ALTO Working Group Q. Wu Internet-Draft Huawei Intended status: Standards Track Y. Yang Expires: September 4, 2017 Yale University Y. Lee D. Dhody Huawei S. Randriamasy Nokia Bell Labs March 3, 2017 ALTO Performance Cost Metrics draft-ietf-alto-performance-metrics-01 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 offers 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]. Wu, et al. Expires September 4, 2017 [Page 1] Internet-Draft ALTO Performance Cost Metrics March 2017 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 September 4, 2017. Copyright Notice Copyright (c) 2017 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. Challenges on data sources and computation of ALTO performance metrics . . . . . . . . . . . . . . . . . . . . . 5 2.1. Data sources . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Computation of ALTO performance metrics . . . . . . . . . 5 3. Cost Metric: POWDelay . . . . . . . . . . . . . . . . . . . . 6 4. Cost Metric: RTT . . . . . . . . . . . . . . . . . . . . . . 8 5. Cost Metric: PDV . . . . . . . . . . . . . . . . . . . . . . 9 6. Cost Metric: Hop Count . . . . . . . . . . . . . . . . . . . 11 7. Cost Metric: Packet Loss . . . . . . . . . . . . . . . . . . 13 8. Traffic Engineering Performance Cost Metrics . . . . . . . . 15 8.1. Cost Metric: Link Maximum Reservable Bandwidth . . . . . 16 8.2. Cost Metric: Link Residue Bandwidth . . . . . . . . . . . 17 8.3. Cost Metric: Link Available Bandwidth . . . . . . . . . . 19 Wu, et al. Expires September 4, 2017 [Page 2] Internet-Draft ALTO Performance Cost Metrics March 2017 8.4. Cost Metric: Link Utilized Bandwidth . . . . . . . . . . 21 9. Security Considerations . . . . . . . . . . . . . . . . . . . 23 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 11.1. Normative References . . . . . . . . . . . . . . . . . . 24 11.2. Informative References . . . . . . . . . . . . . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 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 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 | | | availbw | See Section 8.3,[RFC7810] Section 4.6 | | | utilbw | See Section 8.4,[RFC7810 Section 4.7 | +----------+--------------+---------------------------------------------+ 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 explicitely specified 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. Wu, et al. Expires September 4, 2017 [Page 3] Internet-Draft ALTO Performance Cost Metrics March 2017 An ALTO server may provide a subset of the cost metrics described in this document. These cost metrics can be retrieved and aggregated 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. If some are subject to privacy concerns, 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, it SHOULD announce this metric in its IRD. Additionally, further versions of this document may define network metric values that stem from both measurements and provider policy as for example, many end to end path bandwidth related ALTO metrics. ALTO may convey such information, not available via 3rd party measurement tools. Besides, IPPM informational RFC 5136 points the difficulty to have a unified nomenclature for network capacity related measurements. As for the reliability and trust in the exposed metric values, applications will 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. Wu, et al. Expires September 4, 2017 [Page 4] Internet-Draft ALTO Performance Cost Metrics March 2017 2. Challenges on data sources and computation of ALTO performance metrics 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 describe in this document. One challenge lies in the data sources originating the ALTO metric values. The very 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 them 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. Computation of ALTO performance metrics The metric values exposed by an ALTO server may result from additional processing on measurements from data sources to compute exposed metrics. This may invlove data processing tasks such as aggregating the results across multiple systems, removing outliers, and creating additional statistics. 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, an ALTO server may collect data on time periods covering the past and present 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 may provide the client with the validity period of the exposed metric values. Another challenge relates to the availability of end to end path values for certain metrics. Applications value information relating to bandwidth availability where as bandwidth related metrics can Wu, et al. Expires September 4, 2017 [Page 5] Internet-Draft ALTO Performance Cost Metrics March 2017 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 utilised 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 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: Wu, et al. Expires September 4, 2017 [Page 6] Internet-Draft ALTO Performance Cost Metrics March 2017 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" ] } } 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, } } } Wu, et al. Expires September 4, 2017 [Page 7] Internet-Draft ALTO Performance Cost Metrics March 2017 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 seconds. Measurement Point(s) with Potential Measurement Domain: 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. Wu, et al. Expires September 4, 2017 [Page 8] Internet-Draft ALTO Performance Cost Metrics March 2017 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, } } } 5. Cost Metric: PDV Metric name: Packet Delay Variation Metric Description: Wu, et al. Expires September 4, 2017 [Page 9] Internet-Draft ALTO Performance Cost Metrics March 2017 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 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. Use and Applications: See section 3 for use and application. Wu, et al. Expires September 4, 2017 [Page 10] Internet-Draft ALTO Performance Cost Metrics March 2017 Example 2: 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 Wu, et al. Expires September 4, 2017 [Page 11] Internet-Draft ALTO Performance Cost Metrics March 2017 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 protocols 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. Wu, et al. Expires September 4, 2017 [Page 12] Internet-Draft ALTO Performance Cost Metrics March 2017 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: Wu, et al. Expires September 4, 2017 [Page 13] Internet-Draft ALTO Performance Cost Metrics March 2017 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. Wu, et al. Expires September 4, 2017 [Page 14] Internet-Draft ALTO Performance Cost Metrics March 2017 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, } } } 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. Wu, et al. Expires September 4, 2017 [Page 15] Internet-Draft ALTO Performance Cost Metrics March 2017 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 neighbor, 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. Wu, et al. Expires September 4, 2017 [Page 16] Internet-Draft ALTO Performance Cost Metrics March 2017 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: Wu, et al. Expires September 4, 2017 [Page 17] Internet-Draft ALTO Performance Cost Metrics March 2017 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 neighbor, 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. Wu, et al. Expires September 4, 2017 [Page 18] Internet-Draft ALTO Performance Cost Metrics March 2017 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, } } } 8.3. Cost Metric: Link Available Bandwidth Metric name: Available Bandwidth Metric Description: Wu, et al. Expires September 4, 2017 [Page 19] Internet-Draft ALTO Performance Cost Metrics March 2017 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 level is specified in the query context (e.g., PID to PID, or endpoint to endpoint). Method of Measurement or Calculation: Available bandwidth is the Unidirectional Available bandwidth measured between two directly connected IS-IS neighbors or OSPF neighbor, See section 4.6 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. Besides, knowledge about available bandwidth is essential for applications to distribute or schedule their transmissions. The example below illustrates how this metric is provided in the form of an ALTO calendar, as specified in [XXXX] to help deciding "where" and "when" to transmit. Example 9: availbw value on source-destination endpoint pairs This example assumes that the ALTO Server provides the values for metric "availbw" in the form of an ALTO calendar and declares it in its IRD. POST /endpointcost/lookup HTTP/1.1 Host: alto.example.com Wu, et al. Expires September 4, 2017 [Page 20] Internet-Draft ALTO Performance Cost Metrics March 2017 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": "availbw"}, "calendared" : [true], "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": "availbw" } "calendar-response-attributes" : [ "calendar-start-time" : Tue, 1 Mar 2017 13:00:00 GMT, "time-interval-size" : "1 hour", "numb-intervals" : 8 ] }, "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], } } } 8.4. Cost Metric: Link Utilized Bandwidth Metric name: Utilized Bandwidth Wu, et al. Expires September 4, 2017 [Page 21] Internet-Draft ALTO Performance Cost Metrics March 2017 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 level is specified in the query context (e.g., PID to PID, or endpoint to endpoint). Method of Measurement or Calculation: Link Utilizated bandwidth is Unidirectional utilization bandwidth measured between two directly connected IS-IS neighbors or OSPF neighbor, See section 4.7 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: Link Utilized bandwidth is Unidirectional utilization bandwidth measured between two directly connected IS-IS neighbors or OSPF neighbor, See section 5 of [RFC7810] for Measurement Timing. Use and Applications: See section 3 for use and application. Wu, et al. Expires September 4, 2017 [Page 22] Internet-Draft ALTO Performance Cost Metrics March 2017 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, } } } 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 Wu, et al. Expires September 4, 2017 [Page 23] Internet-Draft ALTO Performance Cost Metrics March 2017 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. 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 . 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| | | availbw | [thisdraft] Section 8.3,[RFC7810],Section 4.6| | | utilbw | [thisdraft] Section 8.4,[RFC7810,Section4.7] | +----------+--------------+---------------------------------------------+ 11. References 11.1. 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-04 (work in progress), October 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-02 (work in progress), October 2016. Wu, et al. Expires September 4, 2017 [Page 24] Internet-Draft ALTO Performance Cost Metrics March 2017 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", March 1997. [RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Delay Metric for IPPM", RFC 2679, DOI 10.17487/RFC2679, September 1999, . [RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip Delay Metric for IPPM", RFC 2681, DOI 10.17487/RFC2681, September 1999, . [RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation Metric for IP Performance Metrics (IPPM)", RFC 3393, DOI 10.17487/RFC3393, November 2002, . [RFC4627] Crockford, D., "The application/json Media Type for JavaScript Object Notation (JSON)", RFC 4627, DOI 10.17487/RFC4627, July 2006, . [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/RFC5234, January 2008, . [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, DOI 10.17487/RFC5305, October 2008, . [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, . [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, . [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, . Wu, et al. Expires September 4, 2017 [Page 25] Internet-Draft ALTO Performance Cost Metrics March 2017 [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, . [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, . 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 Wu, et al. Expires September 4, 2017 [Page 26] Internet-Draft ALTO Performance Cost Metrics March 2017 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 Wu, et al. Expires September 4, 2017 [Page 27]