





Internet Engineering Task Force (IETF)                   T. Senevirathne
Request for Comments: 6905                                         Cisco
Category: Informational                                          D. Bond
ISSN: 2070-1721                                                      IBM
                                                               S. Aldrin
                                                                   Y. Li
                                                                  Huawei
                                                                R. Watve
                                                                   Cisco
                                                              March 2013


   Requirements for Operations, Administration, and Maintenance (OAM)
        in Transparent Interconnection of Lots of Links (TRILL)

Abstract

   Operations, Administration, and Maintenance (OAM) is a general term
   used to identify functions and toolsets to troubleshoot and monitor
   networks.  This document presents OAM requirements applicable to the
   Transparent Interconnection of Lots of Links (TRILL).

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6905.














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Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
      1.1. Scope ......................................................3
   2. Conventions Used in This Document ...............................3
   3. Terminology .....................................................3
   4. OAM Requirements ................................................4
      4.1. Data Plane .................................................4
      4.2. Connectivity Verification ..................................5
           4.2.1. Unicast .............................................5
           4.2.2. Distribution Trees ..................................5
      4.3. Continuity Check ...........................................5
      4.4. Path Tracing ...............................................6
      4.5. General Requirements .......................................6
      4.6. Performance Monitoring .....................................7
           4.6.1. Packet Loss .........................................7
           4.6.2. Packet Delay ........................................7
      4.7. ECMP Utilization ...........................................8
      4.8. Security and Operational Considerations ....................8
      4.9. Fault Indications ..........................................8
      4.10. Defect Indications ........................................9
      4.11. Live Traffic Monitoring ...................................9
   5. Security Considerations .........................................9
   6. References ......................................................9
      6.1. Normative References .......................................9
      6.2. Informative References ....................................10
   7. Acknowledgments ................................................11
   8. Contributors ...................................................11








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1.  Introduction

   The Operations, Administration, and Maintenance (OAM) generally
   covers various production aspects of a network.  In this document, we
   use the term OAM as defined in [RFC6291].

   The success of network operations depends on the ability to
   proactively monitor it for faults, performance, etc., as well as the
   ability to efficiently and quickly troubleshoot defects and failures.
   A well-defined OAM toolset is a vital requirement for wider adoption
   of Transparent Interconnection of Lots of Links (TRILL) as the next
   generation data-forwarding technology in larger networks such as data
   centers.

   In this document, we define the requirements for TRILL OAM.  It is
   assumed that the readers are familiar with the OAM concepts and
   terminologies defined in other OAM standards such as [8021ag],
   [RFC5860], and [RFC4377].  This document does not attempt to redefine
   the terms and concepts specified elsewhere.

1.1.  Scope

   The scope of this document is OAM between Routing Bridges (RBridges)
   of a TRILL campus over links selected by TRILL routing.

2.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].
   Although this document is not a protocol specification, the use of
   this language clarifies the instructions to protocol designers
   producing solutions that satisfy the requirements set out in this
   document.

3.  Terminology

   Section: This term refers to a segment of a path between any two
   given RBridges.  As an example, consider the case where RB1 is
   connected to RBx via RB2, RB3, and RB4.  The segment between RB2 to
   RB4 is referred to as a section of the path RB1 to RBx.  More details
   of this definition can be found in [RFC5960].

   Flow: This term indicates a set of packets that share the same path
   and per-hop behavior (such as priority).  A flow is typically
   identified by a portion of the inner payload that affects the hop-by-
   hop forwarding decisions.  This may contain Layer 2 through Layer 4
   information.



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   All Selectable Least-Cost Paths: This term refers to a subset of all
   potentially available least-cost paths to a specified destination
   RBridge that are available (and usable) for forwarding of frames.  It
   is important to note that in practice, due to limitations in
   implementations, not all available least-cost paths may be selectable
   for forwarding.

   Connectivity: This term indicates reachability between an arbitrary
   RBridge RB1 and any other RBridge RB2.  The specific path can be
   either explicit (i.e., associated with a specific flow) or
   unspecified.  Unspecified means that messages used for connectivity
   verification take whatever path the RBs happen to select.  Please
   refer to [OAMOVER] for details.

   Continuity Verification: This term refers to proactive verification
   of liveliness between two RBridges at periodic intervals and the
   generation of explicit notification when connectivity failures occur.
   Please refer to [OAMOVER] for details.

   Fault: This term refers to an inability to perform a required action,
   e.g., an unsuccessful attempt to deliver a packet.  Please refer to
   [TERMTP] for definition.

   Defect: This term refers to an interruption in the normal operation,
   such that over a period of time no packets are delivered
   successfully.  Please refer to [TERMTP] for definition.

   Failure: This term refers to the termination of the required function
   over a longer period of time.  Persistence of a defect for a period
   of time is interpreted as a failure.  Please refer to [TERMTP] for
   definition.

   Simulated Flow: This term refers to a sequence of OAM-generated
   packets designed to follow a specific path.  The fields of the
   packets in the simulated flow may or may not be identical to the
   fields of data packets of an actual flow being simulated.  However,
   the purpose of the simulated flow is to have OAM packets of the
   simulated flow follow a specific path.

4.  OAM Requirements

4.1.  Data Plane

   OAM frames, utilized for connectivity verification, continuity
   checks, performance measurements, etc., will by default take whatever
   path TRILL chooses based on the current topology and per-hop equal-
   cost path choices.  In some cases, it may be required that the OAM




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   frames utilize specific paths.  Thus, it MUST be possible to arrange
   that OAM frames follow the path taken by a specific flow.

   RBridges MUST have the ability to identify frames that require OAM
   processing.

   TRILL OAM frames MUST remain within a TRILL campus and MUST NOT be
   egressed from a TRILL network as native frames.

   OAM MUST have the ability to include all Ethernet traffic types
   carried by TRILL.

4.2.  Connectivity Verification

4.2.1.  Unicast

   From an arbitrary RBridge RB1, OAM MUST have the ability to verify
   connectivity to any other RBridge RB2.

   From an arbitrary RBridge RB1, OAM MUST have the ability to verify
   connectivity to any other RBridge RB2 for a specific flow via the
   path associated with the specified flow.

4.2.2.  Distribution Trees

   OAM MUST have the ability to verify connectivity from an arbitrary
   RBridge RB1 to either a specific set of RBridges or all member
   RBridges, for a specified distribution tree.  This functionality is
   referred to as verification of the unpruned distribution tree.

   OAM MUST have the ability to verify connectivity from an arbitrary
   RBridge RB1 to either a specific set of RBridges or all member
   RBridges, for a specified distribution tree and for a specified flow.
   This functionality is referred to as verification of the pruned tree.

4.3.  Continuity Check

   OAM MUST provide functions that allow any arbitrary RBridge RB1 to
   perform a Continuity Check to any other RBridge.

   OAM MUST provide functions that allow any arbitrary RBridge RB1 to
   perform a Continuity Check to any other RBridge using a path
   associated with a specified flow.

   OAM SHOULD provide functions that allow any arbitrary RBridge to
   perform a Continuity Check to any other RBridge over any section of
   any selectable least-cost path.




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   OAM SHOULD provide the ability to perform a Continuity Check on
   sections of any selectable path within the network.

   OAM SHOULD provide the ability to perform a multicast Continuity
   Check for specified distribution tree(s), as well as specified
   combinations of distribution trees and flows.  The former is referred
   to as an unpruned multi-destination tree Continuity Check and the
   latter is referred to as a pruned tree Continuity Check.

4.4.  Path Tracing

   OAM MUST provide the ability to trace a path between any two RBridges
   corresponding to a specified unicast flow.

   OAM SHOULD provide the ability to trace all selectable least-cost
   paths between any two RBridges.

   OAM SHOULD provide functionality to trace all branches of a specified
   distribution tree (unpruned tree).

   OAM SHOULD provide functionality to trace all branches of a specified
   distribution tree for a specified flow (pruned tree).

4.5.  General Requirements

   OAM MUST provide the ability to initiate and maintain multiple
   concurrent sessions for multiple OAM functions between any arbitrary
   RBridge RB1 to any other RBridge.  In general, multiple OAM
   operations will run concurrently.  For example, proactive continuity
   checks may take place between RB1 and RB2 at the same time that an
   operator decides to test connectivity between the same two RBs.
   Multiple OAM functions and instances of those functions MUST be able
   to run concurrently without interfering with each other.

   OAM MUST provide a single OAM framework for all TRILL OAM functions
   within the scope of this document.

   OAM, as practical and as possible, SHOULD reuse functional,
   operational, and semantic elements of existing OAM standards.

   OAM MUST maintain related error and operational counters.  Such
   counters MUST be accessible via network management applications
   (e.g., SNMP).

   OAM functions related to continuity and connectivity checks MUST be
   able to be invoked either proactively or on demand.





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   OAM MAY be required to provide the ability to specify a desired
   response mode for a specific OAM message.  The desired response mode
   can be in-band, out-of-band, or none.

   The OAM Framework MUST be extensible to include new functionality.
   For example, the solution needs to include a version number to
   differentiate older and newer implementations and TLV structures for
   flexibility to include new information elements.

   OAM MAY provide methods to verify control-plane and forwarding-plane
   alignments.

   OAM SHOULD leverage existing OAM technologies, where practical.

4.6.  Performance Monitoring

4.6.1.  Packet Loss

   In this document, the term "packet loss" is used as defined in
   Section 2.4 of [RFC2680].

   OAM SHOULD provide the ability to measure packet loss statistics for
   a flow from any arbitrary RBridge RB1 to any other RBridge.

   OAM SHOULD provide the ability to measure packet loss statistics over
   a section for a flow between any arbitrary RBridge RB1 to any other
   RBridge.

   OAM SHOULD provide the ability to measure packet loss statistics
   between any two RBridges over all least-cost paths.

   An RBridge SHOULD be able to perform the above packet loss
   measurement functions either proactively or on demand.

4.6.2.  Packet Delay

   There are two types of packet delays -- one-way delay and two-way
   delay (Round-Trip Delay).

   One-way delay is defined in [RFC2679] as the time elapsed from the
   start of transmission of the first bit of a packet by an RBridge
   until the reception of the last bit of the packet by the destination
   RBridge.








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   Two-way delay is also referred to as Round-Trip Delay and is defined
   similar to [RFC2681]; i.e., the time elapsed from the start of
   transmission of the first bit of a packet from RB1, receipt of the
   packet at RB2, RB2 sending a response packet back to RB1, and RB1
   receiving the last bit of that response packet.

   OAM SHOULD provide functions to measure two-way delay between two
   RBridges.

   OAM MAY provide functions to measure one-way delay between two
   RBridges for a specified flow.

   OAM MAY provide functions to measure one-way delay between two
   RBridges for a specified flow over a specific section.

4.7.  ECMP Utilization

   OAM MAY provide functionality to monitor the effectiveness of per-hop
   Equal-Cost Multipath (ECMP) hashing.  For example, individual
   RBridges could maintain counters that show how packets are being
   distributed across equal-cost next hops for a specified destination
   RBridge or RBridges as a result of ECMP hashing.

4.8.  Security and Operational Considerations

   Methods MUST be provided to protect against exploitation of OAM
   framework for security and denial-of-service attacks.

   Methods MUST be provided to prevent OAM messages from causing
   congestion in the networks.  Periodically generated messages with
   high frequencies may lead to congestion, hence methods such as
   shaping or rate limiting SHOULD be utilized.

   Certain OAM functions may be utilized to gather operational
   information such as topology of the network.  Methods MUST be
   provided to prevent unauthorized users accessing OAM functions to
   gather critical and sensitive information of the network.

   OAM packets MUST be limited to within the TRILL campus, and the
   implementation MUST provide methods to prevent leaking of OAM packets
   out of the TRILL campus.  Additionally, methods MUST be provided to
   prevent accepting OAM packets from outside the TRILL campus.

4.9.  Fault Indications

   OAM MUST provide a Fault Indication framework to notify the packet's
   ingress RBridge or other interested parties (such as syslog servers)
   about faults.



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   OAM MUST provide functions to selectively enable or disable different
   types of Fault Indications.

4.10.  Defect Indications

   OAM SHOULD provide a framework for Defect Detection and Indication.

   OAM Defect Detection and Indication Framework SHOULD provide methods
   to selectively enable or disable Defect Detection per defect type.

   OAM Defect Detection and Indication Framework SHOULD provide methods
   to configure Defect Detection thresholds per different types of
   defects.

   OAM Defect Detection and Indication Framework SHOULD provide methods
   to log defect indications to a locally defined archive (such as log
   buffer) or Simple Network Management Protocol (SNMP) traps.

   OAM Defect Detection and Indication Framework SHOULD provide a Remote
   Defect Indication framework that facilitates notifying the
   originator/owner of the flow experiencing the defect, which is the
   ingress RBridge.

   Remote Defect Indication MAY be either in-band or out-of-band.

4.11.  Live Traffic Monitoring

   OAM implementations MAY provide methods to utilize live traffic for
   troubleshooting and performance monitoring.

5.  Security Considerations

   Security requirements are specified in Section 4.8. For general TRILL
   security considerations, please refer to [RFC6325].

6.  References

6.1.  Normative References

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

   [RFC6291]  Andersson, L., van Helvoort, H., Bonica, R., Romascanu,
              D., and S. Mansfield, "Guidelines for the Use of the "OAM"
              Acronym in the IETF", BCP 161, RFC 6291, June 2011.






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6.2.  Informative References

   [8021ag]   IEEE, "Virtual Bridged Local Area Networks Amendment 5:
              Connectivity Fault Management", IEEE Std 802.1ag-2007,
              2007.

   [OAMOVER]  Mizrahi, T., Sprecher, N., Bellagamba, E., Y. Weingarten,
              "An Overview of Operations, Administration, and
              Maintenance (OAM) Mechanisms", Work in Progress, January
              2013.

   [RFC2679]  Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
              Delay Metric for IPPM", RFC 2679, September 1999.

   [RFC2680]  Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
              Packet Loss Metric for IPPM", RFC 2680, September 1999.

   [RFC2681]  Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
              Delay Metric for IPPM", RFC 2681, September 1999.

   [RFC4377]  Nadeau, T., Morrow, M., Swallow, G., Allan, D., and S.
              Matsushima, "Operations and Management (OAM) Requirements
              for Multi-Protocol Label Switched (MPLS) Networks", RFC
              4377, February 2006.

   [RFC5860]  Vigoureux, M., Ed., Ward, D., Ed., and M. Betts, Ed.,
              "Requirements for Operations, Administration, and
              Maintenance (OAM) in MPLS Transport Networks", RFC 5860,
              May 2010.

   [RFC5960]  Frost, D., Ed., Bryant, S., Ed., and M. Bocci, Ed., "MPLS
              Transport Profile Data Plane Architecture", RFC 5960,
              August 2010.

   [RFC6325]  Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
              Ghanwani, "Routing Bridges (RBridges): Base Protocol
              Specification", RFC 6325, July 2011.

   [TERMTP]   van Helvoort, H., Ed., Andersson, L., Ed., and N.
              Sprecher, Ed., "A Thesaurus for the Terminology used in
              Multiprotocol Label Switching Transport Profile (MPLS-TP)
              drafts/RFCs and ITU-T' Transport Network Recommendations",
              Work in Progress, February 2013.








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7.  Acknowledgments

   Special acknowledgments to IEEE 802.1 chair, Tony Jeffree, for
   allowing us to solicit comments from IEEE 802.1 group.  Also
   recognized are the comments received from the IEEE group, IESG,
   Stewart Bryant, Ralph Droms, Adrian Farrel, Benoit Claise, Ayal Lior,
   and others.

8.  Contributors

   Thomas Narten
   IBM Corporation
   3039 Cornwallis Avenue,
   PO Box 12195
   Research Triangle Park, NC 27709
   USA

   EMail:narten@us.ibm.com


   Donald Eastlake
   Huawei Technologies
   155 Beaver Street,
   Milford, MA 01757
   USA

   EMail: d3e3e3@gmail.com


   Anoop Ghanwani
   Dell
   350 Holger Way
   San Jose, CA 95134
   USA

   Phone: +1-408-571-3500
   EMail: Anoop@alumni.duke.edu


   Jon Hudson
   Brocade
   120 Holger Way
   San Jose, CA 95134
   USA

   EMail: jon.hudson@gmail.com





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   Naveen Nimmu
   Broadcom
   9th Floor, Building no 9, Raheja Mind space
   Hi-Tec City, Madhapur,
   Hyderabad - 500 081
   India

   Phone: +1-408-218-8893
   EMail: naveen@broadcom.com


   Radia Perlman
   Intel Labs
   2700 156th Ave NE, Suite 300,
   Bellevue, WA 98007
   USA

   Phone: +1-425-881-4824
   EMail: radia.perlman@intel.com


   Tal Mizrahi
   Marvell
   6 Hamada St.
   Yokneam, 20692
   Israel

   EMail: talmi@marvell.com

Authors' Addresses

   Tissa Senevirathne
   Cisco Systems
   375 East Tasman Drive
   San Jose, CA 95134
   USA

   Phone: +1-408-853-2291
   EMail: tsenevir@cisco.com












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   David Bond
   IBM
   4400 North 1st Street
   San Jose, CA 95134
   USA

   Phone: +1-603-339-7575
   EMail: mokon@mokon.net


   Sam Aldrin
   Huawei Technologies
   2330 Central Express Way
   Santa Clara, CA 95951
   USA

   EMail: aldrin.ietf@gmail.com


   Yizhou Li
   Huawei Technologies
   101 Software Avenue,
   Nanjing 210012
   China

   Phone: +86-25-56625375
   EMail: liyizhou@huawei.com


   Rohit Watve
   Cisco Systems
   375 East Tasman Drive
   San Jose, CA 95134
   USA

   Phone: +1-408-424-2091
   EMail: rwatve@cisco.com














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