Network Working Group Y. Li Internet-Draft ZTE Intended status: Standards Track January 21, 2012 Expires: July 24, 2012 Link Management Protocol Extensions for Grid Property Negotiation draft-li-ccamp-grid-property-lmp-00 Abstract The recent updated version of ITU-T [G.694.1] has introduced the flexible grid DWDM technique which provides a new tool that operators can implement to provide a higher degree of network optimization than is possible with fixed grid systems. This document describes the extensions to the Link management protocol (LMP) to negotiate link grid property between the adjacent DWDM nodes before the link is brought up. 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 July 24, 2012. 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 (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 Li Expires July 24, 2012 [Page 1] Internet-Draft LMP for grid property January 2012 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Problem statement . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Flexi-fixed Grid Nodes Interworking . . . . . . . . . . . 3 3.2. Flexible Grid Capability Negotiation . . . . . . . . . . . 4 4. LMP extensions . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. Grid Property Subobject . . . . . . . . . . . . . . . . . 5 5. Messages Exchange Procedure . . . . . . . . . . . . . . . . . 7 5.1. Flexi-fixed Grid Nodes Messages Exchange . . . . . . . . . 7 5.2. Flexible Nodes Messages Exchange . . . . . . . . . . . . . 8 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 8.1. Normative references . . . . . . . . . . . . . . . . . . . 9 8.2. Informative References . . . . . . . . . . . . . . . . . . 9 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10 Li Expires July 24, 2012 [Page 2] Internet-Draft LMP for grid property January 2012 1. Introduction The recent updated version of ITU-T [G.694.1] has introduced the flexible grid DWDM technique which provides a new tool that operators can implement to provide a higher degree of network optimization than is possible with fixed grid systems. Flexible grid network is composed of arbitrarily assigned spectral slots. That is the adjacent channel spacing and spectral bandwidth per wavelength are variable. Mixed bitrate transmission systems can allocate their channels with different spectral bandwidths so that they can be optimized for the bandwidth requirements of the particular bitrate and modulation scheme of the individual channels. This technique is regarded to be a promising way to improve the network utilization efficiency and fundamentally reduce the cost of the core network. While during the practical deployment procedure, the fixed grid optical nodes will be replaced by the flexible nodes gradually. This will lead to the problem of interworking between fixed grid DWDM and flexible grid DWDM nodes. Besides, even two flexible grid optical nodes may have different grid properties, leading to link property conflict. Therefore, this document describes the extensions to the Link management protocol (LMP) to negotiate link grid property between the adjacent DWDM nodes before the link is brought up . 2. Terminology 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. Problem statement 3.1. Flexi-fixed Grid Nodes Interworking +---+ +---+ +---+ +---+ +---+ | A |---------| B |=========| C |=========| D +--------+ E | +---+ +---+ +---+ +---+ +---+ figure 1 Li Expires July 24, 2012 [Page 3] Internet-Draft LMP for grid property January 2012 ^ ^ ^ ^ ^ | | | | | __|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_ n= -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 Central frequency granularity=6.25 GHz (Node B,D) ^ ^ ^ ^ ^ | | | | | |<----50GHz---->|<----50GHz---->|<----50GHz---->|<----50GHz---->| __|_______________|_______________|_______________|_______________|_ Fixed channel spacing of 50 GHz (Node C) figure 2 Figure 1 shows an example of interworking between flexible and fixed grid nodes. Node A, B, D, E support flexible grid. All these nodes can support frequency slots with central frequency granularity of 6.25 GHz and slotwidth granularity of 12.5 GHz. At the same time, the channel spacing and slotwidth can be configured to integral multiple of 6.25 GHz and 12.5 GHz respectively. As shown in figure 2, they are backward compatible to the fixed grid situation (flexible frequency slot with channel spacing of 8*6.25 and slotwidth of 4*12.5 GHz is equivalent to fixed-grid DWDM channel with channel spacing of 50 GHz). As node C can only support the fixed grid DWDM property with channel spacing of 50 GHz, to establish a LSP through node B,C,D, the links between B to C and C to D must set to align with the fixed grid values. This link grid property must be negotiated before establishing the LSP. 3.2. Flexible Grid Capability Negotiation +---+ +---+ | F +------------| G | +---+ +---+ +------------------+-------------+-----------+ | Unit (GHz) | Node F | Node G | +------------------+-------------+-----------+ | Grid granularity | 6.25 (12.5) | 12.5 (25) | +------------------+-------------+-----------+ | Tuning range | (12.5, 100) | (25, 200) | +------------------+-------------+-----------+ figure 3 Li Expires July 24, 2012 [Page 4] Internet-Draft LMP for grid property January 2012 Although the updated version of ITU-T [G.694.1] has defined the flexible grid with a nominal central frequency granularity of 6.25 GHz and a slotwidth granularity of 12.5 GHz. However, devices or applications that make use of the flexible grid may not have to be capable of supporting every possible slotwidth or position. In other words, applications may be defined where different grid granularity can be supported. For example, an application could be defined where the nominal central frequency granularity is 12.5 GHz and that only requires slotwidths as a multiple of 25 GHz. Therefore the link between the two grid granularity nodes must be set to align with the larger one. Besides, different nodes may have different slotwidth tuning ranges. For example, in figure 3, node F can only support slotwidth with tuning change from 12.5 to 100 GHz, while node G supports tuning range from 25 GHz to 200 GHz. The link property of slotwidth tuning range between F and G sholud be chosen as an intersection from 25 GHz to 100 GHz. 4. LMP extensions 4.1. Grid Property Subobject According to [RFC4204], the LinkSummary message is used to verify the consistency of the link property on both sides of the link before it is brought up. LinkSummary message contains negotiable and non- negotiable DATA_LINK objects to carry a series of variable-length data items called subobjects to illustrate the detailed link properties. The subobjects are defined in Section 12.12.1 in [RFC4204]. To slove the problems stated in section 3, this draft extends the LMP by introducing a new DATA_LINK subobject called "Grid property" to support the grid property correlation between adjacent nodes. The encoding format of this new subobject is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length |Grid | C.S. | Min | Max | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type=TBD, Grid property type. Grid: The value is used to represent which grid the node/interface supports. Values defined in [RFC6205] identify DWDM [G.694.1] and Li Expires July 24, 2012 [Page 5] Internet-Draft LMP for grid property January 2012 CWDM [G.694.2]. Value defined in [I-D.farrkingel-ccamp-flexigrid-lambda-label] identifies flexible DWDM. +---------------+-------+ | Grid | Value | +---------------+-------+ | Reserved | 0 | +---------------+-------+ | ITU-T DWDM | 1 | +---------------+-------+ | ITU-T CWDM | 2 | +---------------+-------+ | Flexible DWDM | 3 | +---------------+-------+ | Future use | 4-7 | +---------------+-------+ C.S.: With respect to the fixed grid node/interface, the C.S. value is used to represent the channel spacing, as the spacing between adjacent channels is constant. While, for flexible grid node/interface, this field should be used to represent the central frequency granularity. +------------+-------+ | C.S. (GHz) | Value | +------------+-------+ | Reserved | 0 | +------------+-------+ | 100 | 1 | +------------+-------+ | 50 | 2 | +------------+-------+ | 25 | 3 | +------------+-------+ | 12.5 | 4 | +------------+-------+ | 6.25 | 5 | +------------+-------+ | Future use | 6-15 | +------------+-------+ Min & Max: The slotwidth tuning range. For example, with regarding to a node with central frequency granularity of 6.25 (slotwidth granularity of 12.5 GHz) and slotwidth tuning range from 25 GHz to 100 GHz, the Li Expires July 24, 2012 [Page 6] Internet-Draft LMP for grid property January 2012 values of Min and Max should be 2 and 8 respectively. For fixed grid nodes, these two fields is meaningless and should be set to zeros. 5. Messages Exchange Procedure 5.1. Flexi-fixed Grid Nodes Messages Exchange To demonstrate the procedure of grid property correlation, the model shown in figure 1 is reused. The LMP meessages start running from node B to node C. o After inspecting its own node/interface property, node B will send node C a LinkSummary message including the MESSAGE ID, TE_LINK ID and DATA_LINK objects. The setting and negotiating of MESSAGE ID and TE_link ID can be referenced to [RFC4204]. As node B supports flexible grid property, the Grid, C.S. value in the grid property subobject are set to be 3 and 5 respectively. The slotwidth tuning range is from 12.5 GHz to 200 GHz. Meanwhile, the N bit of the DATA_LINK object is set to 1, indicating that the property is negotiable. o When node C has received the LinkSummary message from B, it will analyze the Grid, C.S., Min and Max values in the grid property subobject. But node C can only support fixed grid DWDM and recognize that flexible grid property is not acceptable for the link. However, the receiving N bit in the DATA_LINK object is set, indicating that the Grid property of B is negotiable. Then, node C will respond B a linkSummaryNack containing a new Error_code object and state that the property need further negotiation. Meanwhile, an accepted grid property subobject (Grid=2, C.S.=2, fixed DWDM with channel spacing of 50 GHz) is carried in linkSummaryNack message. At this moment, the N bit in the DATA_LINK object is set to 0, indicating that the grid property subobject is non-negotiable. o As the channel spacing and slotwidth of node B can be configured to be any integral multiples of 6.25 GHz and 12.5 GHz respectively, node B can be compatible to support the fixed DWDM values. Then, node B will resend the LinkSummary message carrying the grid property subobject with values of Grid=2 and C.S.=2. o Once receiving the LinkSummary message from node B, node C will reply with a LinkSummaryACK message. After all these are done, the link between node B and C is brought up with a fixed channel spacing of 50 GHz. The above mentioned grid property correlation scenario starts sending message from flexible grid node to fixed grid node. While for message from fixed grid node to flexible grid node, the procedure is as follows: Li Expires July 24, 2012 [Page 7] Internet-Draft LMP for grid property January 2012 o After inspecting its own interface property, Node C will send B a LinkSummary message containing a grid property subobject with Grid=2, C.S.=2. The N bit in the DATA_LINK object is set to 0, indicating that it is non-negotiable. o As the channel spacing and slotwidth of node B can be configured to be any integral multiples of 6.25 GHz and 12.5 GHz respectively, node B can be compatible to support the fixed DWDM parameters. Then, node B will make appropriate configuration and reply node C the LinkSummaryACK message. o After all these are done, the link between node B and C is brought up with a fixed channel spacing of 50 GHz. 5.2. Flexible Nodes Messages Exchange To demonstrate the procedure of grid property correlation, the model shown in figure 3 is reused. The procedure of grid property correlation (negotiating the grid granularity and slotwidth tuning range) is similar to the scenarios mentioned above. o The Grid, C.S., Min and Max values in the grid property subobject sent from node F to G are set to be 3,5,1,8 respectively. Meanwhile, the N bit of the DATA_LINK object is set to 1, indicating that the grid property is negotiable. o When node G has received the LinkSummary message from F, it will analyze the Grid, C.S., Min and Max values in the Grid property subobject. But node G can only support grid granularity of 12.5 GHz and a slotwdith tuning range from 25 GHz to 200 GHz. Considering the property of node F, node G then will respond F a linkSummaryNack containing a new Error_code object and state that the property need further negotiation. Meanwhile, an accepted grid property subobject (Grid=3, C.S.=4, Min=1, Max=4, the slotwidth tuning range is set to the intersection of Node F and G) is carried in linkSummaryNack message. Meanwhile, the N bit in the DATA_LINK object is set to 1, indicating that the grid property subobject is non-negotiable. o As the channel spacing and slot width of node F can be configured to be any integral multiples of 6.25 GHz and 12.5 GHz respectively, node F can be compatible to support the lager granularity. And the suggested slotwidth tuning range is acceptable for node F. Then, node F will resend the LinkSummary message carrying the grid subobject with values of Grid=3, C.S.=4, Min=1 and Max=4. o Once receiving the LinkSummary message from node F, node G will reply with a LinkSummaryACK message. After all these are done, the link between node F and G is brought up supporting central frequency granularity of 6.25 GHz and slotwidth tuning range from 25 GHz to 100 GHz. Li Expires July 24, 2012 [Page 8] Internet-Draft LMP for grid property January 2012 From the prospective of control plane, once the links have been brought up, wavelength constraint informations can be advertised and the wavelength label can be assigned hop-by-hop when establishing a LSP based on the link grid property. 6. IANA Considerations TBD 7. Security Considerations TBD 8. References 8.1. Normative references [G.694.1] International Telecommunications Union, "Spectral grids for WDM applications: DWDM frequency grid", Recommendation G.694.1, June 2002 . [G.694.2] International Telecommunications Union, "Spectral grids for WDM applications: CWDM wavelength grid", Recommendation G.694.2, December 2003 . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4204] Lang, J., "Link Management Protocol (LMP)", RFC 4204, October 2005. [RFC6205] Otani, T. and D. Li, "Generalized Labels for Lambda- Switch-Capable (LSC) Label Switching Routers", RFC 6205, March 2011. 8.2. Informative References [I-D.farrkingel-ccamp-flexigrid-lambda-label] King, D., Farrel, A., Li, Y., Fei, Z., and R. Casellas, "Generalized Labels for the Flexi-Grid in Lambda-Switch- Capable (LSC) Label Switching Routers", draft-farrkingel-ccamp-flexigrid-lambda-label-01 (work in progress), October 2011. Li Expires July 24, 2012 [Page 9] Internet-Draft LMP for grid property January 2012 Author's Address Yao Li ZTE Email: li.yao3@zte.com.cn Li Expires July 24, 2012 [Page 10]