Network Working Group X. Xu Internet-Draft Huawei Intended status: Standards Track S. Kini Expires: November 4, 2016 Ericsson S. Sivabalan C. Filsfils Cisco S. Litkowski Orange May 3, 2016 Signaling Entropy Label Capability Using OSPF draft-ietf-ospf-mpls-elc-02 Abstract Multi Protocol Label Switching (MPLS) has defined a mechanism to load balance traffic flows using Entropy Labels (EL). An ingress LSR cannot insert ELs for packets going into a given tunnel unless an egress LSR has indicated via signaling that it can process ELs on that tunnel. This draft defines a mechanism to signal that capability using OSPF. This mechanism is useful when the label advertisement is also done via OSPF. 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 November 4, 2016. Copyright Notice Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved. Xu, et al. Expires November 4, 2016 [Page 1] Internet-Draft Signallng ELC Using OSPF May 2016 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 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Advertising ELC Using OSPF . . . . . . . . . . . . . . . . . 3 4. Advertising RLDC Using OSPF . . . . . . . . . . . . . . . . . 3 5. Usage and Applicability . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 8. Security Considerations . . . . . . . . . . . . . . . . . . . 4 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 9.1. Normative References . . . . . . . . . . . . . . . . . . 4 9.2. Informative References . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction Multi Protocol Label Switching (MPLS) has defined a method in [RFC6790] to load balance traffic flows using Entropy Labels (EL). An ingress LSR cannot insert ELs for packets going into a given tunnel unless an egress LSR has indicated that it can process ELs on that tunnel. [RFC6790] defines the signaling of this capability (a.k.a Entropy Label Capability - ELC) via signaling protocols. Recently, mechanisms are being defined to signal labels via link state Interior Gateway Protocols (IGP) such as OSPF [I-D.ietf-ospf-segment-routing-extensions] . In such scenario the signaling mechanisms defined in [RFC6790] are inadequate. This draft defines a mechanism to signal the ELC using OSPF. This mechanism is useful when the label advertisement is also done via OSPF. In addition, in the cases where stacked LSPs are used for whatever reasons (e.g., SPRING-MPLS [I-D.ietf-spring-segment-routing-mpls]), it would be useful for ingress LSRs to know each LSR's capability of reading the maximum label stack deepth. This capability, referred to as Readable Label Deepth Capability (RLDC) can be used by ingress LSRs to determine whether it's necessary to insert an EL for a given LSP tunnel in the case where there has already been at least one EL in the label stack [I-D.ietf-mpls-spring-entropy-label] . Of course, Xu, et al. Expires November 4, 2016 [Page 2] Internet-Draft Signallng ELC Using OSPF May 2016 even it has been determined that it's neccessary to insert an EL for a given LSP tunnel, if the egress LSR of that LSP tunnel has not yet indicated that it can process ELs for that tunnel, the ingress LSR MUST NOT include an entropy label for that tunnel as well. 1.1. Requirements Language 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]. 2. Terminology This memo makes use of the terms defined in [RFC6790] and [RFC4970]. 3. Advertising ELC Using OSPF The OSPF Router Information (RI) Opaque LSA defined in [RFC4970] is used by OSPF routers to announce their capabilities. A new TLV within the body of this LSA, called ELC TLV is defined to advertise the capability of the router to process the ELs. As showed in Figure 1, it is formatted as described in Section 2.1 of [RFC4970]. The Type for the ELC TLV needs to be assigned by IANA and it has a Length of zero. The scope of the advertisement depends on the application but it is recommended that it SHOULD be AS-scoped. If a router has multiple linecards, the router MUST NOT announce the ELC unless all of its linecards are capable of processing ELs. This TLV is applicable to both OSPFv2 and OSPFv3. 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=TBD1 | Length=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: ELC TLV Format. 4. Advertising RLDC Using OSPF A new TLV within the body of the OSPF RI LSA, called RLDC TLV is defined to advertise the capability of the router to read the maximum label stack depth. As showed in Figure 2, it is formatted as described in Section 2.1 of [RFC4970] with a Type code to be assigned by IANA and a Length of one. The Value field is set to the maximum readable label stack depth in the range between 1 to 255. The scope of the advertisement depends on the application but it is RECOMMENDED that it SHOULD be domain-wide. If a router has multiple linecards with different capabilities of reading the maximum label stack Xu, et al. Expires November 4, 2016 [Page 3] Internet-Draft Signallng ELC Using OSPF May 2016 deepth, the router MUST advertise the smallest one in the RLDC TLV. This TLV is applicable to both OSPFv2 and OSPFv3. 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=TBD2 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RLD | +-+-+-+-+-+-+-+-+ Figure 2: RLDC TLV Format 5. Usage and Applicability The EL capability is used by ingress LSRs to determine whether an EL could be inserted into a given LSP tunnel. The RLD capability is used by ingress LSRs to determine whether it's necessary to insert an EL for a given LSP tunnel in the case where there has already been at least one EL in the label stack. This document only describes how to signal the EL capability and RLD capability using OSPF. As for how to apply those capabilities when inserting EL(s) into LSP tunnel(s), it's outside the scope of this document and accordingly would be described in [I-D.ietf-mpls-spring-entropy-label]. 6. Acknowledgements The authors would like to thank Yimin Shen, George Swallow, Acee Lindem and Carlos Pignataro for their valuable comments. 7. IANA Considerations This memo includes a request to IANA to allocate two TLV types from the OSPF RI TLVs registry. 8. Security Considerations The security considerations as described in [RFC4970] is appliable to this document. This document does not introduce any new security risk. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Xu, et al. Expires November 4, 2016 [Page 4] Internet-Draft Signallng ELC Using OSPF May 2016 [RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and S. Shaffer, "Extensions to OSPF for Advertising Optional Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July 2007, . 9.2. Informative References [I-D.ietf-mpls-spring-entropy-label] Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., Shakir, R., and j. jefftant@gmail.com, "Entropy labels for source routed tunnels with label stacks", draft-ietf-mpls- spring-entropy-label-03 (work in progress), April 2016. [I-D.ietf-ospf-segment-routing-extensions] Psenak, P., Previdi, S., Filsfils, C., Gredler, H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF Extensions for Segment Routing", draft-ietf-ospf-segment- routing-extensions-08 (work in progress), April 2016. [I-D.ietf-spring-segment-routing-mpls] Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., Litkowski, S., Horneffer, M., Shakir, R., Tantsura, J., and E. Crabbe, "Segment Routing with MPLS data plane", draft-ietf-spring-segment-routing-mpls-04 (work in progress), March 2016. [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and L. Yong, "The Use of Entropy Labels in MPLS Forwarding", RFC 6790, DOI 10.17487/RFC6790, November 2012, . Authors' Addresses Xiaohu Xu Huawei Email: xuxiaohu@huawei.com Sriganesh Kini Ericsson Email: sriganesh.kini@ericsson.com Xu, et al. Expires November 4, 2016 [Page 5] Internet-Draft Signallng ELC Using OSPF May 2016 Siva Sivabalan Cisco Email: msiva@cisco.com Clarence Filsfils Cisco Email: cfilsfil@cisco.com Stephane Litkowski Orange Email: stephane.litkowski@orange.com Xu, et al. Expires November 4, 2016 [Page 6]