CCAMP Working Group Xian Zhang Internet-Draft Haomian Zheng Intended status: Standards Track Huawei Ramon Casellas CTTC O. Gonzalez de Dios Telefonica D. Ceccarelli Ericsson Expires: December 17, 2015 June 17, 2015 GMPLS OSPF-TE Extensions in support of Flexible Grid draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt Abstract This memo describes the OSPF-TE extensions in support of GMPLS control of networks that include devices that use the new flexible optical grid. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on December 17, 2015. Copyright Notice Zhang et al Expires December 2015 [Page 1] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 Copyright (c) 2013 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 (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 ................................................ 2 2. Terminology ................................................. 3 2.1. Conventions Used in this Document ....................... 3 3. Requirements for Flexi-grid Routing .......................... 3 3.1. Available Frequency Ranges .............................. 4 3.2. Application Compliance Considerations ................... 5 3.3. Comparison with Fixed-grid DWDM Links ................... 6 4. Extensions .................................................. 7 4.1. ISCD for Flexi-grid ..................................... 7 4.2. Extensions to Port Label Restriction sub-TLV ............ 7 4.3. Available Resource sub-TLV .............................. 8 4.3.1. Inclusive/Exclusive Label Ranges ................... 9 4.3.2. Inclusive/Exclusive Label Lists .................... 9 4.3.3. Bitmap Label Set ................................... 9 4.4. Examples for Available Resource Sub-TLV ................ 10 5. IANA Considerations ........................................ 11 6. Implementation Status ....................................... 11 6.1. Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)12 7. Acknowledgments ............................................ 13 8. Security Considerations ..................................... 13 9. References ................................................. 13 9.1. Normative References ................................... 13 9.2. Informative References ................................. 13 10. Authors' Addresses ......................................... 15 11. Contributors' Addresses .................................... 15 1. Introduction [G.694.1] defines the Dense Wavelength Division Multiplexing (DWDM) frequency grids for Wavelength Division Multiplexing (WDM) Zhang et al Expires December 2015 [Page 2] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 applications. A frequency grid is a reference set of frequencies used to denote allowed nominal central frequencies that may be used for defining applications. The channel spacing is the frequency spacing between two allowed nominal central frequencies. All of the wavelengths on a fiber should use different central frequencies and occupy a fixed bandwidth of frequency. Fixed grid channel spacing is selected from 12.5 GHz, 25 GHz, 50 GHz, 100 GHz and integer multiples of 100 GHz. But [G.694.1] also defines "flexible grids", also known as "flexi-grid". The terms "frequency slot" (i.e., the frequency range allocated to a specific channel and unavailable to other channels within a flexible grid) and "slot width" (i.e., the full width of a frequency slot in a flexible grid) are used to define a flexible grid. [FLEX-FWK] defines a framework and the associated control plane requirements for the GMPLS based control of flexi-grid DWDM networks. [RFC6163] provides a framework for GMPLS and Path Computation Element (PCE) control of Wavelength Switched Optical Networks (WSONs), and [WSON-OSPF] defines the requirements and OSPF-TE extensions in support of GMPLS control of a WSON. [FLEX-SIG] describes requirements and protocol extensions for signaling to set up LSPs in networks that support the flexi-grid, and this document complements [FLEX-SIG] by describing the requirement and extensions for OSPF-TE routing in a flexi-grid network. 2. Terminology For terminology related to flexi-grid, please consult [FLEX-FWK] and [G.694.1]. 2.1. 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 RFC-2119 [RFC2119]. 3. Requirements for Flexi-grid Routing The architecture for establishing LSPs in a Spectrum Switched optical Network (SSON) is described in [FLEX-FWK]. A flexi-LSP occupies a specific frequency slot, i.e. a range of frequencies. The process of computing a route and the allocation of Zhang et al Expires December 2015 [Page 3] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 a frequency slot is referred to as RSA (Routing and Spectrum Assignment). [FLEX-FWK] describes three types of architectural approaches to RSA: combined RSA; separated RSA; and distributed SA. The first two approaches among them could be called "centralized SA" because both routing and spectrum (frequency slot) assignment are performed by centralized entity before the signaling procedure. In the case of centralized SA, the assigned frequency slot is specified in the Path message during LSP setup. In the case of distributed SA, the slot width of the flexi-grid LSP is specified in the Path message, allowing the involved network elements to select the frequency slot to be used. If the capability of switching or converting the whole optical spectrum allocated to an optical spectrum LSP is not available at nodes along the path of the LSP, the LSP is subject to the Optical "Spectrum Continuity Constraint", as described in [FLEX-FWK]. The remainder of this section states the additional extensions on the routing protocols in a flexi-grid network. That is, the additional information that must be collected and passed between nodes in the network by the routing protocols in order to enable correct path computation and signaling in support of LSPs within the network. 3.1. Available Frequency Ranges In the case of flexi-grids, the central frequency steps from 193.1 THz with 6.25 GHz granularity. The calculation method of central frequency and the frequency slot width of flexi-LSP are defined in [G.694.1]. On a DWDM link, the frequency slots must not overlap with each other. However, the border frequencies of two frequency slots may be the same frequency, i.e., the highest frequency of a frequency slot may be the lowest frequency of the next frequency slot. Zhang et al Expires December 2015 [Page 4] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 Frequency Slot 1 Frequency Slot 2 +-----------+-----------------------+ | | | -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 ...+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... ------------ ------------------------ ^ ^ Central F = 193.1THz Central F = 193.1375 THz Slot width = 25 GHz Slot width = 50 GHz Figure 1 - Two Frequency Slots on a Link Figure 1 shows two adjacent frequency slots on a link. The highest frequency of frequency slot 1 denoted by n=2 is the lowest frequency of slot 2. In this example, it means that the frequency range from n=-2 to n=10 is occupied and is unavailable to other flexi-LSPs. Hence, in order to clearly show which LSPs can be supported and what frequency slots are unavailable, the available frequency ranges should be advertised by the routing protocol for the flexi-grid DWDM links. A set of non-overlapping available frequency ranges should be disseminated in order to allow efficient resource management of flexi-grid DWDM links and RSA procedures which are described in section 5.8 of [FLEX-FWK]. 3.2. Application Compliance Considerations As described in [G.694.1], devices or applications that make use of the flexi-grid may not be capable of supporting every possible slot width or position (i.e., central frequency). In other words, applications or implementations may be defined where only a subset of the possible slot widths and positions are required to be supported. For example, an application could be defined where the nominal central frequency granularity is 12.5 GHz (by only requiring values of n that are even) and that only requires slot widths as a multiple of 25 GHz (by only requiring values of m that are even). Hence, in order to support all possible applications and implementations the following information should be advertised for a flexi-grid DWDM link: o Central frequency granularity: a multiplier of 6.25 GHz. o Slot width granularity: a multiplier of 12.5 GHz. Zhang et al Expires December 2015 [Page 5] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 o Slot width range: two multipliers of 12.5GHz, each indicate the minimal and maximal slot width supported by a port respectively. The combination of slot width range and slot width granularity can be used to determine the slot widths set supported by a port. 3.3. Comparison with Fixed-grid DWDM Links In the case of fixed-grid DWDM links, each wavelength has a pre- defined central frequency and each wavelength has the same frequency range (i.e., there is a uniform channel spacing). Hence all the wavelengths on a DWDM link can be identified uniquely simply by giving it an identifier (such as the central wavelength [RFC6205]), and the status of the wavelengths (available or not) can be advertised through a routing protocol. Figure 2 shows a link that supports a fixed-grid with 50 GHz channel spacing. The central frequencies of the wavelengths are pre-defined by values of 'n' and each wavelength occupies a fixed 50 GHz frequency range as described in [G.694.1]. W(-2) | W(-1) | W(0) | W(1) | W(2) | ...---------+-----------+-----------+-----------+-----------+----... | 50 GHz | 50 GHz | 50 GHz | 50 GHz | n=-2 n=-1 n=0 n=1 n=2 ...---+-----------+-----------+-----------+-----------+----------... ^ Central F = 193.1THz Figure 2 - A Link Supports Fixed Wavelengths with 50 GHz Channel Spacing Unlike the fixed-grid DWDM links, on a flexi-grid DWDM link the slot width of the frequency slot are flexible as described in section 3.1. That is, the value of m in the formula is uncertain before a frequency slot is actually allocated. For this reason, the available frequency slot/ranges need to be advertised for a flexi- grid DWDM link instead of the specific "wavelengths" that are sufficient for a fixed-grid link. Moreover, thus advertisement is represented by the combination of Central Frequency Granularity and Slot Width Granularity. Zhang et al Expires December 2015 [Page 6] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 4. Extensions As described in [FLEX-FWK], the network connectivity topology constructed by the links/nodes and node capabilities are the same as for WSON, and can be advertised by the GMPLS routing protocols (refer to section 6.2 of [RFC6163]). In the flexi-grid case, the available frequency ranges instead of the specific "wavelengths" are advertised for the link. This section defines the GMPLS OSPF-TE extensions in support of advertising the available frequency ranges for flexi-grid DWDM links. 4.1. ISCD for Flexi-grid Value Type ----- ---- 152 (TBA by IANA) Flexi-Grid-LSC capable (DWDM-LSC) Switching Capability and Encoding values MUST be used as follows: Switching Capability = Flexi-Grid-LSC Encoding Type = lambda [as defined in RFC3471] When Switching Capability and Encoding fields are set to values as stated above, the Interface Switching Capability Descriptor MUST be interpreted as in RFC4203 with the optional inclusion of one or more Switching Capability Specific Information sub-TLVs. The Max LSP Bandwidth can be calculated based on the Max Slot Width defined in Available Resource sub-TLV in Section 4.3, together with corresponding modulation schemes. 4.2. Extensions to Port Label Restriction sub-TLV As described in Section 3.2, a port that supports flexi-grid may support only a restricted subset of the full flexible grid. The Port Label Restriction sub-TLV is defined in [GEN-ENCODE]. It can be used to describe the label restrictions on a port. A new restriction type, the flexi-grid Restriction Type, is defined here to specify the restrictions on a port to support flexi-grid. Zhang et al Expires December 2015 [Page 7] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MatrixID | RstType = TBA | Switching Cap | Encoding | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | C.F.G | S.W.G | Min Slot Width | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ MatrixID (8 bits): As defined in [GEN-ENCODE]. RstType (Restriction Type, 8 bits): Takes the value (TBA) to indicate the restrictions on a port to support flexi-grid. Switching Cap (Switching Capability, 8 bits): As defined in [GEN- ENCODE], must be consistent with the one specified in ISCD as described in Section 4.1. Encoding (8 bits): As defined in [GEN-ENCODE], must be consistent with the one specified in ISCD as described in Section 4.1. C.F.G (Central Frequency Granularity, 8 bits): A positive integer. Its value indicates the multiple of 6.25 GHz in terms of central frequency granularity. S.W.G (Slot Width Granularity, 8 bits): A positive integer. Its value indicates the multiple of 12.5 GHz in terms of slot width granularity. Min Slot Width (16 bits): A positive integer. Its value indicates the multiple of 12.5 GHz in terms of the supported minimal slot width. 4.3. Available Resource sub-TLV The Available Resource sub-TLV is defined to support indicating the flexi-grid label availability as follow: Zhang et al Expires December 2015 [Page 8] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Pri | Max Slot Width | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label Set Field | : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Pri (priority flags): can be referred to Section 2.4 of [GEN-ENCODE]. Max Slot Width (16 bits): A positive integer. Its value indicates the multiple of 12.5 GHz in terms of the supported maximal slot width. Label Set Field: the definition of Label Set Field can be referred to Section 2.6 of [GEN-ENCODE]. According to the possible action value, the usage of Label Set Field is described as the following sections, respectively. 4.3.1. Inclusive/Exclusive Label Ranges The inclusive/exclusive label ranges format of the Label Set Field defined in [GEN-ENCODE] can be used for specifying the frequency ranges of the flexi-grid DWDM links. Note that multiple Available Resource sub-TLVs may be needed if there are multiple discontinuous frequency ranges on a link. 4.3.2. Inclusive/Exclusive Label Lists The inclusive/exclusive label lists format of Available Labels Set sub-TLV defined in [GEN-ENCODE] can be used for specifying the available central frequencies of flexi-grid DWDM links. 4.3.3. Bitmap Label Set The bitmap format of Available Labels Set sub-TLV defined in [GEN- ENCODE] can be used for specifying the available central frequencies of the flexi-grid DWDM links Each bit in the bit map represents a particular central frequency with a value of 1/0 indicating whether the central frequency is in the set or not. Bit position zero represents the lowest central frequency and corresponds to the base label, while each succeeding Zhang et al Expires December 2015 [Page 9] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 bit position represents the next central frequency logically above the previous. Examples of the Available Resource sub-TLV can be found in Section 4.4. 4.4. Examples for Available Resource Sub-TLV Figure 3 shows an example of available frequency range of a flexi- grid DWDM link. -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 ...+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... |--Available Frequency Range--| Figure 3 - Flexi-grid DWDM Link The symbol '+' represents the allowed nominal central frequency. The symbol "--" represents a 6.25 GHz frequency unit. The number on the top of the line represents the 'n' in the frequency calculation formula (193.1 + n * 0.00625). The nominal central frequency is 193.1 THz when n equals zero. The usage of Action, Number of Labels and Length session of the Label set field can be referred to Section 2.6 in [GEN-ENCODE]. Assume that the central frequency granularity is 6.25GHz, the label set can be encoded as follows: Inclusive Label Range: o Start Slot = -2; o End Slot = 8. The available central frequencies (-1, 0, 1, 2, 3, 4, 5, 6, 7) can be deduced by the Inclusive Label Range, because the Central Frequency Granularity is 6.25 GHz. Inclusive Label Lists: Zhang et al Expires December 2015 [Page 10] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 o List Entry 1 = slot -1; o List Entry 2 = slot 0; o List Entry 3 = slot 1; o List Entry 4 = slot 2; o List Entry 5 = slot 3; o List Entry 6 = slot 4; o List Entry 7 = slot 5; o List Entry 8 = slot 6; o List Entry 9 = slot 7. Bitmap: o Base Slot = -1; o Bitmap = 111111111(padded out to a full multiple of 32 bits) 5. IANA Considerations [GEN-OSPF] defines the Port label Restriction sub-TLV of OSPF TE Link TLV. It also creates a registry of values of the Restriction Type field of that sub-TLV IANA is requested to assign a new value from that registry as follows: Value Meaning Reference TBD Flexi-grid restriction [This.I-D] 6. Implementation Status [RFC Editor Note: Please remove this entire seciton prior to publication as an RFC.] This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in RFC 6982[RFC6982]. The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist. Zhang et al Expires December 2015 [Page 11] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 According to RFC 6982, "this will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. It is up to the individual working groups to use this information as they see fit. 6.1. Centre Tecnologic de Telecomunicacions de Catalunya (CTTC) Organization Responsible for the Implementation: CTTC - Centre Tecnologic de Telecomunicacions de Catalunya (CTTC), Optical Networks and Systems Department, http://wikiona.cttc.es. Implementation Name and Details: ADRENALINE testbed, http://networks.cttc.es/experimental-testbeds/ Brief Description: Experimental testbed implementation of GMPLS/PCE control plane. Level of Maturity: Implemented as extensions to a mature GMLPS/PCE control plane. It is limited to research / prototyping stages but it has been used successfully for more than the last five years. Coverage: Support for the 64 bit label [FLEC-LBL] for flexi-grid as described in this document, with available label set encoded as bitmap. It is expected that this implementation will evolve to follow the evolution of this document. Licensing: Proprietary Implementation Experience: Implementation of this document reports no issues. General implementation experience has been reported in a number of journal papers. Contact Ramon Casellas for more information or see http://networks.cttc.es/publications/? search=GMPLS&research_area=optical-networks-systems Contact Information: Ramon Casellas: ramon.casellas@cttc.es Interoperability: No report. Zhang et al Expires December 2015 [Page 12] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 7. Acknowledgments This work was supported in part by the FP-7 IDEALIST project under grant agreement number 317999. 8. Security Considerations This document does not introduce any further security issues other than those discussed in [RFC3630], [RFC4203]. 9. References 9.1. Normative References [RFC2119] S. Bradner, "Key words for use in RFCs to indicate requirements levels", RFC 2119, March 1997. [G.694.1] ITU-T Recommendation G.694.1 (revision 2), "Spectral grids for WDM applications: DWDM frequency grid", February 2012. [GEN-ENCODE] Bernstein, G., Lee, Y., Li, D., and W. Imajuku, "General Network Element Constraint Encoding for GMPLS Controlled Networks", draft-ietf-ccamp-general-constraint- encode, work in progress. [GEN-OSPF] Fatai Zhang, Y. Lee, Jianrui Han, G. Bernstein and Yunbin Xu, " OSPF-TE Extensions for General Network Element Constraints ", draft-ietf-ccamp-gmpls-general-constraints- ospf-te, work in progress. [RFC6205] T. Otani and D. Li, "Generalized Labels for Lambda-Switch- Capable (LSC) Label Switching Routers", RFC 6205, March 2011. [FLEX-LBL] King, D., Farrel, A. and Y. Li, "Generalized Labels for the Flexi-Grid in Lambda Switch Capable (LSC) Label Switching Routers", draft-farrkingel-ccamp-flexigrid- lambda-label, work in progress. 9.2. Informative References [RFC6163] Y. Lee, G. Bernstein and W. Imajuku, "Framework for GMPLS and Path Computation Element (PCE) Control of Wavelength Switched Optical Networks (WSONs)", RFC 6163, April 2011. Zhang et al Expires December 2015 [Page 13] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 [FLEX-SIG] F.Zhang et al, "RSVP-TE Signaling Extensions in support of Flexible-grid", draft-ietf-ccamp-flexible-grid-rsvp- te-ext, work in progress. [FLEX-FWK] Gonzalez de Dios, O,, Casellas R., Zhang, F., Fu, X., Ceccarelli, D., and I. Hussain, "Framework and Requirements for GMPLS based control of Flexi-grid DWDM networks', draft-ietf-ccamp-flexi-grid-fwk, work in progress. [WSON-OSPF] Y. Lee and G. Bernstein, "GMPLS OSPF Enhancement for Signal and Network Element Compatibility for Wavelength Switched Optical Networks ", draft-ietf-ccamp-wson-signal- compatibility-ospf, work in progress. Zhang et al Expires December 2015 [Page 14] draft-ietf-ccamp-flexible-grid-ospf-ext-02.txt June 2015 10. Authors' Addresses Xian Zhang Huawei Technologies Email: zhang.xian@huawei.com Haomian Zheng Huawei Technologies Email: zhenghaomian@huawei.com Ramon Casellas, Ph.D. CTTC Spain Phone: +34 936452916 Email: ramon.casellas@cttc.es Oscar Gonzalez de Dios Telefonica Investigacion y Desarrollo Emilio Vargas 6 Madrid, 28045 Spain Phone: +34 913374013 Email: ogondio@tid.es Daniele Ceccarelli Ericsson Via A. Negrone 1/A Genova - Sestri Ponente Italy Email: daniele.ceccarelli@ericsson.com 11. Contributors' Addresses Adrian Farrel Old Dog Consulting Email: adrian@olddog.co.uk Fatai Zhang Huawei Technologies Email: zhangfatai@huawei.com Lei Wang, ZTE Email: wang.lei31@zte.com.cn Zhang et al Expires December 2015 [Page 15]