GMPLS Signaling Extensions for Optical Impairment Aware Lightpath Setup
draft-martinelli-ccamp-optical-imp-signaling-01.txt

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Abstract

The problem of provisioning a lightpath in a transparent dense wavelength division multiplexing (DWDM) optical island requires the evaluation of of the optical impairments along the selected route. In this draft we propose a GMPLS signaling protocol (RSVP/RSVP-TE) extension to collect and provide the egress node the optical impairment parameters needed to validate a lightpath setup request feasibility.

Table of Contents

1.  Introduction
2.  Conventions Used in This Document
3.  Optical Path Validation Procedure
4.  Physical Parameter Classification and top level TLV
5.  Optical Service Parameters sub-TLV
    5.1.  Forward Error Correction (FEC)
    5.2.  Modulation Format
6.  Optical Path Parameters sub-TLV(s)
    6.1.  Optical Parameter sub-TLV overview
    6.2.  Mandatory Linear Optical Parameters sub-TLVs
        6.2.1.  Optical Power
        6.2.2.  Optical Signal to Noise Ratio
    6.3.  Optional Linear Optical Parameters sub-TLVs
        6.3.1.  Chromatic Dispersion (CD)
        6.3.2.  Polarization Mode Dispersion (PMD)
        6.3.3.  Cross-Talk (XT)
7.  Message Fragmentation
8.  Backward Compatibility
9.  Error management
10.  Acknowledgments
11.  Contributing Authors
12.  IANA Considerations
13.  Security Considerations
14.  References
    14.1.  Normative References
    14.2.  Informative References
§  Authors' Addresses
§  Intellectual Property and Copyright Statements

1.  Introduction

The current Generalized Multi-Protocol Label Switching (GMPLS) specification [RFC3945] (Mannie, E., “Generalized Multi-Protocol Label Switching (GMPLS) Architecture,” October 2004.) and the signaling related documents ([RFC3471] (Berger, L., “Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description,” January 2003.), [RFC3473] (Berger, L., “Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions,” January 2003.), [RFC4328] (Papadimitriou, D., “Generalized Multi-Protocol Label Switching (GMPLS) Signaling Extensions for G.709 Optical Transport Networks Control,” January 2006.)) support optical interfaces with different switching capability to setup a lightpath while [RFC4054] (Strand, J. and A. Chiu, “Impairments and Other Constraints on Optical Layer Routing,” May 2005.) defines the impairments to be considered in optical routing. [I‑D.bernstein‑ccamp‑wavelength‑switched] (Bernstein, G., “Framework for GMPLS and PCE Control of Wavelength Switched Optical Networks,” February 2008.), defines a framework identifying the key components and issues pertaining to wavelength switched optical networks (WSON). [I‑D.otani‑ccamp‑gmpls‑lambda‑labels] (Otani, T., Guo, H., Miyazaki, K., Caviglia, D., and Z. Ali, “Generalized Labels of Lambda-Switching Capable Label Switching Routers (LSR),” February 2008.) proposes a global semantic for wavelength generalized labels taking into account lightpath specific needs.

In transparent optical networks, physical impairments incurred by non-ideal optical transmission medium accumulate along an optical path. Because of these impairments even if there is physical connectivity (fibers, wavelengths, and nodes) between the ingress and egress nodes, there is no guarantee that the optical signal (light) reaches the Egress node with acceptable signal quality, for example in terms of BER/OSNR/Q-factor limit. For a successful lightpath provisioning in a WSON, the set up process must be aware of a set of physical impairments that has effect on the lightpath. A complete set of physical impairments will include linear and non-linear impairments. This preliminary draft proposes a way to collect the optical path linear impairments in the signaling phase by providing suitable extensions to signaling protocol (RSVP/RSVP-TE) assuming that non-linear impairments effects are handled in the network design phase considering a bounded OSNR margin [RFC4054] (Strand, J. and A. Chiu, “Impairments and Other Constraints on Optical Layer Routing,” May 2005.).

The management of physical impairments is done only in the signaling process and it does not require any extension to the traffic engineering database and IGP routing protocols.

The set of parameters carried by the signaling protocol is divided into optical service parameters and optical path parameters:

• The optical service parameters describe the requested signal type, are related to the characteristics of the transponder at ingress node and hence are not changed at transit nodes.
• The optical path parameters describe the signal characteristics evolution along the path from ingress node to egress node, are related to the characteristics of the various links/subsystems and are updated at each transit node. They are divided into mandatory and optional parameters. The mandatory parameters are related to feasibility constraints such as power and OSNR, whereas the optional parameters are expandable linear impairments such as chromatic dispersion (CD), polarization mode dispersion (PMD), crosstalk, etc. The optional parameters can be used to evaluate the feasibility of a lightpath more accurately as an alternate solution to the bounded OSNR margin evaluation. Parameter update methods might use appropriate physical models and are out of scope of this document.

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 are to be interpreted as described in RFC 2119 (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.) [RFC2119].

In additions this document will use terminology from [RFC2205] (Braden, B., Zhang, L., Berson, S., Herzog, S., and S. Jamin, “Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification,” September 1997.), [RFC3209] (Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, “RSVP-TE: Extensions to RSVP for LSP Tunnels,” December 2001.), [RFC4054] (Strand, J. and A. Chiu, “Impairments and Other Constraints on Optical Layer Routing,” May 2005.), and [I‑D.bernstein‑ccamp‑wavelength‑switched] (Bernstein, G., “Framework for GMPLS and PCE Control of Wavelength Switched Optical Networks,” February 2008.).

3.  Optical Path Validation Procedure

The signaling based validation of an optical path in downstream direction in a transparent network (lambda switched LSP) is implemented by the following procedure:

• The ingress node signals in the Path message the supported signal types (FEC and modulation format) and wavelength set (encoded in the LABEL_SET Object) depending on available local transponders.
• Transit nodes update the Path message pruning non cross-connectable wavelengths (LABEL_SET Object) and computing or measuring the path optical characteristics up to the outgoing interface (optical impairments).
• The egress node selects the wavelength and the signal type based on the signaled optical impairments and the available local transponders (supported wavelengths, sensitivity to optical impairments) and signals the selection in the Resv message.
• Transit nodes process the Resv message cross-connecting the selected wavelength in incoming and outgoing interfaces (wavelength continuity constraint).
• The ingress node cross-connects the selected wavelength to a local transponder supporting the selected signal type (FEC and modulation format).

This procedure forces the meeting of the wavelength continuity constraint: the final effect of pruning wavelengths (e.g. removing labels from the LABEL_SET object) in transit nodes is the implementation of a wavelength selection process in the signaling phase. The wavelength assignment will be done at the egress node among all available wavelength for the LSP. The criteria used by the egress node to assign the wavelength is out of the scope of this document.

In the Path message processing, the unavailability of cross-connectable wavelength in transit nodes or of transponders supporting the signal in the egress node causes the request failure (PathErr message).

In the Resv message processing, the unavailability of the selected wavelength in transit nodes or of transponders supporting the signal in the ingress node (race condition in allocating resources) causes the request failure (ResvErr message).

In this document, only the encoding in the RSVP messages of the optical information needed to support the described procedure is defined. The specific policies used to select the resources (wavelength and transponders), the models to compute the optical impairments and the procedure to validate the signal with respect to the transponder sensitivity are not in the scope of this document.

4.  Physical Parameter Classification and top level TLV

RSVP/RSVP-TE requires the following additional information in order to be aware of optical impairments and setup optically feasible lightpaths:

• Optical Service Parameters.
  The standard GENERALIZED_LABEL_REQUEST and TSPEC/FLOW_SPEC objects support the encoding of the information related to service type and service QoS. However for DWDM networks the egress node of an LSP has to know a certain set of specific optical parameters related to the transmitting interface. Section 5 (Optical Service Parameters sub-TLV) reports details of these parameters and their encoding.
• Optical Path Parameters.
  These attributes are required to support transmission of physical impairment parameters for the optical path feasibility evaluation. Details are presented in Section 6 (Optical Path Parameters sub-TLV(s)).

This document defines how to encode the above information through new TLVs according to [RFC4420] (Farrel, A., Papadimitriou, D., Vasseur, J., and A. Ayyangar, “Encoding of Attributes for Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) Establishment Using Resource ReserVation Protocol-Traffic Engineering (RSVP-TE),” February 2006.).

The proposed encoding scheme for the optical parameters defines a TLV (channel optical physical information) associated to a wavelength containing a sub-TLV for each service and path parameter.

Additional set of parameters can be added without affecting the already defined encoding.

A TLV sub-object for each available wavelength (Path message) or selected wavelength (Resv message) is encoded in an LSP_REQUIRED_ATTRIBUTES Object.

The TLV sub-object encoding is defined in the next picture.

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              |           Length              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Wavelength ID                              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
//               Parameters Sub-TLV Sequence                   //
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

• Type: optical channel physical parameters info TLV type (TBA).
• Length: length of the TLV object in bytes without the 4 byte header.
• Wavelength ID: wavelength label identifier according to [I‑D.otani‑ccamp‑gmpls‑lambda‑labels] (Otani, T., Guo, H., Miyazaki, K., Caviglia, D., and Z. Ali, “Generalized Labels of Lambda-Switching Capable Label Switching Routers (LSR),” February 2008.).
• Parameters Sub-TLV Sequence: service and path parameters values.

The TLVs wavelength ID value must be consistent with the presence of LABEL_SET objects and its actions as defined within [RFC3471] (Berger, L., “Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description,” January 2003.) and [RFC3473] (Berger, L., “Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions,” January 2003.).

The Sub-TLV format is defined in the next picture

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       |    Flags      |           Length              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
//               Value                                         //
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type: Sub-TLV type

Flags: bit-mask defining the management of the Sub-TLV

bit 0: if set the parameter is mandatory, otherwise it is optional.

bit 1: if set the parameter is variable and MUST be updated with the local value, otherwise it is a constant value set by the ingress node.

bit 2-7: not used.

Length: Value field length in bytes

Value: variable length Sub-TLV content

The Flags field defines how transit nodes manage the Sub-TLV:

• Constant sub-TLVs are forwarded as-is.
• Mandatory non constant sub-TLVs MUST be updated with the local parameter value, if the parameter is not managed by the node, it MUST reject the request with a failure.
• Optional non constant sub-TLVs MUST be updated with the local parameter value, if the parameter is not managed by the node, it MUST silently drop it from the TLV (the value would be inaccurate).

5.  Optical Service Parameters sub-TLV

The Optical Service Parameters define the signal transmissions characteristics at the ingress node. This type of information is required at the egress node to verify the optical signal compatibility.

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      |    Flags      |           Length              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|             FEC 1             |           Mod Format 1        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//                                                             //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|             FEC n             |           Mod Format n        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type: sub-TLV type (=1)

Flags: Mandatory, Constant

Length: length of the sub-TLV value in bytes

FEC: supported Forward Error Correction Modes (see Section 5.1 (Forward Error Correction (FEC))

Mod Format: supported modulation formats (see Section 5.2 (Modulation Format)) associated with the FEC.

This sub-TLV is used in the PATH message to signal the full list of optical parameters associated with the interface (signal types and wavelengths) available at the ingress node. A DWDM interface might have several sets of optical parameters available, for example a tunable interface has a set of possible wavelengths, together with a set of possible FEC encoding or modulation formats. In the RESV message this information is associated to the selected receiving interface at the egress node. In the RESV message only one tuple (FEC, Mod Format) will be specified.

5.1.  Forward Error Correction (FEC)

FEC (16 bits) field is the Forward Error Correction and has the following values:

0: no FEC

1: standard FEC (according to [ITU.G709] (International Telecommunications Union, “Interface for the Optical Transport Network (OTN),” March 2003.))

2-9: super-FEC according to sub clauses from I.2 to I.9 of [ITU.G975.1] (International Telecommunications Union, “Forward Error Correction for high bit rate DWDM Submarine Systems,” February 2004.)

Values with the format 1bbbbbbbbbbbbbbb are left to represent vendor specific or proprietary FEC encoding.

5.2.  Modulation Format

Mod Format (16 bits) is the modulation and has the following values:

0: NRZ

1: Duo Binary

2: DPSK

Other values might be defined in the future as technology advance. Values with the format 1bbbbbbbbbbbbbbb are left to represent vendor specific or proprietary modulation formats.

6.  Optical Path Parameters sub-TLV(s)

This set of parameters is carried in the PATH message for each available wavelength to allow the optical feasibility evaluation. At each hop, the optical node MUST update these values according to information locally available at the node (say internal amplifiers, wavelength cross connect, etc.).

The way an optical node gets knowledge of this required information (e.g. through NMS, auto-discovery etc.) is out of the scope of this document and highly depends on specific equipment implementation.

This document defines two groups of linear optical parameters.

Mandatory Linear Optical Parameters

This set includes Optical Signal Power and the OSNR with associated variances. It represents the minimum set to asses the feasibility of an optical path. This set will be encoded using mandatory sub-TLVs.

Optional Linear Optical Parameters

This set includes CD, PMD, XT with associated variances. These parameters represent an additional set to allow a more accurate optical feasibility evaluation. This set will be encoded using optional sub-TLVs.

Separation between mandatory and optional parameters allows a rough optical feasibility evaluation where network elements support at least the mandatory set. Depending on how a WSON is designed, the usage of the mandatory set could be an operational choice not to overwhelm the control plane while maintaining reliable feasibility estimation. Moreover it might happens that not all nodes in a networks support the full set of optical path parameters. With this classification, the lightpath signaling still continues to work although with a less accurate evaluation.

The choice of the optional set of parameters depends on several considerations. They are among those reported by the [RFC4054] (Strand, J. and A. Chiu, “Impairments and Other Constraints on Optical Layer Routing,” May 2005.) and provide sufficient accuracy for the linear impairments evaluation.

6.1.  Optical Parameter sub-TLV overview

Each optical parameter will be encoded using 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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    Type       |    Flags      |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Optical Parameter Value                                      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Optical Parameter Variance                                   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type: sub_TLV type > 1.

Flags: mandatory or optional according to each parameter classification, variable.

Length: 4 octets or 8 octets depending if the optical parameter has the variance value associated.

Value associated with the optical parameter.

Variance: the error estimation for optical parameter value calculation. Depending on the length value may not be present.

6.2.  Mandatory Linear Optical Parameters sub-TLVs

The Sub-TLVs encode the following optical parameters of a channel (wavelength) measured at the node egress interface. Flags are: mandatory, variable.

6.2.1.  Optical Power

Type = 2.

Value: 32bit IEEE floating point number. Measurement Unit: dBm.

6.2.2.  Optical Signal to Noise Ratio

Type = 3.

Value: 32bit IEEE floating point number. Measurement Unit: dB.

6.3.  Optional Linear Optical Parameters sub-TLVs

The Sub-TLVs encode the following optical parameters of a channel (wavelength) measured at the node egress interface. Flags are: optional, variable.

6.3.1.  Chromatic Dispersion (CD)

Type = 4.

Value: 32bit IEEE floating point number. Measurement Unit: ps/nm.

6.3.2.  Polarization Mode Dispersion (PMD)

Type = 5.

Value: 32bit IEEE floating point number. Measurement Unit: ps.

6.3.3.  Cross-Talk (XT)

Type = 6.

Value: 32bit IEEE floating point number. Measurement Unit: dB.

7.  Message Fragmentation

In certain cases, the state information carried by the Path message can be quite large. Size estimation for a physical Optical Channel TLV (see Figure 1) can be the following: 8 bytes for type, length and wavelength ID plus, 16 bytes for the Optical Service Parameters sub-TLV considering 3 FEC/modulation format combinations plus, 24 bytes for the Mandatory Linear Optical Path parameters plus 36 bytes for the Optional Linear Optical Parameter sub-TLV. Total is 48 bytes for each wavelength by just considering mandatory sub-TLVs and 84 bytes by considering also the optional part. Given the number of wavelengths today available in DWDM networks, the size of the path message end up in large values. For example to signal just 32 wavelengths the size required for the physical optical parameters ranges at least from 1536 to 2688 bytes.

A possible option is to let the application layer requesting the lightpath setup to decide how many wavelengths to signal according to the MTU available. For example, having an MTU of 1500 bytes the application layer might signal only 10 wavelengths with the full set of parameters taking up 840 bytes, or it might decide to signal 20 wavelengths with just the mandatory parameters. Note that, according to procedure described within Section 3 (Optical Path Validation Procedure), the message size may decrease as long as the Path message pass through transit nodes.

A second solution proposed here implements the semantic fragmentation as suggested by RSVP (Braden, B., Zhang, L., Berson, S., Herzog, S., and S. Jamin, “Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification,” September 1997.) [RFC2205]. The proposed encoding extends the SENDER_TEMPLATE Object with a new Class Type (derived from the LSP_TUNNEL_IPv4 and LSP_TUNNEL_IPv6 RSVP-TE (Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, “RSVP-TE: Extensions to RSVP for LSP Tunnels,” December 2001.) [RFC3209]). The Object includes the additional information on the "fragment id" and on the requested policy for the channel selection at the egress node

Class = SENDER_TEMPLATE, FRAGREQ_LSP_TUNNEL_IPv4 C-Type = TBA

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                   IPv4 tunnel sender address                  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|       Reserved                |            LSP ID             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TotalNo       |  MsgId        |  P    |  Timeout              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Class = SENDER_TEMPLATE, FRAGREQ_LSP_TUNNEL_IPv6 C-Type = TBA

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
+                                                               +
|                   IPv6 tunnel sender address                  |
+                                                               +
|                            (16 bytes)                         |
+                                                               +
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|       Reserved                |            LSP ID             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TotalNo       |  MsgId        |  P    |  Timeout              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Besides the fields already defined in the SENDER_TEMPLATE, the following fields are defined:

• TotalNo: 8 bit integer representing the total number of Path messages issued by the ingress node to setup a single lightpath. When this values is equals to 1 all the other fields MUST be ignored.
• MsgId: 8 bit integer representing the sequential number of a single Path request. Its value must be between 1 and TotalNo, both inclusive.
• P: Policy the egress node must apply upon receiving a fragmented path request:

  1: Take the first message arrived and ignore the following ones.

  2: After the first message arrives, wait for any message within the specified Timeout.

  3: After the first message arrives, waits for all messages. Fail, if the timeout expires, and there's at least one message missing

  The egress node should "reject" (PathErr) all the requests except for the selected one, even if it could rely on the RSVP timeout to clear the unselected requests status in upstream nodes.
• Timeout: 12 bits integer number representing the timeout value used by the policy. The value is in s/100 (hundreds of seconds) All messages MUST have the same value.

This type of encoding is a generic solution to manage the semantic fragmentation and its not strictly related to optical parameters encoding.

8.  Backward Compatibility

The TLV usage as defined by [RFC4420] (Farrel, A., Papadimitriou, D., Vasseur, J., and A. Ayyangar, “Encoding of Attributes for Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) Establishment Using Resource ReserVation Protocol-Traffic Engineering (RSVP-TE),” February 2006.) will guarantee the co-existence of nodes supporting normal RSVP-TE operations and node with optical impairment signaling capability.

A service with the new feature (optical feasibility evaluation) can be setup only if all the nodes in the path support the extensions. Optical Path Parameters are updated hop-by-hop and evaluated at egress node. If a transit node does not support the extensions the collected information is unreliable and the Path request MUST be rejected.

9.  Error management

No additional error code is introduced to manage requests failures; the behavior defined in [RFC4420] (Farrel, A., Papadimitriou, D., Vasseur, J., and A. Ayyangar, “Encoding of Attributes for Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) Establishment Using Resource ReserVation Protocol-Traffic Engineering (RSVP-TE),” February 2006.) applies to the management of the LSP_REQUIRED_ATTRIBUTES Object.

10.  Acknowledgments

11.  Contributing Authors

This document was the collective work of several authors. The text and content of this document was contributed by the editors and the co-authors listed below (the contact information for the editors appears in appropriate section and is not repeated below):

   Gabriele Maria Galimberti              Alberto Tanzi
   Cisco Systems                          Cisco Systems
   via Philips 12                         via Philips 12
   Monza  20052                           Monza  20052
   Italy                                  Italy

   Email: ggalimbe@cisco.com              Email: atanzi@cisco.com

   Domenico La Fauci                      Stefano Piciaccia
   Cisco Systems                          Cisco Systems
   via Philips 12                         via Philips 12
   Monza  20052                           Monza  20052
   Italy                                  Italy

   Email: dlafauci@cisco.com              Email: spiciacc@cisco.com


   Elio Salvadori                         Yabin  Ye
   CREATE-NET                             CREATE-NET
   via alla Cascata 56 C, Povo            via alla Cascata 56 C, Povo
   Trento  38100                          Trento  38100
   Italy                                  Italy

   Email: elio.salvadori@create-net.org   Email: yabin.ye@create-net.org


   Chava Vijaya Saradhi
   CREATE-NET
   via alla Cascata 56 C, Povo
   Trento  38100
   Italy

   Email: saradhi.chava@create-net.org

12.  IANA Considerations

This memo needs the following request to IANA

TLV (see Figure 1 in Section 4 (Physical Parameter Classification and top level TLV))

New class type for sender template (see Section 7 (Message Fragmentation))

All drafts are required to have an IANA considerations section (see the update of RFC 2434 (Narten, T. and H. Alvestrand, “Guidelines for Writing an IANA Considerations Section in RFCs,” March 2008.) [I‑D.narten‑iana‑considerations‑rfc2434bis] for a guide). If the draft does not require IANA to do anything, the section contains an explicit statement that this is the case (as above). If there are no requirements for IANA, the section will be removed during conversion into an RFC by the RFC Editor.

13.  Security Considerations

This document introduces no new security considerations to [RFC3473] (Berger, L., “Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions,” January 2003.). GMPLS security is described in section 11 of [RFC3471] (Berger, L., “Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description,” January 2003.) and refers to [RFC3209] (Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, “RSVP-TE: Extensions to RSVP for LSP Tunnels,” December 2001.) for RSVP-TE.

14.  References

14.1. Normative References

14.2. Informative References

Authors' Addresses

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