



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      To specify spatial and temporal availaible bandwidth over the
      specified source and destination.  The value is calculated by
      subtracting the measured bandwidth used for the actual forwarding
      of best effort traffic from Residue Bandwidth (motivated from
      [RFC7810], Sec.4.6.).  The spatial aggregation unit is specified
      in the query context (e.g., PID to PID, or endpoint to endpoint);
      and the temporal unit is specified as the measurement interval in
      the query context.


   Method of Measurement or Calculation:

      See section 2.2, Computation of metrics.


   Units of Measurement:

      See definition of the general Bandwidth.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 2.1, second paragraph for Measurement Timing.


   Use and Applications:

      See section 3 for use and application.


















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  Example 9: availbw 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":  "numeric",
     "cost-metric":  "availbw"},
      "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": "numeric",
            "cost-metric": "availbw"
           }
     },

    "endpoint-cost-map": {
              "ipv4:192.0.2.2" {
             "ipv4:192.0.2.89" : [6,5,7,8,4,10,7,6],
             "ipv4:198.51.100.34" : [7,4,6,8,5,9,6,7],
             "ipv6:2000::1:2345:6789:abcd" : [7,6,8,5,7,9,6,8],
                            }
           }
    }

13.  Cost Metric: Utilized Bandwidth

   Metric name:

      Utilized Bandwidth





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   Metric Description:

      To specify spatial and temporal utilized bandwidth over the
      specified source and destination.  The value is corresponding to
      the actual measured bandwidth used for all traffic (motivated from
      [RFC7810], Sec.4.7.).  The spatial aggregation unit is specified
      in the query context (e.g., PID to PID, or endpoint to endpoint);
      and the temporal unit is specified as the measurement interval in
      the query context.


   Method of Measurement or Calculation:

      See section 2.2, Computation of metrics.


   Units of Measurement:

      See definition of the general Bandwidth.


   Measurement Point(s) with Potential Measurement Domain:

      See section 2.1, Data sources.


   Measurement Timing:

      See section 2.1, second paragraph for Measurement Timing.


   Use and Applications:

      See section 3 for use and application.

















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  Example 10: utilbw 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" :  "utilbw"},
    "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": "utilbw"
          }
    },
  "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,
                            }
           }
  }

14.  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 and 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.
   One 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.

15.  IANA Considerations

   IANA has added the following entries to the ALTO cost map Properties
   registry, defined in Section 3 of [RFCXXX].

      +-----------+--------------+------------------------+
      | Namespace | Property     | Reference              |
      +-----------+--------------+------------------------+
      |           |  owdelay     | [RFCxxxx], Section 3   |
      |           |   pdv        | [RFCxxxx], Section 4   |
      |           | pktloss      | [RFCxxxx], Section 5   |
      |           | hopcount     | [RFCxxxx], Section 6   |
      |           | bandwidth    | [RFCxxxx], Section 7   |
      |           | maxbw        | [RFCxxxx], Section 8   |
      |           | maxresbw     | [RFCxxxx]  Section 9   |
      |           |  rtt         | [RFCxxxx], Section 10  |
      |           | residbw      | [RFCxxxx], Section 11  |
      |           | availbw      | [RFCxxxx], Section 12  |
      |           | utilbw       | [RFCxxxx], Section 13  |
      +-----------+--------------+------------------------+


16.  References

16.1.  Normative References

   [I-D.ietf-idr-te-pm-bgp]
              Previdi, S., Wu, Q., Gredler, H., Ray, S.,
              jefftant@gmail.com, j., Filsfils, C., and L. Ginsberg,
              "BGP-LS Advertisement of IGP Traffic Engineering
              Performance Metric Extensions", draft-ietf-idr-te-pm-
              bgp-03 (work in progress), May 2016.

   [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-01 (work in progress), July 2016.



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

   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627,
              DOI 10.17487/RFC4627, July 2006,
              <http://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,
              <http://www.rfc-editor.org/info/rfc5234>.

   [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,
              <http://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,
              <http://www.rfc-editor.org/info/rfc7471>.

   [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,
              <http://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,
              <http://www.rfc-editor.org/info/rfc7810>.

16.2.  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.







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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


   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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