Network Working Group A. Kern
Internet-Draft A. Takacs
Intended status: Standards Track Ericsson
Expires: April 29, 2010 October 26, 2009
GMPLS RSVP-TE Extensions for OTN and SONET/SDH OAM Configuration
draft-kern-ccamp-rsvp-te-sdh-otn-oam-ext-01
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Abstract
GMPLS has been extended to support connection establishment in both
SONET/SDH [RFC4606] and OTN [RFC4328] networks. However support for
the configuration of the supervision functions is not specified.
Both SONET/SDH and OTN implement supervision functions to qualify the
transported signals. This document defines extensions to RSVP-TE for
SONET/SDH and OTN OAM configuration based on the OAM Configuration
Framework defined in [GMPLS-OAM-FWK].
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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 RFC 2119 [RFC2119].
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Overview of SONET/SDH and OTN OAM related functions . . . . . 5
2.1. Continuity supervision . . . . . . . . . . . . . . . . . . 5
2.2. Connectivity supervision . . . . . . . . . . . . . . . . . 5
2.2.1. SONET/SDH . . . . . . . . . . . . . . . . . . . . . . 5
2.2.2. OTN . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Signal quality supervision . . . . . . . . . . . . . . . . 5
2.3.1. SONET/SDH . . . . . . . . . . . . . . . . . . . . . . 6
2.3.2. OTN . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. RSVP-TE signaling extensions . . . . . . . . . . . . . . . . . 7
3.1. OAM configuration of switching layers . . . . . . . . . . 7
3.2. OAM configuration of section layers . . . . . . . . . . . 7
3.3. SONET/SDH OAM configuration . . . . . . . . . . . . . . . 9
3.3.1. Generic procedures . . . . . . . . . . . . . . . . . . 9
3.3.2. Connectivity supervision configuration . . . . . . . . 9
3.3.3. Signal quality supervision configuration . . . . . . . 10
3.3.4. Tandem Connection Monitoring support . . . . . . . . . 10
3.3.5. Non intrusive Monitoring support . . . . . . . . . . . 10
3.4. OTN OAM configuration . . . . . . . . . . . . . . . . . . 10
3.4.1. Generic procedures . . . . . . . . . . . . . . . . . . 10
3.4.2. Connectivity monitoring supervision configuration . . 11
3.4.3. Signal quality supervision configuration . . . . . . . 12
3.4.4. Tandem connection monitoring . . . . . . . . . . . . . 12
3.4.5. Signaling support of non-intrusive monitoring . . . . 13
3.5. Signaling support of Virtual Concatenation Groups (VCG) . 13
3.6. OAM types and functions . . . . . . . . . . . . . . . . . 14
3.7. Extensions to LSP_TUNNEL_INTERFACE_ID objects . . . . . . 15
3.8. SONET/SDH OAM Configuration sub-TLV . . . . . . . . . . . 15
3.9. OTN OAM Configuration sub-TLV . . . . . . . . . . . . . . 15
3.10. TTI Configuration Sub-TLV . . . . . . . . . . . . . . . . 16
3.10.1. SDH TTI Configuration Sub-TLV . . . . . . . . . . . . 16
3.10.2. OTN TTI Configuration Sub-TLV . . . . . . . . . . . . 17
3.11. Degraded signal thresholds Sub-TLV . . . . . . . . . . . . 18
4. Error handling . . . . . . . . . . . . . . . . . . . . . . . . 20
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
6. Security Considerations . . . . . . . . . . . . . . . . . . . 22
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 23
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26
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1. Introduction
Both SONET/SDH and OTN implement supervision functions to qualify the
transported signals. Supervision functions include continuity,
connectivity, signal quality, alignment and payload supervision. The
ITU-T G.806 [G.806] recommendation defines the generic framework of
the supervision functions, which are then further specified for
SONET/SDH and OTN in technology specific documents.
GMPLS has been extended to support connection establishment in both
SONET/SDH [RFC4606] and OTN [RFC4328] networks. These documents
however do not support the configuration of the respective
supervision functions.
[GMPLS-OAM-FWK] defines a technology-agnostic framework for GMPLS to
support the establishment and configuration of the pro-active OAM
functions of signalled connections. The properties of the OAM
functions are exchanged during connection establishment and may be
modified during the life of the connection. The technology specific
parameters to be exchanged are to be described in accompanying
documents. This document defines the extensions for SONET/SDH and
OTN OAM configuration.
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2. Overview of SONET/SDH and OTN OAM related functions
SONET/SDH [G.707] and OTN [G.709] provide a variety of supervision
functions. Here we only consider continuity, connectivity and signal
quality supervision functions, as these are the candidates for GMPLS
based configuration.
2.1. Continuity supervision
Continuity supervision provides methods monitoring the health of a
connection (trail).
2.2. Connectivity supervision
The connectivity supervision function provides a method to detect
misconnections. The detection procedure is based on emitting a Trace
Trail Identifier (TTI) known by both endpoints. The TTI is included
by the source node as an overhead signal for each connection. The
receiver node then compares the received TTI with the expected value
and decides if a miss-connection occurred.
2.2.1. SONET/SDH
In case of SONET/SDH, connectivity supervision is implemented in the
Regeneration Section (RS) and in the lower and higher order path
layers (LOVC and HOVC). In all layers the TTI encodes only the
Access Point Identifier (API) of the source node. In the various
layers the lengths of these TTIs are different. In RS the TTI
(encoded in J0 octet) is either 1 or 16 octets long. In higher order
paths the TTI (encoded in J1), is either 16 or 64 octet long. In
lower order paths the TTI is transmitted in the J2 byte and is 16
octet long.
2.2.2. OTN
In case of OTN, connectivity supervision is supported by the OTUk and
ODUk digital hierarchy layers. In both layers, the length of the TTI
is 64 octets, but only the first 32 octets are considered for
connectivity supervision. This first part is further divided into a
Source Access Point Identifier (SAPI) and a Destination Access Point
Identifier (DAPI). Connectivity supervision may consider either the
SAPI or DAPI only or both. The structure of the SAPI and DAPI is
specified in [G.709].
2.3. Signal quality supervision
The quality of the transmitted signal is monitored as a ratio of bad
frames. If the number of such frames reaches a threshold a defect
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state is declared. To detect the correctness of the frames an Error
Detection Code (EDC), such as Bit Interleaved Parity (BIP), is used.
The distribution of the errors is assumed to follow either Poisson or
a bursty distribution. For Poisson distribution an EDC violation
ratio is defined as the threshold; while for the bursty model the
threshold is defined as a number of consecutive 1-second time
intervals in which the EDC violation exceeds a predefined ratio. In
case of Poisson error distribution two defect state levels are
defined: the Excessive Error and Degraded Signal defect. In the case
of the bursty model, only the Degraded Signal defect level is
considered.
2.3.1. SONET/SDH
SONET/SDH supports both Excessive Error and Degraded Signal defect
levels and supports both Poisson and bursty error distribution
models. These signal quality parameters are configured for the
Multiplexing Section (MS) and the LOVC and HOVC path layers. Note,
that Tandem Connection sub-layers support only bursty error
distribution model with Degraded Signal defect level.
2.3.2. OTN
For OTN, in the digital transport layers (OTUk and ODUk) only the
bursty error distribution model errors with the Degraded Signal
defect level is supported. Two parameters are defined: Ratio of the
bad frames in a one second interval (0% to 100% or 0 to number of
frames per 1-second interval) and Number of consecutive intervals
(between 2 and 10). Signal quality supervision in the optical
transport layers is not specified by [G.798], it is indicated to be
for further study.
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3. RSVP-TE signaling extensions
Both SONET/SDH and OTN define hierarchical transport technologies,
where the transport functionalities are distributed between layers.
These layers can be characterized based on whether switching is
performed in that layer or not (See Table 1).
+-------------+------------+----------------------------------------+
| Does | OTN | SONET/SDH |
| switching? | | |
+-------------+------------+----------------------------------------+
| yes | ODU, OCh, | Path (HOVC and LOVC), MS (in case of |
| | OChr | transparent switching) |
| | | |
| no | OTU, OMS | RS, MS (in case of non-transparent |
| | | switching) |
+-------------+------------+----------------------------------------+
Table 1: SONET/SDH and OTN layer examples for switching and section
layers
3.1. OAM configuration of switching layers
Generally, the OAM related parameters of a signalled LSP refer to the
switching layer connection.
o If the flag "Connectivity monitoring" in the OAM Configuration TLV
is set, one or two Connectivity Supervision TLVs are added. One
TLV is added if the connection is either unidirectional or
bidirectional but the same configuration data is used at both
endpoints. Otherwise, two TLV are added, one for each direction.
o If the flag "Performance Monitoring/Loss" in the OAM Configuration
TLV is set, Signal Quality Supervision TLVs can be added.
o Flag "Performance Monitoring/Delay" must be cleared.
The egress node parses and interprets the OAM parameters while
intermediate nodes do not process the information. The technology
independent procedures are as per [GMPLS-OAM-FWK] while the
technology specific steps are defined in Section 3.3 and Section 3.4
in this document.
3.2. OAM configuration of section layers
In the point of view of OAM configuration of connections of a section
layer, two cases can be differentiated:
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When the section layer connection models a link between two
physically adjacent nodes, the related OAM parameters are configured
either manually or by other means (e.g., as part of link property
correlation function of LMP). Therefore, this case is out of scope
of this document.
When a section layer connection models a logical link, which is
implemented with a connection of a server switching layer, the
related OAM parameters are configured along with the signaling of the
implementing server switching layer connection.
In this latter case, if the [LSP-HIER-BIS] signaling is used to setup
the server layer connection and institiate it as FA-LSP, the OAM
Configuration TLV can be added to the LSP_TUNNEL_INTERFACE_ID object
to configure the OAM of the client section layer. As a single link
is monitored: OAM MEP entities are desired while MIP entities are
not. Furthermore, Alarm Indication from server layer is desired as
well. This information is originally encoded in the LSP Attributes
Flags TLV. As fix values for these bits are provided this TLV does
not need to be added to the LSP_TUNNEL_INTERFACE_ID object.
Therefore, the ingress node performs the following steps during
constructing a PATH message:
o Add LSP_TUNNEL_INTERFACE_ID object where a new flag "O" is set
indicating that OAM configuration for the client layer connection
(FA) is desired.
o Adds an OAM Configuration TLV to the LSP_TUNNEL_INDERFACE_ID
object and set its fields appropriately.
o Technology specific OAM Configuration TLV (e.g., SONET/SDH or OTN)
is added and extended as follows:
* If flag "Connectivity monitoring" in OAM Configuration TLV is
set one or two Connectivity Supervision TLVs is added. One TLV
is added if the connection is either unidirectional or
bidirectional but the same configuration data is used on both
endpoints. Otherwise, two TLV are added, one for each
direction.
* If flag "Performance Monitoring/Loss" in OAM Configuration TLV
is set Signal Quality Supervision TLVs can be added.
The egress node performs the following steps at the receipt of a PATH
message:
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o Checks if LSP_TUNNEL_INTERFACE_ID object is added and flag "O" is
set.
o If the "Connectivity monitoring" OAM function is set in the OAM
Configuration TLV, the egress expects one or two Connectivity
Supervision TLVs.
o If the "Performance Monitoring/Loss" OAM function is set in the
OAM Configuration TLV, one or two Signal quality supervision TLVs
can be added to define the parameters to be configured. If no
TLVs are added the suggested default values are used.
3.3. SONET/SDH OAM configuration
3.3.1. Generic procedures
The RS and MS layers of SONET/SDH define sections between two
adjacent nodes. In the basic configuration the supervision
parameters encoded in the signal are terminated and processed in the
adjacent nodes, thus, their configuration depends on whether they run
over a physical link or a logical link implemented by a lower layer
network. In the first case their configuration is done manually or
by other means (not discussed in this document). In the latter case
the RS and MS layer configuration is done along with the
configuration of the connection in the sever layer. This can be
automated using FA-LSPs as described in Section 3.2
The HOVC and LOVC path layers, as well as the RS and MS layers in
transpared forwarding, are configured as in Section 3.1.
The layer to be configured with RSVP-TE is encoded in the signal type
field of the SENDER_TSPEC object. The content of the OAM
configuration TLV is relevant to that layer.
3.3.2. Connectivity supervision configuration
[G.707] defines three bytes (signals) for connectivity supervision
purposes: the J0 byte in RS layer, the J1 and J2 bytes in HOVC and
LOVC layers. These bytes encode 1 octet, 16 octet or 64 octet long
unstructured octet streams. These streams encode the Access Point
Identifier of the source node.
In the case of bidirectional connection, different TTIs have to be
emitted in the upstream and downstream directions. During the
configuration the egress node has to be configured with the TTI value
to be expected in the downstream direction and the TTI value to be
emitted in the upstream direction. Therefore the SONET/SDH OAM
Configuration TLV carries two Connectivity Supervision TLVs.
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3.3.3. Signal quality supervision configuration
Signal quality supervision function is implemented in MS, HOVC, LOVC
layers. All three layers support exceeded error level with Poisson
error distribution model and degraded signal defect level with both,
Poisson and bursty error distribution model. Dedicated Signal
quality supervision TLVs encode each level, therefore when the
"Performance Monitoring/Loss" flag is set; several such TLVs can be
added to the SONET/SDH OAM Configuration TLV. If a configuration TLV
for a particular level is missing the default parameters for that
level is to be applied.
3.3.4. Tandem Connection Monitoring support
TBA
3.3.5. Non intrusive Monitoring support
TBA
3.4. OTN OAM configuration
3.4.1. Generic procedures
The optical transport hierarchy provides connectivity and continuity
supervision functions with appropriate maintenance signals. The OTS
and OMS layers are section layers describing physical links. RSVP-TE
does not support the configuration of these layers [RFC4328], hence
OTS and OMS related OAM parameters are also out of scope of this
document. The OCh layer adds end-to-end management signals.
Although the OCh/OChr transport layer is configured with GMPLS the
related OAM functions do not need configuration.
The digital transport hierarchy has supervision functions as well.
Both OTUk and ODUk layers implement connectivity and signal quality
supervision functions, respectively. The OAM configuration for these
layers is supported by the extensions defined in this document.
o For OTUk connections the OAM functions are provisioned together
with the server OCh/OChr LSP as defined in Section 3.2.
o For ODUk connections the procedure defined in Section 3.1 is used.
If the client layer network has section layer OAM monitoring
capabilities, then the parameters of this latter layer can be
encoded as per Section 3.2.
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3.4.2. Connectivity monitoring supervision configuration
[G.709] defines a 64 octet long TTI, where the first 32 octets have a
generic structure: a zero octet, a 15 octet long SAPI, a second zero
octet and finally the 15 octet long DAPI.
For a unidirectional connection a single Connection Supervision TLV
encodes elements of the TTI to be emitted. This TLV also specifies
which parts of the TTI are compared to the expected values (only
SAPI, only DAPI, both SAPI and DAPI).
In case of a bidirectional connection an endpoint can use a common
API value for SAPI (for transmitted signal) and DAPI (for received
signal). (See Figure 1.) The TTI values used in downstream and
upstream directions are derived from the two API values: the
downstream TTI will have the form of [0, API_a, 0, API_z] while the
upstream TTI will use the form of [0, API_z, 0 API_a].
Ingress Node Egress Node
( API_a ) TTI_upstream = [0, API_z, 0, API_a ] ( API_z )
| Rx port | -- < -- < -- < -- < -- < -- < -- < -- < -- | Tx Port |
| Tx port | -- > -- > -- > -- > -- > -- > -- > -- > -- | Rx Port |
TTI_downstream = [0, API_a, 0, API_z ]
Figure 1: TTI construction when a single API identifies the receiver
and transmitter interfaces
Then, a single Connectivity Supervision TLV is defined. The SAPI
field carries the API of the ingress node (API_a) that initiates the
signaling, while the DAPI carries the API of the egress node (API_z).
On the other hand, it is possible that the endpoints use different
values as SAPI and DAPI to identify the transmitter and receiver
ports of a bidirectional connection (See Figure 2). In this case the
TTIs to be used in the two directions are independent, thus, they
must be explicitly configured. Therefore, two Connectivity
Supervision TLVs are added to the OTN OAM Configuration TLV. Each
TLV encodes whether it defines the downstream or the upstream TTI.
Ingress Node Egress Node
( API_a1 ) TTI_upstream = [0, API_z1, 0, API_a1 ] ( API_z1 )
| Rx port | -- < -- < -- < -- < -- < -- < -- < -- < -- | Tx Port |
| Tx port | -- > -- > -- > -- > -- > -- > -- > -- > -- | Rx Port |
( API_a2 ) TTI_downstream = [0, API_a2, 0, API_z2 ] ( API_z2 )
Figure 2: TTI construction when dedicated APIs identify the receiver
and transmitter interfaces
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3.4.3. Signal quality supervision configuration
OTN supports only Degraded Signal defect with bursty error model in
OTUk and ODUk layers. Thus, the only parameters to be encoded are:
the threshold for bad frames in a 1-second interval and the number of
consecutive 1-second intervals with excessive bad frames.
3.4.4. Tandem connection monitoring
[GMPLS-OAM-FWK] provides a generic mechanism to configure Tandem
Connection Monitoring: the endpoints of a TCM Entity as well as the
relevant OAM attributes are encoded with two TCME Configuration TLVs
carried in HOP_ATTRIBUTES subobjects in the ERO [HOP_ATTR].
In the optical hierarchy, the OCh connections do not support tandem
connection monitoring.
In the digital hierarchy, the ODUk header field implements six
channels for Tandem Connection Monitoring features. This allows
deploying up to six overlapping TCMEs, and disjoint TMCEs may use the
same channels. The Level field defined in [GMPLS-OAM-FWK] with the
limitation that its value must be an integer value from domain 1 to 6
provides a direct mapping to the TCM instance indefiers (TCM1,TCM2,
..., TCM6).
To configure the connection monitoring supervision function for a
TCME the TTIs of the end-to-end connection can be considered as well
as new TTI values can be provisioned. Therefore the TCM ingress
looks for the TCM egress and besides the procedures defined in
[GMPLS-OAM-FWK] it performs the following steps:
If no TTI Configuration TLVs are given at the TCME ingress but are
given at the corresponding TCME egress an error must generated:
"TMCE Problem/TTI Configuration mismatch".
If one or more TTI Configuration TLVs are given the ingress must
check if TTI values are specified at the TCME egress. If not, the
ingress node extends the TCME Configuration TLV of the egress node
with the proper TTI configuration parameters. Otherwise, it must
generate an error: "TMCE Problem/TTI Configuration mismatch".
For signal quality supervision the defect states and thresholds
applicable at the monitoring entity can be specified. As default
value, the treshold parameters used at the (end-to-end connection or
the proper TC) egress are applicable.
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3.4.5. Signaling support of non-intrusive monitoring
OTN supports non-intrusive monitoring of end-to-end optical
connections and end-to-end and tandem connections in the digital
hierarchy. To place and configure a non-intrusive monitoring element
the OAM Configuration framework introduced the NIME Configuration TLV
[GMPLS-OAM-FWK], which is carried in HOP_ATTRIBUTES subobjects in the
ERO [HOP_ATTR].
The Level value of NIME Configuration TLV indicates what is
monitored: either the end-to-end flow (0) or a particular tandem
connection (1..6). As TCM is not supported by optical hierarchy, in
case of monitoring OCh connections the Level value must be set to 0.
For connectivity suppervision the expected TTI value must be
determined. The ingress node of the monitored end-to-end or tandem
connection can extend technology specific sub-TLV of the NIME
Configuration TLV with one or two TTI Configuration TLVs:
The end-to-end connection ingress extends all NIME Configuration
TLVs with LEVEL attribute set to 0.
The TCME ingress extends all NIME Configuration TLVs that are
placed before the TCME egress and have the same Level value as the
TCME ingress.
In case of bidirectional connections with asymmetric TTIs, flags "U"
and "D" selects which of the two TTI values are to be used.
For signal quality supervision the defect states and thresholds
applicable at the monitoring entity can be specified. As default
value, the treshold parameters used at the (end-to-end connection or
the proper TC) egress are applicable.
For OCh connection [G.798] defines two kinds of non-intrusive
monitoring functions. The first option is based on the OCh
attributes, while the second one terminates the optical channel and
processes the carried OTU frames as well. To make distinction
between the two options, the OAM Type of the NIME Configuration TLV
is used: OTN optical hierarchy indicates first option, and OTN
digital hierarchy indicates the second.
3.5. Signaling support of Virtual Concatenation Groups (VCG)
A key capability of both, SONET/SDH and OTN is the support of virtual
concatenation. This inverse multiplexing method uses multiplicity of
parallel basic signals. The supervision function parameters of these
basic signals can be different.
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[GMPLS-VCAT-LCAS] summarises GMPLS signaling capabilities to support
virtual concatenation and proposes extensions to that. A Virtual
Concatenated Group (VCG) is constructed from several individual data
plane signals. Several co-routed data plane signals can be
provisioned together using a single RSVP-TE session (co-signaled).
Multiple RSVP-TE sessions can be merged to form the VCG. These
sessions are then associated using RSVP-TE Calls [RFC4974].
As the scope of a single RSVP-TE session covers the co-signaled
elements of a VCG, the OAM configuration extension is only relevant
for this case too.
We assume that the same OAM type and the same set of OAM functions
apply to every individual signal of the VCG. A single generic OAM
Configuration TLV is added to define these common parameters while
multiple instances of technology specific OAM Configuration TLVs are
listed: one instance per individual signal. The order of these TLVs
refers to logical order of the basic signals (as they are listed in
the label object).
[GMPLS-VCAT-LCAS] allows extension/pruning of a VCG. To achieve it
the traffic descriptor, which encodes how the VCG is structured, in
the RSVP-TE session is updated. If the VCG is extended a new OAM
Configuration TLV is added to the LSP Attributes objects together
with updating the traffic descriptor.
Support of LCAS is FFS.
3.6. OAM types and functions
This document defines three new OAM types [GMPLS-OAM-FWK]: SONET/SDH
OAM, OTN Digital Hierarchy OAM and OTN Optical hierarchy OAM.
OAM Type Description
------------ ------------------
0 Reserved
1 Ethernet OAM
2 SONET/SDH OAM
3 OTN Digital Hierarchy OAM
4 OTN Optical hierarchy OAM
5-256 Reserved
The OAM Configuration TLV defines three OAM functions: Connectivity
Monitoring, Loss Measurement and Delay Measurement. SONET/SDH and
OTN supervision functions support Connectivity Monitoring and Loss
Measurement. Therefore, if Delay measurement function is requested
the nodes must generate an error with value "OAM Problem/Unsupported
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OAM Function".
3.7. Extensions to LSP_TUNNEL_INTERFACE_ID objects
To support the OAM configuration of dynamically configured FAs the
following extension to the LSP_TUNNEL_INTERFACE_ID Object is defined.
A new flag (O) (IANA to assign) is added to the actions field of the
LSP_TUNNEL_INTERFACE_ID Object: this bit indicates whether OAM
monitoring for the section is desired.
The bit can be set independently from the other flags. When it is
set, the following TLVs must be added to the LSP_TUNNEL_INTERFACE_ID
object as sub-TLVs:
o OAM Configuration TLV to declare desired OAM technology and
functions.
o Technology specific OAM Configuration TLVs if needed.
3.8. SONET/SDH OAM Configuration sub-TLV
SONET/SDH OAM Configuration TLV is defined to encode the parameters
of continuity, connectivity and signal quality supervision functions
for SONET/SDH networks.
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 (2) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ sub TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates a new type: the SONET/SDH OAM Configuration TLV (IANA
to define).
Length: indicates the total length including sub-TLVs
3.9. OTN OAM Configuration sub-TLV
OTN OAM Configuration TLV is defined to encode the parameters of
continuity, connectivity and signal quality supervision functions for
OTN.
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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 (3) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ sub TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates a new type: the OTN OAM Configuration TLV (IANA to
define).
Length: indicates the total length including sub-TLVs
3.10. TTI Configuration Sub-TLV
3.10.1. SDH TTI Configuration Sub-TLV
Several SONET/SDH layers support connectivity supervision functions.
In every layer the TTI identifies the source interface (SAPI);
however, the length of this identifier varies layer-by-layer (See
Section 2.2.1). Therefore, a generic TLV is defined supporting
various TTI lengths.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|U| Reserved | TTI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ TTI cont ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Flag "A", when set enables the AIS insertion on detecting TTI
mismatch.
Flat "U" encodes if the TTI refers to the downstream TTI (U=0) or the
upstream one (U=1).
The TTI field carries the TTI to be transmitted by the source node
and to be expected by the sink. The TLV is padded to 4-octets.
If the specified length and format of the TTI carried in this TLV is
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not supported by the referred SONET/SDH layer, error must be
generated: "OAM Problem/TTI Length Mismatch".
3.10.2. OTN TTI Configuration Sub-TLV
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 (2) (IANA) | Length = 32 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|S|D|APP| Reserved | SAPI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SAPI cont |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SAPI cont |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SAPI cont |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SAPI | DAPI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DAPI cont |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DAPI cont |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DAPI cont |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Three control flags are defined. Flag "A" indicates that AIS
insertion on detecting TTI mismatch (failing the connectivity
verification) is required (A=1) or not (A=0). The next two flags
define which parts of the received TTI are compared to the expected
one. If flag "S" is set the TTI octets 1 to 15 are matched to the
expected SAPI value. If the flag "D" is set the TTI octets 17 to 31
are matched to the expected DAPI value. If both "S" and "D" are set
both parts of TTI are compared to SAPI and DAPI values. Setting both
"S" and "D" bits to 0 is invalid, and if encountered error must be
generated: "OAM Problem/Invalid CC/CV configuration".
The next two bits "APP" encode the applicability of the TTI
configuration and the following code points are defined:
0 - Single TTI configuration: the TTI configuration is done
according only to this TLV and no further TTI configuration TLVs
are expected. This code point is used for unidirectional
connections and for bidirectional connections with common APIs
(See Figure 1)
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1 - Downstream TTI for double TTI configuration: the current TLV
instruct the configuration of the TTI to be used in downstream
direction (See Figure 2).
2 - Upstream TTI for double TTI configuration: the current TLV
instruct the configuration of the TTI to be used in upstream
direction (See Figure 2).
3 - Invalid.
This TLV is included only if the "Connection Monitoring" flag in the
OAM Configuration TLV is set.
If the APP is set to 1 and the next or the previous sub-TLV is not an
OTN TTI Configuration TLV with APP code point 2, then an error must
be generated "OAM Problem/Invalid OTN TTI Configuration/Missing
Upstream TTI configuration".
If the APP is set to 2 and the next or the previous sub-TLV is not an
OTN TTI Configuration TLV with APP code point 1, then an error must
be generated "OAM Problem/Invalid OTN TTI Configuration/Missing
Downstream TTI configuration".
If the APP is set to either 1 or 2 and the unidirectional LSP is
signaled (no UPSTREAM_LABEL is added to the message) or the APP is
set to 3, an error must be generated "OAM Problem/Invalid OTN TTI
Configuration/Invalid applicability code"
3.11. Degraded signal thresholds Sub-TLV
The Degraded signal thresholds Sub-TLV instructs the configuration of
the signal quality supervision function. This sub-TLV is applicable
in both SONET/SDH and OTN cases.
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 (3) (IANA) | Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|B|L| Reserved | DEG_THR | DEG_M |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Two flags are defined to encode the signal quality measurement. The
bit "B" encodes if distribution of errors is either Poisson (B=0) or
Bursty (B=1). In case of Poisson distribution of errors two levels
of defects are defined and encoded with bit "L": excessive error
(L=0) and degraded signal (L=1). Since in case of Bursty
distribution of errors only degraded signal defect is to be detected,
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therefore, in this latter case (B=1) the "L" bit must be set.
Otherwise error must be generated: "OAM Problem/Invalid Performance
Monitoring/Loss configuration".
The field "DEG_THR" defines the threshold for the bad frames (BIP-8
violations) in both, Poisson and bursty distributions of errors. In
the first case (B=0) this field encodes the quotient of the threshold
10e-X. The possible values for excessive error are 3,4 and 5, while
for degraded signal defect are 6,7,8 and 9.
In the second case (B=1) it encodes ratio of the bad frames in a
1-second period and can be set between 0 and 100, interpreted as
ratios in percentage.
The field "DEG_M" defines monitoring time-frame in 1 second periods
assuming bursty distribution of errors. The valid values are 2 to 10
periods.
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4. Error handling
In addition to error values specified in [GMPLS-OAM-FWK] this
document defines the following values for the "OAM Problem" Error
Code.
o If Delay measurement function is requested in the OAM
Configuration TLV, an error must be generated "OAM Problem/
Unsupported OAM Function".
o In case of SONET/SDH the length or format of the TTI to be
configured is not supported by the referred SONET/SDH layer, error
must be generated: "OAM Problem/TTI Length Mismatch".
o If both "S" and "D" bits in OTN TTI Configuration TLV are set to
0, error must be generated: "OAM Problem/Invalid CC/CV
configuration"
o If the APP is set to 1 and the next or the previous sub-TLV is not
an OTN TTI Configuration TLV with APP code point 2, then an error
must be generated "OAM Problem/Invalid OTN TTI Configuration/
Missing Upstream TTI configuration".
o If the APP is set to 2 and the next or the previous sub-TLV is not
an OTN TTI Configuration TLV with APP code point 1, then an error
must be generated "OAM Problem/Invalid OTN TTI Configuration/
Missing Downstream TTI configuration".
o If the APP is set to either 1 or 2 and the unidirectional LSP is
signaled (no UPSTREAM_LABEL is added to the message) or the APP is
set to 3, an error must be generated "OAM Problem/Invalid OTN TTI
Configuration/Invalid applicability code"
o If flag "B" in Degraded signal thresholds Sub-TLV is set to 1 and
flag "L" in the same sub-TLV is set to 0 error must be generated
"OAM Problem/Invalid Performance Monitoring/Loss configuration".
o If TTI configurations at TMCE ingress and egress nodes are not
compatible an error must be generated: "TCME Problem/TTI
Configuration mismatch"
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5. IANA Considerations
This document specifies a new SONET/SDH OAM Configuration TLV and OTN
OAM Configuration TLV to be carried in the OAM Configuration TLV in
LSP_ATTRIBUTES and LSP_REQUIRED_ATTRIBUTES objects in Path messages.
The document assigns OAM Types 2 and 3 to OAM Type field of the OAM
Configuration TLV.
The following values need to be assigned under the Error Codes "OAM
Problem/Unsupported OAM Function", "OAM Problem/TTI Length Mismatch",
"OAM Problem/Invalid CC/CV configuration", "OAM Problem/Invalid OTN
TTI Configuration/Missing Upstream TTI configuration", "OAM Problem/
Invalid OTN TTI Configuration/Missing Downstream TTI configuration",
"OAM Problem/Invalid OTN TTI Configuration/Invalid applicability
code", "OAM Problem/Invalid Performance Monitoring/Loss
configuration", "TMCE Problem/TTI Configuration mismatch"
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6. Security Considerations
Security aspects are addressed in the OAM configuration framework
document [GMPLS-OAM-FWK]
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7. Acknowledgements
The authors would like to thank Francesco Fondelli for his useful
comments.
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8. References
[G.707] International Telecommunications Union, "Network node
interface for the synchronous digital hierarchy (SDH)",
ITU-T Recommendation G.707, January 2007.
[G.709] International Telecommunications Union, "Interfaces for
the Optical Transport Network (OTN)", ITU-T
Recommendation G.709, March 2003.
[G.783] International Telecommunications Union, "Characteristics
of synchronous digital hierarchy (SDH) equipment
functional blocks", ITU-T Recommendation G.783,
December 2006.
[G.798] International Telecommunications Union, "Characteristics
of optical transport network hierarchy equipment
functional blocks", ITU-T Recommendation G.798,
December 2006.
[G.806] International Telecommunications Union, "Characteristics
of transport equipment - Description methodology and
generic functionality", ITU-T Recommendation G.806,
January 2009.
[GMPLS-OAM-FWK]
Takacs, A., Fedyk, D., and H. Jia, "OAM Configuration
Framework and Requirements for GMPLS RSVP-TE",
draft-ietf-ccamp-oam-configuration-fwk-01 (work in
progress), March 2009.
[GMPLS-VCAT-LCAS]
Bernstein, G., Rabbat, R., and H. Helvoort, "Operating
Virtual Concatenation (VCAT) and the Link Capacity
Adjustment Scheme (LCAS) with Generalized Multi-Protocol
Label Switching (GMPLS)",
draft-ietf-ccamp-gmpls-vcat-lcas-07 (work in progress),
December 2008.
[HOP_ATTR]
Kern, A. and A. Takacs, "Encoding of Attributes of LSP
hops using RSVP-TE", Internet-draft Work in progress,
October 2009.
[LSP-HIER-BIS]
Shiomoto, K., Farrel, A., Rabbat, R., Ayyangar, A., and Z.
Ali, "Procedures for Dynamically Signaled Hierarchical
Label Switched Paths",
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Internet-Draft GMPLS Based OTN and SDH OAM Configuration October 2009
draft-ietf-ccamp-lsp-hierarchy-bis-06 (work in progress),
December 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC4328] Papadimitriou, D., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Extensions for G.709 Optical
Transport Networks Control", RFC 4328, January 2006.
[RFC4606] Mannie, E. and D. Papadimitriou, "Generalized Multi-
Protocol Label Switching (GMPLS) Extensions for
Synchronous Optical Network (SONET) and Synchronous
Digital Hierarchy (SDH) Control", RFC 4606, August 2006.
[RFC4974] Papadimitriou, D. and A. Farrel, "Generalized MPLS (GMPLS)
RSVP-TE Signaling Extensions in Support of Calls",
RFC 4974, August 2007.
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Authors' Addresses
Andras Kern
Ericsson
Laborc u. 1.
Budapest, 1037
Hungary
Email: andras.kern@ericsson.com
Attila Takacs
Ericsson
Laborc u. 1.
Budapest, 1037
Hungary
Email: attila.takacs@ericsson.com
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