CCAMP Working Group Richard Douville Internet Draft Dimitri Papadimitriou Category: Informational Martin Vigoureux Expires: December 2002 Emmanuel Dotaro Alcatel June 2002 Additional Extensions to Generalized MPLS for Waveband Switching draft-douville-ccamp-gmpls-waveband-extensions-01.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [1]. 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. 1. Abstract Generalized-MPLS (GMPLS) extends the MPLS control plane to encompass time-division, wavelength and spatial switching. A functional description of the extensions to MPLS signaling needed to support the new types of switching is provided in [GMPLS-SIG]. Along with the current development of IP over optical switching, there are considerable developments in optical transport systems based on the multiple optical switching granularities. [GMPLS-SIG] currently defines two layers of optical granularity (wavelength and fiber). As described in [IPO-MG], a revisited definition of waveband switching must be introduced. This document presents a functional description of the extensions, to the GMPLS protocol suite, to integrate the additional requirements of optical multi-granularity and to further benefit from the features of those switching layers. R.Douville et al. - Internet Draft û Expiration December 2002 1 draft-douville-ccamp-gmpls-waveband-extension-01.txt June 2002 2. Summary for Sub-IP Area 2.1. Summary See the Abstract above. 2.2. Where does it fit in the Picture of the Sub-IP Work This work fits the CCAMP box. 2.3. Why is it Targeted at this WG This draft is targeted at the CCAMP WG, because it specifies the extensions to the GMPLS signaling. GMPLS is itself addressed in the CCAMP WG. 2.4. Justification of Work The WG should consider this document as it specifies the extensions to the GMPLS signaling. These extensions are related to the definition of waveband switching and the introduction of optical multi-granularity. 3. 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 [2]. Other abbreviations and terminology in addition to the [GMPLS-ARCH] and [GMPLS-SIG] are: WB-LSP = WaveBand-LSP WBSC = WaveBand Switch Capable WXC = Wavelength Cross-Connect WBXC = WaveBand Cross-Connect FXC = Fiber Cross-Connect MG-OXC = Multi-Granularity Optical Cross Connect MG-PXC = Multi-Granularity Photonic Cross Connect 4. Introduction In optical networks, multi-granularity provides the ability to simultaneously switch different levels of granularity inside a given optical network. The granularities we considered inside optical networks are single wavelengths (L-LSP), bundles of wavelengths that we call wavebands (WB-LSP), and whole fibers (F-LSP). Optical Multi-Granularity (Optical MG) relies on technologies working at the different switching levels (e.g. wavelength, band and fiber). One of the key benefits in optical backbone networks is to simplify the switching procedures of numerous lower granularity LSPs R.Douville et al. - Internet Draft û Expiration December 2002 2 draft-douville-ccamp-gmpls-waveband-extension-01.txt June 2002 (Lambda-LSPs, for instance) by switching these LSPs as a single entity or LSP of higher granularity order (e.g. WB-LSP or F-LSP). To enable such grouping of LSPs, grooming strategies can be employed. We propose to extend GMPLS previous set of switching capabilities in the optical domain, by identifying uncovered characteristics of the optical transport, taking into account interest for optical components working at the band level and its impact on the control of the optical networks. In the efforts of describing the requirements and set of capabilities for optical multi-granularity, three approaches to waveband switching have been identified: - Inverse Multiplexing - Wavelength Concatenation - Waveband The common availability of optical/photonic switching equipment capable to work at the band level motivates the redefinition of waveband switching as defined in the GMPLS architecture. Current definition of waveband switching (see [GMPLS-ARCH] and [GMPLS-SIG]) refers to inverse multiplexing mechanism or wavelength concatenation (ôcontiguousö lambdas in a trunk defining a logical waveband). While this definition is still valid and applicable, it does not consider the approach where band has a physical significance, i.e. where the interface is WaveBand Switch Capable (WBSC). Physical waveband has the ability to switch directly a portion of the frequency spectrum without the need to distinguish between the inner components (e.g. wavelengths). The following document regroups the extensions to the GMPLS protocol suite required to support the introduction of the optical multi- granularity and particularly the new definition and features of waveband switching. 5. Extensions to the GMPLS Protocol Suite 5.1. Hierarchy Overview The integration of optical multi-granularity in the GMPLS architecture requires modifications and extensions to current definitions. For this purpose, we first introduces a new type of switching capable interface: the Waveband Switching Capable Interface (WBSC). The WBSC interface materializes the physical reality of optical waveband as an atomic entity or granularity. As with the introduction of the waveband switch capable interface, a new class of LSP is defined: the WaveBand LSP (WB-LSP). LSP Hierarchy Interfaces Network Element L-LSP (1) <---> LSC <----> WXC - | WB-LSP (1) <---> WBSC <----> WBXC > Optical MG | F-LSP <---> FSC <----> FXC - R.Douville et al. - Internet Draft û Expiration December 2002 3 draft-douville-ccamp-gmpls-waveband-extension-01.txt June 2002 (1) WB-LSPs can be supported on both Lambda and WaveBand Switch Capable interfaces depending on the nature of the waveband being requested (inverse multiplexing, wavelength concatenation, and physical waveband). Note that WXC, BXC and FXC can be part of the same entity referred to as MG-OXC or MG-PXC. The above figure illustrates the hierarchy of the switching layers and highlights the optical multi-granularity part. The network element column shows typical equipment that supports such interfaces. Note that this representation does not aim at restricting interfaces that network elements can support. The [GMPLS-ARCH] document considers waveband switching a particular case of lambda switching. As specified, a waveband represents a set of contiguous wavelengths, which can be switched together to a new waveband. However, definition does not introduce a new LSP Encoding Type. The current definition of the waveband is too restrictive at least on two key aspects. The first one is that current definition of waveband implies a wavelength composition of the waveband, due to waveband switching by wavelength cross-connects (WXC). This definition provides support to inverse multiplexing mechanism and wavelength concatenation. This approach limits the use of waveband to the wavelength switch capable technologies. With waveband switching technologies, the WBSC interface doesnÆt distinguish between the component optical channels, sub-channels (i.e. timeslots) or packets on the waveband which is switch as a single unit (wide frequency spectrum) like it could be done with the fibers (the penultimate frequency spectrum) on photonic cross-connect (PXC). The second restrictive point is that the current definition of the waveband does not enable intermediate grooming strategy. For this purpose, we introduce an additional optical granularity representing the waveband. This definition is quite general and backward compatible, it allows requesting a set of contiguous wavelengths (i.e. inverse multiplexing mechanism and wavelength concatenation) but also address the "real" waveband switching and following the set of capabilities. Therefore, the proposed definition better fits into the GMPLS architecture. It would be noted that "Waveband/Set of wavelength", as it is today defined, form a contiguous optical granularity concatenation/set i.e. nesting of wavelengths in waveband. This general scheme which request contiguous optical granularity concatenation/set could be applied with other optical granularities. 5.2. Generalized Label Request The Generalized Label Request must support the Waveband LSP request. R.Douville et al. - Internet Draft û Expiration December 2002 4 draft-douville-ccamp-gmpls-waveband-extension-01.txt June 2002 For this purpose, we propose to extend field values of the LSP Encoding for the Generalized Label Request by an adjunction of a new LSP Encoding Type, a specific Switching Type and also some enhancement of the already defined Generalized PID (G-PID) values. The information carried in a Generalized Label Request is: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LSP Enc. Type |Switching Type | G-PID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ LSP Encoding Type: 8 bits Indicates the encoding of the LSP being requested. The following Value 14 and Type Waveband (Photonic) is added to the existing LSP Encoding Type values to provide Waveband LSP support: Value Type ----- ---- 1 Packet 2 Ethernet 3 ANSI/ETSI PDH 4 Reserved 5 SDH ITU-T G.707 / SONET ANSI T1.105 6 Reserved 7 Digital Wrapper 8 Lambda (photonic) 9 Fiber 10 Reserved 11 FiberChannel 12 G.709 ODUk (Digital Path) 13 G.709 Optical Channel 14 Waveband (Photonic) For example, consider an LSP signaled with "WaveBand" encoding. It is expected that such an LSP would be supported with no electrical conversion and no knowledge of the frequency cutting, modulation and speed by the transit nodes. Other formats normally require framing knowledge, and field parameters are broken into the framing type and speed. Switching Type: 8 bits Indicates the type of switching that should be performed on a particular link. This field is needed for links that advertise more than one type of switching capability. For OXC or PXC enabling Waveband switching, the WBSC value is used to refer to such switching capability. Other values of this field are as the Switching Capability field defined in [GMPLS-ROUTING]. R.Douville et al. - Internet Draft û Expiration December 2002 5 draft-douville-ccamp-gmpls-waveband-extension-01.txt June 2002 Generalized PID (G-PID): 16 bits An identifier of the payload carried by an LSP, i.e. an identifier of the client layer of that LSP. This is used by the nodes at the endpoints of the LSP, and in some cases by the penultimate hop. Standard Ethertype values are used for packet and Ethernet LSPs; other values are defined in [GMPLS-SIG]. A waveband can carry a Lambda LSP while a Waveband LSP can be transported on a Fiber LSP, the following additional G-PID values must be considered: see [GMPLS-SIG] section 3.1.1 û Required Information, paragraph on Generalized-PID. Value Type Technology ----- ---- ---------- 37 Lambda Waveband, Fiber .. ... ... 55 Waveband Fiber In addition the following existing values must be updated in order to reflect the transport of Ethernet and SDH/SONET payload over a waveband LSP: 33 Ethernet SDH, Lambda, Waveband, Fiber 34 SDH Lambda, Waveband, Fiber 35 Reserved None 36 Digital Wrapper Lambda, Waveband, Fiber 5.3. Generalized Label As currently proposed in [GMPLS-SIG], the waveband label space definition is perfectly suitable and does not require any modification or extension. 5.4. Waveband-Switching Capability A new WaveBand-Switch-Capable (WBSC) Link Multiplex Capability value shall be defined to identify and distinguish the associated multiplexing/demultiplexing capability of a link [MPLS-HIER]. If the switching capability of a (TE) link is of type WBSC, it means that the node receiving data over this link (fiber) can recognize and switch individual WaveBands within the link (without distinguishing lambdas, channels or packets). [GMPLS-RTG] and the new value define the following Interface Switching Capabilities: Packet-Switch Capable-1 (PSC-1) Packet-Switch Capable-2 (PSC-2) Packet-Switch Capable-3 (PSC-3) Packet-Switch Capable-4 (PSC-4) Layer-2 Switch Capable (L2SC) Time-Division-Multiplex Capable (TDM) R.Douville et al. - Internet Draft û Expiration December 2002 6 draft-douville-ccamp-gmpls-waveband-extension-01.txt June 2002 Lambda-Switch Capable (LSC) Waveband-Switch Capable (WBSC) Fiber-Switch Capable (FSC) Note that the node that is advertising a given link (i.e., the node that is transmitting) has to know the "multiplexing/demultiplexing" capabilities at the other end of the link (i.e., the receiving end of the link). One way to accomplish this is through configuration. Other options to accomplish this are outside the scope of this document. 5.4.1. Waveband Switch Capable If an interface is of type WBSC, it means that the node receiving data over this interface can recognize and switch wavebands (sets of contiguous lambdas) within the interface as a unit (without distinguishing lambdas, channels or packets). An interface that allows only one waveband per interface belongs to the WBSC type. 5.4.2. Interface Switching Capability Descriptor For ISIS, the Interface Switching Capability Descriptor is a sub-TLV (of type 21) of the extended IS reachability TLV. The length is the length of value field in octets. For OSPF, the Interface Switching Capability Descriptor is a sub-TLV of the Link TLV with type 15. The length is the length of value field in octets. The common format of Interface Switching Capability Descriptor is defined in [GMPLS-OSPF] and [GMPLS-ISIS], respectively. A new value for the Switching Capability (Switching Cap) field is defined to identify the Waveband-Switch Capable (WBSC) interfaces: 151 Waveband-Switching Capable (WBSC) In an Interface Switching Capability Descriptor, when the Switching Capability (Switching Cap) field contains the value for WBSC, the specific information field includes the Minimum LSP Bandwidth, which is the number of contiguous wavelength constituting a WaveBand entity. Additional technology specific information can be considered in future releases such as the channel spacing. 5.5. LSP Regions and Forwarding Adjacencies The information carried in the Switching Capability field (8 bits) of the Interface Switching Capability Descriptor is used to construct LSP regions, and determine regions' boundaries as defined in [MPLS-HIER]. R.Douville et al. - Internet Draft û Expiration December 2002 7 draft-douville-ccamp-gmpls-waveband-extension-01.txt June 2002 The introduction of the new Link Multiplex Capability WBSC define a new ordering among link multiplexing capabilities as follows: PSC-1 < PSC-2 < PSC-3 < PSC-4 < TDM < LSC < WBSC < FSC. Path computation may take into account this region boundary when computing a path for an LSP. When an LSP need to cross a region boundary, it can trigger the establishment of a Forwarding Adjacency (FA) at the underlying layer. The new cascading of FAs can be triggered between layers with the new following obvious order: L2SC, then TDM, then LSC, then WBSC and then finally FSC. 6. Security Considerations No additional security considerations beyond the one covered in RSVP-TE (see [RFC-3209]) and CR-LDP (see [RFC-3212]). 7. References 7.1 Normative References [GMPLS-LDP] L.Berger (Editor) et al., æGeneralized MPLS Signaling - CR-LDP ExtensionsÆ, Internet Draft, Work in progress, draft-ietf-mpls-generalized-cr-ldp-06.txt, April 2002. [GMPLS-ISIS] K.Kompella et al., æIS-IS Extensions in Support of Generalized MPLSÆ, Internet Draft, Work in progress, draft-ietf-isis-gmpls-extensions-12.txt, May 2002. [GMPLS-OSPF] K.Kompella et al., æOSPF Extensions in Support of Generalized MPLSÆ, Internet Draft, Work in progress, draft-ietf-ccamp-ospf-gmpls-extensions-07.txt, MayÆ02. [GMPLS-RSVP] L.Berger (Editor) et al., æGeneralized MPLS Signaling - RSVP-TE ExtensionsÆ, Internet Draft, Work in progress, draft-ietf-mpls-generalized-rsvp-te-07.txt, April 2002. [GMPLS-RTG] K.Kompella et al., æRouting Extensions in Support of Generalized MPLSÆ, Internet Draft, Work in Progress, draft-ietf-ccamp-gmpls-routing-04.txt, April 2002. [GMPLS-SIG] L.Berger (Editor) et al., æGeneralized MPLS - Signaling Functional DescriptionÆ, Internet Draft, Work in progress, draft-ietf-mpls-generalized- signaling-08.txt, April 2002. [ISIS-TE] T.Li et al.,ÆIS-IS Extensions for Traffic EngineeringÆ, Internet Draft, Work in progress, draft- ietf-isis-traffic-04.txt, November 2001. [MPLS-BUNDLE]K.Kompella et al., æLink Bundling in MPLS Traffic R.Douville et al. - Internet Draft û Expiration December 2002 8 draft-douville-ccamp-gmpls-waveband-extension-01.txt June 2002 EngineeringÆ, Internet Draft, draft-ietf-mpls-bundle- 03.txt, March 2001. [MPLS-HIER] K.Kompella et al., æLSP Hierarchy with MPLS TEÆ, Internet Draft, Work in progress, draft-ietf-mpls-lsp- hierarchy-05.txt, April 2002. [OSPF-TE] D.Katz et al., æTraffic Engineering Extensions to OSPFÆ, Internet Draft, Work in progress, draft-katz- yeung-ospf-traffic-06.txt, September 2001. [RFC-3209] D.Awduche (Editor) et al., æRSVP-TE: Extensions to RSVP for LSP TunnelsÆ, Internet RFC 3209, IETF Proposed Standard, December 2001. [RFC-3212] B.Jamoussi (Editor) et al. æConstraint-Based LSP Setup using LDPÆ, Internet RFC 3212, IETF Proposed Standard, January 2002. 7.2 Informative References [GMPLS-ARCH] E.Mannie (Editor) et al., æGeneralized Multi-Protocol Label Switching (GMPLS) ArchitectureÆ, Internet Draft, Work in progress, draft-ietf-ccamp-gmpls-architecture- 02.txt, February 2002. [RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels," RFC 2119. 8. Author's Addresses Richard Douville (Alcatel) Route de Nozay, 91460 Marcoussis, France Phone: +33 1 6963-4431 Email: richard.douville@alcatel.fr Martin Vigoureux (Alcatel) Route de Nozay, 91460 Marcoussis, France Phone: +33 1 6963-1852 Email: martin.vigoureux@alcatel.fr Emmanuel Dotaro (Alcatel) Route de Nozay, 91460 Marcoussis, France Phone: +33 1 6963-4723 Email: emmanuel.dotaro@alcatel.fr Dimitri Papadimitriou (Alcatel) Francis Wellesplein 1, B-2018 Antwerpen, Belgium Phone: +32 3 240-8491 Email: dimitri.papadimitriou@alcatel.be R.Douville et al. - Internet Draft û Expiration December 2002 9