CCAMP working Group W. Imajuku Internet-Draft Y. Sone Expires: October 16, 2006 NTT I. Nishioka NEC October 16 2006 Routing Extensions to support network elements with switching constraint draft-imajuku-ccamp-rtg-switching-constraint-00.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 April 16, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This document proposes routing extensions in support of carrying switching constraint information in corresponding link state information for Generalized Multi-Protocol Label Switching (GMPLS). With the proposed extension, GMPLS routing protocols can handle the network elements with some blocking constraints. Imajuku, et al. Expires April 16, 2007 [Page 1] draft-imajuku-ccamp-rtg-switching-constraint-00.txt October 2006 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions used in this document . . . . . . . . . . . . . . 2 3. Problem Statements . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Problem Statements . . . . . . . . . . . . . . . . . . . 3 3.2. Example of Problems . . . . . . . . . . . . . . . . . . . 3 3.3. Comments on necessity of extension . . . . . . . . . . . 4 4. Proposal for GMPLS Routing Enhancement . . . . . . . . . . . . 4 5. Compatibility Issues . . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations. . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . .. . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 8.1. Normative references . . . . . . . . . . . . . . . . . . 5 8.2. Informative references . . . . . . . . . . . . . . . . . . 5 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 10. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . . . 6 1. Introduction The routing protocol extensions so far have been made for Generalized Multi-Protocol Switching (GMPLS)[OSPF-TE],[GMPLS-ROUTING],[GMPLS-OSPF]. This document enhances the routing extensions required to support GMPLS Traffic Engineering (TE) over the network elements with blocking constraints. Reconfigurable optical add/drop Multiplexer (ROADM) is one of the network element which employs the blocking switch architecture widely used in commercialized networks. The ROADM has switching constraints in the selectivity of direction when adding/dropping a lambda path from/to a user network interface (UNI) port. The lambda path added from each UNI port is restricted to either east or west bound of the ROADM ring. Similarly, the drop of lambda path to the UNI port also has constraint in the selectivity of the UNI port. The objective of this document is to enhance the routing protocol in support of carrying switching constraint information of the network elements with blocking constraints. The constraint information of each switch is carried within the link state information of Traffic Engineering (TE) links. 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 et al. Expires April 16, 2007 [Page 2] draft-imajuku-ccamp-rtg-switching-constraint-00.txt October 2006 3. Problem Statements 3.1. Problem Statements Many lambda switch capable (LSC) nodes, such as ROADM and Optical Cross-Connects (OXC), employ blocking switch architecture to reduce the cost of switch fabric or wavelength converters. In particular, the ROADM, which has already been commercially deployed, employs unique switch architecture having constraint in TE link selectivity, while the OXC without the wavelength converters has constraint in wavelength label selectivity. For the constraint in wavelength label selectivity, GMPLS has specification to control the label allocation mechanism for Label Switch Paths (LSPs) based on signaling mechanism [RFC3471], [RFC3473]. To the contrary, for the constraint in TE link selectivity, there is no specification at this moment. To combat with the issue of the constraint in TE link selectivity, it is obvious that an extension to GMPLS routing mechanism is essential for all network elements in a domain to understand which TE link can be selectable to forward LSPs at the network elements having the constraint. 3.2. Example of Problem Figure shows an typical example of ROADM ring network to explain the constraint in TE link selectivity. Assuming that each ROADM switches optical signals (LSPs) transparently. The UNI ports of each ROADM are grouped to gwesth and geasth ports. In this network, a lambda LSP added from a UNI west port can not be dropped to a UNI gwesth ports at other nodes, and it is also same in the case of vice versa. For example, a lambda LSP added from UNI port w1 of ROADM #1 can not be dropped to UNI port w1 or w2 of ROADM #2, #3 and #4. Similarly, a lambda LSP added from UNI port e1 of ROADM #1 can not be dropped to UNI port e1 or e2 of ROADM #2, #3 and #4. _________ _________ | | TE #1-E | | TE #2-E ==========|ROADM #1|==============|ROADM #2|========== || TE #1-W |_________| TE #2-W |_________| || || | | | | | | | | || || UNI w1 w2 e1 e2 UNI w1 w2 e1 e2 || || || || || || _________ _________ || || | | TE #4-W | | TE #3-W || ==========|ROADM #4|==============|ROADM #3|========== TE #4-E |_________| TE #3-E |_________| | | | | | | | | UNI e1 e2 w1 w2 UNI e1 e2 w1 w2 Imajuku et al. Expires April 16, 2007 [Page 3] draft-imajuku-ccamp-rtg-switching-constraint-00.txt October 2006 3.3. Comments on necessity of extension The problem statement described in the previous section is not so critical if the network is single ROADM ring network. In such case, the routing of LSPs can be performed based on static routing without using any routing protocols. Employment of inter-domain routing architecture can also be one of solution. By separating ROADM rings from a GMPLS routing domain, the nodes outside ROADM domain assign ROADM node ID or boundary node adjacent to the ROADM domain with loose Explicit Route Object (ERO) to forward Lambda LSP. Then, each ROADM node perform loose hop expansion to forward the lambda LSP toward destination [RFC3209], [per-domain-calc]. The case which essentially requires the extension to GMPLS routing mechanism is the case that 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 domain also required to consider the constraint in TE link selectivity at the ROADM nodes when creating the Lambda LSP. 4. Proposal for GMPLS Routing Enhancement This section proposes a possible solution to advertise the constraint in TE link selectivity. The extended sub-TLVs are indicates 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: 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 5. Compatibility Issues There should be no interoperability issues with routers that do not implement these extensions, as the Opaque LSAs will be silently ignored. The result of having routers that do not implement these extensions is that the traffic engineering topology will be missing pieces. However, if the topology is connected, TE paths can still be calculated and ought to work. Imajuku et al. Expires April 16, 2007 [Page 4] draft-imajuku-ccamp-rtg-switching-constraint-00.txt October 2006 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. 8.2 Informative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 [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. [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. Imajuku et al. Expires April 16, 2007 [Page 5] draft-imajuku-ccamp-rtg-switching-constraint-00.txt October 2006 9. Acknowledgements The authors would like to thank Eiji Oki and Tomonori Takeda 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 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 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. Imajuku et al. Expires April 16, 2007 [Page 6] draft-imajuku-ccamp-rtg-switching-constraint-00.txt October 2006 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. 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