Network Working Group Qilei Wang Internet-Draft Xihua Fu Intended status: Standards Track ZTE Corporation Expires: January 17, 2013 Jul 16, 2012 RSVP-TE Extensions for GMPLS control of Spectrum Switched Optical Networks (SSONs) draft-wang-ccamp-gmpls-sson-rsvpte-01.txt Abstract A new architecture of optical transport networks which is addressed in the newest version of G.872 is being developed in ITU-T SG15. Compared with previous G.872 technology, this new technology allows the switch of group of optical channels as a whole. Since current control plane technology isn't able to control this kind of application, this document describes the signaling extension to support the control of frequency slot channel (i.e., group of optical channels). This document also addresses the interworking between WSON optical channel and SSON (Spectrum Switched Optical Network) optical channel. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on January 17, 2013. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 1] Internet-Draft Spectrum Switched Optical Network Jul 2012 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Requirements and Modeling of SSON . . . . . . . . . . . . . . 5 3.1. Hierarchy between Optical Channel and Frequency Slot Channel . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Switching Type . . . . . . . . . . . . . . . . . . . . . . 6 3.3. Frequency Slot Channel . . . . . . . . . . . . . . . . . . 6 3.3.1. Label Format . . . . . . . . . . . . . . . . . . . . . 6 3.3.2. Traffic Parameters . . . . . . . . . . . . . . . . . . 6 3.3.3. Grid Attributes of Forwarding Adjacency . . . . . . . 7 3.4. Optical Channel . . . . . . . . . . . . . . . . . . . . . 7 3.4.1. Overview of Flexible Grid and Fixed Grid . . . . . . . 7 3.4.2. Interwork between WSON signal and SSON signal . . . . 7 4. Signaling Protocol Extensions to Support Control of SSON . . . 8 4.1. Switching Type . . . . . . . . . . . . . . . . . . . . . . 8 4.2. Label Format Extensions of Frequency Slot Channel Layer . 9 4.3. Traffic Parameters of Frequency Slot Channel Layer . . . . 9 5. Signaling Procedures . . . . . . . . . . . . . . . . . . . . . 10 5.1. RSVP-TE Signaling Procedures to Support the Setup of Frequency Slot Channel . . . . . . . . . . . . . . . . . . 10 5.1.1. Centralized Spectrum Assignment . . . . . . . . . . . 10 5.1.2. Distributed Spectrum Assignment . . . . . . . . . . . 10 5.2. Interconnection between WSON signal and SSON signal . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7.1. Normative References . . . . . . . . . . . . . . . . . . . 13 7.2. Informative References . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 2] Internet-Draft Spectrum Switched Optical Network Jul 2012 1. Introduction In the newest version of G.872, a new kind of spectrum utilization and implementation way is introduced to current optical network. That is, a chunk of contiguous spectrum which is occupied by a group of "express" channels can be forwarded via wide-band filters as a whole without filtering and switching everything down to the individual OCh (Optical Channel) level in long-haul systems. Compared with narrowband, wideband filters and switching has many advantages, for example, building OCh Signals for management convenience, maximizing the reach and traversing more nodes. Optical channels included in the group may have different sizes (more than one OCh signal fits into a slot). From the perspective of management plane and control plane, hierarchy exists between the channels and optical channel group (frequency slot channel). Detailed description about this kind of spectrum utilization and implementation way could be found in the following sections base on the terminology defined in ITU-T. GMPLS protocol extensions are needed to help manage this kind of spectrum utilization and implementation way. This document first describes the layer model base on the hierarchy between optical channels (OCh) and optical channel group (frequency slot channel) from management plane or control plane perspective and defines signaling protocol extension to support the control of frequency slot channel. As the flexible grid framework document describes both the frequency slot channel and optical channel, this document also give a detail description about the interworking between WSON optical channel and SSON (Spectrum Switched Optical Network) optical channel. 1.1. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 2. Terminology o Frequency slot: As defined by Q6 in clause 3.1.2 of G.694.1, a frequency slot is a frequency range which is allocated to a slot and unavailable to other slots within a flexible grid. A frequency slot is defined by its nominal central frequency and its slot width. Detailed description can be found in the framework document. Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 3] Internet-Draft Spectrum Switched Optical Network Jul 2012 o Wavelength Range: [RFC6163] gives a description of this terminology.Wavelength range given a mapping between labels and the ITU-T grids, each range could be expressed in terms of a tuple, (lambda1, lambda2) or (freq1, freq2), where the lambdas or frequencies can be represented by 32-bit integers. o Nominal central frequency (of a frequency slot) - as used by Q6 in G.694.1. [Note: This parameter is associated with a grid position on the fixed grid and a slot in the flexible grid.] o Central frequency - this parameter is associated with an optical signal. It is the nominal mid-point of the optical frequency range over which the digital information of the particular OCh payload is modulated. o Single signal frequency slot: A frequency slot assigned to a single optical signal (that carries a single OCh payload) o Frequency Slot Channel: as defined in the newest version of G.872, the Optical Channel Signal is switched by analogue elements (matrices) and may be switched in larger pieces of spectrum than that occupied by a single optical channel (optical channel slot). The channel that may carry multiple optical channel signals is called a Frequency Slot Channel. o Fiber Frequency Slot: the total allocable spectrum on a fiber. o SSON: Spectrum-Switched Optical Network. This concept and definition is introduced from the framework document. An optical network in which a data plane connection is switched based on an optical spectrum frequency slot of a variable slot width, rather than based on a fixed grid and fixed slot width. o OCh Frequency Slot: The spectrum allocated to transport a single OCh signal. o Waveguide: anything that constrains the E/M radiation and guides the E/M energy to its destination is a waveguide; copper pairs, coaxial pairs and optical fibers are all waveguides. o Media layer: media layer is described as the bottom of the client server recursion. o Media path: a path through a waveguide can be called media path. Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 4] Internet-Draft Spectrum Switched Optical Network Jul 2012 3. Requirements and Modeling of SSON 3.1. Hierarchy between Optical Channel and Frequency Slot Channel Spectrum may be allocated in larger and contiguous piece than a single OCh slot which is called Frequency Slot. Frequency Slot Channel can be described as an optical media path (i.e., waveguide) with a nominal center frequency and slot width across a sequence of network elements. The concatenation of all media elements between two points is called a Frequency Slot Channel. A frequency slot channel is such an optical channel group that more than one optical channel slot can be carried in and transport. SSON allows both frequency slot channel switching and optical channel switching. [Note: The term "channel" here implies all the media between two points.] Frequency Slot channels can be switched in a Frequency Slot Matrix. The Frequency Slot Matrix Connection is described as an optical matrix connection from one fiber to another that has a given nominal center frequency and slot width. The Frequency Slot Matrix connection may interconnect one or more Frequency Slot Channels, which in turn may carry one or more OCh signals. Establishing a Frequency Slot Matrix Connection will limit the connectivity of an OCh signal over that network element within the spectral band of that matrix connection to be between the input and output fibers of that Frequency Slot Matrix Connection. The slots allocated to a single OCh signal is called OCh slot. In the case where the switching granularity of the Frequency Slot Matrix allows for independent switching of each OCh, it can be decided as a matter of policy that a request to establish an OCh connection will, internal to the NE, establish a Frequency Slot Matrix Connection of the same spectral width, and the Frequency Slot Matrix Connection can be released when the OCh connection is released. The Frequency Slot channel is a topological construct which is modeled from management perspective and can be chosen for convenience of managing and describing the network. A frequency slot channel represents a piece of spectrum supported by a concatenation of media elements (e.g. fiber, filters, amplifier). More than one optical channel signal can be carried in a frequency slot channel. As the frequency slots and Optical channel are of different sizes, hierarchy exists between them, current optical transport network can be modeled into two layers and managed independently from the perspective of management, one is optical channel layer and the other is frequency slot channel layer. Frequency slots channel and optical channel Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 5] Internet-Draft Spectrum Switched Optical Network Jul 2012 signals can be managed independently. A frequency slot channel can be switched as a whole by the frequency slot matrix without the need to look into every optical channel. [Notes: We are not going to address the OEO and wavelength converter that may exist in a frequency slot channel, as current version of G.872 doesn't cover the optical frequency changer along the frequency slot channel.] 3.2. Switching Type Switching type can be used to indicate the type of switching that should be performed on a particular link. According to the modeling in the previous section, a new value should be defined to indicate the switching capability of frequency slot channel layer. 3.3. Frequency Slot Channel 3.3.1. Label Format Section 3.3 of [RFC3471] defines waveband switching: "A waveband represents a set of contiguous wavelengths which can be switched together to a new waveband". This is similar to the frequency slot channel switching, because they both switch multiple wavelengths or spectrum as a unit. But the wavelength label defined in [RFC3471] only has significance between neighbors, in order to control the setup and release of frequency slot channel with RSVP-TE signaling, a new frequency slot channel label which has definite information of nominal central frequency and slot width of the spectrum is needed. This chunk of spectrum can be used for subsequent setup of optical channel path. 3.3.2. Traffic Parameters In current network, like MPLS network, OTN network, signaling can be used to reserve bandwidth at each node along the path when set up LSPs. The bandwidth information describes the end-to-end traffic characteristic of a LSP, so the signaling SHOULD be able to carry bandwidth information that a LSP need to occupy. In the process of the setup of frequency slot channel, the most critical traffic characteristic of a LSP is spectrum, i.e., the spectrum width that a LSP can occupy. For example, if a third party wants to manage and operate a chunk of spectrum by itself, carrier could use the signaling to set up a frequency slot channel with a specific spectrum width to satisfy the requirement. Carrier doesn't care how this spectrum can be used by the party and how many data Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 6] Internet-Draft Spectrum Switched Optical Network Jul 2012 this chunk of spectrum can bear. According to the previous description, when we use signaling to set up a frequency slot channel, spectrum resource information (i.e., spectrum width) should be carried in the signaling to reserve the spectrum resource along the path. 3.3.3. Grid Attributes of Forwarding Adjacency Frequency slot matrix connection may interconnect one or more frequency slot channels, which in turn may carry one or more OCh signals. In the case the frequency slot matrix just allow the switching of spectrum as a whole, internal grid attributes should not be known by the forwarding adjacency end points. 3.4. Optical Channel [Notes: This section mainly addresses the current status of optical channel, including WSON optical channel signal and SSON optical channel signal. We will decouple this part and submit another document if people think optical channel and frequency slot channel belong to different layer and they have different signaling format, so they should be decouple from each other.] 3.4.1. Overview of Flexible Grid and Fixed Grid GMPLS and PCE control of fixed grid network (i.e., WSON, Wavelength Switched Optical Network) is close to mature in IETF CCAMP, while flexible grid control plane technology is still being developed in IETF. This section mainly focuses on the interconnection between WSON optical channel signal and SSON optical channel signal. 3.4.2. Interwork between WSON signal and SSON signal Some open issues are listed in the recent flexible grid framework document and still need to be resolved if we want to push the framework document forward. Part of these issues which may have relation to the interwork between SSON and WSON are listed here: 1). If a new switching capability is needed to represent SSON optical channel layer? 2). Potential problems with having the same switching capability but the label format changes compared with WSON optical channel layer. 3). Role of LSP encoding type? I think the issue listed here intends to say if a new LSP encoding type is needed for flexible grid optical channel layer. Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 7] Internet-Draft Spectrum Switched Optical Network Jul 2012 4). Notion of hierarchy? There is no notion of hierarchy between flexible grid OCh and fixed grid OCh. Just from my perspective, I think SSON optical channel layer should use the same switching capability as WSON optical channel layer. Some words are given here to describe my opinion. A LSP which has a bandwidth of 50GHz pass through both WSON network and SSON network. We assume that no OEOs exist in the LSP, so both the WSON optical channel path and SSON optical channel path occupy 50GHz. From the perspective of data plane, there is no change of the signal and no multiplexing when the WSON optical channel path interconnects with SSON optical channel path. From this scenario we can conclude that both WSON optical channel layer and SSON optical channel layer belong to the same layer. No notion of hierarchy exists between them. Base on these words, I think both WSON optical channel layer and SSON optical channel layer should use the same switching capability. The previous words mention the issues 1) and 4). Another two issues are to be discussed in the following description in the process of path setup. Because there is no notion of hierarchy exists between WSON optical channel layer and SSON optical channel layer, hierarchy LSP which is addressed in [RFC4206] and [RFC6107] can't be applied. But stitching LSP which is described in [RFC5150] can be applied in one layer. LSP hierarchy allows more than one LSP to be mapped to an H-LSP, but in case of S-LSP, at most one LSP may be associated with an S-LSP. This is similar to the scenario of interconnection between WSON OCh LSP and SSON OCh LSP. Similar to an H-LSP, an S-LSP could be managed and advertised, although it is not required, as a TE link, either in the same TE domain as it was provisioned or a different one. Path setup procedure of stitching LSP can be applied in the scenario of interconnection between WSON optical channel path and SSON optical channel path. 4. Signaling Protocol Extensions to Support Control of SSON This section mainly addresses the signaling protocol extension in support of the control of spectrum-switched optical netwrok and the facilitating of the setup of forwarding adjacency in G.872 optical transport network. 4.1. Switching Type A new switching type is needed. Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 8] Internet-Draft Spectrum Switched Optical Network Jul 2012 Value Type ------- ------- XX(IANA) Spectrum Switched Capable (SSC) Figure 1: Switching Capability 4.2. Label Format Extensions of Frequency Slot Channel Layer According to the description in the section 3.2, label should be able to describe the frequency slot characteristic in order to facilitate the switch of this large piece of spectrum. Label format of flexible grid can be introduced here to depict the label of frequency slot channel. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Grid | C.S. | Identifier | n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | m | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: label Grid Type: no meaning should be inferred from this field, as frequency slot channel can be used to carry any kind of grid. Reserved value 0 defined in [RFC6205] or value 4 which can be used to indicate any kind of grid is capable of fill in this field. The meaning of C.S. and identifier is maintained from [RFC6205]. Similar to the definition in [draft-farrkingel-ccamp-flexigrid-lambda-label], n is used to identify the central frequency, and m (16bits) is used to identify slot width of the frequency slot channel. [Notes: here we use 16 bits to represent the "m" value, because 8 bits are not enough for the setup of frequency slot channel with large spectrum.] 4.3. Traffic Parameters of Frequency Slot Channel Layer Similar to the original signaling which carry the information of bandwidth that a LSP may reserve at each node along the path, signaling that is used to set up frequency slot channel SHOULD be Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 9] Internet-Draft Spectrum Switched Optical Network Jul 2012 able to carry the information of spectrum width. The spectrum width traffic parameters can be organized as follow, and this information can be carried in the Sender_Tspec object within a path message. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | m | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: traffic parameter m (16 bits): the spectrum width is specified by m*12.5 GHz. 5. Signaling Procedures 5.1. RSVP-TE Signaling Procedures to Support the Setup of Frequency Slot Channel 5.1.1. Centralized Spectrum Assignment In this case, both of the route and the frequency slot information (i.e., central frequency and spectrum width) are provided by the PCE or ingress node. When signaling a LSP, the assigned label information is carried in the ERO label sub-object which is addressed in [RFC3473]. When the nodes along the LSP receive the path message carrying the ERO and ERO label sub-object, the procedure of path setup is the same as the procedure which is described in [RFC3473] and [RFC4003]. RRO and RRO label sub-object are used to record the label information of the egress. 5.1.2. Distributed Spectrum Assignment In this case, only the route is provided by a PCE or ingress node before the signaling procedure. The available spectrum SHALL be collected hop by hop and the egress node SHOULD select a proper label for the LSP. After the route is computed, the ingress node SHOULD find out the available spectrum for the LSP on the next link of the route. Then a path message is sent to the next node along the path according to the route information. The path message MUST contain a Sender_Tspec object to specify the spectrum width of the frequency slot channel. A Label_set object SHALL be added to the path message, which contains the candidate available spectrum for the LSP on the Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 10] Internet-Draft Spectrum Switched Optical Network Jul 2012 next link. When an intermediate node receives the path message, it can deserve the spectrum width information from the Sender_Tspec object. Then it SHOULD find the available spectrum for the LSP on the next link of the route similar to the ingress node. The common part of the two available spectrum sets. If the new set is null, the path message SHALL be rejected by a patherr message. Otherwise, the Label_set object in the path message SHALL be updated according to the new set and the path message is forwarded to the next node according to the route. When an egress node receives a path message, it SHOULD select an available spectrum from the Label_set object based on local policy and determine the frequency slot channel base on the spectrum width and the available spectrum. Then a Resv message is responded so that the nodes along the LSP can establish the optical cross-connect based on the Label object which is determined by the spectrum width in the traffic parameters and the available spectrum in the Label_set object. 5.2. Interconnection between WSON signal and SSON signal The path setup procedure of WSON OCh interworking with SSON OCh can be described as follows: Let's take the example of [RFC5150] into consideration. e2e LSP +++++++++++++++++++++++++++++++++++> (LSP1-2) LSP segment (flexi-LSP) ====================> (LSP-AB) C --- E --- G /|\ | / |\ / | \ | / | \ R1 ---- A \ | \ | / | / B --- R2 \| \ |/ |/ D --- F --- H fixed grid --A-- flexi-grid --B-- fixed grid Figure 4: stitching LSP In this scenario, R1 and R2 are traditional WSON signal capable nodes, A and B are both WSON signal and SSON signal capable nodes, Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 11] Internet-Draft Spectrum Switched Optical Network Jul 2012 the other nodes are only SSON capable nodes. We assume that a 40Gbit/s LSP from R1 to R2 needs to be set up. Node R1 prepares signaling path message for the end-to-end path setup from R1 to the destination node R2. Before R1 sends path message, R1 should send a path computation request to the path computation element in order to compute an end-to-end path from R1 to R2. Path computation response message from PCE to R1 contains ERO and label information. Here we may classify the scenarios into two cases: R1/R2 and the other nodes are in the same AS, R1/R2 and the other nodes are not in the same AS. In this scenario of interconnection between WSON OCh and SSON OCh, I think dynamic stitching LSP setup is frequent, static stitching LSP configuration may not be needed here. 1). R1/R2 and the other nodes are in the same AS: R1 encapsulates the path message which contains ERO to explicitly indicate the path and label used and RRO to record the path traversed and label used by node traversed. Then R1 sends the path message to the next hop node A. Here we assume path computation element is capable of fixed grid and flexible grid path computation, and the ERO contain the path information (R1, A, B, R2). When the path message arrives at node A, node A verifies the path message and finds incomplete ERO information, then send another path computation request message to the PCE in order to obtain the whole path information. PCE sends path computation response message which contain ERO (A, D, F, H, B) and label information. Here the label is flexible label information which is addressed in [draft-farrkingel]. To facilitate the control of stitching LSP boundaries, we may use a different encoding type for flexible grid to help control. Encoding type can be used to help stitching LSP boundaries control. Stitching LSP boundaries control looks like FA-LSP boundaries control, but has many differences. After matching the switching type and encoding type of the interface, Node A blocks the signaling process and decides to set up a stitching LSP according to the flexible grid LSP setup procedure using another signaling process. Procedure for set up stitching LSP can be found in RFC5150. The stitching LSP can be seen as a TE link in the fixed grid network. After the setup of stitching LSP between A and B, A then continues the blocking signaling procedure and sends the path message to the next hop B directly and finishes the end-to-end LSP. 2). R1/R2 and the other nodes are in different AS: Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 12] Internet-Draft Spectrum Switched Optical Network Jul 2012 From signaling perspective, path setup in this scenario is similar to that in the last scenario. If A is a domain boundary node, A can decide to set up a stitching LSP according to local configuration or match of the switching type and encoding type when the R1-R2 path message arrives at boundary node A. Path-key technology which is addressed in [RFC5520] can be used here to help setup of the path. 6. Security Considerations TBD 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching (GMPLS) Architecture", RFC 3945, October 2004. 7.2. Informative References [G.694.1 v1] International Telecommunications Union, "Draft revised G.694.1 version 1.3". [G.872 v11] International Telecommunications Union, "Draft revised Recommendation ITU-T G.872". [flexible-grid-ospf-ext] Fatai Zhang, Xiaobing Zi, Ramon Casellas, O. Gonzalez de Dios, and D. Ceccarelli, "GMPLS OSPF-TE Extensions in support of Flexible-Grid in DWDM Networks", draft-zhang-ccamp-flexible-grid-ospf-ext-00.txt . [flexible-grid-requirements] Fatai Zhang, Xiaobing Zi, O. Gonzalez de Dios, and Ramon Casellas, "Requirements for GMPLS Control of Flexible Grids", draft-zhang-ccamp-flexible-grid-requirements-01.txt . [flexigrid-lambda-label] D. King, A. Farrel, Y. Li, F. Zhang, and R. Casellas, "Generalized Labels for the Flexi-Grid in Lambda-Switch- Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 13] Internet-Draft Spectrum Switched Optical Network Jul 2012 Capable (LSC) Label Switching Routers", draft-farrkingel-ccamp-flexigrid-lambda-label-01.txt . [ospf-ext-constraint-flexi-grid] L Wang, Y Li, "OSPF Extensions for Routing Constraint Encoding in Flexible-Grid Networks", draft-wangl-ccamp-ospf-ext-constraint-flexi-grid-00.txt . Authors' Addresses Qilei Wang ZTE Corporation Email: wang.qilei@zte.com.cn Xihua Fu ZTE Corporation ZTE Plaza, No.10, Tangyan South Road, Gaoxin District Xi'an P.R.China Email: fu.xihua@zte.com.cn Qilei Wang & Xihua Fu Expires January 17, 2013 [Page 14]