Network Working Group Fatai Zhang
Internet Draft Huawei
Category: Standards Track Guoying Zhang
CATR
Sergio Belotti
Alcatel-Lucent
D. Ceccarelli
Ericsson
Expires: August 2010 February 27, 2010
Generalized Multi-Protocol Label Switching (GMPLS) Signaling
Extensions for the evolving G.709 Optical Transport Networks Control
draft-zhang-ccamp-gmpls-evolving-g709-04.txt
Status of this Memo
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This Internet-Draft will expire on August 26, 2010.
Abstract
Recent progress in ITU-T Recommendation G.709 standardization has
introduced new ODU containers (ODU0, ODU4, ODU2e and ODUflex) and
enhanced Optical Transport Networking (OTN) flexibility. Several
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recent documents have proposed ways to modify GMPLS signaling
protocols to support these new OTN features.
It is important that a single solution is developed for use in GMPLS
signaling and routing protocols. This solution must support ODUk
multiplexing capabilities, address all of the new features, be
acceptable to all equipment vendors, and be extensible considering
continued OTN evolution.
This document describes the extensions to the Generalized Multi-
Protocol Label Switching (GMPLS) signaling to control the evolutive
Optical Transport Networks (OTN) addressing ODUk multiplexing and new
features including ODU0, ODU4, ODU2e and ODUflex.
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].
Table of Contents
1. Introduction..................................................3
2. Terminology...................................................4
3. GMPLS Extensions for the Evolutive G.709 - Overview...........4
4. Extensions for Traffic Parameters for the Evolutive G.709.....5
4.1. Usage of ODUflex traffic parameter.......................7
4.2. Example of ODUflex traffic parameter.....................8
5. Generalized Label.............................................9
5.1. New definition of ODUk label.............................9
5.2. Examples................................................11
5.3. Label Distribution Procedure............................12
5.4. Backward Compatibility Considerations...................13
5.4.1. Control Plane Backward Compatibility Considerations13
5.4.2. Data Plane Backward Compatibility Considerations...14
5.5. Collision management....................................15
6. Security Considerations......................................15
7. IANA Considerations..........................................15
8. References...................................................15
8.1. Normative References....................................15
8.2. Informative References..................................16
9. Authors' Addresses...........................................17
Acknowledgment..................................................18
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1. Introduction
Generalized Multi-Protocol Label Switching (GMPLS) [RFC3945] extends
MPLS to include Layer-2 Switching (L2SC), Time-Division Multiplex
(e.g., SONET/SDH, PDH, and ODU), Wavelength (OCh, Lambdas) Switching,
and Spatial Switching (e.g., incoming port or fiber to outgoing port
or fiber). [RFC3471] presents a functional description of the
extensions to Multi-Protocol Label Switching (MPLS) signaling
required to support Generalized MPLS. RSVP-TE-specific formats and
mechanisms and technology specific details are defined in [RFC3473].
With the evolution and deployment of G.709 technology, it is
necessary that appropriate enhanced control technology support be
provided for G.709. [RFC4328] describes the control technology
details that are specific to foundation G.709 Optical Transport
Networks (OTN), as specified in the ITU-T G.709 recommendation [ITUT-
G709], for ODUk deployments without multiplexing.
In addition to increasing need to support ODUk multiplexing, the
evolution of OTN has introduced additional containers and new
flexibility. For example, ODU0, ODU2e, ODU4 containers as described
in [G709-Amd3], and ODUflex being developed in [G709-v3].
In addition, the following issues require consideration:
- Support for ODUflex resizing capabilities, potentially hitless
(similar to LCAS, as defined in [VCAT-LCAS]), which is under
discussion in ITU-T.
- Support for Tributary Port Number. The Tributary Port Number
has to be negotiated on each link for flexible assignment of
tributary ports to tributary slots in case of LO-ODU over HO-
ODU (e.g., ODU2 into ODU3). Alternatively, the nodes of the
network are supposed to run AutoMSI mode.
Therefore, it is clear that [RFC4328] has to be updated or replaced
in order to support ODUk multiplexing, as well as other ODU
enhancements introduced by evolution of OTN standards.
This document updates RFC4328 extending the G.709 ODUk traffic
parameters and also presents a new OTN label format which is very
flexible and scalable.
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2. Terminology
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].
3. GMPLS Extensions for the Evolutive G.709 - Overview
The new features for the evolutive OTN are described in the separate
ITU-T documents, for example, ODU0, ODU2e,ODU4 are described in
[G709-Amd3] and ODUflex is being developed in [G709-v3].
The new signal types of digital wrapper layer for the evolutive OTN
are listed as follows:
- Optical Channel Transport Unit (OTUk):
. OTU4
- Optical Channel Data Unit (ODUk):
. ODU0
. ODU2e
. ODU4
. ODUflex
A new Tributary Slot (TS) granularity (i.e., 1.25 Gbps) is introduced
in [G709-Amd3]. At this point there are two TS granularities for the
original ODU1, ODU2, ODU3. The TS granularity at 2.5 Gbps is used on
legacy interfaces while the new 1.25 Gbps will be used for the new
interfaces.
New ITU-T documents not only introduce new signal types but also
define the new multiplexing hierarchy for the evolutive OTN. In
addition to the support of ODUk mapping into OTUk (k = 1, 2, 3, 4),
G.709 and its amendments, support ODUk multiplexing. For the
evolutive OTN, the multiplexing of ODUj (j = 0, 1, 2, 2e, 3, flex)
into an ODUk (k > j) signal can be depicted as follows:
- ODU0 into ODU1 multiplexing (with 1,25Gbps TS granularity)
- ODU0, ODU1, ODUflex into ODU2 multiplexing (with 1.25Gbps TS
granularity)
- ODU1 into ODU2 multiplexing (with 2.5Gbps TS granularity)
- ODU0, ODU1, ODU2, ODU2e and ODUflex into ODU3 multiplexing
(with 1.25Gbps TS granularity)
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- ODU1, ODU2 into ODU3 multiplexing (with 2.5Gbps TS granularity)
- ODU0, ODU1, ODU2, ODU2e, ODU3 and ODUflex into ODU4
multiplexing (with 1.25Gbps TS granularity)
[RFC4328] describes GMPLS signaling extensions to support the control
for G.709 Optical Transport Networks (OTN) [ITUT-G709]. However,
[RFC4328] need to be updated because it does not provide the means to
signal all the new signal types and related mapping and multiplexing
functionalities. Moreover, it supports only the optional auto-MSI
mode which assumes that the Tributary Port Number is automatically
assigned in the transmit direction and not checked in the receive
direction.
This document extends the G.709 traffic parameters described in
[RFC4328] and also presents a new OTN label format which is very
flexible and scalable.
[Editors note] There are several possibilities to include the
Tributary Port Number information in the signaling. Note that ITU-T
has not yet given a clear interpretation of the Tributary Port number
information in case of bidirectional paths, so the adoption of any
solution should be kept on hold until ITU-T provides an approved
definition.
4. Extensions for Traffic Parameters for the Evolutive G.709
The traffic parameters for G.709 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 | Tolerance | NMC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NVC | Multiplier (MT) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bit_Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
[Editors note] NMC field in RFC4328 had the meaning to indicate how
many labels have to be expected. This information allows the
protocol to operate without specific knowledge of the signal type.
The same effect could be obtained either indicating the bit map
length or indicating the number of labels.
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The Signal Type should be extended to cover the new Signal Type
introduced by the evolutive OTN. The new Signal Type is extended as
follows:
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 ODU4 (i.e., 100 Gbps)
5 Reserved (for future use)
6 OCh at 2.5 Gbps
7 OCh at 10 Gbps
8 OCh at 40 Gbps
9 OCh at 100 Gbps
10~19 Reserved (for future use)
20 ODU0 (i.e., 1.25 Gbps)
21~30 Reserved (for future use)
31 ODU2e (i.e., 10Gbps for FC1200 and GE LAN)
32 ODUflex (i.e., 1.25*N Gbps)
33~255 Reserved (for future use)
In case of ODUflex(CBR), the Bit_Rate and Tolerance fields are used
together to represent the actual bandwidth of ODUflex, where:
- The Bit_Rate field indicates the nominal bit rate of ODUflex(CBR)
encoded as a 32-bit IEEE single-precision floating-point number
(referring to [RFC4506] and [IEEE]).
- The Tolerance field indicates the bit rate tolerance (part per
million, ppm) of the ODUflex(CBR) encoded as an unsigned integer.
For example, for an ODUflex(CBR) service with Bit_Rate = 2.5Gbps and
Tolerance = 50ppm, the actual bandwidth of the ODUflex is:
2.5Gbps * (1 - 50ppm) ~ 2.5Gbps * (1 + 50ppm)
In case of other ODUk signal types, the Bit_Rate and Tolerance fields
are not necessary and MUST be filled with 0.
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4.1. Usage of ODUflex traffic parameter
In case of ODUflex(CBR), the information of Bit_Rate and Tolerance in
the ODUflex traffic parameter is used to determine the total number
of tributary slots N in the HO ODUk link to be reserved. Here:
N = Ceiling of
ODUflex(CBR) nominal bit rate * (1 + ODUflex(CBR) bit rate tolerance)
---------------------------------------------------------------------
ODTUk.ts nominal bit rate * (1 - HO OPUk bit rate tolerance)
Therefore, a node receiving a Path message containing ODUflex(CBR)
traffic parameter can allocate precise number of tributary slots and
set up the cross-connection for the ODUflex service.
The table below shows the actual bandwidth of the tributary slot of
ODUk (in Gbps), referring to [G709-v3].
ODUk Minimum Nominal Maximum
-------------------------------------------------------
ODU2 1.249 384 632 1.249 409 620 1.249 434 608
ODU3 1.254 678 635 1.254 703 729 1.254 728 823
ODU4 1.301 683 217 1.301 709 251 1.301 735 285
Note that:
Minimum bandwidth of ODUTk.ts =
ODTUk.ts nominal bit rate * (1 - HO OPUk bit rate tolerance)
Maximum bandwidth of ODTUk.ts =
ODTUk.ts nominal bit rate * (1 + HO OPUk bit rate tolerance)
Where: HO OPUk bit rate tolerance = 20ppm
For different ODUk, the bandwidths of the tributary slot are
different, and so the total number of tributary slots to be reserved
for the ODUflex(CBR) may not be the same on different HO ODUk links.
This is why the traffic parameter should bring the actual bandwidth
information other than the NMC field.
In case of ODUflex(GFP), the total number of tributary slots to be
reserved for one ODUflex service MUST keep the same in different HO
ODUk links. So the NMC field can be used to indicate the total number
of TS, instead of using the Bit_Rate and Tolerance fields. Therefore,
when Signal Type = ODUflex(32), the zero value of NMC field and
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nonzero values of Bit_Rate and Tolerance fields imply an ODUflex(CBR)
traffic parameter, and the nonzero value of NMC field and zero values
of Bit_Rate and Tolerance fields imply an ODUflex(GFP) traffic
parameter.
4.2. Example of ODUflex traffic parameter
This section gives an example to illustrate the usage of ODUflex(CBR)
traffic parameter.
Assume there is an ODUflex(CBR) service requesting a bandwidth of
(2.5Gbps, +/-20ppm) from node A to node C. In other words, the
ODUflex traffic parameter indicates that Signal Type is 32 (ODUflex),
Bit_Rate is 2.5Gbps and Tolerance is 20ppm.
+-----+ +---------+ +-----+
| +-------------+ +-----+ +-------------+ |
| ===============\| ODU |/=============== |
| ===============/| flex+-=============== |
| +-------------+ | |\=============== |
| +-------------+ +-----+ +-------------+ |
| | | | | |
| | ....... | | ....... | |
| A +-------------+ B +-------------+ C |
+-----+ HO ODU4 +---------+ HO ODU2 +-----+
=========: TS occupied by ODUflex
---------: free TS
- On the HO ODU4 link between node A and B:
The maximum bandwidth of the ODUflex equals 2.5Gbps * (1 + 20ppm),
and the minimum bandwidth of the tributary slot of ODU4 equals
1.301 683 217Gbps, so the total number of tributary slots N1 to
be reserved on this link is:
N1 = ceiling (2.5Gbps * (1 + 20ppm) / 1.301 683 217) = 2
- On the HO ODU2 link between node B and C:
The maximum bandwidth of the ODUflex equals 2.5Gbps * (1 + 20ppm),
and the minimum bandwidth of the tributary slot of ODU2 equals
1.249 384 632Gbps, so the total number of tributary slots N2 to
be reserved on this link is:
N2 = ceiling (2.5Gbps * (1 + 20ppm) / 1.249 384 632) = 3
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5. Generalized Label
[RFC3471] has defined the Generalized Label which extends the
traditional label by allowing the representation of not only labels
which travel in-band with associated data packets, but also labels
which identify time-slots, wavelengths, or space division multiplexed
positions. The format of the corresponding RSVP-TE Generalized Label
object is defined in the Section 2.3 of [RFC3473].
However, for different technologies, we usually need use specific
label rather than the Generalized Label. For example, the label
format described in [RFC4606] could be used for SDH/SONET, the label
format in [RFC4328] for G.709.
According to the ODUk label format defined in [RFC4328], it could be
updated to support new signal types defined in G.709 amendment 3 but
would hardly be further enhanced to support possible new signal types.
Furthermore such label format can face big problems related to
scalability matters due to the high number of labels needed. For
example, when ODU3 is mapped into ODU4 with 1.25G tributary slots, it
will need thirty-one labels (31*4*8=992 bits) to be allocated for one
ODU3 connection. If ODUflex into ODU4, it may need up to eighty
labels (80*4*8=2560 bits) to be allocated for one ODUflex connection.
In this document, a new ODUk label format is defined. The new ODUk
label format is very flexible and scalable.
5.1. New definition of ODUk label
In order to be compatible with new types of ODU signal and new types
of tributary slot, the following new ODUk label format is defined:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ODUj |OD(T)Uk| T | Reserved | Bit Map |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ......... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ODUj and OD(T)Uk (4 bits respectively): indicate that LO ODUj is
multiplexed into HO ODUk(k>j), or LO ODUj is mapped into OTUk (j=k).
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ODUj field Signal type
---------- -----------
0 LO ODU0
1 LO ODU1
2 LO ODU2
3 LO ODU3
4 LO ODU4
5 LO ODU2e
6 LO ODUflex
7-15 Reserved (for future use)
OD(T)Uk field Signal type
------------- -----------
0 Reserved (for future use)
1 HO ODU1 / OTU1
2 HO ODU2 / OTU2
3 HO ODU3 / OTU3
4 HO ODU4 / OTU4
5-15 Reserved (for future use)
T (2 bits): indicates the type of tributary slot of HO ODUk.
Currently, two types of tributary slot are defined in [G.709], the
1.25Gbps tributary slot and the 2.5Gbps tributary slot.
T field TS type
------- -------
0 1.25Gbps TS granularity
1 2.5Gbps TS granularity
2-3 Reserved (for future use)
Bit Map (variable): indicates which tributary slots in HO ODUk that
the LO ODUj will be multiplexed into. The sequence of the Bit Map is
consistent with the sequence of the tributary slots in HO ODUk. Each
bit in the bit map represents the corresponding tributary slot in HO
ODUk with a value of 1 or 0 indicating whether the tributary slot
will be used by LO ODUj or not.
The size of the bit map equals to the total number of the tributary
slots of HO ODUk.
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In case of an ODUk mapped into OTUk, it's no need to indicate which
tributary slots will be used, so the size of Bit Map is 0.
Padded bits are added behind the Bit Map to make the whole label a
multiple of four bytes if necessary. Padded bit MUST be set to 0 and
MUST be ignored.
[Editors note] Tributary Port Number information to be inserted as
soon as clarification from ITU has been provided.
5.2. Examples
The following examples are given in order to illustrate the label
format described in the previous sections of this document.
(1) ODUk into OTUk mapping:
In such conditions, the downstream node along an LSP returns a label
indicating that the ODU1 (ODU2 or ODU3 or ODU4) is directly mapped
into the corresponding OTU1 (OTU2 or OTU3 or ODU4). The following
example label indicates an ODU1 mapped into OTU1.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|0 0 0 1|0 1| Reserved | Padded Bits (0) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(2) ODUj into ODUk multiplexing:
In such conditions, this label indicates that an ODUj is multiplexed
into several tributary slots of OPUk and then mapped into OTUk. Some
instances are shown as follow:
- ODU0 into ODU2 Multiplexing:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0|0 0 1 0|0 0| Reserved |0 1 0 0 0 0 0 0|Padded Bits (0)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This above label indicates an ODU0 multiplexed into the second
tributary slot of ODU2, wherein the type of the tributary slot is
1.25Gbps.
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- ODU1 into ODU2 Multiplexing with 1.25Gbps TS granularity:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|0 0 1 0|0 0| Reserved |0 1 0 1 0 0 0 0|Padded Bits (0)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This above label indicates an ODU1 multiplexed into the 2nd and the
4th tributary slot of ODU2, wherein the type of the tributary slot is
1.25Gbps.
- ODU2 into ODU3 Multiplexing with 2.5Gbps TS granularity:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 1 0|0 0 1 1|0 1| Reserved |0 1 1 0 1 0 1 0 0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This above label indicates an ODU2 multiplexed into the 2nd, 3rd, 5th
and 7th tributary slot of ODU3, wherein the type of the tributary
slot is 2.5Gbps.
5.3. Label Distribution Procedure
This document does not change the existing label distribution
procedures [RFC4328] for GMPLS except that the new ODUk label should
be processed as follows.
When a node receives a generalized label request for setting up an
ODUj LSP from its upstream node, the node should generate an ODU
label according to the signal type of the requested LSP and the free
resources (i.e., free tributary slots of ODUk) that will be reserved
for the LSP, and send the label to its upstream node. Note that these
labels can also be specified by the source node of the connection.
In case of ODUj to ODUk multiplexing, the node should firstly
determine the size of the Bit Map field according to the signal type
and the tributary slot type of ODUk, and then set the bits to 1 in
the Bit Map field corresponding to the reserved tributary slots.
In case of ODUk to OTUk mapping, the node only needs to fill the ODUj
and the ODUk fields with corresponding values in the label. Other
bits are reserved and MUST be set to 0.
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When receiving an ODU label from its downstream node, the node should
learn which ODU signal type is multiplexed or mapped into which ODU
signal type by analyzing the ODUj and the ODUk fields.
In case of ODUj to ODUk multiplexing, the node should firstly
determine the size of the Bit Map field according to the signal type
and the tributary slot type of ODUk, and then obtain which tributary
slots in ODUk are reserved by its downstream node according to the
position of the bits that are set to 1 in the Bit Map field, so that
the node can multiplex the ODUj into the reserved tributary slots of
ODUk after the LSP is established.
In case of ODUk to OTUk mapping, the size of Bit Map field is 0 and
no additional procedure is needed.
5.4. Backward Compatibility Considerations
5.4.1. Control Plane Backward Compatibility Considerations
Since the [RFC4328] has been deployed in the network for the nodes
which support the [ITUT-G709] (herein we call them "old nodes"), the
backward compatibility SHOULD be take into consideration when the new
nodes (i.e., nodes that support the [G709-Amd3] or [G709-v3]) and the
old nodes are interworking.
For backward compatibility consideration, the new node SHOULD have
the ability to generate and parse old labels.
o For the old node, it always generates and sends old label to its
upstream node, no matter the upstream node is new or old, as
described in [RFC4328].
o For the new node, it will generate and send old label if its
upstream node is an old one, and generate and send new label if
its upstream node is a new one.
One backward compatibility example is shown below:
Path Path Path Path
+-----+ ----> +-----+ ----> +-----+ ----> +-----+ ----> +-----+
| | | | | | | | | |
| A +-------+ B +-------+ C +-------+ D +-------+ E |
|(new)| |(new)| |(old)| |(old)| |(new)|
+-----+ <---- +-----+ <---- +-----+ <---- +-----+ <---- +-----+
Resv Resv Resv Resv
(new label) (old label) (old label) (old label)
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As described above, for backward compatibility considerations, it is
necessary for a new node to know whether the neighbor node is new or
old.
One optional method is manual configuration. But it is recommended to
use LMP to discover the capability of the neighbor node automatically,
as described in [OTN-LMP].
When performing the HO ODU link capability negotiation:
o If the neighbor node only support the 2.5Gbps TS and only support
ODU1/ODU2/ODU3, the neighbor node should be treated as an old node.
o If the neighbor node can support the 1.25Gbps TS, or can support
other LO ODU types defined in [G709-Amd3] or [G709-v3]), the
neighbor node should be treated as new node.
o If the neighbor node returns a LinkSummaryNack message including
an ERROR_CODE indicating nonsupport of HO ODU link capability
negotiation, the neighbor node should be treated as an old node.
5.4.2. Data Plane Backward Compatibility Considerations
As described in chapter 3.1 and 4.1 of [OTN-LMP], the node supporting
1.25Gbps TS can interwork with the other nodes that supporting
2.5Gbps TS by combining Specific TSs together in data plane. The
control plane MUST support this TS combination.
Take the following figure as an example. Assume that there is an ODU2
link between node A and B, where node A only supports the 2.5Gbps TS
while node B supports the 1.25Gbps TS. In this case, the TS#i and
TS#i+4 (where i<=4) of node B are combined together. When creating an
ODU1 service in this ODU2 link, node B reserves the TS#i and TS#i+4
with the granularity of 1.25Gbps. But in the label sent from B to A,
it is indicated that the TS#i with the granularity of 2.5Gbps is
reserved.
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Path
+----------+ ------------> +----------+
| TS1==|===========\--------+--TS1 |
| TS2==|=========\--\-------+--TS2 |
| TS3==|=======\--\--\------+--TS3 |
| TS4==|=====\--\--\--\-----+--TS4 |
| | \ \ \ \----+--TS5 |
| | \ \ \------+--TS6 |
| | \ \--------+--TS7 |
| | \----------+--TS8 |
+----------+ <------------ +----------+
node A Resv node B
In the contrary direction, when receiving a label from node A
indicating that the TS#i with the granularity of 2.5Gbps is reserved,
node B will reserved the TS#i and TS#i+4 with the granularity of
1.25Gbps in its control plane.
5.5. Collision management
[Editors note] This chapter should indicate the procedure in case of
collision between Tributary Port Numbers and/or Tributary Slots e.g.
two different LSP setups may choose a disjoint set of Tributary Slots
but they may request the same Tributary Port Number value (same MSI
in G.709 OPUk field).
In this case the first signaling should be successful and the second
one must fail.
6. Security Considerations
TBD.
7. IANA Considerations
TBD.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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[RFC4328] D. Papadimitriou, Ed. "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Extensions for G.709 Optical
Transport Networks Control", RFC 4328, Jan 2006.
[RFC3471] Berger, L., Editor, "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description", RFC
3471, January 2003.
[RFC3473] L. Berger, Ed., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
(GMPLS) Architecture", RFC 3945, October 2004.
[VCAT-LCAS] G. Bernstein, Ed., "Operating Virtual Concatenation (VCAT)
and the Link Capacity Adjustment Scheme (LCAS) with
Generalized Multi-Protocol Label Switching (GMPLS)", draft-
bernstein-ccamp-gmpls-vcat-lcas, July 29, 2009.
[OTN-LMP] Fatai Zhang, Ed., "Link Management Protocol (LMP)
extensions for G.709 Optical Transport Networks", draft-
zhang-ccamp-gmpls-g.709-lmp-discovery-02.txt, Oct 21, 2009.
8.2. Informative References
[ITUT-G709] ITU-T, "Interface for the Optical Transport Network
(OTN)," G.709 Recommendation (and Amendment 1), February
2001 (October 2001).
[G709-Amd3] ITU-T, "Interface for the Optical Transport Network
(OTN)," G.709 Recommendation Amendment3), December 2008.
[G709-v3] ITU-T, "Interfaces for the Optical Transport Network (OTN)
", G.709/Y.1331, December 2009.
[RFC4506] M. Eisler, Ed., "XDR: External Data Representation
Standard", RFC 4506, May 2006.
[IEEE] "IEEE Standard for Binary Floating-Point Arithmetic",
ANSI/IEEE Standard 754-1985, Institute of Electrical and
Electronics Engineers, August 1985.
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9. Authors' Addresses
Fatai Zhang
Huawei Technologies
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28972912
Email: zhangfatai@huawei.com
Guoying Zhang
China Academy of Telecommunication Research of MII
11 Yue Tan Nan Jie Beijing, P.R.China
Phone: +86-10-68094272
Email: zhangguoying@mail.ritt.com.cn
Sergio Belotti
Alcatel-Lucent
Optics CTO
Via Trento 30 20059 Vimercate (Milano) Italy
+39 039 6863033
Email: sergio.belotti@alcatel-lucent.it
Daniele Ceccarelli
Ericsson
Via A. Negrone 1/A
Genova - Sestri Ponente
Italy
Email: daniele.ceccarelli@ericsson.com
Yi Lin
Huawei Technologies
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28972914
Email: linyi_hw@huawei.com
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Yunbin Xu
China Academy of Telecommunication Research of MII
11 Yue Tan Nan Jie Beijing, P.R.China
Phone: +86-10-68094134
Email: xuyunbin@mail.ritt.com.cn
Pietro Grandi
Alcatel-Lucent
Optics CTO
Via Trento 30 20059 Vimercate (Milano) Italy
+39 039 6864930
Email: pietro_vittorio.grandi@alcatel-lucent.it
Diego Caviglia
Ericsson
Via A. Negrone 1/A
Genova - Sestri Ponente
Italy
Email: diego.caviglia@ericsson.com
Acknowledgment
TBD.
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