One document matched: draft-khuzema-ccamp-gmpls-signaling-g709-00.txt
CCAMP Working Group Mohit Misra
Internet-Draft Rajan Rao
Intended status: Proposed Standard Ashok Kunjidhapatham
Expires: April 27, 2011 Khuzema Pithewan
Infinera Corp
November 08, 2010
Signaling Extensions for Generalized MPLS (GMPLS) Control of
G.709 Optical Transport Networks
draft-khuzema-ccamp-gmpls-signaling-g709-00.txt
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Abstract
As OTN network capabilities continue to evolve, there is an increased
need to support GMPLS control for the same. [RFC4328] introduced
GMPLS signaling extensions for supporting early version of G.709
[G.709-v1].The basic routing considerations from signaling
perspective is also specified in [RFC4328].
The recent revision of ITU-T Recommendation G.709 [G.709-v3] and
[GSUP.43] have introduced new ODU containers (both fixed and
flexible) and additional ODU multiplexing capabilities, enabling
support for optimal service aggregation.
This document extends [RFC4328] to provide GMPLS signaling support
for the new OTN capabilities defined in [G.709-v3] and [GSUP.43]. The
signaling extensions described in this document caters to ODU layer
switching only. Optical Channel Layer switching considerations in
[RFC4328] are not modified in this document.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . . 4
3. Overview of GMPLS Signaling Extensions required for the
Evolving OTN . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Extensions to G.709 Traffic Parameters . . . . . . . . . . . . . 5
4.1. Usage of Bit_Rate and Tolerance for ODUflex Service . . . . 6
5. New Generalized Label Format . . . . . . . . . . . . . . . . . . 7
5.1. Label format for NVC or Multiplier > 1 . . . . . . . . . . 9
6. Label Distribution Rules . . . . . . . . . . . . . . . . . . . . 9
7. Interoperability Considerations . . . . . . . . . . . . . . . 10
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
10.1. Normative References . . . . . . . . . . . . . . . . . 11
10.2. Informative References . . . . . . . . . . . . . . . . 11
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
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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].
ITU-T Recommendations G.709 and G.872 provide specifications for OTN
interface and network architecture respectively. As OTN network
capabilities continue to evolve; there is an increased need to
support GMPLS control for the same.
GMPLS signaling extensions to support [G.709-v1] OTN interfaces are
specified in [RFC4328]. Further extensions are required to support
the new capabilities introduced since [G.709-v1]. Following are the
features added in OTN since the first version [G.709-v1].
(a) OTU Containers:
Pre-existing Containers: OTU1, OTU2 and OTU3
New Containers introduced in [G.709-v3]: OTU2e and OTU4
New Containers introduced in [GSUP.43]: OTU1e, OTU3e1 and OTU3e2
(b) Fixed ODU Containers:
Pre-existing Containers: ODU1, ODU2 and ODU3
New Containers introduced in [G.709-v3]: ODU0, ODU2e and ODU4
New Containers introduced in [GSUP.43]: ODU1e, ODU3e1 and ODU3e2
(c) Flexible ODU Containers:
ODUflex for CBR and GFP-F mapped services. ODUflex uses 'n'
number of OPU Tributary Slots where 'n' is different from the
number of OPU Tributary Slots used by the Fixed ODU Containers.
(d) Tributary Slot Granularity:
OPU2 and OPU3 support two Tributary Slot Granularities: (i)
1.25Gbps and (ii) 2.5Gbps.
(e) Multi-stage ODU Multiplexing:
Multi-stage multiplexing of LO-ODUs into HO-ODU is supported.
Also, multiplexing could be heterogeneous (meaning LO-ODUs of
different rates can be multiplexed into a HO-ODU).
OTN networks support switching at two layers: (i) ODU Layer - TDM
Switching and (ii) OCH Layer - Lambda (LSC) Switching. The nodes on
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the network may support one or both the switching types. When
multiple switching types are supported MLN based routing [RFC5339] is
assumed.
This document extends [RFC4328] to provide GMPLS signaling support
for the new OTN capabilities defined in [G.709-v3] and [GSUP.43].
This complies with the requirements outlined in the framework
document [G.709-FRAME]. The signaling extensions described in this
document caters to ODU layer switching only. Optical Channel Layer
switching considerations in [RFC4328] are not modified in this
document.
Following are the extensions described in this document:
(i) G.709 Traffic Parameters defined in [RFC4328] is extended to
include Bit Rate (in bytes/second) and Tolerance (in ppm) fields for
supporting ODUflex service.
(ii) New Generalized Label Format is introduced to provide compact
encoding of Tributary Slot information and support multi-stage
multiplexing.
2. 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 is to be interpreted as described in RFC-2119 [RFC2119].
In addition, the reader is assumed to be familiar with the
terminology used in ITU-T [G.709-v3], [G.872] and [GSUP.43], as well
as [RFC4201] and [RFC4203].
3. Overview of GMPLS Signaling Extensions required for the Evolving OTN
The GMPLS signaling extensions introduced in [RFC4328] cover OTN
switching requirement pertaining to [G.709-v1]. The signaling
objects defined in [RFC4328] need to be further extended to cover the
new capabilities added to OTN since the first version of G.709
[G.709-v1]. A brief overview of the extensions required are captured
below:
(a) Support for the new ODU containers
The new ODU containers added since [G.709-v1] are listed in the
section-1. SignalType attribute defined in [RFC4328] need to be
extended to cover the new signal types. This is captured in [OSPF-
EXTN-FOR-OTN].
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(b) Support for ODUflex
Unlike the other ODUj signal types, ODUflex requires an user
specified bit-rate (together with a Tolerance value) to be mapped to
'n' TSs of an higher-order container. Even within the same Tributary
Slot Granularity, the Tributary Slot size varies among the ODU
container of different rate. This results in ODUflex service of
certain bit-rate and tolerance requiring different number of TSs on
different higher order ODU containers. The present way of specifying
bandwidth requirement (via NMC field in G.709 Traffic Parameters)
will not work for ODUflex. G.709 Traffic Parameters object need to be
extended to include Bit-Rate (in bytes/sec) and Tolerance (in ppm)
fields as well.
(c) Support for multi-stage multiplexing
The G.709 Traffic Parameter and Generalized Label Format defined in
[RFC4328] supports single stage multiplexing only. A new Generalized
Label Format need to be introduced to support specification of multi-
stage label.
ODUk-------------------ODUj-------------------ODUh
Label for Stage-1 Label for Stage-2
Figure-1: Multi-stage Label
(d) Support for different OPU Tributary Slot Granularities
The G.709 Traffic Parameters and Generalized Label Format defined in
[RFC4328] supports 2.5Gbps Tributary Slot Granularity only. With
[G.709-v3], two types of tributary slots are supported - viz.,
1.25Gbps and 2.5Gbps. The Generalized Label Format need to be
equipped with Tributary Slot Type indicator to facilitate
interpretation of the encoded TS information.
(e) Exchange of Tributary Port Number
A Tributary Port Number (TPN) in MSI field of OPU-OH is used to
correlate the TSs used for mapping a LO-ODU on a HO-ODU. This needs
to be exchanged along with the Label such that each neighbor on a
span knows the TPN value to expect for a given ODUj mapping. This
applies to each stage associated with a multi-stage label. The
Generalized Label Format needs to be extended to include TPN value
for each stage of multiplexing.
4. Extensions to G.709 Traffic Parameters
G.709 Traffic Parameters defined in [RFC4328] is extended to include
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additional fields in support of ODUflex service as explained in the
previous section. The modified object format is captured below:
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/Tolerance |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NVC | Multiplier (MT) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bit_Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Signal Type
As explained in the previous section, Signal Type attribute needs to
be extended to cover the new ODU containers added. This is captured
in [OSPF-EXTN-FOR-OTN].
NMC/Tolerance
This field is redefined from the original definition in [RFC4328].
NMC field defined in [RFC4328] can not be fixed value for an end-to-
end circuit involving dissimilar OTN link types. For example, ODU2e
requires 9 TS on ODU3 and 8 TS on ODU4. Usage of NMC field is
deprecated and should be used only with [RFC4328] generalized label
format for backwards compatibility reasons.
For the new generalized label format as defined in this document this
field is interpreted as Tolerance. The unit of tolerance is ppm and
is encoded as unsigned integer. For signal types other than ODUflex,
Tolerance field should be coded as 0.
Bit_Rate
Bit_Rate is used when signal Type is ODUFlex. For all the other
signal types, this field should be coded as zero.
4.1. Usage of Bit_Rate and Tolerance for ODUflex Service
Bit_Rate and Tolerance are used together to compute number of
Tributary slots required for ODUFlex(CBR) traffic on a given higher
order ODU container. The computation of Number of Tributary Slot (n)
is as follows.
Ceiling of Bit_Rate * (1 + Tolerance)
n = --------------------------------------------------
ODTUk.ts nominal bit rate * (1 - HO OPUk bit rate tolerance)
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5. New Generalized Label Format
As explained in section 3, the Generalized Label format defined in
[RFC4328] can not accommodate the new features added in [G.709v3].
Further the label format as defined in [RFC4328] is not scalable for
large number of Tributary Slots (at 1.25G granularity) associated
with bigger containers such as ODU3 and ODU4.
The Generalized Label for G.709 may contain one more multi-stage
label. A multi-stage label includes TS and TPN information for all
stages of a multi-stage multiplexing hierarchy.
The format of a multi-stage label is explained below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num MUX Stages| OD(T)Uk (ST) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stage-1 Time Slot Info |
| (Variable Length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stage-n Time Slot Info |
| (Variable Length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Num MUX Stages
This field indicates the number of multiplexing stages specified by
the label.
OD(T)Uk
This field encodes the signal type of HO OD(T)Uk container.
TS Information for a single stage is encoded 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ODUj (ST) | T | Length | Tributary Port Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Length Bit Map (4-byte boundary aligned) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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ODUj
This field indicates the signal type of a LO-ODU being multiplexed
into its immediate HO-ODU.
T
This is a 2 bit field, which defines the granularity of tributary
slots for this multiplexing stage. It can take following values
T field TS Granularity type
------- -------------------
0 1.25Gbps
1 2.5Gbps
2-3 Reserved (for future use)
Length
This field indicates the number of valid Bits in the of Bit Map
excluding the filler bits.
Tributary Port Number(TPN)
This field is encoded with TPN value assigned for a ODTUjk or
ODTUk.ts on a OPUk. TPN assignment could be fixed or flexible.
For fixed TPN assignment scheme, TPN value need not be specified. In
this case, TPN value should be coded as 0xFFFFFFFF.
For flexible TPN assignment scheme, TPN value should contain the
assigned logical value. Not all the bits of TPN are used. Only a
subset of bits are used depending on the OPUk type.
Bits Used ODU Container
--------- -------------
0-5 ODU1 to ODU3
0-6 ODU4
7-15 Reserved
The reserved bits should be coded as zeros for flexible assignment
scheme.
Bit Map
This is a multi-byte bit map field. The length of this field varies
depending on the number of TSs associated with the immediate HO-ODU
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pertaining to the stage. Each bit represents one TS. Bit values are
interpreted as follows
Bit Value Meaning
--------- -------
0 Not Used
1 Used
This field must be 4 byte aligned using filler bytes.
5.1. Label format for NVC or Multiplier > 1
For NVC or Multiplier field value > 1, the label format defined in
section 5 needs to be repeated NVC/multiplier times.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Instance #1 |
| (Variable Length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Instance #n |
| (n = NVC/Multiplier) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
6. Label Distribution Rules
This document does not change the existing label distribution
procedures defined in [RFC4328] except that the new ODU label should
be processed as follows.
A. Sending Side
When Generalized Label Request is received on given node for setting
up a ODU LSP from its upstream neighbor, it reserves the resources
required on an OTN interface and send the label back to upstream
neighbor. Note that Label can also be explicitly specified by source
node.
The encoding of Generalized Label is as follows:
For ODUj to ODUk multiplexing, the length field indicates the number
of TS supported on ODUk. TS reserved for ODUj are marked as 1.
For ODUk to OTUk mapping, the length field is coded as 0 and BitMap
field is not included.
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B. Receiving Side
For ODUj to ODUk multiplexing, the node extracts the Bit Map field
using the Length field. The position of Bit in the Bitmap interpreted
as the Trib Slot Number. The value stored in the bit indicates if it
is reserved for the ODUj.
For ODUk to OTUk mapping, the length is 0. Hence, bitmap field is not
expected.
7. Interoperability Considerations
The neighbor nodes on a TE-Link span should exchange the signaling
stack versions (via some link discovery mechanism) in order to
determine the Generalized Label Format to use.
In the following example, Switch B and C are running the newer
version of signaling stack (that support the new G.709 Traffic
Parameters and Generalized Label Format) while Switch A is running
the older version.
+-------+ +-------+ +-------+
| OTN | | OTN | | OTN |
|Switch |<- OTUk Link ->|Switch |<- OTUk Link ->|Switch |
| A | | B | | C |
+-------+ +-------+ +-------+
|<-- Legacy -->| |<-- New TE-Link -->|
Figure-1: OTUk TE-Link
Link A-B: G.709-v1 version (2001) based OTUk link
TSG: 2.5G;
Label format: as per RFC 4328
Link B-C: G.709-v3 version based OTUk link (12/09)
TSG: 1.25G;
Label format: new label format proposed in this draft.
For an ODU2 connection going from A-C,
On link A-B : NMC is set to 4 & [RFC4328] label format is used.
On link B-C : NMC is not used & new label format is used.
7. Examples
<Will be added in the next revision of this draft>
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8. Security Considerations
There are no additional security implications to Signaling protocol
due to the extensions captured in this document.
9. IANA Considerations
TBD
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels".
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630
[RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Functional Description", RFC 3471,
January 2003.
[RFC4201] Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling in
MPLS Traffic Engineering (TE)"
[RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support of
Generalized Multi-Protocol Label Switching (GMPLS)"
[RFC4204] Lang, J., Ed., "Link Management Protocol (LMP)", RFC
4204, October 2005.
[RFC4328] Papadimitriou, D., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Extensions for G.709 Optical
Transport Networks Control", RFC 4328, January 2006.
[RFC5339] Le Roux, JL. and D. Papadimitriou, "Evaluation of Existing
GMPLS Protocols against Multi-Layer and Multi-Region
Networks (MLN/MRN)", RFC 5339, September 2008.
[G.709-v3] ITU-T, "Interfaces for the Optical Transport Network
(OTN)", G.709 Recommendation, December 2009.
10.2. Informative References
[RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
(GMPLS) Architecture", RFC 3945, October 2004.
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[G.709-v1] ITU-T, "Interface for the Optical Transport Network
(OTN)," G.709 Recommendation (and Amendment 1), February
2001 (October 2001).
[G.872] ITU-T, "Architecture of optical transport networks",
November 2001 (11 2001).
[G.709-FRAME] F. Zhang, D. Li, H. Li, S. Belotti, "Framework for
GMPLS and PCE Control of G.709 Optical Transport
Networks", draft-zhang-ccamp-gmpls-g709-framework-02,
work in progress.
[WSON-FRAME] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS
and PCE Control of Wavelength Switched Optical Networks
(WSON)", draft-ietf-ccamp-rwa-wson-framework, work in
progress.
11. Acknowledgements
Authors would like to thank Lou Berger and Biao Lu for review
comments and suggestions.
Author's Addresses
Mohit Misra
Infinera Corporation
169, Java Drive
Sunnyvale, CA-94089
USA
Email: mmisra@infinera.com
Rajan Rao
Infinera Corporation
169, Java Drive
Sunnyvale, CA-94089
USA
Email: rrao@infinera.com
Ashok Kunjidhapatham
Infinera Corporation
169, Java Drive
Sunnyvale, CA-94089
USA
Email: akunjidhapatham@infinera.com
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Khuzema Pithewan
Infinera Corporation
169, Java Drive
Sunnyvale, CA-94089
USA
Email: kpithewan@infinera.com
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