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.
Senevirathne, et al. Informational [Page 1]RFC 6905 TRILL OAM Requirements March 2013
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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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RFC 6905 TRILL OAM Requirements March 2013
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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RFC 6905 TRILL OAM Requirements March 2013
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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