Samsung Electronics

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This document provides Path Computation Element Communication Protocol (PCEP) extensions for the support of Routing and Wavelength Assignment (RWA) in Wavelength Switched Optical Networks (WSONs). Path provisioning in WSONs requires an RWA process. From a path computation perspective, wavelength assignment is the process of determining which wavelength can be used on each hop of a path and forms an additional routing constraint to optical path computation.

Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at .

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Table of Contents

• .  Introduction
• .  Terminology
• .  Requirements Language
• .  Encoding of an RWA Path Request
  • .  Wavelength Assignment (WA) Object
  • .  Wavelength Selection TLV
  • .  Wavelength Restriction TLV
    • .  Link Identifier Field
    • .  Wavelength Constraint Field
  • .  Signal Processing Capability Restrictions
    • .  Signal Processing Exclusion
    • .  Signal Processing Inclusion
• .  Encoding of an RWA Path Reply
  • .  Wavelength Allocation TLV
  • .  Error Indicator
  • .  NO-PATH Indicator
• .  Manageability Considerations
  • .  Control of Function and Policy
  • .  Liveness Detection and Monitoring
  • .  Verifying Correct Operation
  • .  Requirements on Other Protocols and Functional Components
  • .  Impact on Network Operation
• .  Security Considerations
• .  IANA Considerations
  • .  New PCEP Object: Wavelength Assignment Object
  • .  WA Object Flag Field
  • .  New PCEP TLV: Wavelength Selection TLV
  • .  New PCEP TLV: Wavelength Restriction TLV
  • .  Wavelength Restriction TLV Action Values
  • .  New PCEP TLV: Wavelength Allocation TLV
  • .  Wavelength Allocation TLV Flag Field
  • .  New PCEP TLV: Optical Interface Class List TLV
  • .  New PCEP TLV: Client Signal Information TLV
  • . New Bit Flag for NO-PATH-VECTOR TLV
  • . New Error-Types and Error-Values
  • . New Subobjects for the Exclude Route Object
  • . New Subobjects for the Include Route Object
  • . Request for Updated Note for LMP TE Link Object Class Type
• .  References
  • .  Normative References
  • .  Informative References
• Acknowledgments
• Contributors
• Authors' Addresses

Introduction specifies the Path Computation Element Communication Protocol (PCEP) for communications between a Path Computation Client (PCC) and a PCE, or between two PCEs. Such interactions include Path Computation Requests (PCReqs) and Path Computation Replies (PCReps) as well as notifications of specific states related to the use of a PCE in the context of Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering (TE). A PCC is said to be any network component that makes such a request and may be, for instance, an optical switching element within a Wavelength Division Multiplexing (WDM) network. The PCE, itself, can be located anywhere within the network and may be within an optical switching element, a Network Management System (NMS), or an Operational Support System (OSS), or it may be an independent network server. This document provides the PCEP extensions for the support of Routing and Wavelength Assignment (RWA) in Wavelength Switched Optical Networks (WSONs) based on the requirements specified in and . WSON refers to WDM-based optical networks in which switching is performed selectively based on the wavelength of an optical signal. The devices used in WSONs that are able to switch signals based on signal wavelength are known as Lambda Switch Capable (LSC). WSONs can be transparent or translucent. A transparent optical network is made up of optical devices that can switch but not convert from one wavelength to another, all within the optical domain. On the other hand, translucent networks include 3R regenerators (reamplification, reshaping, and retiming) that are sparsely placed. The main function of the 3R regenerators is to convert one optical wavelength to another. An LSC Label Switched Path (LSP) may span one or several transparent segments, which are delimited by 3R regenerators typically with electronic regenerator and optional wavelength conversion. Each transparent segment or path in WSON is referred to as an optical path. An optical path may span multiple fiber links, and the path should be assigned the same wavelength for each link. In a case, the optical path is said to satisfy the wavelength-continuity constraint. illustrates the relationship between an LSC LSP and transparent segments (optical paths).

Illustration of an LSC LSP and Transparent Segments +---+ +-----+ +-----+ +-----+ +-----+ | |I1 | | | | | | I2| | | |o------| |-------[(3R) ]------| |--------o| | | | | | | | | | | | +---+ +-----+ +-----+ +-----+ +-----+ (X LSC) (LSC LSC) (LSC LSC) (LSC X) <-------> <-------> <-----> <-------> <-----------------------><----------------------> Transparent Segment Transparent Segment <-------------------------------------------------> LSC LSP

Note that two transparent segments within a WSON LSP do not need to operate on the same wavelength (due to wavelength conversion capabilities). Two optical channels that share a common fiber link cannot be assigned the same wavelength; otherwise, the two signals would interfere with each other. Note that advanced additional multiplexing techniques such as polarization-based multiplexing are not addressed in this document since the physical-layer aspects are not currently standardized. Therefore, assigning the proper wavelength on a path is an essential requirement in the optical path computation process. When a switching node has the ability to perform wavelength conversion, the wavelength-continuity constraint can be relaxed, and an LSP may use different wavelengths on different links along its route from origin to destination. It is, however, to be noted that wavelength converters may be limited due to their relatively high cost, while the number of WDM channels that can be supported in a fiber is also limited. As a WSON can be composed of network nodes that cannot perform wavelength conversion, nodes with limited wavelength conversion, and nodes with full wavelength conversion abilities, wavelength assignment is an additional routing constraint to be considered in all optical path computation. For example (see ), within a translucent WSON, an LSC LSP may be established between interfaces I1 and I2, spanning two transparent segments (optical paths) where the wavelength continuity constraint applies (i.e., the same unique wavelength must be assigned to the LSP at each TE link of the segment). If the LSC LSP induced a Forwarding Adjacency / TE link, the switching capabilities of the TE link would be (X X), where X refers to the switching capability of I1 and I2. For example, X can be Packet Switch Capable (PSC), Time-Division Multiplexing (TDM), etc. This document aligns with for generic properties such as label, label set, and label assignment, noting that a wavelength is a type of label. Wavelength restrictions and constraints are also formulated in terms of labels per . The optical modulation properties, which are also referred to as signal compatibility, are already considered in the signaling in and . In order to improve the signal quality and limit some optical effects, several advanced modulation processing capabilities are used by the mechanisms specified in this document. These modulation capabilities not only contribute to optical signal quality checks but also constrain the selection of sender and receiver, as they should have matching signal processing capabilities. This document includes signal compatibility constraints as part of RWA path computation. That is, the signal processing capabilities (e.g., modulation and Forward Error Correction (FEC)) indicated by means of the Optical Interface Class (OIC) must be compatible between the sender and the receiver of the optical path across all optical elements. This document, however, does not address optical impairments as part of RWA path computation. See for the framework for optical impairments.

Terminology This document uses the terminology defined in and .

Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Encoding of an RWA Path Request shows one typical PCE-based implementation, which is referred to as the Combined Process (R&WA). With this architecture, the two processes of routing and wavelength assignment are accessed via a single PCE. This architecture is the base architecture specified in , and the PCEP extensions that are specified in this document are based on this architecture.

Combined Process (R&WA) Architecture +----------------------------+ +-----+ | +-------+ +--+ | | | | |Routing| |WA| | | PCC |<----->| +-------+ +--+ | | | | | +-----+ | PCE | +----------------------------+

Wavelength Assignment (WA) Object Wavelength allocation can be performed by the PCE by means of:

1. Explicit Label Control where the PCE allocates which label to use for each interface/node along the path. The allocated labels MAY appear after an interface route subobject.
2. A Label Set where the PCE provides a range of potential labels to be allocated by each node along the path.

Option (b) allows distributed label allocation (performed during signaling) to complete wavelength assignment. Additionally, given a range of potential labels to allocate, a PCReq SHOULD convey the heuristic or mechanism used for the allocation. Per , the format of a PCReq message after incorporating the Wavelength Assignment (WA) object is as follows: <PCReq Message> ::= <Common Header> [<svec-list>] <request-list> Where: <request-list>::=<request>[<request-list>] <request>::= <RP> <END-POINTS> <WA> [other optional objects...] If the WA object is present in the request, it MUST be encoded after the END-POINTS object as defined in . The WA object is mandatory in this document. Orderings for the other optional objects are irrelevant. For the WA object, the Object-Class is 42, and the Object-Type is 1. The format of the WA object body is as follows:

WA Object 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 | Flags |M| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | // TLVs // | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Reserved (16 bits):

Reserved for future use and SHOULD be zeroed and ignored on receipt.

Flags field (16 bits):

One flag bit is allocated as follows:

M (1 bit):

Wavelength Allocation Mode. The M bit is used to indicate the mode of wavelength assignment. When the M bit is set to 1, this indicates that the label assigned by the PCE must be explicit. That is, the selected way to convey the allocated wavelength is by means of Explicit Label Control for each hop of a computed LSP. Otherwise (M bit is set to 0), the label assigned by the PCE need not be explicit (i.e., it can be suggested in the form of Label Set objects in the corresponding response, to allow distributed WA. If M is 0, the PCE MUST return a Label Set Field as described in in the response. See of this document for the encoding discussion of a Label Set Field in a PCRep message.

All unused flags SHOULD be zeroed. IANA has created a new registry to manage the Flags field of the WA object.

TLVs (variable):

In the TLVs field, the following two TLVs are defined. At least one TLV MUST be present.

Wavelength Selection TLV:

The type of this TLV is 8, and it has a fixed length of 32 bits. This TLV indicates the wavelength selection. See for details.

Wavelength Restriction TLV:

The type of this TLV is 9, and it has a variable length. This TLV indicates wavelength restrictions. See for details.

Wavelength Selection TLV The Wavelength Selection TLV is used to indicate the wavelength selection constraint in regard to the order of wavelength assignment to be returned by the PCE. This TLV is only applied when the M bit is set in the WA object specified in . This TLV MUST NOT be used when the M bit is cleared. The encoding of this TLV is specified as the WavelengthSelection sub-TLV in . IANA has allocated a new TLV type for the Wavelength Selection TLV (Type 8).

Wavelength Restriction TLV For any request that contains a wavelength assignment, the requester (PCC) MUST specify a restriction on the wavelengths to be used. This restriction is to be interpreted by the PCE as a constraint on the tuning ability of the origination laser transmitter or on any other maintenance-related constraints. Note that if the LSC LSP spans different segments, the PCE must have mechanisms to know the tunability restrictions of the involved wavelength converters/regenerators, e.g., by means of the Traffic Engineering Database (TED) via either IGP or NMS. Even if the PCE knows the tunability of the transmitter, the PCC must be able to apply additional constraints to the request. The format of the Wavelength Restriction TLV is as follows: <Wavelength Restriction> ::= (<Action> <Count> <Reserved> <Link Identifiers> <Wavelength Constraint>)... Where: <Link Identifiers> ::= <Link Identifier> [<Link Identifiers>] See for the encoding of the Link Identifier field. These fields (i.e., <Action>, <Link Identifiers>, and <Wavelength Constraint>, etc.) MAY appear together more than once to be able to specify multiple actions and their restrictions. IANA has allocated a new TLV type for the Wavelength Restriction TLV (Type 9). The TLV data is defined as follows:

Wavelength Restriction TLV Encoding 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action | Count | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link Identifiers | // . . . // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Wavelength Constraint | // . . . . // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ . . . . ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action | Count | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link Identifiers | // . . . // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Wavelength Constraint | // . . . . // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Action (8 bits):

0:

Inclusive List. Indicates that one or more link identifiers are included in the Link Set. Each identifies a separate link that is part of the set.

1:

Inclusive Range. Indicates that the Link Set defines a range of links. It contains two link identifiers. The first identifier indicates the start of the range (inclusive). The second identifier indicates the end of the range (inclusive). All links with numeric values between the bounds are considered to be part of the set. A value of zero in either position indicates that there is no bound on the corresponding portion of the range.

2-255:

Unassigned.

IANA has created a new registry to manage the Action values of the Wavelength Restriction TLV. If a PCE receives an unrecognized Action value, the PCE MUST send a PCEP Error (PCErr) message with a PCEP-ERROR object with Error-Type=27 and an Error-value=3. See for details. Note that "links" are assumed to be bidirectional.

Count (8 bits):

The number of the link identifiers. Note that a PCC MAY add a Wavelength restriction that applies to all links by setting the Count field to zero and specifying just a set of wavelengths. Note that all link identifiers in the same list MUST be of the same type.

Reserved (16 bits):

Reserved for future use and SHOULD be zeroed and ignored on receipt.

Link Identifiers:

Identifies each link ID for which restriction is applied. The length is dependent on the link format and the Count field. See for encoding of the Link Identifier field.

Wavelength Constraint:

See for the encoding of the Wavelength Constraint field.

Various encoding errors are possible with this TLV (e.g., not exactly two link identifiers with the range case, unknown identifier types, no matching link for a given identifier, etc.). To indicate errors associated with this encoding, a PCEP speaker MUST send a PCErr message with Error-Type=27 and Error-value=3. See for details.

Link Identifier Field The Link Identifier field can be an IPv4 , IPv6 , or unnumbered interface ID . <Link Identifier> ::= <IPv4 Address> | <IPv6 Address> | <Unnumbered IF ID> The encoding of each case is as follows.

IPv4 Address Field 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 1 | Reserved (24 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 address (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 Address Field 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 2 | Reserved (24 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (16 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Unnumbered Interface ID Address Field 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 3 | Reserved (24 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TE Node ID (32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface ID (32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type (8 bits):

Indicates the type of the link identifier.

Reserved (24 bits):

Reserved for future use and SHOULD be zeroed and ignored on receipt.

Link Identifier:

When the Type field is 1, a 4-byte IPv4 address is encoded; when the Type field is 2, a 16-byte IPv6 address is encoded; and when the Type field is 3, a tuple of a 4-byte TE node ID and a 4-byte interface ID is encoded.

The Type field is extensible and matches the "TE_LINK Object Class type name space (Value 11)" registry created for the Link Management Protocol (LMP) (see ). IANA has added an introductory note before the aforementioned registry stating that the values have additional usage for the Link Identifier Type field. See .

Wavelength Constraint Field The Wavelength Constraint field of the Wavelength Restriction TLV is encoded as a Label Set Field as specified in with the base label encoded as a 32-bit LSC label, as defined in . The Label Set format is repeated here for convenience, with the base label internal structure included. See for a description of Grid, Channel Spacing (C.S.), Identifier, and n, and see for the details of each action.

Wavelength Constraint Field 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action| Num Labels | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Grid | C.S. | Identifier | n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Additional fields as necessary per action | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Action (4 bits):

0:

Inclusive List

1:

Exclusive List

2:

Inclusive Range

3:

Exclusive Range

4:

Bitmap Set

Num Labels (12 bits):

It is generally the number of labels. It has a specific meaning depending on the action value.

Length (16 bits):

It is the length in bytes of the entire Wavelength Constraint field.

Identifier (9 bits):

The Identifier is always set to 0. If PCC receives the value of the identifier other than 0, it will ignore.

See Sections - of for details on additional field discussion for each action.

Signal Processing Capability Restrictions Path computation for WSON includes the checking of signal processing capabilities at each interface against requested capability; the PCE MUST have mechanisms to know the signal processing capabilities at each interface, e.g., by means of (TED) via either IGP or NMS. Moreover, a PCC should be able to indicate additional restrictions to signal processing compatibility, on either the endpoint or any given link. The supported signal processing capabilities considered in the RWA Information Model are:

• Optical Interface Class List
• Bit Rate
• Client Signal

The bit rate restriction is already expressed in the BANDWIDTH object in . In order to support the optical interface class information and the client signal information, new TLVs are introduced as endpoint restrictions in the END-POINTS type Generalized Endpoint:

• Client Signal Information TLV
• Optical Interface Class List TLV

The END-POINTS type Generalized Endpoint is extended as follows: <endpoint-restriction> ::= <LABEL-REQUEST> <label-restriction-list> <label-restriction-list> ::= <label-restriction> [<label-restriction-list>] <label-restriction> ::= (<LABEL-SET>| [<Wavelength Restriction>] [<signal-compatibility-restriction>]) Where: <signal-compatibility-restriction> ::= [<Optical Interface Class List>] [<Client Signal Information>] The Wavelength Restriction TLV is defined in . A new Optical Interface Class List TLV (Type 11) is defined; the encoding of the value part of this TLV is described in . A new Client Signal Information TLV (Type 12) is defined; the encoding of the value part of this TLV is described in .

Signal Processing Exclusion The PCC/PCE should be able to exclude particular types of signal processing along the path in order to handle client restriction or multi-domain path computation. defines how the Exclude Route Object (XRO) subobject is used. In this document, we add two new XRO Signal Processing Exclusion subobjects. The first XRO subobject type (8) is the Optical Interface Class List, which is defined as follows:

Optical Interface Class List XRO Subobject 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |X| Type=8 | Length | Reserved | Attribute | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // Optical Interface Class List // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Refer to for the definitions of X, Length, and Attribute.

Type (7 bits):

The type of the Signaling Processing Exclusion field. IANA has assigned value 8 for the Optical Interface Class List XRO subobject type.

Reserved bits (8 bits):

These are for future use and SHOULD be zeroed and ignored on receipt.

Attribute (8 bits):

defines several Attribute values; the only permitted Attribute values for this field are 0 (Interface) or 1 (Node).

Optical Interface Class List:

This field is encoded as described in .

The second XRO subobject type (9) is the Client Signal Information, which is defined as follows:

Client Signal Information XRO Subobject 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |X| Type=9 | Length | Reserved | Attribute | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // Client Signal Information // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Refer to for the definitions of X, Length, and Attribute.

Type (7 bits):

The type of the Signaling Processing Exclusion field. IANA has assigned value 9 for the Client Signal Information XRO subobject type.

Reserved bits (8 bits):

These are for future use and SHOULD be zeroed and ignored on receipt.

Attribute (8 bits):

defines several Attribute values; the only permitted Attribute values for this field are 0 (Interface) or 1 (Node).

Client Signal Information:

This field is encoded as described in .

The XRO needs to support the new Signaling Processing Exclusion XRO subobject types:

• 8:

  Optical Interface Class List

  9:

  Client Signal Information

Signal Processing Inclusion Similar to the XRO subobject, the PCC/PCE should be able to include particular types of signal processing along the path in order to handle client restriction or multi-domain path computation. defines how the Include Route Object (IRO) subobject is used. In this document, we add two new Signal Processing Inclusion subobjects. The IRO needs to support the new IRO subobject types (8 and 9) for the PCEP IRO object :

• 8:

  Optical Interface Class List

  9:

  Client Signal Information

The encoding of the Signal Processing Inclusion subobjects is similar to the process in where the 'X' field is replaced with the 'L' field; all the other fields remain the same. The 'L' field is described in .

Encoding of an RWA Path Reply This section provides the encoding of an RWA Path Reply for a wavelength allocation request as discussed in .

Wavelength Allocation TLV Recall that wavelength allocation can be performed by the PCE by means of:

1. Explicit Label Control (ELC) where the PCE allocates which label to use for each interface/node along the path.
2. A Label Set where the PCE provides a range of potential labels to be allocated by each node along the path.

Option (b) allows distributed label allocation (performed during signaling) to complete wavelength allocation. The type for the Wavelength Allocation TLV is 10 (see ). Note that this TLV is used for both (a) and (b) above. The TLV data is defined as follows:

Wavelength Allocation TLV Encoding 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 | Flags |M| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link Identifier | // . . . // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Allocated Wavelength(s) | // . . . . // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Reserved (16 bits):

Reserved for future use.

Flags field (16 bits):

One flag bit is allocated as follows:

M (1 bit):

Wavelength Allocation Mode.

0:

Indicates the allocation relies on the use of Label Sets.

1:

Indicates the allocation is done using Explicit Label Control.

IANA has created a new registry to manage the Flags field of the Wavelength Allocation TLV.

Link Identifier:

Identifies the interface to which the assignment wavelength(s) is applied. See for encoding of the Link Identifier field.

Allocated Wavelength(s):

Indicates the allocated wavelength(s) to be associated with the link identifier. See for encoding details.

This TLV is carried in a PCRep message as an Attribute TLV in the Hop Attribute subobjects in the Explicit Route Object (ERO) .

Error Indicator To indicate errors associated with the RWA request, a new Error-Type 27 (WSON RWA Error) and subsequent Error-values are defined as follows for inclusion in the PCEP-ERROR object:

• Error-Type=27; Error-value=1: If a PCE receives an RWA request and the PCE is not capable of processing the request due to insufficient memory, the PCE MUST send a PCErr message with a PCEP-ERROR object with Error-Type=27 and Error-value=1. The PCE stops processing the request. The corresponding RWA request MUST be canceled at the PCC.
• Error-Type=27; Error-value=2: If a PCE receives an RWA request and the PCE is not capable of RWA computation, the PCE MUST send a PCErr message with a PCEP-ERROR object with Error-Type=27 and Error-value=2. The PCE stops processing the request. The corresponding RWA computation MUST be canceled at the PCC.
• Error-Type=27; Error-value=3: If a PCE receives an RWA request and there are syntactical encoding errors (e.g., not exactly two link identifiers with the range case, unknown identifier types, no matching link for a given identifier, unknown Action value, etc.), the PCE MUST send a PCErr message with a PCEP-ERROR object with Error-Type=27 and Error-value=3.

NO-PATH Indicator To communicate the reason(s) for not being able to find RWA for the path request, the NO-PATH object can be used in the corresponding response. The format of the NO-PATH object body is defined in . The object may contain a NO-PATH-VECTOR TLV to provide additional information about why a path computation has failed. This document defines a new bit flag to be carried in the Flags field in the NO-PATH-VECTOR TLV, which is carried in the NO-PATH object:

Bit 23:

When set, the PCE indicates no feasible route was found that meets all the constraints (e.g., wavelength restriction, signal compatibility, etc.) associated with RWA.

Manageability Considerations Manageability of WSON RWA with PCE must address the considerations in the following subsections.

Control of Function and Policy In addition to the parameters already listed in , a PCEP implementation SHOULD allow configuration of the following PCEP session parameters on a PCC:

• The ability to send a WSON RWA request.

In addition to the parameters already listed in , a PCEP implementation SHOULD allow configuration of the following PCEP session parameters on a PCE:

• The support for WSON RWA.
• A set of WSON-RWA-specific policies (authorized sender, request rate limiter, etc).

These parameters may be configured as default parameters for any PCEP session the PCEP speaker participates in, or they may apply to a specific session with a given PCEP peer or a specific group of sessions with a specific group of PCEP peers.

Liveness Detection and Monitoring Mechanisms defined in this document do not imply any new liveness detection and monitoring requirements, aside from those already listed in .

Verifying Correct Operation Mechanisms defined in this document do not imply any new verification requirements, aside from those already listed in .

Requirements on Other Protocols and Functional Components The PCEP Link-State mechanism may be used to advertise WSON RWA path computation capabilities to PCCs.

Impact on Network Operation Mechanisms defined in this document do not imply any new network operation requirements, aside from those already listed in .

Security Considerations The security considerations discussed in are relevant for this document; this document does not introduce any new security issues. If an operator wishes to keep the information distributed by WSON private, PCEPS (Usage of TLS to Provide a Secure Transport for PCEP) SHOULD be used.

IANA Considerations IANA maintains a registry of PCEP parameters. IANA has made allocations from the subregistries as described in the following sections.

New PCEP Object: Wavelength Assignment Object As described in , a new PCEP object is defined to carry wavelength-assignment-related constraints. IANA has allocated the following in the "PCEP Objects" subregistry :

Object-Class Value	Name	Object-Type	Reference
42	WA	0: Reserved	RFC 8780
		1: Wavelength Assignment	RFC 8780

WA Object Flag Field As described in , IANA has created the "WA Object Flag Field" subregistry under the "Path Computation Element Protocol (PCEP) Numbers" registry to manage the Flags field of the WA object. New values are to be assigned by Standards Action . Each bit should be tracked with the following qualities:

• Bit number (counting from bit 0 as the most significant bit)
• Capability description
• Defining RFC

The initial contents of this registry are shown below. One bit has been allocated for the flag defined in this document:

Bit	Description	Reference
0-14	Unassigned
15	Wavelength Allocation Mode	RFC 8780

New PCEP TLV: Wavelength Selection TLV In , a new PCEP TLV is defined to indicate wavelength selection constraints. IANA has made the following allocation in the "PCEP TLV Type Indicators" subregistry :

Value	Description	Reference
8	Wavelength Selection	RFC 8780

New PCEP TLV: Wavelength Restriction TLV In , a new PCEP TLV is defined to indicate wavelength restrictions. IANA has made the following allocation in the "PCEP TLV Type Indicators" subregistry :

Value	Description	Reference
9	Wavelength Restriction	RFC 8780

Wavelength Restriction TLV Action Values As described in , IANA has created the new "Wavelength Restriction TLV Action Values" subregistry under the "Path Computation Element Protocol (PCEP) Numbers" registry to manage the Action values of the Action field of the Wavelength Restriction TLV. New values are assigned by Standards Action . Each value should be tracked with the following qualities:

• Value
• Meaning
• Defining RFC

The initial contents of this registry are shown below:

Value	Meaning	Reference
0	Inclusive List	RFC 8780
1	Inclusive Range	RFC 8780
2-255	Unassigned

New PCEP TLV: Wavelength Allocation TLV In , a new PCEP TLV is defined to indicate the allocation of the wavelength(s) by the PCE in response to a request by the PCC. IANA has made the following allocation in "PCEP TLV Type Indicators" subregistry :

Value	Description	Reference
10	Wavelength Allocation	RFC 8780

Wavelength Allocation TLV Flag Field As described in , IANA has created a new "Wavelength Allocation TLV Flag Field" subregistry under the "Path Computation Element Protocol (PCEP) Numbers" registry to manage the Flags field of the Wavelength Allocation TLV. New values are to be assigned by Standards Action . Each bit should be tracked with the following qualities:

• Bit number (counting from bit 0 as the most significant bit)
• Capability description
• Defining RFC

One bit is defined for the flag defined in this document. The initial contents of this registry are shown below:

Bit	Description	Reference
0-14	Unassigned
15	Wavelength Allocation Mode	RFC 8780

New PCEP TLV: Optical Interface Class List TLV In , a new PCEP TLV is defined to indicate the Optical Interface Class List. IANA has made the following allocation in the "PCEP TLV Type Indicators" subregistry :

Value	Description	Reference
11	Optical Interface Class List	RFC 8780

New PCEP TLV: Client Signal Information TLV In , a new PCEP TLV is defined to indicate the Client Signal Information. IANA has made the following allocation in the "PCEP TLV Type Indicators" subregistry :

Value	Description	Reference
12	Client Signal Information	RFC 8780

New Bit Flag for NO-PATH-VECTOR TLV In , a new bit flag is defined to be carried in the Flags field in the NO-PATH-VECTOR TLV, which is carried in the NO-PATH object. This flag, when set, indicates that no feasible route was found that meets all the RWA constraints (e.g., wavelength restriction, signal compatibility, etc.) associated with an RWA path computation request. IANA has made the following allocation for this new bit flag in the "NO-PATH-VECTOR TLV Flag Field" subregistry :

Bit	Description	Reference
23	No RWA constraints met	RFC 8780

New Error-Types and Error-Values In , new PCEP error codes are defined for WSON RWA errors. IANA has made the following allocations in the "PCEP-ERROR Object Error Types and Values" subregistry :

Error-Type	Meaning	Error-value	Reference
27	WSON RWA error	0: Unassigned	RFC 8780
		1: Insufficient memory	RFC 8780
		2: RWA computation not supported	RFC 8780
		3: Syntactical encoding error	RFC 8780
		4-255: Unassigned	RFC 8780

New Subobjects for the Exclude Route Object The "Path Computation Element Protocol (PCEP) Numbers" registry contains a subregistry titled "XRO Subobjects" . Per , IANA has added the following subobjects that can be carried in the XRO:

Value	Description	Reference
8	Optical Interface Class List	RFC 8780
9	Client Signal Information	RFC 8780

New Subobjects for the Include Route Object The "Path Computation Element Protocol (PCEP) Numbers" registry contains a subregistry titled "IRO Subobjects" . Per , IANA has added the following subobjects that can be carried in the IRO:

Value	Description	Reference
8	Optical Interface Class List	RFC 8780
9	Client Signal Information	RFC 8780

Request for Updated Note for LMP TE Link Object Class Type The "TE_LINK Object Class type name space (Value 11)" registry was created for the Link Management Protocol (LMP) . As discussed in , IANA has added the following note at the top of the "TE_LINK Object Class type name space (Value 11)" registry :

• These values have additional usage for the Link Identifier Type field.

References Normative References In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. This document describes the use of RSVP (Resource Reservation Protocol), including all the necessary extensions, to establish label-switched paths (LSPs) in MPLS (Multi-Protocol Label Switching). Since the flow along an LSP is completely identified by the label applied at the ingress node of the path, these paths may be treated as tunnels. A key application of LSP tunnels is traffic engineering with MPLS as specified in RFC 2702. [STANDARDS-TRACK] This document describes extensions to the OSPF protocol version 2 to support intra-area Traffic Engineering (TE), using Opaque Link State Advertisements. This document describes extensions to OSPFv3 to support intra-area Traffic Engineering (TE). This document extends OSPFv2 TE to handle IPv6 networks. A new TLV and several new sub-TLVs are defined to support IPv6 networks. [STANDARDS-TRACK] This document specifies the Path Computation Element (PCE) Communication Protocol (PCEP) for communications between a Path Computation Client (PCC) and a PCE, or between two PCEs. Such interactions include path computation requests and path computation replies as well as notifications of specific states related to the use of a PCE in the context of Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering. PCEP is designed to be flexible and extensible so as to easily allow for the addition of further messages and objects, should further requirements be expressed in the future. [STANDARDS-TRACK] Technology in the optical domain is constantly evolving, and, as a consequence, new equipment providing lambda switching capability has been developed and is currently being deployed. Generalized MPLS (GMPLS) is a family of protocols that can be used to operate networks built from a range of technologies including wavelength (or lambda) switching. For this purpose, GMPLS defined a wavelength label as only having significance between two neighbors. Global wavelength semantics are not considered. In order to facilitate interoperability in a network composed of next generation lambda-switch-capable equipment, this document defines a standard lambda label format that is compliant with the Dense Wavelength Division Multiplexing (DWDM) and Coarse Wavelength Division Multiplexing (CWDM) grids defined by the International Telecommunication Union Telecommunication Standardization Sector. The label format defined in this document can be used in GMPLS signaling and routing protocols. [STANDARDS-TRACK] RFC 5420 extends RSVP-TE to specify or record generic attributes that apply to the whole of the path of a Label Switched Path (LSP). This document defines an extension to the RSVP Explicit Route Object (ERO) and Record Route Object (RRO) to allow them to specify or record generic attributes that apply to a given hop. Generalized Multiprotocol Label Switching (GMPLS) can be used to control a wide variety of technologies. In some of these technologies, network elements and links may impose additional routing constraints such as asymmetric switch connectivity, non-local label assignment, and label range limitations on links. This document provides efficient, protocol-agnostic encodings for general information elements representing connectivity and label constraints as well as label availability. It is intended that protocol-specific documents will reference this memo to describe how information is carried for specific uses. A Wavelength Switched Optical Network (WSON) requires certain key information fields be made available to facilitate path computation and the establishment of Label Switched Paths (LSPs). The information model described in "Routing and Wavelength Assignment Information Model for Wavelength Switched Optical Networks" (RFC 7446) shows what information is required at specific points in the WSON. Part of the WSON information model contains aspects that may be of general applicability to other technologies, while other parts are specific to WSONs. This document provides efficient, protocol-agnostic encodings for the WSON-specific information fields. It is intended that protocol- specific documents will reference this memo to describe how information is carried for specific uses. Such encodings can be used to extend GMPLS signaling and routing protocols. In addition, these encodings could be used by other mechanisms to convey this same information to a Path Computation Element (PCE). This document provides Generalized Multiprotocol Label Switching (GMPLS) Open Shortest Path First (OSPF) routing enhancements to support signal compatibility constraints associated with Wavelength Switched Optical Network (WSON) elements. These routing enhancements are applicable in common optical or hybrid electro-optical networks where not all the optical signals in the network are compatible with all network elements participating in the network. This compatibility constraint model is applicable to common optical or hybrid electro-optical systems such as optical-electronic-optical (OEO) switches, regenerators, and wavelength converters, since such systems can be limited to processing only certain types of WSON signals. This document provides extensions to Generalized Multiprotocol Label Switching (GMPLS) signaling for control of Wavelength Switched Optical Networks (WSONs). Such extensions are applicable in WSONs under a number of conditions including: (a) when optional processing, such as regeneration, must be configured to occur at specific nodes along a path, (b) where equipment must be configured to accept an optical signal with specific attributes, or (c) where equipment must be configured to output an optical signal with specific attributes. This document provides mechanisms to support distributed wavelength assignment with a choice of distributed wavelength assignment algorithms. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. The Path Computation Element Communication Protocol (PCEP) defines the mechanisms for the communication between a Path Computation Client (PCC) and a Path Computation Element (PCE), or among PCEs. This document describes PCEPS -- the usage of Transport Layer Security (TLS) to provide a secure transport for PCEP. The additional security mechanisms are provided by the transport protocol supporting PCEP; therefore, they do not affect the flexibility and extensibility of PCEP. This document updates RFC 5440 in regards to the PCEP initialization phase procedures. Informative References IANA In order to compute and provide optimal paths, Path Computation Elements (PCEs) require an accurate and timely Traffic Engineering Database (TED). Traditionally this Link State and TE information has been obtained from a link state routing protocol (supporting traffic engineering extensions). This document extends the Path Communication Element Communication Protocol (PCEP) with Link-State and TE information for optical networks. Work in Progress IANA This document describes extensions to Multi-Protocol Label Switching (MPLS) signaling required to support Generalized MPLS. Generalized MPLS extends the MPLS control plane to encompass time-division (e.g., Synchronous Optical Network and Synchronous Digital Hierarchy, SONET/SDH), wavelength (optical lambdas) and spatial switching (e.g., incoming port or fiber to outgoing port or fiber). This document presents a functional description of the extensions. Protocol specific formats and mechanisms, and technology specific details are specified in separate documents. [STANDARDS-TRACK] This document specifies encoding of extensions to the OSPF routing protocol in support of Generalized Multi-Protocol Label Switching (GMPLS). [STANDARDS-TRACK] For scalability purposes, multiple data links can be combined to form a single traffic engineering (TE) link. Furthermore, the management of TE links is not restricted to in-band messaging, but instead can be done using out-of-band techniques. This document specifies a link management protocol (LMP) that runs between a pair of nodes and is used to manage TE links. Specifically, LMP will be used to maintain control channel connectivity, verify the physical connectivity of the data links, correlate the link property information, suppress downstream alarms, and localize link failures for protection/restoration purposes in multiple kinds of networks. [STANDARDS-TRACK] Constraint-based path computation is a fundamental building block for traffic engineering systems such as Multiprotocol Label Switching (MPLS) and Generalized Multiprotocol Label Switching (GMPLS) networks. Path computation in large, multi-domain, multi-region, or multi-layer networks is complex and may require special computational components and cooperation between the different network domains. This document specifies the architecture for a Path Computation Element (PCE)-based model to address this problem space. This document does not attempt to provide a detailed description of all the architectural components, but rather it describes a set of building blocks for the PCE architecture from which solutions may be constructed. This memo provides information for the Internet community. Multiprotocol Label Switching (MPLS) Label Switched Paths (LSPs) may be established using the Resource Reservation Protocol Traffic Engineering (RSVP-TE) extensions. This protocol includes an object (the SESSION_ATTRIBUTE object) that carries a Flags field used to indicate options and attributes of the LSP. That Flags field has eight bits, allowing for eight options to be set. Recent proposals in many documents that extend RSVP-TE have suggested uses for each of the previously unused bits. This document defines a new object for RSVP-TE messages that allows the signaling of further attribute bits and also the carriage of arbitrary attribute parameters to make RSVP-TE easily extensible to support new requirements. Additionally, this document defines a way to record the attributes applied to the LSP on a hop-by-hop basis. The object mechanisms defined in this document are equally applicable to Generalized MPLS (GMPLS) Packet Switch Capable (PSC) LSPs and to GMPLS non-PSC LSPs. This document replaces and obsoletes the previous version of this work, published as RFC 4420. The only change is in the encoding of the Type-Length-Variable (TLV) data structures. [STANDARDS-TRACK] The Path Computation Element (PCE) provides functions of path computation in support of traffic engineering (TE) in Multi-Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks. When a Path Computation Client (PCC) requests a PCE for a route, it may be useful for the PCC to specify, as constraints to the path computation, abstract nodes, resources, and Shared Risk Link Groups (SRLGs) that are to be explicitly excluded from the computed route. Such constraints are termed "route exclusions". The PCE Communication Protocol (PCEP) is designed as a communication protocol between PCCs and PCEs. This document presents PCEP extensions for route exclusions. [STANDARDS-TRACK] This document provides a framework for applying Generalized Multi-Protocol Label Switching (GMPLS) and the Path Computation Element (PCE) architecture to the control of Wavelength Switched Optical Networks (WSONs). In particular, it examines Routing and Wavelength Assignment (RWA) of optical paths. This document focuses on topological elements and path selection constraints that are common across different WSON environments; as such, it does not address optical impairments in any depth. This document is not an Internet Standards Track specification; it is published for informational purposes. As an optical signal progresses along its path, it may be altered by the various physical processes in the optical fibers and devices it encounters. When such alterations result in signal degradation, these processes are usually referred to as "impairments". These physical characteristics may be important constraints to consider when using a GMPLS control plane to support path setup and maintenance in wavelength switched optical networks. This document provides a framework for applying GMPLS protocols and the Path Computation Element (PCE) architecture to support Impairment-Aware Routing and Wavelength Assignment (IA-RWA) in wavelength switched optical networks. Specifically, this document discusses key computing constraints, scenarios, and architectural processes: routing, wavelength assignment, and impairment validation. This document does not define optical data plane aspects; impairment parameters; or measurement of, or assessment and qualification of, a route; rather, it describes the architectural and information components for protocol solutions. This document is not an Internet Standards Track specification; it is published for informational purposes. This document provides a model of information needed by the Routing and Wavelength Assignment (RWA) process in Wavelength Switched Optical Networks (WSONs). The purpose of the information described in this model is to facilitate constrained optical path computation in WSONs. This model takes into account compatibility constraints between WSON signal attributes and network elements but does not include constraints due to optical impairments. Aspects of this information that may be of use to other technologies utilizing a GMPLS control plane are discussed. This memo provides application-specific requirements for the Path Computation Element Communication Protocol (PCEP) for the support of Wavelength Switched Optical Networks (WSONs). Lightpath provisioning in WSONs requires a Routing and Wavelength Assignment (RWA) process. From a path computation perspective, wavelength assignment is the process of determining which wavelength can be used on each hop of a path and forms an additional routing constraint to optical light path computation. Requirements for PCEP extensions in support of optical impairments will be addressed in a separate document. Many protocols make use of points of extensibility that use constants to identify various protocol parameters. To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper. For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA). To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed. This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry. This is the third edition of this document; it obsoletes RFC 5226.

Acknowledgments The authors would like to thank , , , and for many helpful comments that greatly improved the contents of this document.

Contributors Huawei Technologies

zhangfatai@huawei.com

Nokia Siemens Networks

St. Martin Strasse 76 Munich 81541 Germany +49 89 5159 16934 cyril.margaria@nsn.com

Telefonica Investigacion y Desarrollo

C/ Emilio Vargas 6 Madrid 28043 Spain +34 91 3374013 ogondio@tid.es

Grotto Networking

Fremont CA United States of America +1 510 573 2237 gregb@grotto-networking.com

Authors' Addresses Samsung Electronics

younglee.tx@gmail.com

CTTC

Carl Friedrich Gauss 7 PMT Ed B4 Av. Castelldefels Barcelona 08860 Spain +34 936452916 ramon.casellas@cttc.es