Internet DRAFT - draft-ietf-ccamp-oam-configuration-fwk
draft-ietf-ccamp-oam-configuration-fwk
Network Working Group A. Takacs
Internet-Draft Ericsson
Intended status: Standards Track D. Fedyk
Expires: August 29, 2014 Hewlett-Packard Company
J. He
Huawei
February 25, 2014
GMPLS RSVP-TE extensions for OAM Configuration
draft-ietf-ccamp-oam-configuration-fwk-13
Abstract
Operations, Administration and Maintenance (OAM) is an integral part
of transport connections, hence it is required that OAM functions are
activated/deactivated in sync with connection commissioning/
decommissioning; avoiding spurious alarms and ensuring consistent
operation. In certain technologies, OAM entities are inherently
established once the connection is set up, while other technologies
require extra configuration to establish and configure OAM entities.
This document specifies extensions to RSVP-TE to support the
establishment and configuration of OAM entities along with Label
Switched Path signaling.
Requirements Language
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 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 29, 2014.
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Copyright Notice
Copyright (c) 2014 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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4
3. RSVP-TE based OAM Configuration . . . . . . . . . . . . . . . 6
3.1. Establishment of OAM Entities and Functions . . . . . . . 8
3.2. Adjustment of OAM Parameters . . . . . . . . . . . . . . 9
3.3. Deleting OAM Entities . . . . . . . . . . . . . . . . . . 10
4. RSVP-TE Extensions . . . . . . . . . . . . . . . . . . . . . 11
4.1. LSP Attributes Flags . . . . . . . . . . . . . . . . . . 11
4.2. OAM Configuration TLV . . . . . . . . . . . . . . . . . . 12
4.2.1. OAM Function Flags Sub-TLV . . . . . . . . . . . . . 14
4.2.2. Technology Specific Sub-TLVs . . . . . . . . . . . . 14
4.3. Administrative Status Information . . . . . . . . . . . . 15
4.4. Handling OAM Configuration Errors . . . . . . . . . . . . 15
4.5. Considerations on Point-to-Multipoint OAM Configuration . 16
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
5.1. ADMIN_STATUS Object Bit Flags . . . . . . . . . . . . . . 17
5.2. LSP Attributes Flags . . . . . . . . . . . . . . . . . . 17
5.3. New LSP Attributes . . . . . . . . . . . . . . . . . . . 18
5.4. RSVP Error Code . . . . . . . . . . . . . . . . . . . . . 18
5.5. RSVP-TE OAM Configuration Registry . . . . . . . . . . . 19
5.5.1. OAM Types Sub-Registry . . . . . . . . . . . . . . . 19
5.5.2. OAM Sub-TLVs Sub-Registry . . . . . . . . . . . . . . 19
5.5.3. OAM Function Flags Sub-Registry . . . . . . . . . . . 20
6. Security Considerations . . . . . . . . . . . . . . . . . . . 20
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1. Normative References . . . . . . . . . . . . . . . . . . 21
8.2. Informative References . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Introduction
GMPLS is designed as an out-of-band control plane supporting dynamic
connection provisioning for any suitable data plane technology;
including spatial switching (e.g., incoming port or fiber to outgoing
port or fiber), wavelength-division multiplexing (e.g., Dense
Wavelength Division Multiplexing (DWDM)), time-division multiplexing
(e.g., SONET/SDH, G.709), and Ethernet Provider Backbone Bridging -
Traffic Engineering (PBB-TE) and MPLS. In most of these
technologies, there are Operations, Administration and Maintenance
(OAM) functions employed to monitor the health and performance of the
connections and to trigger data plane (DP) recovery mechanisms.
Similar to connection provisioning, OAM functions follow general
principles, but also have some technology specific characteristics.
OAM is an integral part of transport connections. Therefore it is
required that OAM functions are activated/deactivated in sync with
connection commissioning/decommissioning; avoiding spurious alarms
and ensuring consistent operation. In certain technologies, OAM
entities are inherently established once the connection is set up,
while other technologies require extra configuration to establish and
configure OAM entities. In some situations the use of OAM functions,
such as Fault Management (FM) and Performance Management (PM), may be
optional (based on network management policies). Hence, the network
operator must be able to choose which set of OAM functions to apply
to specific connections and which parameters should be configured and
activated. To achieve this objective, OAM entities and specific
functions must be selectively configurable.
In general, it is required that the management plane and control
plane connection establishment mechanisms are synchronized with OAM
establishment and activation. In particular, if the GMPLS control
plane is employed, it is desirable to bind OAM setup and
configuration to connection establishment signaling to avoid two
separate management/configuration steps (connection setup followed by
OAM configuration) which increases delay, processing, and more
importantly may be prone to misconfiguration errors. Once OAM
entities are setup and configured, pro-active as well as on-demand
OAM functions can be activated via the management plane. On the
other hand, it should be possible to activate/deactivate pro-active
OAM functions via the GMPLS control plane as well. In some
situations it may be possible to use the GMPLS control plane to
control on-demand OAM functions too.
This document describes requirements for OAM configuration and
control via Resource Reservation Protocol - Traffic Engineering
(RSVP-TE). Extensions to the RSVP-TE protocol are specified
providing a framework to configure and control OAM entities along
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with the capability to carry technology specific information.
Extensions can be grouped into: generic elements that are applicable
to any OAM solution; and technology specific elements that provide
additional configuration parameters, which may only be needed for a
specific OAM technology. This document specifies the technology
agnostic elements and specifies the way additional technology
specific OAM parameters are provided.
This document addresses end-to-end OAM configuration, that is, the
setup of OAM entities bound to an end-to-end Label-Switched Path
(LSP), and configuration and control of OAM functions running end-to-
end in the LSP. Configuration of OAM entities for LSP segments and
tandem connections are out of the scope of this document.
The mechanisms described in this document provide an additional
option for bootstrapping OAM that is not intended to replace or
deprecate the use of other technology specific OAM bootstrapping
techniques; e.g., LSP Ping [RFC4379] for MPLS networks. The
procedures specified in this document are intended only for use in
environments where RSVP-TE signaling is used to set up the LSPs that
are to be monitored using OAM.
2. Requirements
This section summarizes various technology-specific OAM requirements
which can be used as a basis for an OAM configuration framework.
MPLS OAM requirements are described in [RFC4377], which provides
requirements to create consistent OAM functionality for MPLS
networks. The following list is an excerpt of MPLS OAM requirements
documented in [RFC4377] that bear a direct relevance to the
discussion set forth in this document.
o It is desired to support the automation of LSP defect detection.
It is especially important in cases where large numbers of LSPs
might be tested.
o In particular some LSPs may require automated ingress-LSR to
egress-LSR testing functionality, while others may not.
o Mechanisms are required to coordinate network responses to
defects. Such mechanisms may include alarm suppression,
translating defect signals at technology boundaries, and
synchronizing defect detection times by setting appropriately
bounded detection time frames.
MPLS-TP defines a profile of MPLS targeted at transport applications
[RFC5921]. This profile specifies the specific MPLS characteristics
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and extensions required to meet transport requirements, including
providing additional OAM, survivability, and other maintenance
functions not currently supported by MPLS. Specific OAM requirements
for MPLS-TP are specified in [RFC5654] and [RFC5860]. MPLS-TP poses
the following requirements on the control plane to configure and
control OAM entities:
o From [RFC5860]: OAM functions MUST operate and be configurable
even in the absence of a control plane. Conversely, it SHOULD be
possible to configure as well as enable/disable the capability to
operate OAM functions as part of connectivity management, and it
SHOULD also be possible to configure as well as enable/disable the
capability to operate OAM functions after connectivity has been
established.
o From [RFC5654]: The MPLS-TP control plane MUST support the
configuration and modification of OAM maintenance points as well
as the activation/ deactivation of OAM when the transport path or
transport service is established or modified.
Ethernet Connectivity Fault Management (CFM) defines an adjunct
connectivity monitoring OAM flow to check the liveliness of Ethernet
networks [IEEE.802.1Q-2011]. With PBB-TE [IEEE.802.1Q-2011] Ethernet
networks support explicitly-routed Ethernet connections. CFM can be
used to track the liveliness of PBB-TE connections and detect data
plane failures. In the IETF, the GMPLS controlled Ethernet Label
Switching (GELS) (see [RFC5828] and [RFC6060]) work extended the
GMPLS control plane to support the establishment of PBB-TE data plane
connections. Without control plane support separate management
commands would be needed to configure and start CFM.
GMPLS based OAM configuration and control needs to provide a general
framework to be applicable to a wide range of data plane technologies
and OAM solutions. There are three typical data plane technologies
used for transport applications: wavelength based such as Wavelength
Switched Optical Networks (WSON), Time-Division Multiplexing (TDM)
based such as Synchronous Digital Hierarchy (SDH) and Synchronous
Optical Networking (SONET), and packet based such as MPLS-TP
[RFC5921] and Ethernet PBB-TE [IEEE.802.1Q-2011]. For all these data
planes, the operator MUST be able to configure and control the
following OAM functions:
o It MUST be possible to explicitly request the setup of OAM
entities for the signaled LSP and provide specific information for
the setup if this is required by the technology.
o Control of alarms is important to avoid false alarm indications
and reporting to the management system. It MUST be possible to
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enable/disable alarms generated by OAM functions. In some cases,
selective alarm control may be desirable when, for instance, the
operator is only concerned about critical alarms. Therefore the
non-service affecting alarms should be inhibited.
o When periodic messages are used for liveliness check (continuity
check) of LSPs, it MUST be possible to set the frequency of
messages. This allows proper configuration for fulfilling the
requirements of the service and/or meeting the detection time
boundaries posed by possible congruent connectivity check
operations of higher layer applications. For a network operator
to be able to balance the trade-off between fast failure detection
and data overhead, it is beneficial to configure the frequency of
continuity check messages on a per LSP basis.
o Pro-active Performance Monitoring (PM) functions are used to
continuously collect information about specific characteristics of
the connection. For consistent measurement of Service Level
Agreements (SLAs), it MUST be possible to set common configuration
parameters for the LSP.
o The extensions MUST allow the operator to use only a minimal set
of OAM configuration and control features if supported by the OAM
solution or network management policy. Generic OAM parameters and
data plane or OAM technology specific parameters MUST be
supported.
3. RSVP-TE based OAM Configuration
In general, two types of maintenance points can be distinguished:
Maintenance Entity Group End Points (MEPs) and Maintenance Entity
Group Intermediate Points (MIPs). MEPs reside at the ends of an LSP
and are capable of initiating and terminating OAM messages for Fault
Management (FM) and Performance Monitoring (PM). MIPs on the other
hand, are located at transit nodes of an LSP and are capable of
reacting to some OAM messages but otherwise do not initiate messages.
Maintenance Entity (ME) refers to an association of MEPs and MIPs
that are provisioned to monitor an LSP.
When an LSP is signaled, a forwarding association is established
between endpoints and transit nodes via label bindings. This
association creates a context for the OAM entities monitoring the
LSP. On top of this association, OAM entities may be configured to
unambiguously identify MEs.
In addition to ME identification parameters, pro-active OAM functions
(e.g., Continuity Check (CC) and Performance Monitoring (PM)) may
have additional parameters that require configuration as well. In
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particular, the frequency of periodic CC packets and the measurement
interval for loss and delay measurements may need to be configured.
The above parameters may be either derived from LSP provisioning
information, or alternatively, pre-configured default values can be
used. In the simplest case, the control plane MAY provide
information on whether or not OAM entities need to be setup for the
signaled LSP. If OAM entities are created, control plane signaling
MUST also provide a means to activate/deactivate OAM message flows
and associated alarms.
OAM identifiers, as well as the configuration of OAM functions, are
technology specific (i.e., vary depending on the data plane
technology and the chosen OAM solution). In addition, for any given
data plane technology, a set of OAM solutions may be applicable.
Therefore, the OAM configuration framework allows selecting a
specific OAM solution to be used for the signaled LSP and provides
means to carry detailed OAM configuration information in technology
specific TLVs.
Administrative Status Information is carried in the ADMIN_STATUS
Object. The Administrative Status Information is described in
[RFC3471], the ADMIN_STATUS Object is specified for RSVP-TE in
[RFC3473]. Two bits are allocated for the administrative control of
OAM monitoring: the "OAM Flows Enabled" (M) and "OAM Alarms Enabled"
(O) bits. When the "OAM Flows Enabled" bit is set, OAM mechanisms
MUST be enabled; if it is cleared, OAM mechanisms MUST be disabled.
When the "OAM Alarms Enabled" bit is set OAM triggered alarms are
enabled and associated consequent actions MUST be executed including
the notification to the management system. When this bit is cleared,
alarms are suppressed and no action SHOULD be executed and the
management system SHOULD NOT be notified.
The LSP_ATTRIBUTES and the LSP_REQUIRED_ATTRIBUTES objects are
defined in [RFC5420] to provide means to signal LSP attributes and
options in the form of TLVs. Options and attributes signaled in the
LSP_ATTRIBUTES object can be passed transparently through LSRs not
supporting a particular option or attribute, while the contents of
the LSP_REQUIRED_ATTRIBUTES object MUST be examined and processed by
each LSR. One bit "OAM MEP entities desired" is allocated in the LSP
Attributes Flags TLV to be used in the LSP_ATTRIBUTES object. If the
"OAM MEP entities desired" bit is set it is indicating that the
establishment of OAM MEP entities are required at the endpoints of
the signaled LSP. One bit "OAM MIP entities desired" is allocated in
the LSP Attributes Flags TLV to be used in the LSP_ATTRIBUTES or
LSP_REQUIRED_ATTRIBUES objects. If the "OAM MIP entities desired"
bit is set in the LSP_ATTRIBUTES Flags TLV in the
LSP_REQUIRED_ATTRIBUTES Object, it is indicating that the
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establishment of OAM MIP entities is required at every transit node
of the signaled LSP.
3.1. Establishment of OAM Entities and Functions
In order to avoid spurious alarms, OAM functions should be setup and
enabled in the appropriate order. When using the GMPLS control plane
for both LSP establishment and to enable OAM functions on the LSPs,
the control of both processes is bound to RSVP-TE message exchanges.
An LSP may be signaled and established without OAM configuration
first, and OAM entities may be added later with a subsequent re-
signaling of the LSP. Alternatively, the LSP may be setup with OAM
entities with the first signaling of the LSP. The below procedures
apply to both cases.
Before initiating a Path message with OAM Configuration information,
an initiating node MUST establish and configure the corresponding OAM
entities locally. But until the LSP is established, OAM source
functions MUST NOT start sending any OAM messages. In the case of
bidirectional connections, in addition to the OAM source function,
the initiator node MUST set up the OAM sink function and prepare it
to receive OAM messages. During this time the OAM alarms MUST be
suppressed (e.g., due to missing or unidentified OAM messages). To
achieve OAM alarm suppression, Path message MUST be sent with the
"OAM Alarms Enabled" ADMIN_STATUS flag cleared.
When the Path message arrives at the receiver, the remote end MUST
establish and configure OAM entities according to the OAM information
provided in the Path message. If this is not possible, a PathErr
message SHOULD be sent and neither the OAM entities nor the LSP
SHOULD be established. If OAM entities are established successfully,
the OAM sink function MUST be prepared to receive OAM messages, but
MUST NOT generate any OAM alarms (e.g., due to missing or
unidentified OAM messages). In the case of bidirectional
connections, in addition to the OAM sink function, an OAM source
function MUST be set up and, according to the requested
configuration, the OAM source function MUST start sending OAM
messages. Then a Resv message MUST be sent back, including the
LSP_Attributes Flags TLV, with the appropriate setting of the "OAM
MEP entities desired" and "OAM MIP entities desired" flags, and the
OAM Configuration TLV that corresponds to the established and
configured OAM entities and functions. Depending on the OAM
technology, some elements of the OAM Configuration TLV MAY be updated
/changed; i.e., if the remote end is not supporting a certain OAM
configuration it may suggest an alternative setting, which may or may
not be accepted by the initiator of the Path message. If it is
accepted, the initiator will reconfigure its OAM functions according
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to the information received in the Resv message. If the alternate
setting is not acceptable a ResvErr message MAY be sent tearing down
the LSP. Details of this operation are technology specific and
should be described in accompanying technology specific documents.
When the initiating side receives the Resv message, it completes any
pending OAM configuration and enables the OAM source function to send
OAM messages.
After this exchange, OAM entities are established and configured for
the LSP and OAM messages are exchanged. OAM alarms can now be
enabled. The initiator, during the period when OAM alarms are
disabled, sends a Path message with "OAM Alarms Enabled" ADMIN_STATUS
flag set. The receiving node enables the OAM alarms after processing
the Path message. The initiator enables OAM alarms after it receives
the Resv message. Data plane OAM is now fully functional.
In case an egress LSR does not support the extensions defined in this
document, according to [RFC5420], it will silently ignore the new LSP
Attributes Flags as well as the TLVs carrying additional OAM
configuration information, and therefore no error will be raised that
would notify the ingress LSR about the missing OAM configuration
actions on the egress side. However, as described above, an egress
LSR conformant to the specification of this document will set the LSP
Attributes Flags and include the OAM Configuration TLV in the Resv
message indicating the configuration of the OAM mechanisms, therefore
an ingress LSR by detecting the missing information in the Resv
message will be able to recognize that the remote end does not
support the OAM configuration functionality and therefore it SHOULD
tear down the LSP, and if appropriate, signal the LSP without any OAM
configuration information.
3.2. Adjustment of OAM Parameters
There may be a need to change the parameters of an already
established and configured OAM function during the lifetime of the
LSP. To do so the LSP needs to be re-signaled with the updated
parameters. OAM parameters influence the content and timing of OAM
messages and identify the way OAM defects and alarms are derived and
generated. Hence, to avoid spurious alarms, it is important that
both sides, OAM sink and source, are updated in a synchronized way.
First, the alarms of the OAM sink function should be suppressed and
only then should expected OAM parameters be adjusted. Subsequently,
the parameters of the OAM source function can be updated. Finally,
the alarms of the OAM sink side can be enabled again.
In accordance with the above operation, the LSP MUST first be re-
signaled with "OAM Alarms Enabled" ADMIN_STATUS flag cleared,
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including the updated OAM Configuration TLV corresponding to the new
parameter settings. The initiator MUST keep its OAM sink and source
functions running unmodified, but it MUST suppress OAM alarms after
the updated Path message is sent. The receiver MUST first disable
all OAM alarms, then update the OAM parameters according to the
information in the Path message and reply with a Resv message
acknowledging the changes by including the OAM Configuration TLV.
Note that the receiving side has the possibility to adjust the
requested OAM configuration parameters and reply with an updated OAM
Configuration TLV in the Resv message, reflecting the actually
configured values. However, in order to avoid an extensive
negotiation phase, in the case of adjusting already configured OAM
functions, the receiving side SHOULD NOT update the parameters
requested in the Path message to an extent that would provide lower
performance (e.g., lower frequency of monitoring packets) than what
has been in operation previously.
The initiator MUST only update its OAM sink and source functions
after it received the Resv message. After this Path/Resv message
exchange (in both unidirectional and bidirectional LSP cases) the OAM
parameters are updated and OAM is running according the new parameter
settings. However, OAM alarms are still disabled. A subsequent Path
/Resv message exchange with "OAM Alarms Enabled" ADMIN_STATUS flag
set is needed to enable OAM alarms again.
3.3. Deleting OAM Entities
In some cases it may be useful to remove some or all OAM entities and
functions from an LSP without actually tearing down the connection.
To avoid any spurious alarms, first the LSP MUST be re-signaled with
"OAM Alarms Enabled" ADMIN_STATUS flag cleared but unchanged OAM
configuration. Subsequently, the LSP is re-signaled with "OAM MEP
Entities desired" and "OAM MIP Entities desired" LSP ATTRIBUTES flags
cleared, and without the OAM Configuration TLV, this MUST result in
the deletion of all OAM entities associated with the LSP. All
control and data plane resources in use by the OAM entities and
functions SHOULD be freed up. Alternatively, if only some OAM
functions need to be removed, the LSP is re-signaled with the updated
OAM Configuration TLV. Changes between the contents of the
previously signaled OAM Configuration TLV and the currently received
TLV represent which functions MUST be removed/added.
OAM source functions MUST be deleted first and only after the "OAM
Alarms Disabled" can the associated OAM sink functions be removed,
this will ensure that OAM messages do not leak outside the LSP. To
this end the initiator, before sending the Path message, MUST remove
the OAM source, hence terminating the OAM message flow associated to
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the downstream direction. In the case of a bidirectional connection,
it MUST leave in place the OAM sink functions associated to the
upstream direction. The remote end, after receiving the Path
message, MUST remove all associated OAM entities and functions and
reply with a Resv message without an OAM Configuration TLV. The
initiator completely removes OAM entities and functions after the
Resv message arrived.
4. RSVP-TE Extensions
RFC Editor Note: remove/update "IANA" and "IANA to assign" notes in
the document once the assignments have been made.
4.1. LSP Attributes Flags
In RSVP-TE the Flags field of the SESSION_ATTRIBUTE object is used to
indicate options and attributes of the LSP. The Flags field has 8
bits and hence is limited to differentiate only 8 options. [RFC5420]
defines new objects for RSVP-TE messages to allow the signaling of
arbitrary attribute parameters making RSVP-TE easily extensible to
support new applications. Furthermore, [RFC5420] allows options and
attributes that do not need to be acted on by all Label Switched
Routers (LSRs) along the path of the LSP. In particular, these
options and attributes may apply only to key LSRs on the path such as
the ingress LSR and egress LSR. Options and attributes can be
signaled transparently, and only examined at those points that need
to act on them. The LSP_ATTRIBUTES and the LSP_REQUIRED_ATTRIBUTES
objects are defined in [RFC5420] to provide means to signal LSP
attributes and options in the form of TLVs. Options and attributes
signaled in the LSP_ATTRIBUTES object can be passed transparently
through LSRs not supporting a particular option or attribute, while
the contents of the LSP_REQUIRED_ATTRIBUTES object MUST be examined
and processed by each LSR. One TLV is defined in [RFC5420]: the
Attributes Flags TLV.
One bit (IANA to assign): "OAM MEP entities desired" is allocated in
the LSP Attributes Flags TLV to be used in the LSP_ATTRIBUTES object.
If the "OAM MEP entities desired" bit is set it is indicating that
the establishment of OAM MEP entities are required at the endpoints
of the signaled LSP. If the establishment of MEPs is not supported
an error MUST be generated: "OAM Problem/MEP establishment not
supported".
If the "OAM MEP entities desired" bit is set and additional
parameters need to be configured, an OAM Configuration TLV MAY be
included in the LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES object.
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One bit (IANA to assign): "OAM MIP entities desired" is allocated in
the LSP Attributes Flags TLV to be used in the LSP_ATTRIBUTES or
LSP_REQUIRED_ATTRIBUES objects. If the "OAM MEP entities desired"
bit is not set then this bit MUST NOT be set. If the "OAM MIP
entities desired" bit is set in the LSP_ATTRIBUTES Flags TLV in the
LSP_REQUIRED_ATTRIBUTES Object, it is indicating that the
establishment of OAM MIP entities is required at every transit node
of the signaled LSP. If the establishment of a MIP is not supported
an error MUST be generated: "OAM Problem/MIP establishment not
supported". If an intermediate LSR does not support the extensions
defined in this document it will not recognize the "OAM MIP entities
desired" flag and although the LSP_REQUIRED_ATTRIBUTES object was
used it will not configure MIP entities and will not raise any
errors. If LSRs that are not supporting this document are to be
assumed in the network, the ingress LSR SHOULD collect per-hop
information about the LSP Attributes utilizing the LSP Attributes
sub-object of the Record Route Object as defined in [RFC5420]. When
the Record Route object is received the ingress SHOULD check whether
all intermediate LSRs set the "OAM MIP entities desired" flag
indicating support of the function, if not, depending on operator
policy the LSP MAY need to be torn down.
4.2. OAM Configuration TLV
This TLV provides information about which OAM technology/method
should be used and carries sub-TLVs for any additional OAM
configuration information. One OAM Configuration TLV MAY be carried
in the LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES object in Path and
Resv messages. When carried in the LSP_REQUIRED_ATTRIBUTES object,
it is indicating that intermediate nodes MUST recognize and react on
the OAM configuration information.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OAM Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ sub-TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates a new type: the OAM Configuration TLV (IANA to
assign).
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OAM Type: specifies the technology specific OAM method. When carried
in the LSP_REQUIRED_ATTRIBUTES Object, if the requested OAM method is
not supported at any given node an error MUST be generated: "OAM
Problem/Unsupported OAM Type". When carried in the LSP_ATTRIBUTES
Object, intermediate nodes not supporting the OAM Type pass the
object forward unchanged as specified in [RFC5420]. Ingress and
egress nodes that support the OAM Configuration TLV but that do not
support a specific OAM Type MUST respond with an error indicating
"OAM Problem/Unsupported OAM Type".
OAM Type Description
------------ --------------------
0-255 Reserved
This document defines no types. IANA is requested to maintain the
values in a new "RSVP-TE OAM Configuration Registry".
Length: indicates the total length of the TLV in octets. The TLV
MUST be zero-padded so that the TLV is four octet aligned.
Two groups of TLVs are defined: generic sub-TLVs and technology
specific sub-TLVs. Generic sub-TLVs carry information that are
applicable independent of the actual OAM technology, while technology
specific sub-TLVs are providing configuration parameters for specific
OAM technologies. This document defines one generic sub-TLV, see
Section 4.2.1, while it is foreseen that technology specific sub-TLVs
will be defined by separate documents.
The receiving node, based on the OAM Type, will check if a
corresponding technology specific OAM configuration sub-TLV is
included in the OAM Configuration TLV. If the included technology
specific OAM configuration sub-TLV is different from what is
specified in the OAM Type an error MUST be generated: "OAM Problem/
OAM Type Mismatch". IANA is requested to maintain the sub-TLV space
in the new "RSVP-TE OAM Configuration Registry".
Sub-TLV Type Description
------------ ------------------------------------
0 Reserved
1 OAM Function Flags Sub-TLV
2-31 Reserved for generic Sub-TLVs
32- Reserved for technology specific Sub-TLVs
Note that there is a hierarchical dependency between the OAM
configuration elements. First, the "OAM MEP entities desired" flag
needs to be set. Only when that flag is set MAY an "OAM
Configuration TLV" be included in the LSP_ATTRIBUTES or
LSP_REQUIRED_ATTRIBUTES Object. When this TLV is present, based on
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the "OAM Type" field, it MAY carry a technology specific OAM
configuration sub-TLV. If this hierarchy is broken (e.g., "OAM MEP
entities desired" flag is not set but an OAM Configuration TLV is
present) an error MUST be generated: "OAM Problem/Configuration
Error".
4.2.1. OAM Function Flags Sub-TLV
The "OAM Configuration TLV" MUST always include a single instance of
the "OAM Function Flags Sub-TLV" and it MUST always be the first sub-
TLV. "OAM Function Flags" specifies which pro-active OAM functions
(e.g., connectivity monitoring, loss and delay measurement) and which
fault management signals MUST be established and configured. If the
selected OAM Function(s) is(are) not supported, an error MUST be
generated: "OAM Problem/Unsupported OAM Function".
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (1) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ OAM Function Flags ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
OAM Function Flags is bitmap with extensible length based on the
Length field of the TLV. Bits are numbered from left to right. The
TLV is padded to 4-octet alignment. The Length field indicates the
size of the padded TLV in octets. IANA is requested to maintain the
OAM Function Flags in the new "RSVP-TE OAM Configuration Registry".
This document defines the following flags.
OAM Function Flag bit# Description
--------------------- ---------------------------
0 Continuity Check (CC)
1 Connectivity Verification (CV)
2 Fault Management Signal (FMS)
3 Performance Monitoring/Loss (PM/Loss)
4 Performance Monitoring/Delay (PM/Delay)
5 Performance Monitoring/Throughput Measurement
(PM/Throughput)
4.2.2. Technology Specific Sub-TLVs
If technology-specific configuration information is needed for a
specific "OAM Type", then this information is carried in a
technology-specific sub-TLV. Such sub-TLVs are OPTIONAL and an OAM
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Configuration TLV MUST NOT contain more than one technology- specific
sub-TLV. IANA is requested to maintain the OAM technology specific
sub-TLV space in the new "RSVP-TE OAM Configuration Registry".
4.3. Administrative Status Information
Administrative Status Information is carried in the ADMIN_STATUS
Object, which is specified for RSVP-TE in [RFC3473]. The
Administrative Status Information is described in [RFC3471].
Two bits are allocated for the administrative control of OAM
monitoring. Two bits (IANA to assign) are allocated by this
document: the "OAM Flows Enabled" (M) and "OAM Alarms Enabled" (O)
bits. When the "OAM Flows Enabled" bit is set, OAM mechanisms MUST
be enabled; if it is cleared, OAM mechanisms MUST be disabled. When
the "OAM Alarms Enabled" bit is set OAM triggered alarms are enabled
and associated consequent actions MUST be executed including the
notification to the management system. When this bit is cleared,
alarms are suppressed and no action SHOULD be executed and the
management system SHOULD NOT be notified. For a detailed description
of the use of these flags see Section 3.
4.4. Handling OAM Configuration Errors
To handle OAM configuration errors, a new Error Code (IANA to assign)
"OAM Problem" is introduced. To refer to specific problems, a set of
Error Values are defined under the "OAM Problem" error code.
If a node does not support the establishment of OAM MEP or MIP
entities it MUST use the error value: "MEP establishment not
supported" or "MIP establishment not supported" respectively in the
PathErr message.
If a node does not support a specific OAM technology/solution it MUST
use the error value: "Unsupported OAM Type" in the PathErr message.
If a different technology specific OAM configuration TLV is included
than what was specified in the OAM Type an error MUST be generated
with error value: "OAM Type Mismatch" in the PathErr message.
There is a hierarchy between the OAM configuration elements. If this
hierarchy is broken, the error value: "Configuration Error" MUST be
used in the PathErr message.
If a node does not support a specific OAM Function, it MUST use the
error value: "Unsupported OAM Function" in the PathErr message.
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4.5. Considerations on Point-to-Multipoint OAM Configuration
RSVP-TE extensions for the establishment of point-to-multipoint
(P2MP) LSPs are specified in [RFC4875]. A P2MP LSP is comprised of
multiple source-to-leaf (S2L) sub-LSPs. These S2L sub-LSPs are set
up between the ingress and egress LSRs, and are appropriately
combined by the branch LSRs using RSVP semantics to result in a P2MP
TE LSP. One Path message may signal one or multiple S2L sub-LSPs for
a single P2MP LSP. Hence, the S2L sub-LSPs belonging to a P2MP LSP
can be signaled using one Path message or split across multiple Path
messages.
P2MP OAM mechanisms are very specific to the data plane technology,
therefore in this document, we only highlight the basic principles of
P2MP OAM configuration. We consider only the root to leaf OAM flows,
and as such, aspects of the configuration of return paths are outside
the scope of our discussions. We also limit our consideration to the
case where all leaves must successfully establish OAM entities with
identical configuration in order the P2MP OAM is successfully
established. In any case, the discussion set forth below provides
only guidelines for P2MP OAM configuration. However at minimum the
below procedures SHOULD be specified for P2MP OAM configuration in a
technology specific document.
The root node may use a single Path message or multiple Path messages
to setup the whole P2MP tree. In the case when multiple Path
messages are used, the root node is responsible to keep the OAM
Configuration information consistent in each of the sent Path
messages, i.e., the same information MUST be included in all Path
messages used to construct the multicast tree. Each branching node
will propagate the Path message downstream on each of the branches,
when constructing a Path message the OAM Configuration information
MUST be copied unchanged from the received Path message, including
the related ADMIN_STATUS bits, LSP Attribute Flags and the OAM
Configuration TLV. The latter two also imply that the LSP_ATTRIBUTES
and LSP_REQUIRED_ATTRIBUTES Object MUST be copied for the upstream
Path message to the subsequent downstream Path messages.
Leaves MUST create and configure OAM sink functions according to the
parameters received in the Path message, for P2MP OAM configuration
there is no possibility for parameter negotiation on a per leaf
basis. This is due to the fact that the OAM source function,
residing in the root of the tree, will operate with a single
configuration, which then must be obeyed by all leaves. If a leaf
cannot accept the OAM parameters it MUST use the RRO Attributes sub-
object [RFC5420] to notify the root about the problem. In
particular, if the OAM configuration was successful, the leaf would
set the "OAM MEP entities desired" flag in the RRO Attributes sub-
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object in the Resv message. On the other hand, if OAM entities could
not be established the Resv message should be sent with the "OAM MEP
entities desired" bit cleared in the RRO Attributes sub-object.
Branching nodes should collect and merge the received RROs according
to the procedures described in [RFC4875]. This way, the root when
receiving the Resv message (or messages if multiple Path messages
were used to set up the tree) will have a clear information about
which of the leaves could establish the OAM functions. If all leaves
established OAM entities successfully, the root can enable the OAM
message flow. On the other hand, if at some leaves the establishment
was unsuccessful additional actions will be needed before the OAM
message flow can be enabled. Such action could be to setup two
independent P2MP LSPs. One LSP with OAM Configuration information
towards leaves which could successfully setup the OAM function. This
can be done by pruning the leaves which failed to setup OAM of the
previously signaled P2MP LSP. The other P2MP LSP could be
constructed for leaves without OAM entities. The exact procedures
will be described in technology specific documents.
5. IANA Considerations
5.1. ADMIN_STATUS Object Bit Flags
IANA maintains a registry called "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Parameters" with a sub-registry called
"Administrative Status Information Flags".
IANA is requested to allocate two new flags as follows:
Bit Number | Hex Value | Name | Reference
-----------+------------+--------------------------+-----------
TBA | TBA | OAM Alarms Enabled (O) | [This.ID]
TBA | TBA | OAM Flows Enabled (M) | [This.ID]
5.2. LSP Attributes Flags
IANA maintains a registry called "Resource Reservation Protocol-
Traffic Engineering (RSVP-TE) Parameters" with a subregistry called
"Attribute Flags".
IANA is requested to allocate two new flags as follows:
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Bit | Name | Attribute | Attribute | RRO | Reference
No | | Flags Path | Flags Resv | |
----+------------------+------------+------------+-----+----------
TBA | OAM MEP | | | |
| entities desired | Yes | Yes | Yes | [This.ID]
| | | | |
TBA | OAM MIP | | | |
| entities desired | Yes | Yes | Yes | [This.ID]
5.3. New LSP Attributes
IANA maintains a registry called "Resource Reservation Protocol-
Traffic Engineering (RSVP-TE) Parameters" with a subregistry called
"Attributes TLV Space"
IANA is requested to allocate one new TLV type as follows:
Type| Name |Allowed on |Allowed on |Reference
| |LSP_ATTRIBUTES|LSP_REQUIRED_|
| | |ATTRIBUTES |
----+----------------------+--------------+-------------+---------
TBA| OAM Configuration TLV| Yes | Yes |[This.ID]
5.4. RSVP Error Code
IANA maintains a registry called "Resource Reservation Protocol
(RSVP) Parameters" with a subregistry called "Error Codes and
Globally-Defined Error Value Sub-Codes".
IANA is requested to allocate one new Error Code as follows:
Error Code | Meaning | Reference
-----------+-------------+-------------
TBA | OAM Problem | [This.ID]
The value is to be selected from the range 0-239.
The following Error Value sub-codes are defined for this new Error
Code as follows:
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Value | Description | Reference
--------+---------------------------------+--------------
0 | Reserved | [This.ID]
1 | MEP establishment not supported | [This.ID]
2 | MIP establishment not supported | [This.ID]
3 | Unsupported OAM Type | [This.ID]
4 | Configuration Error | [This.ID]
5 | OAM Type Mismatch | [This.ID]
6 | Unsupported OAM Function | [This.ID]
7-32767 | Unassigned |
32768-65535| Reserved for Private Use | [This.ID]
5.5. RSVP-TE OAM Configuration Registry
IANA is requested to create a new registry called "RSVP-TE OAM
Configuration Registry".
IANA is requested to create sub-registries as defined in the
following subsections. The registration procedures specified are as
defined in [RFC5226].
5.5.1. OAM Types Sub-Registry
IANA is requested to create the "OAM Types" sub-registry of the
"RSVP-TE OAM Configuration Registry" as follows:
Range | Registration Procedures
-------+-------------------------
0-255 | IETF Review
There are no initial values in this registry. IANA should show the
registry as follows:
OAM Type Number | OAM Type Description | Reference
----------------+----------------------+--------------
0-255 | Unassigned |
5.5.2. OAM Sub-TLVs Sub-Registry
IANA is requested to create the "OAM Sub-TLVs" sub-registry of the
"RSVP-TE OAM Configuration Registry" as follows:
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Range | Purpose | Registration Procedures
------------+------------------------------|------------------------
0-31 | Generic Sub-TLVs | IETF Review
32-65534 | Technology-specific Sub-TLVs | IETF Review
65535-65536 | Experimental Sub-TLVs | Experimental
IANA is requested to populate the registry as follows:
Sub-TLV Type | Description | Reference
-------------+----------------------------+-------
0 | Reserved | [This.ID]
1 | OAM Function Flags Sub-TLV | [This.ID]
2-31 | Unassigned |
32-65534 | Unassigned |
5.5.3. OAM Function Flags Sub-Registry
IANA is requested to create the "OAM Function Flags Sub-Registry"
sub-registry of the "RSVP-TE OAM Configuration Registry".
New values in the registry are allocated by "IETF Review". There is
no top value to the range. Bits are counted from bit 0 as the first
bit transmitted.
IANA is requested to populate the registry as follows.
OAM Function Flag | Description
bit number |
------------------+---------------------------------------------
0 | Continuity Check (CC)
1 | Connectivity Verification (CV)
2 | Fault Management Signal (FMS)
3 | Performance Monitoring/Loss (PM/Loss)
4 | Performance Monitoring/Delay (PM/Delay)
5 | Performance Monitoring/Throughput Measurement
| (PM/Throughput)
6-... | Unassigned
6. Security Considerations
The signaling of OAM related parameters and the automatic
establishment of OAM entities based on RSVP-TE messages adds a new
aspect to the security considerations discussed in [RFC3473]. In
particular, a network element could be overloaded, if a remote
attacker could request liveliness monitoring, with frequent periodic
messages, for a high number of LSPs, targeting a single network
element. Such an attack can efficiently be prevented when mechanisms
for message integrity and node authentication are deployed. Since
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the OAM configuration extensions rely on the hop-by-hop exchange of
exiting RSVP-TE messages, procedures specified for RSVP message
security in [RFC2747] can be used to mitigate possible attacks.
For a more comprehensive discussion of GMPLS security, and attack
mitigation techniques, please see the Security Framework for MPLS and
GMPLS Networks [RFC5920].
7. Acknowledgements
The authors would like to thank Francesco Fondelli, Adrian Farrel,
Loa Andersson, Eric Gray and Dimitri Papadimitriou for their useful
comments.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Functional Description", RFC 3471,
January 2003.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5420] Farrel, A., Papadimitriou, D., Vasseur, JP., and A.
Ayyangarps, "Encoding of Attributes for MPLS LSP
Establishment Using Resource Reservation Protocol Traffic
Engineering (RSVP-TE)", RFC 5420, February 2009.
8.2. Informative References
[IEEE.802.1Q-2011]
IEEE, "IEEE Standard for Local and metropolitan area
networks -- Media Access Control (MAC) Bridges and Virtual
Bridged Local Area Networks", IEEE Std 802.1Q, 2011.
[RFC2747] Baker, F., Lindell, B., and M. Talwar, "RSVP Cryptographic
Authentication", RFC 2747, January 2000.
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[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.
[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379,
February 2006.
[RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa,
"Extensions to Resource Reservation Protocol - Traffic
Engineering (RSVP-TE) for Point-to-Multipoint TE Label
Switched Paths (LSPs)", RFC 4875, May 2007.
[RFC5654] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N.,
and S. Ueno, "Requirements of an MPLS Transport Profile",
RFC 5654, September 2009.
[RFC5828] Fedyk, D., Berger, L., and L. Andersson, "Generalized
Multiprotocol Label Switching (GMPLS) Ethernet Label
Switching Architecture and Framework", RFC 5828, March
2010.
[RFC5860] Vigoureux, M., Ward, D., and M. Betts, "Requirements for
Operations, Administration, and Maintenance (OAM) in MPLS
Transport Networks", RFC 5860, May 2010.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
[RFC5921] Bocci, M., Bryant, S., Frost, D., Levrau, L., and L.
Berger, "A Framework for MPLS in Transport Networks", RFC
5921, July 2010.
[RFC6060] Fedyk, D., Shah, H., Bitar, N., and A. Takacs,
"Generalized Multiprotocol Label Switching (GMPLS) Control
of Ethernet Provider Backbone Traffic Engineering (PBB-
TE)", RFC 6060, March 2011.
Authors' Addresses
Attila Takacs
Ericsson
Konyves Kalman krt. 11.
Budapest 1097
Hungary
Email: attila.takacs@ericsson.com
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Don Fedyk
Hewlett-Packard Company
153 Taylor Street
Littleton, MA 01460
USA
Email: don.fedyk@hp.com
Jia He
Huawei
Email: hejia@huawei.com
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