MPLS Domain Wide Labels
Author(s): Robert Raszuk
This document describes a mechanism of using concept of Domain Wide MPLS Labels in parallel with any of the existing deployments using other label distribution and allocation methods where multi protocol label switching paradigm is used for transport....
MPLS Working Group R. Raszuk Internet-Draft NTT I3 Intended status: Standards Track July 14, 2013 Expires: January 15, 2014 MPLS Domain Wide Labels draft-raszuk-mpls-domain-wide-labels-00 Abstract This document describes a mechanism of using concept of Domain Wide MPLS Labels in parallel with any of the existing deployments using other label distribution and allocation methods where multi protocol label switching paradigm is used for transport. Specifically it defines a new type of context label which can be used to differentiate lookup tables when using Domain Wide transport Labels from other downstream or upstream assigned transport labels. The end result is creation of clean new label space in data plane allowing very easy and smooth migration to the number of applications choosing to use Domain Wide MPLS Labels. 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 January 15, 2014. Copyright Notice 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 Raszuk Expires January 15, 2014 [Page 1] Internet-Draft mpls-domain-wide-labels July 2013 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. MPLS Domain Wide Label Indicator . . . . . . . . . . . . . . 3 3. Control plane . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Data plane . . . . . . . . . . . . . . . . . . . . . . . . . 3 5. Advantages . . . . . . . . . . . . . . . . . . . . . . . . . 4 6. Deployment considerations . . . . . . . . . . . . . . . . . . 4 7. Security considerations . . . . . . . . . . . . . . . . . . . 4 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 10.1. Normative References . . . . . . . . . . . . . . . . . . 5 10.2. Informative References . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction With the growing number of applications for Domain Wide Labels (by some also referred to as "global labels") there is also growing concern related to the ease of deployment considering various restrictions for available in the platform's data plane label space or taking into account existing deployments of LDP, RSVP-TE, BGP3107 etc and their coexistence with the introduction of new MPLS signalling and mpls switching data plane paradigm. To list just a few examples number of related work has been already seen in this space: Segment Routing [I-D.filsfils-rtgwg-segment-routing], PCE [I-D.sivabalan-pce-segment-routing], RFC5331 [RFC5331], Advertising MPLS labels in IGP [I-D.gredler-rtgwg-igp-label-advertisement], 2547 egress PE Fast Failure Protection [I-D.minto-2547-egress-node-fast-protection] etc... Fundamentally there are two solutions to address this problem. One solution revolves around using the notion of local per node label pools with offset added at each node resulting in making the label locally assigned yet still globally significant. While doable and successfully used as application labels (example: RFC4761 [RFC4761]) authors believe that for transport the further simplification to such scheme is helpful. Raszuk Expires January 15, 2014 [Page 2] Internet-Draft mpls-domain-wide-labels July 2013 The second solution described in this memo proposes an explicit separation of domain wide label space from any other transport or application label space used already today. Such separation into different LFIB is accomplished with the use of new type of context label RFC5331 defined as MPLS Domain Wide Label Indicator. 2. MPLS Domain Wide Label Indicator In order to explicitly indicate that next label in the MPLS label stack of each transported packet is Domain Wide Labels the new context label Domain Wide Label Indicator has been defined. The value of the label is taken from the reserved label pool and has been allocated by IANA *TBD* The MPLS label stack entry has 4 octets where 20 bits indicate the label value, S bit indicates End of Stack, 3 bits indicate QoS value and remaining 8 bits indicate TTL field. In Domain Wide Label Indicator the label value determines the separate LFIB to be used during packet processing. The S bit MUST be set to 0 and QoS bits are to be reserved. The TTL field MAY be copied from the first transport label in the MPLS stack. 3. Control plane The signalling of Domain Wide Labels itself is out of scope of this document as there are already specifications for both ISIS [I-D.previdi-isis-segment-routing-extensions] and OSPF [I-D.psenak-ospf-segment-routing-extensions] protocols describing the required extensions. The existing IGP protocol specifications can be very easily extended with a new flag indicating support for Domain Wide Label Indicator. 4. Data plane The processing of MPLS packets already supports the notion of context labels, recognizing and processing the reserved label space or both. Redirection for lookup to separate LFIB table has also been supported already by number of platforms mainly for efficient protection and restoration applications. In one of the application called Segment Routing the LER performing the imposition may require multiple transport labels to be imposed on the packet each indicating the segment to be traversed. The LSR (often a PHP node, but also gateway between Domain Wide labels and traditional/legacy label distribution protocols) which preforms the POP of the last Domain Wide transport Label *as determined by the control plane signalling* MUST also strip Domain Wide Label Indicator Raszuk Expires January 15, 2014 [Page 3] Internet-Draft mpls-domain-wide-labels July 2013 before passing the remaining of the label stack (possibly containing application labels) to other components or to other peers. 5. Advantages This document provides ability to explicitly signal the notion of Domain Wide Labels carried in the MPLS header of the packets. The main objective is to simplify forwarding planes of LSRs to perform lookup based forwarding without additional label swap actions therefore further contributing to cost reduction, and increase of speed and port density. Such technique is equally applicable to traditional routers as well as to new class of emerging forwarding devices where FIBs or LFIBs are programmed remotely by centralized or semi-centralized entities. While this memo solely focuses on transport labels the notion of domain wide labels can also be found applicable to application labels. It is however out of scope of this document. 6. Deployment considerations There are no new deployment requirements introduced by this document. The ability to recognize support of domain wide label is to be embedded within the specifications defining protocol extensions used for signalling of domain wide labels. 7. Security considerations No new security issues are introduced by this specification. There is also no operator configuration or risk of misconfiguration introduced by this specification. 8. IANA Considerations IANA is requested to allocate a new reserved space MPLS label value to be used as MPLS Domain Wide Label Indicator. 9. Acknowledgments TBD 10. References Raszuk Expires January 15, 2014 [Page 4] Internet-Draft mpls-domain-wide-labels July 2013 10.1. Normative References [RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC3031, January 2001. [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Encoding", RFC3032, January 2001. [RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream Label Assignment and Context-Specific Label Space", RFC 5331, August 2008. 10.2. Informative References [I-D.filsfils-rtgwg-segment-routing] Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R., Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe, "Segment Routing Architecture", draft-filsfils-rtgwg- segment-routing-00 (work in progress), June 2013. [I-D.gredler-rtgwg-igp-label-advertisement] Gredler, H., Amante, S., Scholl, T., and L. Jalil, "Advertising MPLS labels in IGPs", draft-gredler-rtgwg- igp-label-advertisement-05 (work in progress), May 2013. [I-D.minto-2547-egress-node-fast-protection] Jeganathan, J. and H. Gredler, "2547 egress PE Fast Failure Protection", draft-minto-2547-egress-node-fast- protection-01 (work in progress), October 2012. [I-D.previdi-isis-segment-routing-extensions] Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., and S. Litkowski, "IS-IS Extensions for Segment Routing", draft-previdi-isis-segment-routing-extensions-02 (work in progress), July 2013. [I-D.psenak-ospf-segment-routing-extensions] Psenak, P., Previdi, S., Filsfils, C., Gredler, H., and R. Shakir, "OSPF Extensions for Segment Routing", draft- psenak-ospf-segment-routing-extensions-02 (work in progress), July 2013. [I-D.sivabalan-pce-segment-routing] Raszuk Expires January 15, 2014 [Page 5] Internet-Draft mpls-domain-wide-labels July 2013 Sivabalan, S., Medved, J., Filsfils, C., Crabbe, E., and R. Raszuk, "PCEP Extensions for Segment Routing", draft- sivabalan-pce-segment-routing-01 (work in progress), July 2013. [RFC4761] Kompella, K. and Y. Rekhter, "Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling", RFC 4761, January 2007. Author's Address Robert Raszuk NTT I3 101 S Ellsworth Avenue Suite 350 San Mateo, CA 94401 US Email: email@example.com Raszuk Expires January 15, 2014 [Page 6]