I2RS                                                           J. Clarke
Internet-Draft                                              G. Salgueiro
Intended status: Informational                              C. Pignataro
Expires: June 14, 2015                                             Cisco
                                                       December 11, 2014

   Interface to the Routing System (I2RS) Traceability: Framework and
                           Information Model


   This document describes a framework for traceability in the Interface
   to the Routing System (I2RS) and information model for that
   framework.  It specifies the motivation, requirements, use cases, and
   defines an information model for recording interactions between
   elements implementing the I2RS protocol.  This framework provides a
   consistent tracing interface for components implementing the I2RS
   architecture to record what was done, by which component, and when.
   It aims to improve the management of I2RS implementations, and can be
   used for troubleshooting, auditing, forensics, and accounting

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology and Conventions . . . . . . . . . . . . . . . . .   3
   3.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Information Model . . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  I2RS Traceability Framework . . . . . . . . . . . . . . .   4
     5.2.  I2RS Trace Log Mandatory Fields . . . . . . . . . . . . .   5
     5.3.  End of Message Marker . . . . . . . . . . . . . . . . . .   7
     5.4.  I2RS Trace Log Extensibility and Optional Fields  . . . .   7
   6.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   7.  Operational Guidance  . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Trace Log Creation  . . . . . . . . . . . . . . . . . . .   8
     7.2.  Trace Log Temporary Storage . . . . . . . . . . . . . . .   8
     7.3.  Trace Log Rotation  . . . . . . . . . . . . . . . . . . .   8
     7.4.  Trace Log Retrieval . . . . . . . . . . . . . . . . . . .   8
       7.4.1.  Retrieval Via Syslog  . . . . . . . . . . . . . . . .   9
       7.4.2.  Retrieval Via I2RS Information Collection . . . . . .   9
       7.4.3.  Retrieval Via I2RS Pub-Sub  . . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  10
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     11.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   The architecture for the Interface to the Routing System
   ([I-D.ietf-i2rs-architecture]) specifies that I2RS Clients wishing to
   retrieve or change routing state on a routing element MUST
   authenticate to an I2RS Agent.  The I2RS Client will have a unique
   identity it provides for authentication, and should provide another,
   opaque identifier for applications (or actors) communicating through
   it.  The programming of routing state will produce a return code
   containing the results of the specified operation and associated
   reason(s) for the result.  All of this is critical information to be
   used for understanding the history of I2RS interactions.

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   This document describes use cases for I2RS traceability.  Based on
   these use cases, the document proposes an information model and
   reporting requirements to provide for effective recording of I2RS
   interactions.  In this context, effective troubleshooting means being
   able to identify what operation was performed by a specific I2RS
   Client, what was the result of the operation, and when that operation
   was performed.

   Discussions about the retention of the data logged as part of I2RS
   traceability, while important, are outside of the scope of this

2.  Terminology and Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

   The architecture specification for I2RS [I-D.ietf-i2rs-architecture]
   defines additional terms used in this document that are specific to
   the I2RS domain, such as "I2RS Agent", "I2RS Client", etc.  The
   reader is expected to be familiar with the terminology and concepts
   defined in [I-D.ietf-i2rs-architecture].

   The IP addresses used in the example in this document correspond to
   the documentation address blocks (TEST-NET-1), (TEST-NET-2) and (TEST-NET-3) as
   described in [RFC5737].

3.  Motivation

   As networks scale and policy becomes an increasingly important part
   of the control plane that creates and maintains the forwarding state,
   operational complexity increases as well.  I2RS offers more granular
   and coherent control over policy and control plane state, but it also
   removes or reduces the locality of the policy that has been applied
   to the control plane at any individual forwarding device.  The
   ability to automate and abstract even complex policy-based controls
   highlights the need for an equally scalable traceability function to
   provide event-level granularity of the routing system compliant with
   the requirements of I2RS (Section 5 of

4.  Use Cases

   An obvious motivation for I2RS traceability is the need to
   troubleshoot and identify root-causes of problems in these
   increasingly complex routing systems.  For example, since I2RS is a

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   high-throughput multi-channel, full duplex and highly responsive
   interface, I2RS Clients may be performing a large number of
   operations on I2RS Agents concurrently or at nearly the same time and
   quite possibly in very rapid succession.  As these many changes are
   made, the network reacts accordingly.  These changes might lead to a
   race condition, performance issues, data loss, or disruption of
   services.  In order to isolate the root cause of these issues it is
   critical that a network operator or administrator has visibility into
   what changes were made via I2RS at a specific time.

   Some network environments have strong auditing requirements for
   configuration and runtime changes.  Other environments have policies
   that require saving logging information for operational or regulatory
   compliance considerations.  These requirements therefore demand that
   I2RS provides an account of changes made to network element routing

   As I2RS becomes increasingly pervasive in routing environments, a
   traceability model offers significant advantages and facilitates the
   following use cases:

   o  Automated event correlation, trend analysis, and anomaly

   o  Trace log storage for offline (manual or tools) analysis.

   o  Improved accounting of routing system transactions.

   o  Standardized structured data format for writing common tools.

   o  Common reference for automated testing and incident reporting.

   o  Real-time monitoring and troubleshooting.

   o  Enhanced network audit, management and forensic analysis

5.  Information Model

5.1.  I2RS Traceability Framework

   This section describes a framework for I2RS traceability based on the
   I2RS Architecture.  Some notable elements on the architecture are
   highlighted herein.

   The interaction between the optional northbound actor, I2RS Client,
   I2RS Agent, the Routing System and the data captured in the I2RS
   trace log is shown in Figure 1.

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         |Actor        |
         |  Actor ID   |
                |   0 .. N
         |I2RS Client  |
         |  Client ID  |
                |  1 .. N
         +-------------+                 +-----------------------------+
         |I2RS Agent   |---------------->|Trace Log                    |
         |             |                 |.............................|
         +-------------+                 |Log Entry  [1 .. N]          |
                ^                        |.............................|
                |                        |Timestamp                    |
                |                        |Client ID                    |
                |      ^                 |Actor ID                     |
    Operation + | Result Code            |Client Address               |
     Op Data    |                        |Operation                    |
        V       |                        |Operation Data               |
                |                        |Result Code                  |
                V                        |End Of Message               |
         +-------------+                 +-----------------------------+
         |Routing      |
         |System       |

               Figure 1: I2RS Interaction Trace Log Capture

5.2.  I2RS Trace Log Mandatory Fields

   In order to ensure that each I2RS interaction can be properly traced
   back to the Client that made the request at a specific point in time,
   the following information MUST be collected and stored by the Agent.

   The list below describes the fields captured in the I2RS trace log.

   Entry ID:   This is a unique identifier for each entry in the I2RS
      trace log.  Since multiple operations can occur from the same

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      client at the same time, it is important to have an identifier
      that can be unambiguously associated to a specific entry.

   Timestamp:   The specific time, adhering to [RFC3339] format, at
      which the I2RS transaction occurred.  Given that many I2RS
      transactions can occur in rapid succession, the use of fractional
      seconds MUST be used to provide adequate granularity.

   Client Identifier:   The I2RS Client identifier used to authenticate
      the Client to the I2RS Agent.

   Actor Identifier:   This is an opaque identifier that may be known to
      the Client from a northbound controlling application.  This is
      used to trace the northbound actor driving the actions of the
      Client.  The Client may not provide this identifier to the Agent
      if there is no external actor driving the Client.  However, this
      field MUST be logged.  If the Client does not provide an actor ID,
      then the Agent MUST log an UNAVAILABLE value in the field.

   Client Address:   This is the network address of the client that
      connected to the Agent.  For example, this may be an IPv4 or IPv6
      address.  [Note: will I2RS support interactions that have no
      network address?  If so this field will need to be updated.]

   Operation:   This is the I2RS operation performed.  For example, this
      may be an add route operation if a route is being inserted into a
      routing table.

   Operation Data:   This field comprises the data passed to the Agent
      to complete the desired operation.  For example, if the operation
      is a route add operation, the Operation Data would include the
      route prefix, prefix length, and next hop information to be
      inserted as well as the specific routing table to which the route
      will be added.  The operation data can also include interface
      information.  Some operations may not provide operation data, and
      in those cases this field MUST be logged as a NULL string.

   Result Code:   This field holds the result of the operation.  In the
      case of RIB operations, this MUST be the return code as specified
      in Section 4 of [I-D.nitinb-i2rs-rib-info-model].  The operation
      may not complete with a result code in the case of a timeout.  If
      the operation fails to complete, it MUST still log the attempted
      operation with an appropriate result code (e.g., a result code
      indicating a timeout).

   End Of Message:   Each log entry SHOULD have an appropriate End Of
      Message (EOM) indicator.  See section Section 5.3 below for more

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5.3.  End of Message Marker

   Because of variability within I2RS trace log fields, implementors
   MUST use a format-appropriate end of message (EOM) indicator in order
   to signify the end of a particular record.  That is, regardless of
   format, the I2RS trace log MUST provide a distinct way of
   distinguishing between the end of one record and the beginning of
   another.  For example, in a linear formated log (similar to syslog)
   the EOM marker may be a newline character.  In an XML formated log,
   the schema would provide for element tags that denote beginning and
   end of records.  In a JSON formated log, the syntax would provide
   record separation (likely by comma-separated array elements).

5.4.  I2RS Trace Log Extensibility and Optional Fields

   [NOTE: This section is TBD based on further development of I2RS WG

6.  Examples

   Here is a proposed sample of what the fields might look like in an
   I2RS trace log.  This is only an early proposal.  These values are
   subject to change.

   Entry ID:       1
   Timestamp:      2013-09-03T12:00:01.21+00:00
   Client ID:      5CEF1870-0326-11E2-A21F-0800200C9A66
   Actor ID:       com.example.RoutingApp
   Client Address:
   Operation:      ROUTE_ADD
   Operation Data: PREFIX PREFIX-LEN 24 NEXT-HOP
   Result Code:    SUCCESS(0)

7.  Operational Guidance

   Specific operational procedures regarding temporary log storage,
   rollover, retrieval, and access of I2RS trace logs is out of scope
   for this document.  Organizations employing I2RS trace logging are
   responsible for establishing proper operational procedures that are
   appropriately suited to their specific requirements and operating
   environment.  In this section we only provide fundamental and
   generalized operational guidelines that are implementation-

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7.1.  Trace Log Creation

   The I2RS Agent interacts with the Routing and Signaling functions of
   the Routing Element.  Since the I2RS Agent is responsible for
   actually making the routing changes on the associated network device,
   it creates and maintains a log of transactions that can be retrieved
   to troubleshoot I2RS-related impact to the network.

7.2.  Trace Log Temporary Storage

   The trace information may be temporarily stored either in an in-
   memory buffer or as a file local to the Agent.  Care should be given
   to the number of I2RS transactions expected on a given agent so that
   the appropriate storage medium is used and to maximize the
   effectiveness of the log while not impacting the performance and
   health of the Agent.  Section 7.3 talks about rotating the trace log
   in order to preserve the transaction history without exhausting Agent
   or network device resources.  It is perfectly acceptable, therefore,
   to use both an in-memory buffer for recent transactions while
   rotating or archiving older transactions to a local file.

   It is outside the scope of this document to specify the
   implementation details (i.e., size, throughput, data protection,
   privacy, etc.) for the physical storage of the I2RS log file.  Data
   retention policies of the I2RS traceability log is also outside the
   scope of this document.

7.3.  Trace Log Rotation

   In order to prevent the exhaustion of resources on the I2RS Agent or
   its associated network device, it is RECOMMENDED that the I2RS Agent
   implements trace log rotation.  The details on how this is achieved
   are left to the implementation and outside the scope of this
   document.  However, it should be possible to do file rotation based
   on either time or size of the current trace log.  If file rollover is
   supported, multiple archived log files should be supported in order
   to maximize the troubleshooting and accounting benefits of the trace

7.4.  Trace Log Retrieval

   Implementors are free to provide their own, proprietary interfaces
   and develop custom tools to retrieve and display the I2RS trace log.
   These may include the display of the I2RS trace log as Command Line
   Interface (CLI) output.  However, a key intention of defining this
   information model is to establish an implementor-agnostic and
   consistent interface to collect I2RS trace data.  Correspondingly,
   retrieval of the data should also be made implementor-agnostic.

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   The following three sections describe potential ways the trace log
   can be accessed.  At least one of these three MUST be used, with the
   I2RS mechanisms being preferred as they are implementor-independent
   approaches to retrieving the data.

7.4.1.  Retrieval Via Syslog

   The syslog protocol [RFC5424] is a standard way of sending event
   notification messages from a host to a collector.  However, the
   protocol does not define any standard format for storing the
   messages, and thus implementors of I2RS tracing would be left to
   define their own format.  So, while the data contained within the
   syslog message would adhere to this information model, and may be
   consumable by a human operator, it would not be easily parseable by a
   machine.  Therefore, syslog MAY be employed as a means of retrieving
   or disseminating the I2RS trace log contents.

7.4.2.  Retrieval Via I2RS Information Collection

   Section 6.7 of the I2RS architecture [I-D.ietf-i2rs-architecture]
   defines a mechanism for information collection.  The information
   collected includes obtaining a snapshot of a large amount of data
   from the network element.  It is the intent of I2RS to make this data
   available in an implementor-agnostic fashion.  Therefore, the I2RS
   trace log SHOULD be made available via the I2RS information
   collection mechanism either as a single snapshot or via a
   subscription stream.

7.4.3.  Retrieval Via I2RS Pub-Sub

   Section 6.7 of the I2RS architecture [I-D.ietf-i2rs-architecture]
   goes on to define a publish-subscribe mechanism for a feed of changes
   happening within the I2RS layer.  I2RS Agents SHOULD support
   publishing I2RS trace log information to that feed as described in
   that document.  Subscribers would then receive a live stream of I2RS
   interactions in trace log format and could flexibly choose to do a
   number of things with the log messages.  For example, the subscribers
   could log the messages to a datastore, aggregate and summarize
   interactions from a single client, etc.  Using pub-sub for the
   purpose of logging I2RS interactions augments the areas described by
   [I-D.camwinget-i2rs-pubsub-sec].  The full range of potential
   activites is virtually limitless and the details of how they are
   performed are outside the scope of this document, however.

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8.  IANA Considerations

   This document makes no request of IANA.

9.  Security Considerations

   The I2RS trace log, like any log file, reveals the state of the
   entity producing it as well as the identifying information elements
   and detailed interactions of the system containing it.  The
   information model described in this document does not itself
   introduce any security issues, but it does define the set of
   attributes that make up an I2RS log file.  These attributes may
   contain sensitive information and thus should adhere to the security,
   privacy and permission policies of the organization making use of the
   I2RS log file.

   It is outside the scope of this document to specify how to protect
   the stored log file, but it is expected that adequate precautions and
   security best practices such as disk encryption, appropriately
   restrictive file/directory permissions, suitable hardening and
   physical security of logging entities, mutual authentication,
   transport encryption, channel confidentiality, and channel integrity
   if transferring log files.  Additionally, the potentially sensitive
   information contained in a log file SHOULD be adequately anonymized
   or obfuscated by operators to ensure its privacy.

10.  Acknowledgments

   The authors would like to thank Alia Atlas for her initial feedback
   and overall support for this work.  Additionally, the authors
   acknowledge Alvaro Retana, Russ White, Matt Birkner, Jeff Haas, Joel
   Halpern and Dean Bogdanovich for their reviews, contributed text, and
   suggested improvements to this document.

11.  References

11.1.  Normative References

              Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
              Nadeau, "An Architecture for the Interface to the Routing
              System", draft-ietf-i2rs-architecture-06 (work in
              progress), December 2014.

              Atlas, A., Nadeau, T., and D. Ward, "Interface to the
              Routing System Problem Statement", draft-ietf-i2rs-
              problem-statement-04 (work in progress), June 2014.

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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

11.2.  Informative References

              Beck, K., Cam-Winget, N., and D. McGrew, "Using the
              Publish-Subscribe Model in the Interface to the Routing
              System", draft-camwinget-i2rs-pubsub-sec-00 (work in
              progress), July 2013.

              Bahadur, N., Folkes, R., Kini, S., and J. Medved, "Routing
              Information Base Info Model", draft-nitinb-i2rs-rib-info-
              model-02 (work in progress), August 2013.

   [RFC3339]  Klyne, G., Ed. and C. Newman, "Date and Time on the
              Internet: Timestamps", RFC 3339, July 2002.

   [RFC5424]  Gerhards, R., "The Syslog Protocol", RFC 5424, March 2009.

   [RFC5737]  Arkko, J., Cotton, M., and L. Vegoda, "IPv4 Address Blocks
              Reserved for Documentation", RFC 5737, January 2010.

Authors' Addresses

   Joe Clarke
   Cisco Systems, Inc.
   7200-12 Kit Creek Road
   Research Triangle Park, NC  27709

   Phone: +1-919-392-2867
   Email: jclarke@cisco.com

   Gonzalo Salgueiro
   Cisco Systems, Inc.
   7200-12 Kit Creek Road
   Research Triangle Park, NC  27709

   Email: gsalguei@cisco.com

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   Carlos Pignataro
   Cisco Systems, Inc.
   7200-12 Kit Creek Road
   Research Triangle Park, NC  27709

   Email: cpignata@cisco.com

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