Internet-Draft Export of Forwarding Path Delay in IPFIX July 2022
Graf, et al. Expires 9 January 2023 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-tgraf-opsawg-ipfix-inband-telemetry-00
Published:
Intended Status:
Standards Track
Expires:
Authors:
T. Graf
Swisscom
B. Claise
Huawei
A. Huang Feng
INSA-Lyon

Export of Forwarding Path Delay in IPFIX

Abstract

This document introduces new IP Flow Information Export (IPFIX) information elements to expose the Inband Telemetry measured forwarding path delay in passport and postcard mode on the transit and decapsulation nodes.

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 9 January 2023.

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Table of Contents

1. Introduction

With Inband Telemetry, defined in In-situ OAM [I-D.ietf-ippm-ioam-deployment], Path Tracing [I-D.filsfils-spring-path-tracing] and In-situ Flow Information Telemetry [I-D.song-opsawg-ifit-framework], the path delay between two endpoints is measured by inserting a timestamp in the packet.

Inband Telemetry can be distinguished between two modes. Passport mode where only the last hop in the forwarding path of the Inband Telemetry domain exposes all the metrics and postcard mode where the transit nodes also expose metrics. In both modes the forwarding path is exposed thus allowing to determine how much delay has been accumulated hop by hop.

This document defines eight new IPFIX Information Elements (IEs) with their four corresponding entries in the performance metrics registry to expose the forwarding path delay on the transit and decapsulation nodes.

The delay is measured by calculating the difference between the timestamp imposed with Inband Telemetry in the packet at the encapsulation node and the timestamp exported in the IPFIX flow record from the transit and decapsulation nodes. Depending on the IE, the lowest, highest or the sum of measured delay is being exported.

2. IP One-Way Delay Hybrid Type I Passive Registry Entries

This section specifies four Registry Entries for the Hybrid Type I Passive assessment of IP One-Way Delay.

All column entries besides the ID, Name, Description, and Output Reference Method categories are the same; thus, this section defines four closely related Registry Entries. As a result, IANA has assigned corresponding URLs to each of the four Named Metrics.

2.1. Summary

This category includes multiple indexes to the Registry Entry: the element ID and Metric Name.

2.1.1. ID (Identifier)

<insert a numeric Identifier, an integer, TBD>

2.1.2. Name

IANA has allocated the numeric Identifiers TBD1-4 for the four Named Metric Entries in this section

2.1.3. Name

TBD1: OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Mean

TBD2: OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Min

TBD3: OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Max

TBD4: OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Sum

2.1.4. URI

URL: https://www.iana.org/assignments/performance-metrics/OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Mean

URL: https://www.iana.org/assignments/performance-metrics/OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Min

URL: https://www.iana.org/assignments/performance-metrics/OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Max

URL: https://www.iana.org/assignments/performance-metrics/OWDelay_HybridType1_Passive_IP_RFCTBD_Seconds_Sum

2.2. Description

This metric assesses the one-way delay of IP packets constituting a single connection, exchanged between two hosts. We consider the measurement of one-way delay based on a single Observation Point (OP) [RFC7011] somewhere in the network. The output is the one-way delay for all successfully exchanged packets expressed as the <statistic> of their conditional delay distribution, where <statistic> is one of:

2.3. Change Controller

IETF

2.4. Version of Registry Format

1.0

3. Metric Definition

This category includes columns to prompt the entry of all necessary details related to the metric definition, including the immutable document reference and values of input factors, called "Fixed Parameters".

3.1. Reference Definition

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>. [RFC7679]

Morton, A. and E. Stephan, "Spatial Composition of Metrics", RFC 6049, DOI 10.17487/RFC6049, January 2011, <https://www.rfc-editor.org/info/rfc6049>. [RFC6049]

Section 3.4 of [RFC7679] provides the reference definition of the singleton (single value) one-way delay metric. Section 4.4 of [RFC7679] provides the reference definition expanded to cover a multi-value sample. Note that terms such as "singleton" and "sample" are defined in section 2 of [RFC2330].

With the OP [RFC7011] typically located between the hosts participating in the IP connection, the one-way delay metric requires one individual measurement between the OP and sourcing host, such that the Spatial Composition [RFC6049] of the measurements yields a one-way delay singleton.

3.2. Fixed Parameters

Traffic Filters:

 IPv4 header values:
   DSCP: Set to 0

 IPv6 header values:
   DSCP: Set to 0
   Hop Count: Set to 255
   Flow Label: Set to 0
   Extension Headers: None

4. Method of Measurement

This category includes columns for references to relevant sections of the RFC(s) and any supplemental information needed to ensure an unambiguous method for implementations.

4.1. Reference Methods

The foundational methodology for this metric is defined in section 4 of [RFC7323] using the Timestamps option with modifications that allow application at a mid-path OP [RFC7011].

The Traffic Filter at the OP is configured to observe a single IP connection.

4.2. Packet Stream Generation

N/A

4.3. Traffic Filtering (Observation) Details

The Fixed Parameters above give a portion of the Traffic Filter. Other aspects will be supplied as Runtime Parameters (below).

4.4. Sampling Distribution

This metric requires a partial sample of all packets that qualify according to the Traffic Filter criteria.

4.5. Runtime Parameters and Data Format

Runtime Parameters are input factors that must be determined, configured into the measurement system, and reported with the results for the context to be complete.

Src:
The IP address of the host in the host A Role (format ipv4‑address-no-zone value for IPv4 or ipv6-address-no-zone value for IPv6; see section 4 of [RFC6991].
Dst:
The IP address of the host in the host B Role (format ipv4‑address-no-zone value for IPv4 or ipv6-address-no-zone value for IPv6; see section 4 of [RFC6991].
TTL or Hop Limit:
Set at desired value.
DSCP:
Set at desired value.
IPv6 Flow Label:
Set at desired value.
Timestamp:
The timestamp when the packet is being received at IOAM encapsulation node. Format depends on Inband Telemetry implementation. For IOAM, Section 4.4.1 of [RFC9197] describes what kind of timestamps are supported. Section 4.4.2.3 and 4.4.2.4 describe where the timestamp is being inserted. For Path Tracing, Section 4.1 of [I-D.filsfils-spring-path-tracing] describes what kind of timestamps are supported. Section 9.2 describe the SRH path tracing TLV where the timestamp is being inserted.

4.6. Roles

host A:
Launches the IP packet to open the connection. The Role of "host A" is synonymous with the IP address used at host A.
host B:
Receives the IP packet to open the connection. The Role of "host B" is synonymous with the IP address used at host B.
Encapsulation Node:
Receives the IP packet to open the connection and encapsulates the timestamp into the packet. The Role of "Encapsulation Node" is synonymous with the timestamp inserted in the packet.
Transit Node:
Receives the IP packet to open the connection and measures the delay between the timestamp in the packet and the timestamp when the packet was received.
Decapsulation Node:
Receives the IP packet to open the connection and measures the delay between the timestamp in the packet and the timestamp when the packet was received and removes the IOAM header from the packet.

5. Output

This category specifies all details of the output of measurements using the metric.

5.1. Type

OWDelay Types are discussed in the subsections below.

5.2. Reference Definition

For all output types:

OWDelay_HybridType1_Passive_IP:
The one-trip delay of one IP packet is a Singleton

For each <statistic>, Singleton one of the following subsections applies.

5.2.1. Mean

The mean SHALL be calculated using the conditional distribution of all packets with a finite value of one-way delay (undefined delays are excluded) -- a single value, as follows:

See section 4.1 of [RFC3393] for details on the conditional distribution to exclude undefined values of delay, and see section 5 of [RFC6703] for background on this analysis choice.

See section 4.2.2 of [RFC6049] for details on calculating this statistic; see also section 4.2.3 of [RFC6049].

Mean:
The time value of the result is expressed in units of seconds, as a positive value of type decimal64 with fraction digits = 9 (see section 9.3 of [RFC6020]) with a resolution of 0.000000001 seconds (1.0 ns), and with lossless conversion to/from the 64-bit NTP timestamp as per section 6 of [RFC5905].

5.2.2. Min

The minimum SHALL be calculated using the conditional distribution of all packets with a finite value of one-way delay (undefined delays are excluded) -- a single value, as follows:

See section 4.1 of [RFC3393] for details on the conditional distribution to exclude undefined values of delay, and see section 5 of [RFC6703] for background on this analysis choice.

See section 4.3.2 of [RFC6049] for details on calculating this statistic; see also section 4.3.3 of [RFC6049].

Min:
The time value of the result is expressed in units of seconds, as a positive value of type decimal64 with fraction digits = 9 (see section 9.3 of [RFC6020]) with a resolution of 0.000000001 seconds (1.0 ns), and with lossless conversion to/from the 64-bit NTP timestamp as per section 6 of [RFC5905].

5.2.3. Max

The maximum SHALL be calculated using the conditional distribution of all packets with a finite value of one-way delay (undefined delays are excluded) -- a single value, as follows:

See section 4.1 of [RFC3393] for details on the conditional distribution to exclude undefined values of delay, and see section 5 of [RFC6703] for background on this analysis choice.

See section 4.3.2 of [RFC6049] for a closely related method for calculating this statistic; see also section 4.3.3 of [RFC6049]. The formula is as follows:

 Max = (FiniteDelay[j])
 such that for some index, j, where 1 <= j <= N
 FiniteDelay[j] >= FiniteDelay[n] for all n
Max:
The time value of the result is expressed in units of seconds, as a positive value of type decimal64 with fraction digits = 9 (see section 9.3 of [RFC6020]) with a resolution of 0.000000001 seconds (1.0 ns), and with lossless conversion to/from the 64-bit NTP timestamp as per section 6 of [RFC5905].

5.2.4. Sum

The sum SHALL be calculated using the conditional distribution of all packets with a finite value of one-way delay (undefined delays are excluded) -- a single value, as follows:

See section 4.1 of [RFC3393] for details on the conditional distribution to exclude undefined values of delay, and see section 5 of [RFC6703] for background on this analysis choice.

See section 4.3.5 of [RFC6049] for details on calculating this statistic. However in this case FiniteDelay or MaxDelay MAY be used.

Sum:
The time value of the result is expressed in units of seconds, as a positive value of type decimal64 with fraction digits = 9 (see section 9.3 of [RFC6020]) with a resolution of 0.000000001 seconds (1.0 ns), and with lossless conversion to/from the 64-bit NTP timestamp as per section 6 of [RFC5905].

5.2.5. Metric Units

The <statistic> of one-way delay is expressed in seconds, where <statistic> is one of:

The one-way delay of the IP connection singleton is expressed in seconds.

5.2.6. Calibration

Passive Measurements at an OP could be calibrated against an Active Measurement at host A where the Active Measurement represents the ground truth.

5.3. Administrative Items

5.3.1. Status

Current

5.3.2. Requester

This RFC

5.3.3. Revision

1.0

5.3.4. Revision Date

RFC Date

5.4. Comments and Remarks

None

6. IPFIX Information Elements

This section defines and describes the new IPFIX IEs.

PathDelayMeanDeltaMicroseconds
16-bit unsigned integer that identifies the mean path delay.
PathDelayMeanDeltaNanoseconds
32-bit unsigned integer that identifies the mean path delay.
PathDelayMinDeltaMicroseconds
16-bit unsigned integer that identifies the lowest path delay.
PathDelayMinDeltaNanoseconds
32-bit unsigned integer that identifies the lowest path delay.
PathDelayMaxDeltaMicroseconds
16-bit unsigned integer that identifies the highest path delay.
PathDelayMaxDeltaNanoseconds
32-bit unsigned integer that identifies the highest path delay.
PathDelaySumDeltaMicroseconds
32-bit unsigned integer that identifies the sum of the path delay.
PathDelaySumDeltaNanoseconds
64-bit unsigned integer that identifies the sum of the path delay.

7. Use Cases

The measured forwarding path delay can be aggregated with Flow Aggregation as defined in [RFC7015] to the following device and control-plane dimensions to determine:

8. IANA Considerations

This document requests IANA to create new IEs (see table 1) and assign the following initial code points.

     +-------+--------------------------------+
     |Element|              Name              |
     |   ID  |                                |
     +-------+--------------------------------+
     | TBD5  | PathDelayMeanDeltaMicroseconds |
     |       |                                |
     +-------+--------------------------------+
     | TBD6  | PathDelayMeanDeltaNanoseconds  |
     |       |                                |
     +-------+--------------------------------+
     | TBD7  | PathDelayMinDeltaMicroseconds  |
     |       |                                |
     +-------+--------------------------------+
     | TBD8  | PathDelayMinDeltaNanoseconds   |
     |       |                                |
     +-------+--------------------------------+
     | TBD9  | PathDelayMaxDeltaMicroseconds  |
     |       |                                |
     +-------+--------------------------------+
     | TBD10 | PathDelayMaxDeltaNanoseconds   |
     |       |                                |
     +-------+--------------------------------+
     | TBD11 | PathDelaySumDeltaMicroseconds  |
     |       |                                |
     +-------+--------------------------------+
     | TBD12 | PathDelaySumDeltaNanoseconds   |
     |       |                                |
     +-------+--------------------------------+
  Table 1: Creates IEs in the "IPFIX Information Elements" registry

Note to the RFC-Editor:

8.1. PathDelayMeanDeltaMicroseconds

Name: PathDelayMeanDeltaMicroseconds ElementID: TBD5 Description: This Information Element identifies the mean path delay in microseconds. Abstract Data Type: unsigned16 Data Type Semantics: OctedDelta Reference: [RFC-to-be], xxx

8.2. PathDelayMeanDeltaNanoseconds

Name: PathDelayMeanDeltaNanoseconds ElementID: TBD6 Description: This Information Element identifies the mean path delay in nanoseconds. Abstract Data Type: unsigned32 Data Type Semantics: OctedDelta Reference: [RFC-to-be], xxx

8.3. PathDelayMinDeltaMicroseconds

Name: PathDelayMinDeltaMicroseconds ElementID: TBD7 Description: This Information Element identifies the lowest path delay in microseconds. Abstract Data Type: unsigned16 Data Type Semantics: OctedDelta Reference: [RFC-to-be], xxx

8.4. PathDelayMinDeltaNanoseconds

Name: PathDelayMinDeltaNanoseconds ElementID: TBD8 Description: This Information Element identifies the lowest path delay in nanoseconds. Abstract Data Type: unsigned32 Data Type Semantics: OctedDelta Reference: [RFC-to-be], xxx

8.5. PathDelayMaxDeltaMicroseconds

Name: PathDelayMaxDeltaMicroseconds ElementID: TBD9 Description: This Information Element identifies the highest path delay in microseconds. Abstract Data Type: unsigned16 Data Type Semantics: OctedDelta Reference: [RFC-to-be], xxx

8.6. PathDelayMaxDeltaNanoseconds

Name: PathDelayMaxDeltaNanoseconds ElementID: TBD10 Description: This Information Element identifies the highest path delay in nanoseconds. Abstract Data Type: unsigned32 Data Type Semantics: OctedDelta Reference: [RFC-to-be], xxx

8.7. PathDelaySumDeltaMicroseconds

Name: PathDelaySumDeltaMicroseconds ElementID: TBD11 Description: This Information Element identifies the sum of the path delay in microseconds. Abstract Data Type: unsigned32 Data Type Semantics: OctedDelta Reference: [RFC-to-be], xxx

8.8. PathDelaySumDeltaNanoseconds

Name: PathDelaySumDeltaNanoseconds ElementID: TBD12 Description: This Information Element identifies the sum of the path delay in nanoseconds. Abstract Data Type: unsigned64 Data Type Semantics: OctedDelta Reference: [RFC-to-be], xxx

9. Operational Considerations

9.1. Time Accuracy

The same recommendation as defined in section 4.5 of [RFC5153] for IPFIX applies in terms of clock precision to this document as well.

9.2. Mean Delay

The mean (average) path delay can be calculated by dividing the PathDelaySumDeltaMicroseconds(TBD5) or PathDelaySumDeltaNanoseconds(TBD6) by the packetDeltaCount(2) at the IPFIX data collection.

9.3. IOAM Packet Time Stamps

For IOAM, Section 4.4.1 of [RFC9197] describes what kind of timestamps are supported. Section 4.4.2.3 and 4.4.2.4 describe where the timestamp is being inserted.

For Path Tracing, Section 4.1 of [I-D.filsfils-spring-path-tracing] describes what kind of timestamps are supported. Section 9.2 describe the SRH path tracing TLV where the timestamp is being inserted.

10. Security Considerations

There are no significant extra security considerations regarding the allocation of these new IPFIX IEs compared to [RFC7012].

11. Acknowledgements

The authors would like to thank xxx for their review and valuable comments.

12. References

12.1. Normative References

[RFC7012]
Claise, B., Ed. and B. Trammell, Ed., "Information Model for IP Flow Information Export (IPFIX)", RFC 7012, DOI 10.17487/RFC7012, , <https://www.rfc-editor.org/info/rfc7012>.

12.2. Informative References

[I-D.filsfils-spring-path-tracing]
Filsfils, C., Abdelsalam, A., Garvia, P. C., Yufit, M., Graf, T., Su, Y., Matsushima, S., and M. Valentine, "Path Tracing in SRv6 networks", Work in Progress, Internet-Draft, draft-filsfils-spring-path-tracing-01, , <https://www.ietf.org/archive/id/draft-filsfils-spring-path-tracing-01.txt>.
[I-D.ietf-ippm-ioam-deployment]
Brockners, F., Bhandari, S., Bernier, D., and T. Mizrahi, "In-situ OAM Deployment", Work in Progress, Internet-Draft, draft-ietf-ippm-ioam-deployment-01, , <https://www.ietf.org/archive/id/draft-ietf-ippm-ioam-deployment-01.txt>.
[I-D.song-opsawg-ifit-framework]
Song, H., Qin, F., Chen, H., Jin, J., and J. Shin, "A Framework for In-situ Flow Information Telemetry", Work in Progress, Internet-Draft, draft-song-opsawg-ifit-framework-17, , <https://www.ietf.org/archive/id/draft-song-opsawg-ifit-framework-17.txt>.
[I-D.tgraf-opsawg-ipfix-srv6-srh]
Graf, T., Claise, B., and P. Francois, "Export of Segment Routing IPv6 Information in IP Flow Information Export (IPFIX)", Work in Progress, Internet-Draft, draft-tgraf-opsawg-ipfix-srv6-srh-04, , <https://www.ietf.org/archive/id/draft-tgraf-opsawg-ipfix-srv6-srh-04.txt>.
[RFC2330]
Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, "Framework for IP Performance Metrics", RFC 2330, DOI 10.17487/RFC2330, , <https://www.rfc-editor.org/info/rfc2330>.
[RFC3393]
Demichelis, C. and P. Chimento, "IP Packet Delay Variation Metric for IP Performance Metrics (IPPM)", RFC 3393, DOI 10.17487/RFC3393, , <https://www.rfc-editor.org/info/rfc3393>.
[RFC5153]
Boschi, E., Mark, L., Quittek, J., Stiemerling, M., and P. Aitken, "IP Flow Information Export (IPFIX) Implementation Guidelines", RFC 5153, DOI 10.17487/RFC5153, , <https://www.rfc-editor.org/info/rfc5153>.
[RFC5905]
Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, "Network Time Protocol Version 4: Protocol and Algorithms Specification", RFC 5905, DOI 10.17487/RFC5905, , <https://www.rfc-editor.org/info/rfc5905>.
[RFC6020]
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, , <https://www.rfc-editor.org/info/rfc6020>.
[RFC6049]
Morton, A. and E. Stephan, "Spatial Composition of Metrics", RFC 6049, DOI 10.17487/RFC6049, , <https://www.rfc-editor.org/info/rfc6049>.
[RFC6703]
Morton, A., Ramachandran, G., and G. Maguluri, "Reporting IP Network Performance Metrics: Different Points of View", RFC 6703, DOI 10.17487/RFC6703, , <https://www.rfc-editor.org/info/rfc6703>.
[RFC6991]
Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, , <https://www.rfc-editor.org/info/rfc6991>.
[RFC7011]
Claise, B., Ed., Trammell, B., Ed., and P. Aitken, "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information", STD 77, RFC 7011, DOI 10.17487/RFC7011, , <https://www.rfc-editor.org/info/rfc7011>.
[RFC7015]
Trammell, B., Wagner, A., and B. Claise, "Flow Aggregation for the IP Flow Information Export (IPFIX) Protocol", RFC 7015, DOI 10.17487/RFC7015, , <https://www.rfc-editor.org/info/rfc7015>.
[RFC7323]
Borman, D., Braden, B., Jacobson, V., and R. Scheffenegger, Ed., "TCP Extensions for High Performance", RFC 7323, DOI 10.17487/RFC7323, , <https://www.rfc-editor.org/info/rfc7323>.
[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, , <https://www.rfc-editor.org/info/rfc7679>.
[RFC9197]
Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi, Ed., "Data Fields for In Situ Operations, Administration, and Maintenance (IOAM)", RFC 9197, DOI 10.17487/RFC9197, , <https://www.rfc-editor.org/info/rfc9197>.

Authors' Addresses

Thomas Graf
Swisscom
Binzring 17
CH-8045 Zurich
Switzerland
Benoit Claise
Huawei
Alex Huang Feng
INSA-Lyon
Lyon
France