Network Management Research Group                               J. Nobre
Internet-Draft                       University of Vale do Rio dos Sinos
Intended status: Informational                              L. Granville
Expires: August 2, 2017          Federal University of Rio Grande do Sul
                                                                A. Clemm
                                                               A. Prieto
                                                           Cisco Systems
                                                        January 29, 2017

     Autonomic Networking Use Case for Distributed Detection of SLA


   This document describes a use case for autonomic networking in
   distributed detection of Service Level Agreement (SLA) violations.
   It is one of a series of use cases intended to illustrate
   requirements for autonomic networking.

Status of This Memo

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   This Internet-Draft will expire on August 2, 2017.

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   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definitions and Acronyms  . . . . . . . . . . . . . . . . . .   4
   3.  Current Approaches  . . . . . . . . . . . . . . . . . . . . .   4
   4.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Benefits of an Autonomic Solution . . . . . . . . . . . . . .   5
   6.  Intended User and Administrator Experience  . . . . . . . . .   6
   7.  Analysis of Parameters and Information Involved . . . . . . .   6
     7.1.  Device Based Self-Knowledge and Decisions . . . . . . . .   6
     7.2.  Interaction with other devices  . . . . . . . . . . . . .   7
   8.  Comparison with current solutions . . . . . . . . . . . . . .   7
   9.  Related IETF Work . . . . . . . . . . . . . . . . . . . . . .   7
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   12. Security Considerations . . . . . . . . . . . . . . . . . . .   8
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     13.1.  Normative References . . . . . . . . . . . . . . . . . .   8
     13.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   The Internet has been growing dramatically in terms of size and
   capacity, and accessibility in the last years.  Communication
   requirements of distributed services and applications running on top
   of the Internet have become increasingly demanding.  Some examples
   are real-time interactive video or financial trading.  Providing such
   services involves stringent requirements in terms of acceptable
   latency, loss, or jitter.  Those requirements lead to the
   articulation of Service Level Objectives (SLOs) which are to be met.
   Those SLOs become part of Service Level Agreements (SLAs) that
   articulate a contract between the provider and the consumer of a
   service.  To fulfill a service, it needs to be ensured that the SLOs
   are met.  Examples of service fulfillment clauses can be found on
   [RFC7297]).  Violations of SLOs can be associated with significant
   financial loss, which can by divided in two types.  First, there is
   the loss incurred by the service users (e.g., the trader whose orders
   are not executed in a timely manner) and the loss incurred by the
   service provider in terms of penalties for not meeting the service
   and loss of revenues due to reduced customer satisfaction.  Thus, the
   service level requirements of critical network services have become a

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   key concern for network administrators.  To ensure that SLAs are not
   being violated, service levels need to be constantly monitored at the
   network infrastructure layer.  To that end, network measurements must
   take place.

   Network measurement mechanisms are performed through either active or
   passive measurement techniques.  In passive measurements, production
   traffic is observed.  Network conditions are checked in a non
   intrusive way because no monitoring traffic is created by the
   measurement process itself.  In the context of IP Flow Information
   EXport (IPFIX) WG, several documents were produced to define passive
   measurement mechanisms (e.g., flow records specification [RFC3954]).
   Active measurement, on the other hand, is intrusive because it
   injects synthetic traffic into the network to measure the network
   performance.  The IP Performance Metrics (IPPM) WG produced documents
   that describe active measurement mechanisms, such as: One-Way Active
   Measurement Protocol (OWAMP) [RFC4656], Two-Way Active Measurement
   Protocol (TWAMP) [RFC5357], and Cisco Service Level Assurance
   Protocol (SLA) [RFC6812].  Besides that, there are some mechanisms
   that do not fit into either active or passive categories, such as
   Performance and Diagnostic Metrics Destination Option (PDM)
   techniques [draft-ietf-ippm-6man-pdm-option].

   Active measurement mechanisms offer a high level of control of what
   and how to measure.  It also does not require inspecting production
   traffic.  Because of this, it usually offers better accuracy and
   privacy than passive measurement mechanisms.  Traffic encryption and
   regulations that limit the amount of payload inspection that can
   occur are non-issues.  Furthermore, active measurement mechanisms are
   able to detect end-to-end network performance problems in a fine-
   grained way (e.g., simulating the traffic that must be handled
   considering specific Service Level Objectives - SLOs).  As a result,
   active measurements are often preferred over passive measurement for
   SLA monitoring.  Measurement probes must be hosted in network devices
   and measurement sessions must be activated to compute the current
   network metrics (e.g., considering those described in [RFC4148]).
   This activation should be dynamic in order to follow changes in
   network conditions, such as those related with routes being added or
   new customer demands.

   The activation of active measurement sessions (hosted in senders and
   responders considering the architecture described by Cisco [RFC6812])
   is expensive in terms of the resource consumption, e.g., CPU cycle
   and memory footprint, and monitoring functions compete for resources
   with other functions, including routing and switching.  Besides that,
   the activated sessions also increase the network load because of the
   injected traffic.  The resources required and traffic generated by
   the active measurement sessions are a function of the number of

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   measured network destinations, i.e., with more destinations the
   larger will be the resources and the traffic needed to deploy the
   sessions.  Thus, to have a better monitoring coverage it is necessary
   to deploy more sessions what consequently turns increases consumed
   resources.  Otherwise, enabling the observation of just a small
   subset of all network flows can lead to an insufficient coverage.
   Hence, the decision how to place measurement probes becomes an
   important management activity, so that with a limited amount of
   measurement overhead the maximum benefits in terms of service level
   monitoring are obtained.

2.  Definitions and Acronyms

   Active Measurements: Techniques to measure service levels that
   involves generating and observing synthetic test traffic

   Passive Measurements: Techniques used to measure levels based on
   observation of production traffic

   SLA: Service Level Parameter

   SLO: Service Level Objective

   P2P: Peer-to-Peer

3.  Current Approaches

   The current best practice in feasible deployments of active
   measurement solutions to distribute the available measurement
   sessions along the network consists in relying entirely on the human
   administrator expertise to infer which would be the best location to
   activate such sessions.  This is done through several steps.  First,
   it is necessary to collect traffic information in order to grasp the
   traffic matrix.  Then, the administrator uses this information to
   infer which are the best destinations for measurement sessions.
   After that, the administrator activates sessions on the chosen subset
   of destinations considering the available resources.  This practice,
   however, does not scale well because it is still labor intensive and
   error-prone for the administrator to compute which sessions should be
   activated given the set of critical flows that needs to be measured.
   Even worse, this practice completely fails in networks whose critical
   flows are too short in time and dynamic in terms of traversing
   network path, like in modern cloud environments.  That is so because
   fast reactions are necessary to reconfigure the sessions and
   administrators are not just enough in computing and activating the
   new set of required sessions every time the network traffic pattern
   changes.  Finally, the current active measurements practice usually
   covers only a fraction of the network flows that should be observed,

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   which invariably leads to the damaging consequence of undetected SLA

4.  Problem Statement

   The problem to solve involves automating the placement of active
   measurement probes in the most effective manner possible.
   Specifically, assuming a bounded resource budget that is available
   for measurements, the problem becomes how to place those measurement
   probes such that the likelihood of detecting service level violations
   is maximized, and subsequently performing the required
   configurations.  The method should be embeddable as management
   software inside network devices that controls the deployment of
   active measurement mechanisms.  The method shall furthermore be
   dynamic and be able to adapt to changing network conditions.

5.  Benefits of an Autonomic Solution

   The use case considered here is the distributed autonomic detection
   of SLA violations.  The use of Autonomic Networking (AN) properties
   can help such detection through an efficient activation of
   measurement sessions [P2PBNM-Nobre-2012].  The problem to be solved
   by AN in the present use case is how to steer the process of
   measurement session activation by a complete solution that sets all
   necessary parameters for this activation to operate efficiently,
   reliably and securely, with no required human intervention, while
   allowing for their input.

   We advocate for embedding Peer-to-Peer (P2P) technology in network
   devices in order to improve the measurement session activation
   decisions using autonomic control loops.  The provisioning of the P2P
   management overlay should be transparent for the network
   administrator.  It would be possible to control the measurement
   session activation using local data and logic and to share
   measurement results among different network devices.

   An autonomic solution for the distributed detection of SLA violations
   can provide several benefits.  First, efficiency: this solution could
   optimize the resource consumption and avoid resource starvation on
   the network devices.  In practice, the solution should maximize the
   benefits of SLA monitoring (i.e., maximize the likelihood of SLA
   violations being detected) by operating within a given resource
   budget.  This optimization comes from different sources: taking into
   account past measurement results, taking into account other
   observations (such as, observations of link utilizations and passive
   measurements, where available) sharing of measurement results between
   network devices, better efficiency in the probe activation decisions,
   etc.  Second, effectiveness: the number of detected SLA violations

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   could be increased.  This increase is related with a better coverage
   of the network.  Third, the solution could decrease the time
   necessary to detect SLA violations.  Adaptivity features of an
   autonomic loop could capture faster the network dynamics than an
   human administrator.  Finally, the solution could help to reduce the
   workload of human administrator, or, at least, to avoid their need to
   perform operational tasks.

6.  Intended User and Administrator Experience

   The autonomic solution should not require the human intervention in
   the distributed detection of SLA violations.  Besides that, it could
   enable the control of SLA monitoring by less experienced human
   administrators.  However, some information may be provided from the
   human administrator.  For example, the human administrator may
   provide the SLOs regarding the SLA being monitored.  The
   configuration and bootstrapping of network devices using the
   autonomic solution should be minimal for the human administrator.
   Probably it would be necessary just to inform the address of a device
   which is already using the solution and the devices themselves could
   exchange configuration data.

7.  Analysis of Parameters and Information Involved

   The active measurement model assumes that a typical infrastructure
   will have multiple network segments and Autonomous Systems (ASs), and
   a reasonably large number of several of routers and hosts.  It also
   considers that multiple SLOs can be in place in a given time.  Since
   interoperability in a heterogenous network is a goal, features found
   on different active measurement mechanisms (e.g.  OWAMP, TWAMP, and
   IPSLA) and programability interfaces (e.g., Cisco's EEM and onePK)
   could be used for the implementation.  The autonomic solution should
   include and/or reference specific algorithms, protocols, metrics and
   technologies for the implementation of distributed detection of SLA
   violations as a whole.

7.1.  Device Based Self-Knowledge and Decisions

   Each device has self-knowledge about the local SLA monitoring.  This
   could be in the form of historical measurement data and SLOs.
   Besides that, the devices would have algorithms that could decide
   which probes should be activated in a given time.  The choice of
   which algorithm is better for a specific situation would be also

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7.2.  Interaction with other devices

   Network devices should share information about service level
   measurement results.  This information can speed up the detection of
   SLA violations and increase the number of detected SLA violations.
   In any case, it is necessary to assure that the results from remote
   devices have local relevancy.  The definition of network devices that
   exchange measurement data, i.e., management peers, creates a new
   topology.  Different approaches could be used to define this topology
   (e.g., correlated peers [P2PBNM-Nobre-2012]).  To bootstrap peer
   selection, each device should use its known endpoints neighbors
   (e.g., FIB and RIB tables) as the initial seed to get possible peers.

8.  Comparison with current solutions

   There is no standartized solution for distributed autonomic detection
   of SLA violations.  Current solutions are restricted to ad hoc
   scripts running on a per node fashion to automate some
   administrator's actions.  There some proposals for passive probe
   activation (e.g., DECON and CSAMP), but without the focus on
   autonomic features.  It is also mentioning a proposal from Barford et
   al. to detect and localize links which cause anomalies along a
   network path.

9.  Related IETF Work

   The following paragraphs discuss related IETF work and are provided
   for reference.  This section is not exhaustive, rather it provides an
   overview of the various initiatives and how they relate to autonomic
   distributed detection of SLA violations.  1.  [LMAP]: The Large-Scale
   Measurement of Broadband Performance Working Group aims at the
   standards for performance management.  Since their mechanisms also
   consist in deploying measurement probes the autonomic solution could
   be relevant for LMAP specially considering SLA violation screening.
   Besides that, a solution to decrease the workload of human
   administrators in service providers is probably highly desirable.  2.
   [IPFIX]: IP Flow Information EXport (IPFIX) aims at the process of
   standardization of IP flows (i.e., netflows).  IPFIX uses measurement
   probes (i.e., metering exporters) to gather flow data.  In this
   context, the autonomic solution for the activation of active
   measurement probes could be possibly extended to address also passive
   measurement probes.  Besides that, flow information could be used in
   the decision making of probe activation.  3.  [ALTO]: The Application
   Layer Traffic Optimization Working Group aims to provide topological
   information at a higher abstraction layer, which can be based upon
   network policy, and with application-relevant service functions
   located in it.  Their work could be leveraged for the definition of

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   the topology regarding the network devices which exchange measurement

10.  Acknowledgements

   We wish to acknowledge the helpful contributions, comments, and
   suggestions that were received from Mohamed Boucadair, Bruno Klauser,
   Eric Voit, and Hanlin Fang.

11.  IANA Considerations

   This memo includes no request to IANA.

12.  Security Considerations

   The bootstrapping of a new device follows the approach proposed on
   anima wg [draft-anima-boot], thus in order to exchange data a device
   should register first.  This registration could be performed by a
   "Registrar" device or a cloud service provided by the organization to
   facilitate autonomic mechanisms.  The new device sends its own
   credentials to the Registrar, and after successful authentication,
   receives domain information, to enable subsequent enrolment to the
   domain.  The Registrar sends all required information: a device name,
   domain name, plus some parameters for the operation.  Measurement
   data should be exchanged signed and encripted among devices since
   these data could carry sensible information about network
   infrastructures.  Some attacks should be considering when analyzing
   the security of the autonomic solution.  Denial of service (DoS)
   attacks could be performed if the solution be tempered to active more
   local probe than the available resources allow.  Besides that,
   results could be forged by a device (attacker) in order to this
   device be considered peer of a specific device (target).  This could
   be done to gain information about a network.

13.  References

13.1.  Normative References

              Pritikin, M., Richardson, M., Behringer, M., and S.
              Bjarnason, "draft-ietf-anima-bootstrapping-keyinfra",
              draft-ietf-anima-bootstrapping-keyinfra-03 (work in
              progress), June 2016.

              Elkins, N., Hamilton, R., and M. Ackermann, "draft-ietf-
              ippm-6man-pdm-option", draft-ietf-ippm-6man-pdm-option-06
              (work in progress), September 2016.

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              Nobre, J., Granville, L., Clemm, A., and A. Prieto,
              "Decentralized Detection of SLA Violations Using P2P
              Technology, 8th International Conference Network and
              Service Management (CNSM)", 2012,

   [RFC4656]  Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
              Zekauskas, "A One-way Active Measurement Protocol
              (OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006,

   [RFC5357]  Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
              Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
              RFC 5357, DOI 10.17487/RFC5357, October 2008,

   [RFC6812]  Chiba, M., Clemm, A., Medley, S., Salowey, J., Thombare,
              S., and E. Yedavalli, "Cisco Service-Level Assurance
              Protocol", RFC 6812, DOI 10.17487/RFC6812, January 2013,

   [RFC7297]  Boucadair, M., Jacquenet, C., and N. Wang, "IP
              Connectivity Provisioning Profile (CPP)", RFC 7297,
              DOI 10.17487/RFC7297, July 2014,

13.2.  Informative References

   [RFC3954]  Claise, B., Ed., "Cisco Systems NetFlow Services Export
              Version 9", RFC 3954, DOI 10.17487/RFC3954, October 2004,

   [RFC4148]  Stephan, E., "IP Performance Metrics (IPPM) Metrics
              Registry", BCP 108, RFC 4148, DOI 10.17487/RFC4148, August
              2005, <>.

Authors' Addresses

   Jeferson Campos Nobre
   University of Vale do Rio dos Sinos
   Porto Alegre


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   Lisandro Zambenedetti Granvile
   Federal University of Rio Grande do Sul
   Porto Alegre


   Alexander Clemm
   Santa Clara, California


   Alberto Gonzalez Prieto
   Cisco Systems
   San Jose


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