CCAMP working Group W. Imajuku Internet-Draft Y. Sone Updates: RFC 4202 NTT Proposed Status: Standards Track I. Nishioka Expires January 2008 NEC S. Seno Mitsubishi Electric Corporation July 2007 Routing Extensions to Support Network Elements with Switching Constraint draft-imajuku-ccamp-rtg-switching-constraint-02.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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 January 8, 2008. Abstract This document shares problem statements of the routing of optical Label Switched Paths(LSPs) over network elements with blocking switch architecture in fiber port selectivity. Also, this document provides a direction of solution to take into account the switching constraint within the scope of GMPLS Traffic Engineering (TE) over network elements with blocking switch architecture in fiber port selectivity in addition to wavelength selectivity. Table of Contents Imajuku, Nishioka, Seno Expires January 2008 [Page 1]
draft-imajuku-ccamp-rtg-switching-constraint-02.txt July 2007 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions used in this document . . . . . . . . . . . . . . 2 3. Problem Statements . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Problem Statements . . . . . . . . . . . . . . . . . . . . 3 3.2. Problem Example . . . . . . . . . . . . . . . . . . . . . 3 3.3. Comments on Necessity of Extension . . . . . . . . . . . . 4 4. Proposal for GMPLS Routing Enhancement . . . . . . . . . . . . 5 4.1. Possible Routing Enhancement . . . . . . . . . . . . . . . 5 4.2. Comments on Other Possible Solutions . . . . . . . . . . . 5 5. Compatibility and Inter-domain Issues . . . . . . . . . . . . 5 6. Security Considerations. . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8.1. Normative references . . . . . . . . . . . . . . . . . . 6 8.2. Informative references . . . . . . . . . . . . . . . . . . 6 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 10. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . . . 7 Copyright Statement. . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction The routing protocol extensions so far have been developed for Generalized Multi-Protocol Switching (GMPLS)[OSPF-TE],[GMPLS-ROUTING], [GMPLS-OSPF]. This document explains the necessity of routing extensions required to support GMPLS Traffic Engineering (TE) over network elements with blocking switch architecture in fiber port selectivity in addition to wavelength selectivity. A reconfigurable optical add/drop multiplexer (ROADM) is a network element that employs the blocking switch architecture widely used in commercialized networks. The ROADM has switching constraints with respect to selecting the fiber port when adding/dropping a lambda path from/to a tributary port. The lambda path added from each tributary port is restricted to either east or west fiber port of the ROADM ring. Similarly, the dropping of a lambda path connected to the tributary port also has a constraint with respect to the selection of the tributary port. The objective of this document is to share problem statement within this community and to provide a direction of solution to support the routing of Optical Label Switched Paths with blocking switch architecture having the constraint of selecting fiber ports. 2. 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]. Imajuku, Nishioka, Seno Expires January 2008 [Page 2]
draft-imajuku-ccamp-rtg-switching-constraint-02.txt July 2007 3. Problem Statements 3.1. Problem Statements Many lambda switch capable (LSC) nodes such as ROADM and Optical Cross-Connects (OXC) employ the blocking switch architecture to reduce the cost of the switch fabric or wavelength converters. In particular, the ROADM, which was already commercially deployed, employs a unique switch architecture that has a constraint with respect to the TE link selectivity, while the OXC without wavelength converters has a constraint with respect to wavelength label selectivity. For the wavelength label selectivity constraint, GMPLS has a specification to control the label allocation mechanism for Label Switch Paths (LSPs) based on the signaling mechanism [RFC3471], [RFC3473]. On the contrary, for the TE link selectivity constraint, there is currently no specification. To address this issue regarding the TE link selectivity constraint, it is clear that an extension to the GMPLS routing mechanism is essential for all network elements in a domain in order to understand which TE link can be selected to forward LSPs at the network elements that have the constraint. 3.2. Problem Example Figure shows a typical example using ROADM systems and ROADM ring network architecture to illustrate the TE link selectivity constraint. In this example, we assume that each ROADM switches optical signals (LSPs) transparently and a ROADM system comprises four tributary interfaces, i.e., w1, w2, e1, and e2. Lambda LSPs from TE-Wx can only be dropped to w1 or w2, and lambda LSPs can only be added from e1 and e2, if these LSPs are forwarded to TE-Ex. Similarly, lambda LSPs from TE-Ex can only be dropped from e1 or e2, and lambda LSPs can only be added from w1 and w2 if these LSPs are forwarded to TE-Wx. Thus, the ports for each ROADM are grouped into "west" and "east" ports from the viewpoint of TE link selectivity. ________________________________________________ | ROADM __ __ __ __ | | |Rx| |Rx| |Tx| |Tx| | | w1 |__| |__|w2 e1 |__| |__|e2 | | /|\ /|\ \|/ \|/ | | __|____|___ ___|____|__ | | /|->-| |-->--| |->-|\ | | | |->-| Drop |-->--| Add |->-| | | --->----| |->-| |-->--| |->-| |---->---- | | |->-| switches |-->--| switches |->-| | | | \|->-|___________|-->--|___________|->-|/ | Imajuku, Nishioka, Seno Expires January 2008 [Page 3]
draft-imajuku-ccamp-rtg-switching-constraint-02.txt July 2007 TE-Wx | ___________ ___________ | TE-Ex | /|-<-| |--<--| |-<-|\ | | | |-<-| Add |--<--| Drop |-<-| | | ----<----| |-<-| |--<--| |-<-| |----<--- | | |-<-| switches |--<--| switches |-<-| | | | \|-<-|___________|--<--|___________|-<-|/ | | /|\ /|\ \|/ \|/ | | |_ |_ |_ |_ | | |Tx| |Tx| |Rx| |Rx| | | |__| |__| |__| |__| | | w1 w2 e1 e2 | |________________________________________________| In a ring network using ROADM systems, a lambda LSP added from a west tributary port cannot be dropped to a "west" tributary port at another node, and this is also true for the "east" bound case. For example, a lambda LSP added from tributary port w1 of ROADM #1 cannot be dropped to tributary port w1 or w2 of ROADM #2, #3, or #4. Similarly, a lambda LSP added from tributary port e1 of ROADM #1 Cannot be dropped to tributary port e1 or e2 of ROADM #2, #3, or #4. _________ _________ | | TE #1-E | | TE #2-E ==========|ROADM #1|==============|ROADM #2|========== || TE #1-W |_________| TE #2-W |_________| || || | | | | | | | | || ||Tributary w1 w2 e1 e2 Tributary w1 w2 e1 e2 || || || || || || _________ _________ || || | | TE #4-W | | TE #3-W || ==========|ROADM #4|==============|ROADM #3|========== TE #4-E |_________| TE #3-E |_________| | | | | | | | | Tributary e1 e2 w1 w2 Tributary e1 e2 w1 w2 3.3. Comments on Necessity of Extension The problem described in the previous section is not so critical if the network comprises a single ROADM ring network. In such a case, the routing of LSPs can be performed based on static routing without using any routing protocols. Assignment of a destination node ID with a loose option in the Explicit Route Object (ERO) of the signaling message and execution of loose hop expansion [RFC3209] in each ROADM may result in successfully establishing an LSP. Employing an inter-domain routing architecture can also be a solution [per-domain-calc]. By separating ROADM rings from a GMPLS routing domain, the nodes outside the ROADM domain assign a ROADM Imajuku, Nishioka, Seno Expires January 2008 [Page 4]
draft-imajuku-ccamp-rtg-switching-constraint-02.txt July 2007 node ID or boundary node adjacent to the ROADM domain with a loose ERO to forward the Lambda LSP. Then, each ROADM node performs loose hop expansion to forward the lambda LSP toward the destination. The case that essentially requires an extension of the GMPLS routing mechanism is the case in which the ROADM and other Lambda or Fiber Switch capable nodes co-exist in the same routing domain. Packet and TDM switch capable nodes attached to such a domain must also consider the TE link selectivity constraint at the ROADM nodes when creating a Lambda LSP. 4. Proposal for GMPLS Routing Enhancement 4.1. Possible Routing Enhancement This section proposes advertising the TE link selectivity constraint as a solution. The extended sub-TLVs indicate the list of selectable and/or unselectable TE links from the TE link indicated in sub-TLV Type 2 (Link ID). The possible extensions to sub-TLV are described below. Sub-TLV Type Length Name TBD variable Selectable numbered TE link list TBD variable Unselectable numberd TE link list TBD variable Selectable unnumberd TE link list TBD variable Unselectable unnumberd TE link list 4.2. Comments on Other Possible Solutions Employing a virtual TE link model as discussed in L1-VPN WG is also a possible solution [l1-vpn-frwk]. An optical network domain that has a switching constraint can be modeled as an abstract mesh network. Note that this routing architecture requires a hierarchical routing mechanism in each border node of the optical network domain. 5. Inter-domain and Compatibility Issues Note that it is essential to share switching constraint information pertaining to each node in order for the border nodes to advertise abstract information to other network domains. Also, note that it is essential to share switching constraint information pertaining to each node with the Path Computation Element (PCE), if the PCE based inter-domain routing architecture is employed. There should be no interoperability issues with routers that do not implement these extensions, as the Opaque LSAs will be silently ignored. Imajuku, Nishioka, Seno Expires January 2008 [Page 5]
draft-imajuku-ccamp-rtg-switching-constraint-02.txt July 2007 6. Security considerations TBD 7. IANA considerations TBD 8. References 8.1 Normative References [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, September 2003. [RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4202, October 2005. [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4203, October 2005. [RFC3471] Berger, L., et al, "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description", RFC 3471, January 2003. [RFC3473] Berger, L., et al, "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V. and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. 8.2 Informative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 [per-domain-calc] Vasseur, J. P., Ayyanger, A., Zhang, R., "A Per- domain path computation method for establishing Inter-domain Traffic Engineering (TE) Label Switched Paths (LSPs)", RFC 3471, January 2003. [l1-vpn-frwk] Takeda, T (editor), "Framework and Requirements for Layer 1 Virtual Private Networks", Imajuku, Nishioka, Seno Expires January 2008 [Page 6]
draft-imajuku-ccamp-rtg-switching-constraint-02.txt July 2007 work in progress. 9. Acknowledgements The authors would like to thank Eiji Oki, Tomonori Takeda, Akira Nagata, and Akira Chugo for helpful discussion. 10. Authors' Addresses Wataru Imajuku NTT Network Innovation Laboratories 1-1 Hikari-no-oka, Yokosuka, Kanagawa 239-0847 Japan Phone: +81 46 859 4315 Email: imajuku.wataru@lab.ntt.co. jp Yoshiaki Sone NTT Network Innovation Laboratories 1-1 Hikari-no-oka, Yokosuka, Kanagawa 239-0847 Japan Phone: +81 46 859 2456 Email: sone.yoshiaki@lab.ntt.co.jp Itaru Nishioka NEC Corp. 1753 Simonumabe, Nakahara-ku, Kawasaki, Kanagawa 211-8666 Japan Phone: +81 44 396 3287 Email: i-nishioka@cb.jp.nec.com Shoichiro Seno Mitsubishi Electric Corporation 5-1-1 Ofuna, Kamakura, Kanagawa 247-8501 Japan Phone: +81 467 41 2881 Email: Senoo.Shoichiro@dc.MitsubishiElectric.co.jp Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be Imajuku, Nishioka, Seno Expires January 2008 [Page 7]
draft-imajuku-ccamp-rtg-switching-constraint-02.txt July 2007 found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Imajuku, Nishioka, Seno Expires January 2008 [Page 8]