Network Working Group A. Kern
Internet-Draft A. Takacs
Intended status: Standards Track Ericsson
Expires: March 2013 September 2012
GMPLS RSVP-TE Extensions for SONET/SDH and OTN OAM Configuration
draft-ietf-ccamp-rsvp-te-sdh-otn-oam-ext-05
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].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on March 2013.
Copyright Notice
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document authors. All rights reserved.
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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 . . . . . . . . . . . . . . . . 6
2.3.1. SONET/SDH . . . . . . . . . . . . . . . . . . . . . . 6
2.3.2. OTN . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.4. Delay measurement . . . . . . . . . . . . . . . . . . . . 6
3. RSVP-TE signaling extensions . . . . . . . . . . . . . . . . . 7
3.1. Operation overview . . . . . . . . . . . . . . . . . . . . 7
3.1.1. Continuity Check supervision . . . . . . . . . . . . . 7
3.1.2. Connectivity Monitoring supervision . . . . . . . . . 8
3.1.2.1. SDH/SONET . . . . . . . . . . . . . . . . . . . . 8
3.1.2.2. OTN . . . . . . . . . . . . . . . . . . . . . . . 8
3.1.3. Signal quality supervision . . . . . . . . . . . . . . 9
3.2. Signaling support of Virtual Concatenation Groups (VCG) . 9
3.3. OAM types and functions . . . . . . . . . . . . . . . . . 10
3.4. SONET/SDH OAM Configuration sub-TLV . . . . . . . . . . . 10
3.5. OTN OAM Configuration sub-TLV . . . . . . . . . . . . . . 11
3.6. TTI Configuration Sub-TLV . . . . . . . . . . . . . . . . 11
3.6.1. SDH TTI Configuration Sub-TLV . . . . . . . . . . . . 11
3.6.2. OTN TTI Configuration Sub-TLV . . . . . . . . . . . . 12
3.7. Degraded signal thresholds Sub-TLV . . . . . . . . . . . . 14
4. Error handling . . . . . . . . . . . . . . . . . . . . . . . . 16
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
6. Security Considerations . . . . . . . . . . . . . . . . . . . 18
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.1. Normative References . . . . . . . . . . . . . . . . . . . 20
8.2. Informative References . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
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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 SONET/
SDH [RFC4606], OTN [RFC4328] and OTNv3 [OTNv3_SIG] 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 for end-to-end monitoring.
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2. Overview of SONET/SDH and OTN OAM related functions
SONET/SDH [G.707] and OTN [G.709v3] provide a variety of supervision
functions. Among these functions we consider continuity,
connectivity and signal quality supervision functions, as these are
the candidates for GMPLS based configuration. We also consider delay
measurement management function of OTN.
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].
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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
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.
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.
2.4. Delay measurement
[G.709v3] introduced a tool for measuring round-trip delay of a
bidirectional ODU path or tandem connection. For implementing delay
measurement a one-bit delay measurement (DM) signal is defined in the
ODUk header. That signal is constant value (either 0 or 1). One
endpoint initiates a delay measurement by inverting the bit emitted
in the DM signal. The remote endpoint loops back the DM signal;
therefore, the delay measurement initiating node will receive the
inverted signal from the remote endpoint. This way the initiating
endpoint will determine the round trip delay.
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3. RSVP-TE signaling extensions
3.1. Operation overview
RFC 4606 and RFC 4328 define the RSVP-TE extensions necessary to
manage SDH/SONET and OTN optical and digital hierarchy connections.
Connections for recent version of OTN, the OTNv3 are configured
according to [OTNv3_SIG]. The monitoring functions associated to
these connections may be configured together with configuring the
connection itself.
The LSP Attribute Flag "OAM MEP entities desired" [GMPLS-OAM-FWK] is
used to signal that the monitoring functions at the endpoints must be
established. The "OAM MIP entities desired" flag must be set to 0
and must be ignored.
To configure OAM parameters the OAM Configuration TLV can be included
in the LSP_ATTRIBUTES object. The TLV identifies which OAM
technology ("OAM Type" field) to be used as well as which OAM
functions are to be enabled (OAM Function Flags sub-TLV). For SONET/
SDH and OTN the "Continuity Check" and "Connectivity Verification"
flags control the Continuity and Connectivity supervision functions,
while the "Performance Monitoring/Loss" flag enables the Signal
Quality supervision function.
Recent release of OTN [G.709v3] introduced delay measurement for
paths. Such node enables delay measurement by setting "Performance
Monitoring/Delay" flag. By setting that flag the node also indicates
that it will initiate the delay measurement proactively; therefore,
the remote endpoint node should not initate delay measurement over
the configured connection proactively. Equipments designed according
to earlier version of G709 must clear "Performance Monitoring/Loss"
flag and upon receiving OAM configuration message with "Performance
Monitoring/Delay" flag set must generate "OAM Problem/Unsupported OAM
Function" error. The "Performance Monitoring/Delay" flag must be
cleared for SONET/SDH as it is not supported by SONET/SDH.
For additional details the appropriate technology specific sub-TLV
can be carried in the OAM Configuration TLV.
3.1.1. Continuity Check supervision
In case of both discussed technologies, setting up continuity
supervision function for a connection does not need further
configuration besides enabling it. Therefore, by setting the
"Connectivity Monitoring" Flag of OAM Function implicitly enables the
continuity supervision function as well.
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3.1.2. Connectivity Monitoring supervision
3.1.2.1. SDH/SONET
[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. The source node emits this stream and
the destination node matches it with an expected one. When the
destination detects mismatch, defect state will be declared.
Since these streams encode an identifier defined for the source node,
different stream will to be emitted in the upstream and downstream
directions for bidirectional connections. 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.
3.1.2.2. OTN
[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
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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
3.1.3. Signal quality supervision
Signal quality supervision function is implemented in MS, HOVC, LOVC
layers of SDH/SONET. 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.
The 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.
Furthermore, as only one level is allowed a single Signal quality
supervision TLV is added to the OTN OAM Configuration TLV.
3.2. 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.
[RFC6344] summarises GMPLS signaling capabilities to support virtual
concatenation and proposes extensions to that. A Virtual
Concatenated Group (VCG) is constructed from several individual data
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plane signals. The co-routed signals of a VCG could be provisioned
together using a single RSVP-TE session (co-signaled). As different
OAM configuration may be applied to each of these individual signals,
the OAM configuration extension is applied as follows.
We assume that the same OAM type and the same set of OAM functions
apply to every individual signal of the VCG. A single OAM
Configuration TLV is carried in the LSP_ATTRIBUTES Object, while
multiple instances of technology specific OAM configuration sub-TLVs
are added: one instance per individual signal. The order of these
TLVs refers to the logical order of the basic signals (as they are
listed in the Label Object).
[RFC6344] 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 updated the contents of
the OAM Configuration TLV needs to be updated accordingly.
3.3. OAM types and functions
This document defines two new code points for the "OAM Type" field of
the OAM Configuration TLV, defined in [GMPLS-OAM-FWK]: SONET/SDH OAM
and OTN Digital Hierarchy OAM.
OAM Type Description
------------ ------------------
3 SONET/SDH OAM
4 OTN Digital Hierarchy OAM
The "OAM Function Flags sub-TLV", defined in [GMPLS-OAM-FWK]. SONET/
SDH and OTN supervision functions are defined in this document for
the following flags: "Continuity Check", "Connectivity Verification",
"Performance Monitoring/Loss" and "Performance Monitoring/Delay".
3.4. SONET/SDH OAM Configuration sub-TLV
SONET/SDH OAM Configuration sub-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 (4) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ sub TLVs ~
| |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: indicates a new type: the SONET/SDH OAM Configuration TLV (IANA
to define).
Length: indicates the total length including sub-TLVs
3.5. 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.
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 (5) (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
3.6. TTI Configuration Sub-TLV
3.6.1. SDH TTI Configuration Sub-TLV
This sub-TLV is carried in the SONET/SDH OAM Configuration sub-TLV,
if the Connectivity Verification OAM Function Flag is set. In every
supporting layers 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.
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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 (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
not supported by the referred SONET/SDH layer, error must be
generated: "OAM Problem/TTI Length Mismatch".
3.6.2. OTN TTI Configuration Sub-TLV
This sub-TLV is carried in the OTN OAM Configuration sub-TLV, if the
Connectivity Verification OAM Function Flag is set.
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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 (1) (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)
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
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direction (See Figure 2).
3 - Invalid.
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"
3.7. 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. This sub-TLV can be carried in both
the SONET/SDH OAM Configuration sub-TLV or OTN OAM Configuration sub-
TLV, if the PerformanceMonitoring/Loss OAM Function Flag is set.
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 = 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,
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
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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 In case of SONET/SDH if Performance Measurement/Delay flag is set
in the OAM Functions Flag sub-TLV, an error must be generated "OAM
Problem/Unsupported OAM Function".
o In case of OTN if the equipment does not support delay measurement
and the Performance Measurement/Delay flag is set in the received
OAM Functions Flag sub-TLV, an error must be generated "OAM
Problem/Unsupported OAM Function".
o In case of SONET/SDH OAM when the length or format of the TTI to
be configured is not supported by the referred SONET/SDH layer, an
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".
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5. IANA Considerations
This document specifies two new sub-TLVs to be carried in the OAM
Configuration TLV in the LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES
Objects in Path and Resv messages. The document assigns values 3 and
4 from the "OAM Type" field of the OAM Configuration TLV.
The following error values need to be assigned under "OAM Problem"
error code: "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".
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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
8.1. Normative References
[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.
8.2. Informative 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.709v3] International Telecommunications Union, "Interfaces for
the Optical Transport Network (OTN)", ITU-T
Recommendation G.709, December 2009.
[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.
[OTNv3_SIG]
Zhang, F., Zhang, G., Belotti, S., Ceccarelli, D., and K.
Pithewan, "Operating Virtual Concatenation (VCAT) and the
Link Capacity Adjustment Scheme (LCAS) with Generalized
Multi-Protocol Label Switching (GMPLS)",
draft-ietf-ccamp-gmpls-signaling-g709v3-01 (work in
progress), October 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4328] Papadimitriou, D., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Extensions for G.709 Optical
Transport Networks Control", RFC 4328, January 2006.
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[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.
[RFC6344] Bernstein, G., Caviglia, D., Rabbat, R., and H. Helvoort,
"Operating Virtual Concatenation (VCAT) and the Link
Capacity Adjustment Scheme (LCAS) with Generalized Multi-
Protocol Label Switching (GMPLS)", RFC 6344, August 2011.
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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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