Network Working Group A. Kern
Internet-Draft A. Takacs
Intended status: Standards Track Ericsson
Expires: January 7, 2010 July 6, 2009
GMPLS RSVP-TE Extensions for OTN and SONET/SDH OAM Configuration
draft-kern-ccamp-rsvp-te-sdh-otn-oam-ext-00
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Abstract
GMPLS has been extended to support connection establishment in both
SONET/SDH [RFC4606] and OTN [RFC4328] networks. These documents do
not support the configuration of the supervision functions. Both
SONET/SDH and OTN implement supervision functions to qualify the
transported signals. [GMPLS-OAM-FWK] defines a technology-agnostic
framework for GMPLS to support the establishment and configuration of
pro-active OAM monitoring of signalled connections. This document
defines extensions to RSVP-TE for SONET/SDH and OTN OAM
configuration.
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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. Signaling support of Virtual Concatenation Groups (VCG) . 9
3.4. SONET/SDH OAM configuration . . . . . . . . . . . . . . . 9
3.4.1. Generic procedures . . . . . . . . . . . . . . . . . . 10
3.4.2. Connectivity supervision configuration . . . . . . . . 10
3.4.3. Signal quality supervision configuration . . . . . . . 10
3.5. OTN OAM configuration . . . . . . . . . . . . . . . . . . 11
3.5.1. Generic procedures . . . . . . . . . . . . . . . . . . 11
3.5.2. Connectivity monitoring supervision configuration . . 11
3.5.3. Signal quality supervision configuration . . . . . . . 12
3.6. OAM Configuration TLV . . . . . . . . . . . . . . . . . . 12
3.7. Extensions to LSP_TUNNEL_INTERFACE_ID objects . . . . . . 13
3.8. SONET/SDH OAM Configuration sub-TLV . . . . . . . . . . . 13
3.9. OTN OAM Configuration sub-TLV . . . . . . . . . . . . . . 14
3.10. TTI Configuration Sub-TLV . . . . . . . . . . . . . . . . 14
3.10.1. SDH TTI Configuration Sub-TLV . . . . . . . . . . . . 14
3.10.2. OTN TTI Configuration Sub-TLV . . . . . . . . . . . . 15
3.11. Degraded signal thresholds Sub-TLV . . . . . . . . . . . . 16
4. Error handling . . . . . . . . . . . . . . . . . . . . . . . . 18
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
6. Security Considerations . . . . . . . . . . . . . . . . . . . 20
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24
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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 do
not support the configuration of the supervision functions.
[GMPLS-OAM-FWK] defines a technology-agnostic framework for GMPLS to
support the establishment and configuration of pro-active OAM
monitoring 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 extensions to RSVP-TE 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 great 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 functions are 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 16 octet
long.
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, and 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 distributions an EDC violation
ratio is defined as the threshold; while for bursty error 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 distribution of errors.
These signal quality parameters are configured for Multiplexing
Section (MS) and the LOVC and HOVC path layers. Note, that the
Tandem Connection sub-layers support only bursty error distribution
model with Degraded Signal defect level.
For OTN, in the digital transport layers (OTUk and ODUk) only bursty
distribution of errors and the Degraded Signal defect level are
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 being 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 due to whether switching happens in
that layer (See Table 1).
+------------------+-----------+------------------------------------+
| Does switching | OTN | SONET/SDH |
| performed? | | |
+------------------+-----------+------------------------------------+
| yes | ODU, OCh, | Path (HOVC and LOVC), MS (in case |
| | OChr | of 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
The OAM related parameters of the LSP that we signal refer to the
switching layer connection. For this the [GMPLS-OAM-FWK] needs to be
extended with technology specific OAM Configuration TLVs.
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 3.4 and Section 3.5
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 are 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. If the
[LSP-HIER-BIS] signaling is used to setup the server layer connection
and institiate 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 Add 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:
o Checks if LSP_TUNNEL_INTERFACE_ID object is added and flag "O" is
set.
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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. 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.
[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 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 covers is relevant
only for this case.
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.
3.4. SONET/SDH OAM configuration
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3.4.1. 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.
3.4.2. Connectivity supervision configuration
The [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
expected in 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.
3.4.3. 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 are
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.
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3.5. OTN OAM configuration
3.5.1. 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. The
RSVP-TE does not support the configuration of these layers [RFC4328].
Therefore, OTS and OMS related OAM parameters are out of the scope of
this document as well. 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.
3.5.2. Connectivity monitoring supervision configuration
The [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].
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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
3.5.3. 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.
3.6. OAM Configuration TLV
This TLV is specified in [GMPLS-OAM-FWK] and is used to select which
OAM technology/method should be used for the LSP. In this document
two new OAM types are defined: SONET/SDH and OTN OAM.
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OAM Type Description
------------ ------------------
0 Reserved
1 Ethernet OAM
2 SONET/SDH OAM
3 OTN OAM
4-256 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
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 ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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
3.9. 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.
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 ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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".
3.10.2. 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".
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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
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.
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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 = 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
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".
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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"
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6. Security Considerations
The signaling of OAM related parameters and the automatic
establishment of OAM entities may introduce additional security
considerations to those discussed in [RFC3473]. Security aspects are
collected in the OAM 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.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.
[LSP-HIER-BIS]
Shiomoto, K., Farrel, A., Rabbat, R., Ayyangar, A., and Z.
Ali, "Procedures for Dynamically Signaled Hierarchical
Label Switched Paths",
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.
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[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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