draft-ietf-ippm-route-08.txt   draft-ietf-ippm-route-09.txt 
Network Working Group J. Alvarez-Hamelin Network Working Group J. Alvarez-Hamelin
Internet-Draft Universidad de Buenos Aires Internet-Draft Universidad de Buenos Aires
Updates: 2330 (if approved) A. Morton Updates: 2330 (if approved) A. Morton
Intended status: Standards Track AT&T Labs Intended status: Standards Track AT&T Labs
Expires: December 20, 2020 J. Fabini Expires: January 10, 2021 J. Fabini
TU Wien TU Wien
C. Pignataro C. Pignataro
Cisco Systems, Inc. Cisco Systems, Inc.
R. Geib R. Geib
Deutsche Telekom Deutsche Telekom
June 18, 2020 July 9, 2020
Advanced Unidirectional Route Assessment (AURA) Advanced Unidirectional Route Assessment (AURA)
draft-ietf-ippm-route-08 draft-ietf-ippm-route-09
Abstract Abstract
This memo introduces an advanced unidirectional route assessment This memo introduces an advanced unidirectional route assessment
(AURA) metric and associated measurement methodology, based on the IP (AURA) metric and associated measurement methodology, based on the IP
Performance Metrics (IPPM) Framework RFC 2330. This memo updates RFC Performance Metrics (IPPM) Framework RFC 2330. This memo updates RFC
2330 in the areas of path-related terminology and path description, 2330 in the areas of path-related terminology and path description,
primarily to include the possibility of parallel subpaths between a primarily to include the possibility of parallel subpaths between a
given Source and Destination pair, owing to the presence of multi- given Source and Destination pair, owing to the presence of multi-
path technologies. path technologies.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 20, 2020. This Internet-Draft will expire on January 10, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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3.6. Reporting the Metric . . . . . . . . . . . . . . . . . . 10 3.6. Reporting the Metric . . . . . . . . . . . . . . . . . . 10
4. Route Assessment Methodologies . . . . . . . . . . . . . . . 10 4. Route Assessment Methodologies . . . . . . . . . . . . . . . 10
4.1. Active Methodologies . . . . . . . . . . . . . . . . . . 11 4.1. Active Methodologies . . . . . . . . . . . . . . . . . . 11
4.1.1. Temporal Composition for Route Metrics . . . . . . . 13 4.1.1. Temporal Composition for Route Metrics . . . . . . . 13
4.1.2. Routing Class Identification . . . . . . . . . . . . 14 4.1.2. Routing Class Identification . . . . . . . . . . . . 14
4.1.3. Intermediate Observation Point Route Measurement . . 15 4.1.3. Intermediate Observation Point Route Measurement . . 15
4.2. Hybrid Methodologies . . . . . . . . . . . . . . . . . . 15 4.2. Hybrid Methodologies . . . . . . . . . . . . . . . . . . 15
4.3. Combining Different Methods . . . . . . . . . . . . . . . 16 4.3. Combining Different Methods . . . . . . . . . . . . . . . 16
5. Background on Round-Trip Delay Measurement Goals . . . . . . 17 5. Background on Round-Trip Delay Measurement Goals . . . . . . 17
6. RTD Measurements Statistics . . . . . . . . . . . . . . . . . 18 6. RTD Measurements Statistics . . . . . . . . . . . . . . . . . 18
7. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 20 7. Security Considerations . . . . . . . . . . . . . . . . . . . 20
8. Security Considerations . . . . . . . . . . . . . . . . . . . 20 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 10. Appendix I MPLS Methods for Route Assessment . . . . . . . . 20
11. Appendix I MPLS Methods for Route Assessment . . . . . . . . 21 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 11.1. Normative References . . . . . . . . . . . . . . . . . . 21
12.1. Normative References . . . . . . . . . . . . . . . . . . 22 11.2. Informative References . . . . . . . . . . . . . . . . . 24
12.2. Informative References . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction 1. Introduction
The IETF IP Performance Metrics (IPPM) working group first created a The IETF IP Performance Metrics (IPPM) working group first created a
framework for metric development in [RFC2330]. This framework has framework for metric development in [RFC2330]. This framework has
stood the test of time and enabled development of many fundamental stood the test of time and enabled development of many fundamental
metrics. It has been updated in the area of metric composition metrics. It has been updated in the area of metric composition
[RFC5835], and in several areas related to active stream measurement [RFC5835], and in several areas related to active stream measurement
of modern networks with reactive properties [RFC7312]. of modern networks with reactive properties [RFC7312].
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interrogation protocol. Nodes SHOULD also provide information interrogation protocol. Nodes SHOULD also provide information
such as arrival/departure interface identification, arrival such as arrival/departure interface identification, arrival
timestamp, and any relevant information about the Node or specific timestamp, and any relevant information about the Node or specific
link which delivered the query to the Node. link which delivered the query to the Node.
Hop A Hop MUST contain a Node Identity, and MAY contain arrival and/ Hop A Hop MUST contain a Node Identity, and MAY contain arrival and/
or departure interface identification, round trip delay, and an or departure interface identification, round trip delay, and an
arrival timestamp. arrival timestamp.
Routing Class A route that treats equally a class C of different Routing Class A route that treats equally a class C of different
types of packets. Knowledge of such a class allows any one of the types of packets (unrelated to address classes of the past).
types of packets within that class to be used for subsequent Knowledge of such a class allows any one of the types of packets
measurement of the route. within that class to be used for subsequent measurement of the
route.
3.1. Formal Name 3.1. Formal Name
Type-P-Route-Ensemble-Method-Variant, abbreviated as Route Ensemble. Type-P-Route-Ensemble-Method-Variant, abbreviated as Route Ensemble.
Note that Type-P depends heavily on the chosen method and variant. Note that Type-P depends heavily on the chosen method and variant.
3.2. Parameters 3.2. Parameters
This section lists the REQUIRED input factors to specify a Route This section lists the REQUIRED input factors to specify a Route
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keeping the FlowLabel constant in all packets. keeping the FlowLabel constant in all packets.
Paris-traceroute allows its users to measure RTD in every hop of the Paris-traceroute allows its users to measure RTD in every hop of the
path for a particular flow. Furthermore, either Paris-traceroute or path for a particular flow. Furthermore, either Paris-traceroute or
Scamper is capable of unveiling the many available paths between a Scamper is capable of unveiling the many available paths between a
source and destination (which are visible to this method). This task source and destination (which are visible to this method). This task
is accomplished by repeating complete traceroute measurements with is accomplished by repeating complete traceroute measurements with
different flow parameters for each measurement; Paris-traceroute different flow parameters for each measurement; Paris-traceroute
provides "exhaustive" mode while scamper provides "tracelb" (stands provides "exhaustive" mode while scamper provides "tracelb" (stands
for traceroute load balance). The Framework for IP Performance for traceroute load balance). The Framework for IP Performance
Metrics (IPPM) ([RFC2330] updated by [RFC7312]) has the flexibility Metrics (IPPM) ([RFC2330] updated by[RFC7312]) has the flexibility to
to require that the Round-Trip Delay measurement [RFC2681] uses require that the Round-Trip Delay measurement [RFC2681] uses packets
packets with the constraints to assure that all packets in a single with the constraints to assure that all packets in a single
measurement appear as the same flow. This flexibility covers ICMP, measurement appear as the same flow. This flexibility covers ICMP,
UDP, and TCP. The accompanying methodology of [RFC2681] needs to be UDP, and TCP. The accompanying methodology of [RFC2681] needs to be
expanded to report the sequential hop identifiers along with RTD expanded to report the sequential hop identifiers along with RTD
measurements, but no new metric definition is needed. measurements, but no new metric definition is needed.
The advanced route assessment methods used in Paris-traceroute [PT] The advanced route assessment methods used in Paris-traceroute [PT]
keep the critical fields constant for every packet to maintain the keep the critical fields constant for every packet to maintain the
appearance of the same flow. In IPv6, it is sufficient to be routed appearance of the same flow. In IPv6, it is sufficient to be routed
identically if the IP source and destination addresses and the identically if the IP source and destination addresses and the
FlowLabel are constant, see [RFC6437]. In IPv4, certain fields of FlowLabel are constant, see [RFC6437]. In IPv4, certain fields of
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To understand the ongoing process, examining the quartiles provides a To understand the ongoing process, examining the quartiles provides a
non-parametric way of analysis. Quartiles are defined by five non-parametric way of analysis. Quartiles are defined by five
values: minimum RTD (m), RTD value of the 25% of the Empirical values: minimum RTD (m), RTD value of the 25% of the Empirical
Cumulative Distribution Function (ECDF) (Q1), the median value (Q2), Cumulative Distribution Function (ECDF) (Q1), the median value (Q2),
the RTD value of the 75% of the ECDF (Q3) and the maximum RTD (M). the RTD value of the 75% of the ECDF (Q3) and the maximum RTD (M).
Congestion can be inferred when RTD measurements are spread apart, Congestion can be inferred when RTD measurements are spread apart,
and consequently, the Inter-Quartile Range (IQR), the distance and consequently, the Inter-Quartile Range (IQR), the distance
between Q3 and Q1, increases its value. between Q3 and Q1, increases its value.
This procedure requires to compute quartile values "on the fly" using This procedure requires the algorithm presented in [P2] to compute
the algorithm presented in [P2]. quartile values "on the fly".
This procedure allows us to update the quartiles value whenever a new This procedure allows us to update the quartiles value whenever a new
measurement arrives, which is radically different from classic measurement arrives, which is radically different from classic
methods of computing quartiles because they need to use the whole methods of computing quartiles because they need to use the whole
dataset to compute the values. This way of calculus provides savings dataset to compute the values. This way of calculus provides savings
in memory and computing time. in memory and computing time.
To sum up, the proposed measurement procedure consists of performing To sum up, the proposed measurement procedure consists of performing
traceroutes several times to obtain samples of the RTD in every hop traceroutes several times to obtain samples of the RTD in every hop
from a path, during a time window (W), and compute the quartiles for from a path, during a time window (W), and compute the quartiles for
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returns a list of tuples (m,Q1,Q2,Q3,M) for each intermediate hop, or returns a list of tuples (m,Q1,Q2,Q3,M) for each intermediate hop, or
"Alt" in as a function of the 5-tuple, in the path towards the Dst. "Alt" in as a function of the 5-tuple, in the path towards the Dst.
Finally, lines 10 through 12 stores each measurement into the real- Finally, lines 10 through 12 stores each measurement into the real-
time quartiles computation. time quartiles computation.
Notice there are cases where the even having a unique hop at distance Notice there are cases where the even having a unique hop at distance
h from the Src to Dst, the returning path could have several h from the Src to Dst, the returning path could have several
possibilities, yielding in different total paths. In this situation, possibilities, yielding in different total paths. In this situation,
the algorithm will return more "Alt" for this particular hop. the algorithm will return more "Alt" for this particular hop.
7. Conclusions 7. Security Considerations
This document introduces a method to perform statistical RTD
measurements in a path, according to the actual state of the art
regarding the traffic nature and the flow balance method in ECMP
cases, which can help to tackle different performance situations in
the network. Some of these cases are enumerated in Section 5, while
our method is proposed in Section 4, and the algorithm in Section 6.
The importance of this algorithm is that it deals with the different
topological aspects and the self-similar (i.e., not Poisson-
distributed) nature of the traffic.
8. Security Considerations
The security considerations that apply to any active measurement of The security considerations that apply to any active measurement of
live paths are relevant here as well. See [RFC4656] and [RFC5357]. live paths are relevant here as well. See [RFC4656] and [RFC5357].
The active measurement process of "changing several fields to keep The active measurement process of "changing several fields to keep
the checksum of different packets identical" does not require special the checksum of different packets identical" does not require special
security considerations because it is part of synthetic traffic security considerations because it is part of synthetic traffic
generation, and is designed to have minimal to zero impact on network generation, and is designed to have minimal to zero impact on network
processing (to process the packets for ECMP). processing (to process the packets for ECMP).
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When considering privacy of those involved in measurement or those When considering privacy of those involved in measurement or those
whose traffic is measured, the sensitive information available to whose traffic is measured, the sensitive information available to
potential observers is greatly reduced when using active techniques potential observers is greatly reduced when using active techniques
which are within this scope of work. Passive observations of user which are within this scope of work. Passive observations of user
traffic for measurement purposes raise many privacy issues. We refer traffic for measurement purposes raise many privacy issues. We refer
the reader to the privacy considerations described in the Large Scale the reader to the privacy considerations described in the Large Scale
Measurement of Broadband Performance (LMAP) Framework [RFC7594], Measurement of Broadband Performance (LMAP) Framework [RFC7594],
which covers active and passive techniques. which covers active and passive techniques.
9. IANA Considerations 8. IANA Considerations
This memo makes no requests of IANA. We thank the good folks at IANA This memo makes no requests of IANA. We thank the good folks at IANA
for having checked this section anyway. for having checked this section anyway.
10. Acknowledgements 9. Acknowledgements
The original 3 authors acknowledge Ruediger Geib, for his penetrating The original 3 authors acknowledge Ruediger Geib, for his penetrating
comments on the initial draft, and his initial text for the comments on the initial draft, and his initial text for the
Appendix on MPLS. Carlos Pignataro challenged the authors to Appendix on MPLS. Carlos Pignataro challenged the authors to
consider a wider scope, and applied his substantial expertise with consider a wider scope, and applied his substantial expertise with
many technologies and their measurement features in his extensive many technologies and their measurement features in his extensive
comments. Frank Brockners also shared useful comments, so did Footer comments. Frank Brockners also shared useful comments, so did Footer
Foote. We thank them all! Foote. We thank them all!
11. Appendix I MPLS Methods for Route Assessment 10. Appendix I MPLS Methods for Route Assessment
A Node assessing an MPLS path must be part of the MPLS domain where A Node assessing an MPLS path must be part of the MPLS domain where
the path is implemented. When this condition is met, RFC 8029 the path is implemented. When this condition is met, RFC 8029
provides a powerful set of mechanisms to detect "correct operation of provides a powerful set of mechanisms to detect "correct operation of
the data plane, as well as a mechanism to verify the data plane the data plane, as well as a mechanism to verify the data plane
against the control plane" [RFC8029]. against the control plane" [RFC8029].
MPLS routing is based on the presence of a Forwarding Equivalence MPLS routing is based on the presence of a Forwarding Equivalence
Class (FEC) Stack in all visited Nodes. Selecting one of several Class (FEC) Stack in all visited Nodes. Selecting one of several
Equal Cost Multi Path (ECMP) is however based on information hidden Equal Cost Multi Path (ECMP) is however based on information hidden
deeper in the stack. Early deployments may support a so called deeper in the stack. Late deployments may support a so called
"Entropy label" for this purpose. State of the art deployments base "Entropy label" for this purpose. State of the art deployments base
their choice of an ECMP member based on the IP addresses (see their choice of an ECMP member interface on the complete MPLS label
Section 2.4 of [RFC7325]). Both methods allow load sharing stack and on IP addresses up to the complete 5 tuple IP header
information to be decoupled from routing information. Thus, an MPLS information (see Section 2.4 of [RFC7325]). Load Sharing based on IP
traceroute is able to check how packets with a contiguous number of information decouples this function from the actual MPLS routing
ECMP relevant addresses (and the same destination) are routed by a information. Thus, an MPLS traceroute is able to check how packets
particular router. The minimum number of MPLS paths traceable at a with a contiguous number of ECMP relevant IP addresses (and an
router should be 32. Implementations supporting more paths are identical MPLS label stack) are forwarded by a particular router.
available. The minimum number of equivalent MPLS paths traceable at a router
should be 32. Implementations supporting more paths are available.
The MPLS echo request and reply messages offering this feature must The MPLS echo request and reply messages offering this feature must
support the Downstream Detailed Mapping TLV (was Downstream Mapping support the Downstream Detailed Mapping TLV (was Downstream Mapping
initially, but the latter has been deprecated). The MPLS echo initially, but the latter has been deprecated). The MPLS echo
response includes the incoming interface where a router received the response includes the incoming interface where a router received the
MPLS Echo request. The MPLS Echo reply further informs which of the MPLS Echo request. The MPLS Echo reply further informs which of the
n addresses relevant for the load sharing decision results in a n addresses relevant for the load sharing decision results in a
particular next hop interface and contains the next hop's interface particular next hop interface and contains the next hop's interface
address (if available). This ensures that the next hop will receive address (if available). This ensures that the next hop will receive
a properly coded MPLS Echo request in the next step route of a properly coded MPLS Echo request in the next step route of
assessment. assessment.
[RFC8403] explains how a central Path Monitoring System could be used [RFC8403] explains how a central Path Monitoring System could be used
to detect arbitrary MPLS paths between any routers within a single to detect arbitrary MPLS paths between any routers within a single
MPLS domain. The combination of MPLS forwarding, Segment Routing and MPLS domain. The combination of MPLS forwarding, Segment Routing and
MPLS traceroute offers a simple architecture and a powerful mechanism MPLS traceroute offers a simple architecture and a powerful mechanism
to detect and validate (segment routed) MPLS paths. to detect and validate (segment routed) MPLS paths.
12. References 11. References
12.1. Normative References
11.1. Normative References
[I-D.ietf-ippm-ioam-data] [I-D.ietf-ippm-ioam-data]
Brockners, F., Bhandari, S., Pignataro, C., Gredler, H., Brockners, F., Bhandari, S., Pignataro, C., Gredler, H.,
Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov, Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
P., remy@barefootnetworks.com, r., daniel.bernier@bell.ca, P., remy@barefootnetworks.com, r., daniel.bernier@bell.ca,
d., and J. Lemon, "Data Fields for In-situ OAM", draft- d., and J. Lemon, "Data Fields for In-situ OAM", draft-
ietf-ippm-ioam-data-09 (work in progress), March 2020. ietf-ippm-ioam-data-09 (work in progress), March 2020.
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, DOI 10.17487/RFC0792, September 1981, RFC 792, DOI 10.17487/RFC0792, September 1981,
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8468] Morton, A., Fabini, J., Elkins, N., Ackermann, M., and V. [RFC8468] Morton, A., Fabini, J., Elkins, N., Ackermann, M., and V.
Hegde, "IPv4, IPv6, and IPv4-IPv6 Coexistence: Updates for Hegde, "IPv4, IPv6, and IPv4-IPv6 Coexistence: Updates for
the IP Performance Metrics (IPPM) Framework", RFC 8468, the IP Performance Metrics (IPPM) Framework", RFC 8468,
DOI 10.17487/RFC8468, November 2018, DOI 10.17487/RFC8468, November 2018,
<https://www.rfc-editor.org/info/rfc8468>. <https://www.rfc-editor.org/info/rfc8468>.
12.2. Informative References 11.2. Informative References
[bdrmap] Luckie, M., Dhamdhere, A., Huffaker, B., Clark, D., and [bdrmap] Luckie, M., Dhamdhere, A., Huffaker, B., Clark, D., and
KC. Claffy, "bdrmap: Inference of Borders Between IP KC. Claffy, "bdrmap: Inference of Borders Between IP
Networks", In Proceedings of the 2016 ACM on Internet Networks", In Proceedings of the 2016 ACM on Internet
Measurement Conference, pp. 381-396. ACM, 2016. Measurement Conference, pp. 381-396. ACM, 2016.
[IDCong] Luckie, M., Dhamdhere, A., Clark, D., and B. Huffaker, [IDCong] Luckie, M., Dhamdhere, A., Clark, D., and B. Huffaker,
"Challenges in inferring Internet interdomain "Challenges in inferring Internet interdomain
congestion", In Proceedings of the 2014 Conference on congestion", In Proceedings of the 2014 Conference on
Internet Measurement Conference, pp. 15-22. ACM, 2014. Internet Measurement Conference, pp. 15-22. ACM, 2014.
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