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Network Working Group D. Papadimitriou, Ed.
Request for Comments: 4328 Alcatel
Updates: 3471 January 2006
Category: Standards Track
Generalized Multi-Protocol Label Switching (GMPLS)
Signaling Extensions for G.709 Optical Transport Networks Control
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document is a companion to the Generalized Multi-Protocol Label
Switching (GMPLS) signaling documents. It describes the technology-
specific information needed to extend GMPLS signaling to control
Optical Transport Networks (OTN); it also includes the so-called
pre-OTN developments.
Table of Contents
1. Introduction ....................................................2
1.1. Conventions Used in This Document ..........................3
2. GMPLS Extensions for G.709 - Overview ...........................3
3. Generalized Label Request .......................................4
3.1. Common Part ................................................5
3.1.1. LSP Encoding Type ...................................5
3.1.2. Switching Type ......................................6
3.1.3. Generalized-PID (G-PID) .............................6
3.2. G.709 Traffic Parameters ...................................8
3.2.1. Signal Type (ST) ....................................8
3.2.2. Number of Multiplexed Components (NMC) ..............9
3.2.3. Number of Virtual Components (NVC) .................10
3.2.4. Multiplier (MT) ....................................10
3.2.5. Reserved Fields ....................................10
4. Generalized Label ..............................................10
4.1. ODUk Label Space ..........................................11
4.2. Label Distribution Rules ..................................13
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RFC 4328 GMPLS Signaling Extensions for G.709 January 2006
4.3. Optical Channel Label Space ...............................14
5. Examples .......................................................14
6. RSVP-TE Signaling Protocol Extensions ..........................16
7. Security Considerations ........................................16
8. IANA Considerations ............................................16
9. Acknowledgements ...............................................18
10. References ....................................................18
10.1. Normative References .....................................18
10.2. Informative References ...................................19
11. Contributors ..................................................19
Appendix A. Abbreviations .........................................21
Appendix B. G.709 Indexes .........................................22
1. Introduction
Generalized Multi-Protocol Label Switching (GMPLS) [RFC3945] extends
MPLS from supporting Packet Switching Capable (PSC) interfaces and
switching to include support of four new classes of interfaces and
switching: Layer-2 Switching (L2SC), Time-Division Multiplex (TDM),
Lambda Switch (LSC), and Fiber-Switch (FSC) Capable. A functional
description of the extensions to MPLS signaling that are needed to
support these new classes of interfaces and switching is provided in
[RFC3471]. [RFC3473] describes the RSVP-TE-specific formats and
mechanisms needed to support all four classes of interfaces.
This document presents the technology details that are specific to
G.709 Optical Transport Networks (OTN) as specified in the ITU-T
G.709 recommendation [ITUT-G709] (and referenced documents),
including pre-OTN developments. Per [RFC3471], G.709 technology-
specific parameters are carried through the signaling protocol in
dedicated traffic parameter objects.
The G.709 traffic parameters defined hereafter (see Section 3.2) MUST
be used when the label is encoded as defined in this document.
Moreover, the label MUST be encoded as defined in Section 4 when
these G.709 traffic parameters are used.
In the context of this memo, by pre-OTN developments, one refers to
Optical Channel, Digital Wrapper and Forward Error Correction (FEC)
solutions that are not fully G.709 compliant. Details concerning
pre-OTN Synchronous Optical Network (SONET)/Synchronous Digital
Hierarchy (SDH) based solutions including Section/Regenerator Section
overhead (SOH/RSOH) and Line/Multiplex Section overhead (LOH/MSOH)
transparency are covered in [RFC3946].
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RFC 4328 GMPLS Signaling Extensions for G.709 January 2006
*** Note on ITU-T G.709 Recommendation ***
The views on the ITU-T G.709 OTN Recommendation presented in this
document are intentionally restricted to the GMPLS perspective within
the IETF CCAMP WG context. Hence, the objective of this document is
not to replicate the content of the ITU-T OTN recommendations.
Therefore, readers interested in more details concerning the
corresponding technologies are strongly invited to consult the
corresponding ITU-T documents (also referenced in this memo).
1.1. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
In addition, the reader is assumed to be familiar with the
terminology used in ITU-T [ITUT-G709], as well as [RFC3471] and
[RFC3473]. Abbreviations used in this document are detailed in
Appendix 1.
2. GMPLS Extensions for G.709 - Overview
[ITUT-G709] defines several networking layers constituting the
optical transport hierarchy:
- with full functionality:
. Optical Transmission Section (OTS)
. Optical Multiplex Section (OMS)
. Optical Channel (OCh)
- with reduced functionality:
. Optical Physical Section (OPS)
. Optical Channel with reduced functionality (OChr)
It also defines two layers constituting the digital transport
hierarchy:
- Optical Channel Transport Unit (OTUk)
- Optical Channel Data Unit (ODUk)
However, only the OCh and the ODUk layers are defined as switching
layers. Both OCh (but not OChr) and ODUk layers include the overhead
for supervision and management. The OCh overhead is transported in a
non-associated manner (also referred to as the non-associated
overhead naOH) in the Optical Transport Module (OTM) Overhead Signal
(OOS), together with the OTS and OMS non-associated overhead. The
OOS is transported via a dedicated wavelength, referred to as the
Optical Supervisory Channel (OSC). It should be noticed that the
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RFC 4328 GMPLS Signaling Extensions for G.709 January 2006
naOH is only functionally specified and as such, it is open to
vendor-specific solutions. The ODUk overhead is transported in an
associated manner as part of the digital ODUk frame.
As described in [ITUT-G709], in addition to the support of ODUk
mapping into OTUk (k = 1, 2, 3), G.709 supports ODUk multiplexing.
It refers to the multiplexing of ODUj (j = 1, 2) into an ODUk (k > j)
signal, in particular:
- ODU1 into ODU2 multiplexing
- ODU1 into ODU3 multiplexing
- ODU2 into ODU3 multiplexing
- ODU1 and ODU2 into ODU3 multiplexing
Adapting GMPLS to control G.709 OTN can be achieved by creating:
- a Digital Path layer, by extending the previously defined
"Digital Wrapper" in [RFC3471] corresponding to the ODUk
(digital) path layer.
- an Optical Path layer, by extending the "Lambda" concept (defined
in [RFC3471]) to the OCh (optical) path layer.
- a label space structure, by considering a tree whose root is an
OTUk signal and leaves the ODUj signals (k >= j); enabling the
identification of the exact position of a particular ODUj signal
in an ODUk multiplexing structure.
Thus, the GMPLS signaling extensions for G.709 need to cover the
Generalized Label Request, the Generalized Label as well as the
specific technology dependent objects included in the so-called
traffic parameters as specified in [RFC3946] for SONET/SDH networks.
Moreover, because multiplexing in the digital domain (such as ODUk
multiplexing) has been specified in the amended version of the G.709
ITU-T recommendation (October 2001), this document also proposes a
label space definition suitable for that purpose. Notice also that
one uses the G.709 ODUk (i.e., Digital Path) and OCh (i.e., Optical
Path) layers directly in order to define the corresponding label
spaces.
3. Generalized Label Request
The Generalized Label Request, as defined in [RFC3471], includes a
common part (i.e., used for any switching technology) and a
technology dependent part (i.e., the traffic parameters). In this
section, both parts are extended to accommodate GMPLS Signaling to
the G.709 transport plane recommendation (see [ITUT-G709]).
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3.1. Common Part
As defined in [RFC3471], the LSP Encoding Type, the Switching Type
and the Generalized Protocol Identifier (Generalized-PID) constitute
the common part of the Generalized Label Request. The encoding of
the RSVP-TE GENERALIZED_LABEL_REQUEST object is specified in
[RFC3473] Section 2.1.
As mentioned above, this document extends the LSP Encoding Type, the
Switching Type, and G-PID (Generalized-PID) values to accommodate
G.709 Recommendation [ITUT-G709].
3.1.1. LSP Encoding Type
Because G.709 Recommendation defines two networking layers (ODUk
layers and OCh layer), the LSP Encoding Type code-points can reflect
these two layers defined in [RFC3471] Section 3.1 as "Digital
Wrapper" and "Lambda" code. The LSP Encoding Type is specified per
networking layer or, more precisely, per group of functional
networking layers: the ODUk layers and the OCh layer.
Therefore, an additional LSP Encoding Type code-point for the G.709
Digital Path layer is defined; it enlarges the existing "Digital
Wrapper" code-point defined in [RFC3471]. The former MUST be
generated when the interface or tunnel on which the traffic will be
transmitted supports G.709 compliant Digital Path layer encoding.
The latter MUST only be used for non-G.709 compliant Digital Wrapper
layer(s) encoding. A transit or an egress node (receiving a Path
message containing a GENERALIZED_LABEL_REQUEST object) MUST generate
a PathErr message, with a "Routing problem/Unsupported Encoding"
indication, if the requested LSP Encoding Type cannot be supported on
the corresponding incoming interface.
In the same way, an additional LSP Encoding Type code-point for the
G.709 Optical Channel layer is defined; it enlarges the existing
"Lambda" code-point defined in [RFC3471]. The former MUST be
generated when the interface or tunnel on which the traffic will be
transmitted supports G.709-compliant Optical Channel layer encoding.
The latter MUST only be used for non-G.709 compliant Lambda layer(s)
encoding. A transit or an egress node (receiving a Path message that
contains a GENERALIZED_LABEL_REQUEST object) MUST generate a PathErr
message with a "Routing problem/Unsupported Encoding" indication, if
the requested LSP Encoding Type cannot be supported on the
corresponding incoming interface.
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Consequently, the following additional code-points for the LSP
Encoding Type are defined:
Value Type
----- ----
12 G.709 ODUk (Digital Path)
13 G.709 Optical Channel
Moreover, the code-point for the G.709 Optical Channel (OCh) layer
will indicate the requested capability of an end-system to use the
G.709 non-associated overhead (naOH), i.e., the OTM Overhead Signal
(OOS) multiplexed into the OTM-n.m interface signal.
3.1.2. Switching Type
The Switching Type indicates the type of switching that should be
performed at the termination of a particular link (see [RFC4202]).
No additional Switching Type values are to be considered in order to
accommodate G.709 switching types, because an ODUk switching (and
thus LSPs) belongs to the TDM class, while an OCh switching (and thus
LSPs) belong to the Lambda class (i.e., LSC).
Intermediate and egress nodes MUST verify that the value indicated in
the Switching Type field is supported on the corresponding incoming
interface. If the requested value can not be supported, the node
MUST generate a PathErr message with a "Routing problem/Switching
Type" indication.
3.1.3. Generalized-PID (G-PID)
The G-PID (16 bits field), as defined in [RFC3471], identifies the
payload carried by an LSP, i.e., an identifier of the client layer of
that LSP. This identifier is used by the endpoints of the G.709 LSP.
The G-PID can take one of the following values when the client
payload is transported over the Digital Path layer, in addition to
the payload identifiers defined in [RFC3471]:
- CBRa: asynchronous Constant Bit Rate (i.e., mapping of STM-16/OC-
48, STM-64/OC-192 and STM-256/OC-768)
- CBRb: bit synchronous Constant Bit Rate (i.e., mapping of STM-
16/OC-48, STM-64/OC-192 and STM-256/OC-768)
- ATM: mapping at 2.5, 10 and 40 Gbps
- BSOT: non-specific client Bit Stream with Octet Timing (i.e.,
Mapping of 2.5, 10 and 40 Gbps Bit Stream)
- BSNT: non-specific client Bit Stream without Octet Timing (i.e.,
Mapping of 2.5, 10 and 40 Gbps Bit Stream)
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RFC 4328 GMPLS Signaling Extensions for G.709 January 2006
- ODUk: transport of Digital Paths at 2.5, 10 and 40 Gbps
- ESCON: Enterprise Systems Connection
- FICON: Fiber Connection
The G-PID can take one of the following values when the client
payload is transported over the Optical Channel layer, in addition to
the payload identifiers defined in [RFC3471]:
- CBR: Constant Bit Rate (i.e., mapping of STM-16/OC-48, STM-64/OC-
192 and STM-256/OC-768)
- OTUk/OTUkV: transport of Digital Section at 2.5, 10 and 40 Gbps
Also, when client payloads such as Ethernet MAC/PHY and IP/PPP are
encapsulated through the Generic Framing Procedure (GFP), as
described in ITU-T G.7041, dedicated G-PID values are defined.
In order to include pre-OTN developments, the G-PID field can take
one of the values (currently defined in [RFC3471]) when the following
client payloads are transported over a so-called lambda LSP:
- Ethernet PHY (1 Gbps and 10 Gbps)
- Fiber Channel
The following table summarizes the G-PID with respect to the LSP
Encoding Type:
Value G-PID Type LSP Encoding Type
----- ---------- -----------------
47 G.709 ODUj G.709 ODUk (with k > j)
48 G.709 OTUk(v) G.709 OCh
ODUk mapped into OTUk(v)
49 CBR/CBRa G.709 ODUk, G.709 OCh
50 CBRb G.709 ODUk
51 BSOT G.709 ODUk
52 BSNT G.709 ODUk
53 IP/PPP (GFP) G.709 ODUk (and SDH)
54 Ethernet MAC (framed GFP) G.709 ODUk (and SDH)
55 Ethernet PHY (transparent GFP) G.709 ODUk (and SDH)
56 ESCON G.709 ODUk, Lambda, Fiber
57 FICON G.709 ODUk, Lambda, Fiber
58 Fiber Channel G.709 ODUk, Lambda, Fiber
Note: Values 49 and 50 include mapping of SDH.
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The following table summarizes the update of the G-PID values defined
in [RFC3471]:
Value G-PID Type LSP Encoding Type
----- ---------- -----------------
32 ATM Mapping SDH, G.709 ODUk
33 Ethernet PHY SDH, G.709 OCh, Lambda, Fiber
34 Sonet/SDH G.709 OCh, Lambda, Fiber
35 Reserved (SONET Dep.) G.709 OCh, Lambda, Fiber
3.2. G.709 Traffic Parameters
When G.709 Digital Path Layer or G.709 Optical Channel Layer is
specified in the LSP Encoding Type field, the information referred to
as technology dependent (or simply traffic parameters) is carried
additionally to the one included in the Generalized Label Request.
The G.709 traffic parameters are defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Signal Type | Reserved | NMC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NVC | Multiplier (MT) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In this frame, NMC stands for Number of Multiplexed Components, NVC
for Number of Virtual Components, and MT for Multiplier. Each of
these fields is tailored to support G.709 LSP requests.
The RSVP-TE encoding of the G.709 traffic-parameters is detailed in
Section 6.
3.2.1. Signal Type (ST)
This field (8 bits) indicates the type of G.709 Elementary Signal
that comprises the requested LSP. The permitted values are:
Value Type
----- ----
0 Not significant
1 ODU1 (i.e., 2.5 Gbps)
2 ODU2 (i.e., 10 Gbps)
3 ODU3 (i.e., 40 Gbps)
4 Reserved (for future use)
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RFC 4328 GMPLS Signaling Extensions for G.709 January 2006
5 Reserved (for future use)
6 OCh at 2.5 Gbps
7 OCh at 10 Gbps
8 OCh at 40 Gbps
9-255 Reserved (for future use)
The value of the Signal Type field depends on LSP Encoding Type value
defined in Section 3.1.1 and [RFC3471]:
- if the LSP Encoding Type value is the G.709 Digital Path layer,
then the valid values are the ODUk signals (k = 1, 2 or 3).
- if the LSP Encoding Type value is the G.709 Optical Channel
layer, then the valid values are the OCh at 2.5, 10, or 40 Gbps.
- if the LSP Encoding Type is "Lambda" (which includes the pre-OTN
Optical Channel layer) then the valid value is irrelevant (Signal
Type = 0).
- if the LSP Encoding Type is "Digital Wrapper", then the valid
value is irrelevant (Signal Type = 0).
Several transforms can be sequentially applied on the Elementary
Signal to build the Final Signal that is actually requested for the
LSP. Each transform application is optional and must be ignored if
zero; this does not include the Multiplier (MT), which cannot be zero
and must be ignored if equal to one. Transforms must be applied
strictly in the following order:
- First, virtual concatenation (by using the NVC field) can be
optionally applied directly on the Elementary Signal to form a
Composed Signal
- Second, a multiplication (by using the Multiplier field) can be
optionally applied, either directly on the Elementary Signal, or
on the virtually concatenated signal obtained from the first
phase. The resulting signal is referred to as Final Signal.
3.2.2. Number of Multiplexed Components (NMC)
The NMC field (16 bits) indicates the number of ODU tributary slots
used by an ODUj when multiplexed into an ODUk (k > j) for the
requested LSP. This field is not applicable when an ODUk is mapped
into an OTUk and irrelevant at the Optical Channel layer. In both
cases, it MUST be set to zero (NMC = 0) when sent and should be
ignored when received.
When applied at the Digital Path layer, in particular for ODU2
connections multiplexed into one ODU3 payload, the NMC field
specifies the number of individual tributary slots (NMC = 4) that
constitute the requested connection. These components are still
processed within the context of a single connection entity. For all
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other currently defined multiplexing cases (see Section 2), the NMC
field is set to 1.
3.2.3. Number of Virtual Components (NVC)
The NVC field (16 bits) is dedicated to ODUk virtual concatenation
(i.e., ODUk Inverse Multiplexing) purposes. It indicates the number
of ODU1, ODU2, or ODU3 Elementary Signals that are requested to be
virtually concatenated to form an ODUk-Xv signal. By definition,
these signals MUST be of the same type.
This field is set to 0 (default value) to indicate that no virtual
concatenation is requested.
Note that the current usage of this field only applies for G.709 ODUk
LSPs, i.e., values greater than zero, are only acceptable for ODUk
Signal Types. Therefore, it MUST be set to zero (NVC = 0), and
should be ignored when received, when a G.709 OCh LSP is requested.
3.2.4. Multiplier (MT)
The Multiplier field (16 bits) indicates the number of identical
Elementary Signals or Composed Signals that are requested for the
LSP, i.e., that form the Final Signal. A Composed Signal is the
resulting signal from the application of the NMC and NVC fields to an
elementary Signal Type. GMPLS signaling currently implies that all
the Composed Signals must be part of the same LSP.
This field is set to one (default value) to indicate that exactly one
instance of a signal is being requested. Intermediate and egress
nodes MUST verify that the node itself and the interfaces on which
the LSP will be established can support the requested multiplier
value. If the requested values cannot be supported, the receiver
node MUST generate a PathErr message (see Section 6).
Zero is an invalid value for the MT field. If received, the node
MUST generate a PathErr message (see Section 6).
3.2.5. Reserved Fields
The reserved fields (8 bits in row 1 and 32 bits in row 3) are
dedicated for future use. Reserved bits SHOULD be set to zero when
sent and MUST be ignored when received.
4. Generalized Label
This section describes the Generalized Label value space for Digital
Paths and Optical Channels. The Generalized Label is defined in
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[RFC3471]. The format of the corresponding RSVP-TE GENERALIZED_LABEL
object is specified in [RFC3473] Section 2.3.
The label distribution rules detailed in Section 4.2 follow (when
applicable) the ones defined in [RFC3946].
4.1. ODUk Label Space
At the Digital Path layer (i.e., ODUk layers), G.709 defines three
different client payload bit rates. An Optical Data Unit (ODU) frame
has been defined for each of these bit rates. ODUk refers to the
frame at bit rate k, where k = 1 (for 2.5 Gbps), 2 (for 10 Gbps), or
3 (for 40 Gbps).
In addition to the support of ODUk mapping into OTUk, the G.709
label space supports the sub-levels of ODUk multiplexing. ODUk
multiplexing refers to multiplexing of ODUj (j = 1, 2) into an ODUk
(k > j), in particular:
- ODU1 into ODU2 multiplexing
- ODU1 into ODU3 multiplexing
- ODU2 into ODU3 multiplexing
- ODU1 and ODU2 into ODU3 multiplexing
More precisely, ODUj into ODUk multiplexing (k > j) is defined when
an ODUj is multiplexed into an ODUk Tributary Unit Group (i.e., an
ODTUG constituted by ODU tributary slots) that is mapped into an
OPUk. The resulting OPUk is mapped into an ODUk, and the ODUk is
mapped into an OTUk.
Therefore, the label space structure is a tree whose root is an OTUk
signal and whose leaves are the ODUj signals (k >= j) that can be
transported via the tributary slots and switched between these slots.
A G.709 Digital Path layer label identifies the exact position of a
particular ODUj signal in an ODUk multiplexing structure.
The G.709 Digital Path Layer label or ODUk label has the following
format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | t3 | t2 |t1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reserved bits MUST be set to zero when sent and SHOULD be ignored
when received.
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The specification of the fields t1, t2, and t3 self-consistently
characterizes the ODUk label space. The value space for the t1, t2,
and t3 fields is defined as follows:
1. t1 (1-bit):
- t1=1 indicates an ODU1 signal.
- t1 is not significant for the other ODUk signal types (i.e.,
t1 value MUST be set to 0 and ignored).
2. t2 (3-bit):
- t2=1 indicates an ODU2 signal that is not further sub-
divided.
- t2=[2..5] indicates the tributary slot (t2th-2) used by the
ODU1 in an ODTUG2 mapped into an ODU2 (via OPU2).
- t2 is not significant for an ODU3 (i.e., t2 value MUST be
set to 0 and ignored).
3. t3 (6-bit):
- t3=1 indicates an ODU3 signal that is not further sub-
divided.
- t3=[2..17] indicates the tributary slot (t3th-1) used by the
ODU1 in an ODTUG3 mapped into an ODU3 (via OPU3).
- t3=[18..33] indicates the tributary slot (t3th-17) used by
the ODU2 in an ODTUG3 mapped into an ODU3 (via OPU3).
Note: in case of ODU2 into ODU3 multiplexing, 4 labels are required
to identify the 4 tributary slots used by the ODU2; these tributary
time slots have to be allocated in ascending order.
If the label sub-field value t[i]=1 (i, j = 1, 2 or 3) and t[j]=0 (j
> i), the corresponding ODUk signal ODU[i] is directly mapped into
the corresponding OTUk signal (k=i). This is referred to as the
mapping of an ODUk signal into an OTUk of the same order. Therefore,
the numbering starts at 1; zero is used to indicate a non-significant
field. A label field equal to zero is an invalid value.
Examples:
- t3=0, t2=0, t1=1 indicates an ODU1 mapped into an OTU1
- t3=0, t2=1, t1=0 indicates an ODU2 mapped into an OTU2
- t3=1, t2=0, t1=0 indicates an ODU3 mapped into an OTU3
- t3=0, t2=3, t1=0 indicates the ODU1 in the second tributary slot
of the ODTUG2 mapped into an ODU2 (via OPU2) mapped into an OTU2
- t3=5, t2=0, t1=0 indicates the ODU1 in the fourth tributary slot
of the ODTUG3 mapped into an ODU3 (via OPU3) mapped into an OTU3
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RFC 4328 GMPLS Signaling Extensions for G.709 January 2006
4.2. Label Distribution Rules
In case of ODUk in OTUk mapping, only one label can appear in the
Generalized Label. The unique label is encoded as a single 32-bit
label value (as defined in Section 4.1) of the GENERALIZED_LABEL
object (Class-Num = 16, C-Type = 2).
In case of ODUj in ODUk (k > j) multiplexing, the explicit ordered
list of the labels in the multiplex is given (this list can be
restricted to only one label when NMC = 1). Each label indicates a
component (ODUj tributary slot) of the multiplexed signal. The order
of the labels must reflect the order of the ODUj into the multiplex
(not the physical order of tributary slots). This ordered list of
labels is encoded as a sequence of 32-bit label values (as defined in
Section 4.1) of the GENERALIZED_LABEL object (Class-Num = 16, C-Type
= 2).
In case of ODUk virtual concatenation, the explicit ordered list of
all labels in the concatenation is given. Each label indicates a
component of the virtually concatenated signal. The order of the
labels must reflect the order of the ODUk to concatenate (not the
physical order of time-slots). This representation limits virtual
concatenation to remain within a single (component) link. In case of
multiplexed virtually concatenated signals, the first set of labels
indicates the components (ODUj tributary slots) of the first
virtually concatenated signal, the second set of labels indicates the
components (ODUj tributary slots) of the second virtually
concatenated signal, and so on. This ordered list of labels is
encoded as a sequence of 32-bit label values (as defined in Section
4.1) of the GENERALIZED_LABEL object (Class-Num = 16, C-Type = 2).
In case of ODUk virtual concatenation, the number of label values is
determined by the NVC value. Multiplexed ODUk virtual concatenation
additionally uses the NMC value to determine the number of labels per
set (equal in size).
In case of multiplication (i.e., when using the MT field), the
explicit ordered list of all labels taking part in the composed
signal is given. The above representation limits multiplication to
remain within a single (component) link. In case of multiplication
of multiplexed virtually concatenated signals, the first set of
labels indicates the components of the first multiplexed virtually
concatenated signal, the second set of labels indicates components of
the second multiplexed virtually concatenated signal, and so on.
This ordered list of labels is encoded as a sequence of 32-bit label
values (as defined in Section 4.1) of the GENERALIZED_LABEL object
(Class-Num = 16, C-Type = 2). In case of multiplication of (equal)
ODUk virtual concatenated signals, the number of label values per
signal is determined by the NVC value. Multiplication of multiplexed
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(equal) ODUk virtual concatenation additionally uses the NMC value to
determine the number of labels per set (equal in size).
4.3. Optical Channel Label Space
At the Optical Channel layer, the label space must be consistently
defined as a flat space whose values reflect the local assignment of
OCh identifiers that correspond to the OTM-n.m sub-interface signals
(m = 1, 2 or 3). Note that these identifiers do not cover OChr
because the corresponding Connection Function (OChr-CF) between OTM-
nr.m/OTM-0r.m is not defined in [ITUT-G798].
The OCh label space values are defined by either absolute values
(i.e., channel identifiers or Channel ID, also referred to as
wavelength identifiers) or relative values (channel spacing, also
referred to as inter-wavelength spacing). The latter is strictly
confined to a per-port label space, whereas the former could be
defined as a local or a global (per node) label space. Such an OCh
label space is applicable to both OTN Optical Channel layer and pre-
OTN Optical Channel layer.
Optical Channel label encoding (and distribution) rules are defined
in [RFC3471]. They MUST be used for the Upstream Label, the
Suggested Label, and the Generalized Label.
5. Examples
The following examples are given in order to illustrate the
processing described in the previous sections of this document.
1. ODUk in OTUk mapping: when one ODU1 (ODU2 or ODU3) signal is
directly transported in an OTU1 (OTU2 or OTU3), the upstream node
requests results simply in an ODU1 (ODU2 or ODU3) signal request.
In such conditions, the downstream node has to return a unique
label because the ODU1 (ODU2 or ODU3) is directly mapped into the
corresponding OTU1 (OTU2 or OTU3). Because a single ODUk signal
is requested (Signal Type = 1, 2 or 3), the downstream node has to
return a single ODUk label, which can be, for instance, one of the
following when the Signal Type = 1:
- t3=0, t2=0, t1=1 indicating a single ODU1 mapped into an OTU1
- t3=0, t2=1, t1=0 indicating a single ODU2 mapped into an OTU2
- t3=1, t2=0, t1=0 indicating a single ODU3 mapped into an OTU3
2. ODU1 into ODUk multiplexing (k > 1): when one ODU1 is multiplexed
into the payload of a structured ODU2 (or ODU3), the upstream node
requests results simply in an ODU1 signal request.
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In such conditions, the downstream node has to return a unique
label because the ODU1 is multiplexed into one ODTUG2 (or ODTUG3).
The latter is then mapped into the ODU2 (or ODU3) via OPU2 (or
OPU3) and then mapped into the corresponding OTU2 (or OTU3).
Because a single ODU1 multiplexed signal is requested (Signal Type
= 1 and NMC = 1), the downstream node has to return a single ODU1
label, which can take, for instance, one of the following values:
- t3=0,t2=4,t1=0 indicates the ODU1 in the third TS of the ODTUG2
- t3=2,t2=0,t1=0 indicates the ODU1 in the first TS of the ODTUG3
- t3=7,t2=0,t1=0 indicates the ODU1 in the sixth TS of the ODTUG3
3. ODU2 into ODU3 multiplexing: when one unstructured ODU2 is
multiplexed into the payload of a structured ODU3, the upstream
node requests results simply in an ODU2 signal request.
In such conditions, the downstream node has to return four labels
since the ODU2 is multiplexed into one ODTUG3. The latter is
mapped into an ODU3 (via OPU3) and then mapped into an OTU3.
Since an ODU2 multiplexed signal is requested (Signal Type = 2,
and NMC = 4), the downstream node has to return four ODU labels
which can take for instance the following values:
- t3=18, t2=0, t1=0 (first part of ODU2 in first TS of ODTUG3)
- t3=22, t2=0, t1=0 (second part of ODU2 in fifth TS of ODTUG3)
- t3=23, t2=0, t1=0 (third part of ODU2 in sixth TS of ODTUG3)
- t3=26, t2=0, t1=0 (fourth part of ODU2 in ninth TS of ODTUG3)
4. When a single OCh signal of 40 Gbps is requested (Signal Type =
8), the downstream node must return a single wavelength label as
specified in [RFC3471].
5. When requesting multiple ODUk LSP (i.e., with a multiplier (MT)
value > 1), an explicit list of labels is returned to the
requestor node.
When the downstream node receives a request for a 4 x ODU1 signal
(Signal Type = 1, NMC = 1 and MT = 4) multiplexed into an ODU3, it
returns an ordered list of four labels to the upstream node: the
first ODU1 label corresponds to the first signal of the LSP, the
second ODU1 label corresponds to the second signal of the LSP,
etc. For instance, the corresponding labels can take the
following values:
- First ODU1: t3=2, t2=0, t1=0 (in first TS of ODTUG3)
- Second ODU1: t3=10, t2=0, t1=0 (in ninth TS of ODTUG3)
- Third ODU1: t3=7, t2=0, t1=0 (in sixth TS of ODTUG3)
- Fourth ODU1: t3=6, t2=0, t1=0 (in fifth TS of ODTUG3)
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6. RSVP-TE Signaling Protocol Extensions
This section specifies the [RFC3473] protocol extensions needed to
accommodate G.709 traffic parameters.
The G.709 traffic parameters are carried in the G.709 SENDER_TSPEC
and FLOWSPEC objects. The same format is used both for SENDER_TSPEC
object and FLOWSPEC objects. The content of the objects is defined
above in Section 3.2. The objects have the following class and type
for G.709:
- G.709 SENDER_TSPEC Object: Class = 12, C-Type = 5
- G.709 FLOWSPEC Object: Class = 9, C-Type = 5
There is no Adspec associated with the G.709 SENDER_TSPEC. Either
the Adspec is omitted or an Int-serv Adspec with the Default General
Characterization Parameters and Guaranteed Service fragment is used,
see [RFC2210].
For a particular sender in a session, the contents of the FLOWSPEC
object received in a Resv message SHOULD be identical to the contents
of the SENDER_TSPEC object received in the corresponding Path
message. If the objects do not match, a ResvErr message with a
"Traffic Control Error/Bad Flowspec value" error SHOULD be generated.
Intermediate and egress nodes MUST verify that the node itself, and
the interfaces on which the LSP will be established, can support the
requested Signal Type, NMC, and NVC values (as defined in Section
3.2). If the requested value(s) cannot be supported, the receiver
node MUST generate a PathErr message with a "Traffic Control
Error/Service unsupported" indication (see [RFC2205]).
In addition, if the MT field is received with a zero value, the node
MUST generate a PathErr message with a "Traffic Control Error/Bad
Tspec value" indication (see [RFC2205]).
7. Security Considerations
This document introduces no new security considerations to [RFC3473].
8. IANA Considerations
Two values have been defined by IANA for this document:
Two RSVP C-Types in registry:
http://www.iana.org/assignments/rsvp-parameters
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- A G.709 SENDER_TSPEC object: Class = 12, C-Type = 5 - see
Section 6.
- A G.709 FLOWSPEC object: Class = 9, C-Type = 5 - see
Section 6.
IANA will also track the code-point spaces extended and/or updated by
this document. For this purpose, the following new registry entries
have been added in the newly requested registry entry:
http://www.iana.org/assignments/gmpls-sig-parameters
- LSP Encoding Type:
Name: LSP Encoding Type
Format: 8-bit number
Values:
[1..11] defined in [RFC3471]
12 defined in Section 3.1.1
13 defined in Section 3.1.1
Allocation Policy:
[0..239] Assigned by IANA via IETF Standards Track RFC
Action.
[240..255] Assigned temporarily for Experimental Usage.
These will not be registered with IANA
- Switching Type:
Name: Switching Type
Format: 8-bit number
Values: defined in [RFC3471]
Allocation Policy:
[0..255] Assigned by IANA via IETF Standards Track RFC
Action.
- Generalized PID (G-PID):
Name: G-PID
Format: 16-bit number
Values:
[0..31] defined in [RFC3471]
[32..35] defined in [RFC3471] and updated by Section
3.1.3
[36..46] defined in [RFC3471]
[47..58] defined in Section 3.1.3
Allocation Policy:
[0..31743] Assigned by IANA via IETF Standards Track RFC
Action.
[31744..32767] Assigned temporarily for Experimental Usage
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[32768..65535] Not assigned. Before any assignments can be
made in this range, there MUST be a Standards
Track RFC that specifies IANA Considerations
that covers the range being assigned.
Note: per [RFC3471], Section 3.1.1, standard Ethertype values are
used as G-PIDs for packet and Ethernet LSPs.
9. Acknowledgements
The authors would like to thank Jean-Loup Ferrant, Mathieu Garnot,
Massimo Canali, Germano Gasparini, and Fong Liaw for their
constructive comments and inputs as well as James Fu, Siva
Sankaranarayanan, and Yangguang Xu for their useful feedback. Many
thanks to Adrian Farrel for having thoroughly reviewed this document.
This document incorporates (upon agreement) material and ideas from a
work in progress, "Common Label and Label Request Specification for
Automatic Switched Transport Network", by Zhi Lin.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, R., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version
1 Functional Specification", RFC 2205, September 1997.
[RFC2210] Wroclawski, J., "The Use of RSVP with IETF Integrated
Services", RFC 2210, September 1997.
[RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Functional Description", RFC 3471,
January 2003.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January
2003.
[RFC3946] Mannie, E. and D. Papadimitriou, "Generalized Multi-
Protocol Label Switching (GMPLS) Extensions for
Synchronous Optical Network (SONET) and Synchronous
Digital Hierarchy (SDH) Control", RFC 3946, October
2004.
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RFC 4328 GMPLS Signaling Extensions for G.709 January 2006
[RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing
Extensions in Support of Generalized Multi-Protocol
Label Switching (GMPLS)", RFC 4202, September 2005.
10.2. Informative References
[RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
(GMPLS) Architecture", RFC 3945, October 2004.
For information on the availability of the following documents,
please see http://www.itu.int
[ITUT-G709] ITU-T, "Interface for the Optical Transport Network
(OTN)," G.709 Recommendation (and Amendment 1), February
2001 (October 2001).
[ITUT-G798] ITU-T, "Characteristics of Optical Transport Network
Hierarchy Equipment Functional Blocks," G.798
Recommendation, October 2001.
11. Contributors
Alberto Bellato (Alcatel)
Via Trento 30,
I-20059 Vimercate, Italy
EMail: alberto.bellato@alcatel.it
Sudheer Dharanikota (Consult)
EMail: sudheer@ieee.org
Michele Fontana (Alcatel)
Via Trento 30,
I-20059 Vimercate, Italy
EMail: michele.fontana@alcatel.it
Nasir Ghani (Sorrento Networks)
9990 Mesa Rim Road,
San Diego, CA 92121, USA
EMail: nghani@sorrentonet.com
Gert Grammel (Alcatel)
Lorenzstrasse, 10,
70435 Stuttgart, Germany
EMail: gert.grammel@alcatel.de
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RFC 4328 GMPLS Signaling Extensions for G.709 January 2006
Dan Guo (Turin Networks)
1415 N. McDowell Blvd,
Petaluma, CA 94954, USA
EMail: dguo@turinnetworks.com
Juergen Heiles (Siemens)
Hofmannstr. 51,
D-81379 Munich, Germany
EMail: juergen.heiles@siemens.com
Jim Jones (Alcatel)
3400 W. Plano Parkway,
Plano, TX 75075, USA
EMail: jim.d.jones@alcatel.com
Zhi-Wei Lin (Lucent)
101 Crawfords Corner Rd, Rm 3C-512
Holmdel, New Jersey 07733-3030, USA
EMail: zwlin@lucent.com
Eric Mannie (Consult)
EMail: eric_mannie@hotmail.com
Maarten Vissers (Alcatel)
Lorenzstrasse, 10,
70435 Stuttgart, Germany
EMail: maarten.vissers@alcalel.de
Yong Xue (WorldCom)
22001 Loudoun County Parkway,
Ashburn, VA 20147, USA
EMail: yong.xue@wcom.com
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Appendix A. Abbreviations
BSNT Bit Stream without Octet Timing
BSOT Bit Stream with Octet Timing
CBR Constant Bit Rate
ESCON Enterprise Systems Connection
FC Fiber Channel
FEC Forward Error Correction
FICON Fiber Connection
FSC Fiber Switch Capable
GCC General Communication Channel
GFP Generic Framing Procedure
LSC Lambda Switch Capable
LSP Label Switched Path
MS Multiplex Section
naOH non-associated Overhead
NMC Number of Multiplexed Components
NVC Number of Virtual Components
OCC Optical Channel Carrier
OCG Optical Carrier Group
OCh Optical Channel (with full functionality)
OChr Optical Channel (with reduced functionality)
ODTUG Optical Date Tributary Unit Group
ODU Optical Channel Data Unit
OH Overhead
OMS Optical Multiplex Section
OMU Optical Multiplex Unit
OOS OTM Overhead Signal
OPS Optical Physical Section
OPU Optical Channel Payload Unit
OSC Optical Supervisory Channel
OTH Optical Transport Hierarchy
OTM Optical Transport Module
OTN Optical Transport Network
OTS Optical Transmission Section
OTU Optical Channel Transport Unit
OTUkV Functionally Standardized OTUk
PPP Point to Point Protocol
PSC Packet Switch Capable
RES Reserved
RS Regenerator Section
TTI Trail Trace Identifier
TDM Time Division Multiplex
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Appendix B. G.709 Indexes
- Index k: The index "k" is used to represent a supported bit rate
and the different versions of OPUk, ODUk and OTUk. k=1 represents an
approximate bit rate of 2.5 Gbit/s, k=2 represents an approximate bit
rate of 10 Gbit/s, k = 3 an approximate bit rate of 40 Gbit/s and k =
4 an approximate bit rate of 160 Gbit/s (under definition). The
exact bit-rate values are in kbits/s:
. OPU: k=1: 2 488 320.000, k=2: 9 995 276.962, k=3: 40 150 519.322
. ODU: k=1: 2 498 775.126, k=2: 10 037 273.924, k=3: 40 319 218.983
. OTU: k=1: 2 666 057.143, k=2: 10 709 225.316, k=3: 43 018 413.559
- Index m: The index "m" is used to represent the bit rate or set of
bit rates supported on the interface. This is a one or more digit
"k", where each "k" represents a particular bit rate. The valid
values for m are (1, 2, 3, 12, 23, 123).
- Index n: The index "n" is used to represent the order of the OTM,
OTS, OMS, OPS, OCG and OMU. This index represents the maximum number
of wavelengths that can be supported at the lowest bit rate supported
on the wavelength. It is possible that a reduced number of higher
bit rate wavelengths are supported. The case n=0 represents a single
channel without a specific wavelength assigned to the channel.
- Index r: The index "r", if present, is used to indicate a reduced
functionality OTM, OCG, OCC and OCh (non-associated overhead is not
supported). Note that for n=0 the index r is not required as it
implies always reduced functionality.
Editor's Address
Dimitri Papadimitriou (Alcatel)
Francis Wellesplein 1,
B-2018 Antwerpen, Belgium
Phone: +32 3 240-8491
EMail: dimitri.papadimitriou@alcatel.be
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Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
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