--- 1/draft-ietf-ospf-mpls-elc-07.txt 2019-05-13 04:13:51.973331150 -0700 +++ 2/draft-ietf-ospf-mpls-elc-08.txt 2019-05-13 04:13:51.989331552 -0700 @@ -1,44 +1,42 @@ OSPF Working Group X. Xu Internet-Draft Alibaba Inc Intended status: Standards Track S. Kini -Expires: March 29, 2019 - S. Sivabalan +Expires: November 14, 2019 + P. Psenak C. Filsfils Cisco S. Litkowski Orange - September 25, 2018 + May 13, 2019 Signaling Entropy Label Capability and Entropy Readable Label-stack Depth Using OSPF - draft-ietf-ospf-mpls-elc-07 + draft-ietf-ospf-mpls-elc-08 Abstract Multiprotocol Label Switching (MPLS) has defined a mechanism to load balance traffic flows using Entropy Labels (EL). An ingress Label Switching Router (LSR) cannot insert ELs for packets going into a given tunnel unless an egress LSR has indicated via signaling that it has the capability of processing ELs, referred to as Entropy Label Capability (ELC), on that tunnel. In addition, it would be useful for ingress LSRs to know each LSR's capability of reading the maximum label stack depth and performing EL-based load-balancing, referred to as Entropy Readable Label Depth (ERLD), in the cases where stacked - LSPs are used for whatever reasons. This document defines mechanisms - to signal these two capabilities using OSPF. These mechanisms are - useful when the label advertisement is also done via OSPF. In - addition, this document introduces the Non-IGP Functional - Capabilities TLV for advertising OSPF router's actual non-IGP - functional capabilities. ELC is one of such non-IGP functional - capabilities. + LSPs are used. This document defines a mechanisms to signal these + two capabilities using OSPF and OSPFv3. These mechanisms are + particularly useful in the environment where Segment Routing (SR) is + used, where label advertisements are done via protocols like OSPF and + OSPFv3. 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]. Status of This Memo This Internet-Draft is submitted in full conformance with the @@ -47,239 +45,244 @@ 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 https://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 March 29, 2019. + This Internet-Draft will expire on November 14, 2019. Copyright Notice - Copyright (c) 2018 IETF Trust and the persons identified as the + Copyright (c) 2019 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 (https://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 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 3. Non-OSPF Functional Capabilities TLV . . . . . . . . . . . . 3 - 4. Advertising ELC Using OSPF . . . . . . . . . . . . . . . . . 4 - 5. Advertising ERLD Using OSPF . . . . . . . . . . . . . . . . . 4 - 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 - 8. Security Considerations . . . . . . . . . . . . . . . . . . . 5 - 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 9.1. Normative References . . . . . . . . . . . . . . . . . . 5 - 9.2. Informative References . . . . . . . . . . . . . . . . . 6 + 3. Advertising ELC Using OSPF . . . . . . . . . . . . . . . . . 3 + 3.1. Advertising ELC Using OSPFv2 . . . . . . . . . . . . . . 4 + 3.2. Advertising ELC Using OSPFv3 . . . . . . . . . . . . . . 4 + 4. Advertising ERLD Using OSPF . . . . . . . . . . . . . . . . . 4 + 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 + 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 + 8.1. Normative References . . . . . . . . . . . . . . . . . . 5 + 8.2. Informative References . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction [RFC6790] describes a method to load balance Multiprotocol Label - Switching (MPLS) traffic flows using Entropy Labels (EL). [RFC6790] + Switching (MPLS) traffic flows using Entropy Labels (EL). It also introduces the concept of Entropy Label Capability (ELC) and defines the signalings of this capability via MPLS 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 [RFC6790] using OSPF. This - mechanism is useful when the label advertisement is also done via - OSPF. + 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., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it would be useful for ingress LSRs to know each intermediate LSR's capability of reading the maximum label stack depth and performing EL-based load-balancing. This capability, referred to as Entropy Readable Label Depth (ERLD) as defined in [I-D.ietf-mpls-spring-entropy-label] may be used by ingress LSRs to determine whether it's necessary to insert an EL for a given LSP of the stacked 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]. 2. Terminology This memo makes use of the terms defined in [RFC6790] and [RFC7770]. -3. Non-OSPF Functional Capabilities TLV - - This document defines the Router Non-IGP Functional Capabilities TLV - with TLV type code of TBD1 within the body of the OSPF Router - Information LSA. An OSPF router advertising an OSPF RI LSA MAY - include the Router Non-IGP Functional Capabilities TLV. If included, - it MUST be included in the first instance of the LSA. Additionally, - the TLV MUST reflect the advertising OSPF router's actual non-IGP - functional capabilities in the flooding scope of the containing OSPF - RI LSA. +3. Advertising ELC Using OSPF - The format of the Router Non-OSPF Functional Capabilities TLV is as - follows: + Even though ELC is a property of the node, in some cases it is + advantageous to associate and advertise the ELC with the prefix. In + multi-area network, routers may not know the identity of the prefix + originator in the remote area, or may not know the capabilities of + such originator. Similarly in the multi domain network, the identity + of the prefix originator and its capabilities may not be known to the + ingress LSR. - 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 | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Non-IGP Functional Capabilities | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 1: Non-OSPF Functional Capabilities TLV Format + If a router has multiple line cards, the router MUST NOT announce ELC + unless all of its linecards are capable of processing ELs. - Type: TBD1. + If the router support ELs on all of its line cards, it SHOULD + advertise the ELC with every local host prefix it advertises in OSPF. - Length: Indicates the length of the value portion in octets and - will be a multiple of 4 octets dependent on the number of - capabilities advertised. Initially, the length will be 4, - denoting 4 octets of Non-IGP Functional Capabilities Bits as - defined in [I-D.ietf-isis-mpls-elc]. + When an OSPF Area Border Router (ABR) advertises the prefix to the + connected area based on the intra-area or inter-area prefix that is + reachable in some other area, it MUST preserve the ELC signalling for + such prefix. - Value: contains the Non-IGP Functional Capabilities Bits as - defined in [I-D.ietf-isis-mpls-elc]. + When an OSPF Autonomous System Boundary Router (ASBR) redistributes + the prefix from other instance of the OSPF or from some other + protocol, it SHOULD preserve the ELC signalling for the prefix. + Exact mechanism on how to exchange ELC between protocol instances on + the ASBR is outside of the scope of this document and is + implementation specific. - The Non-IGP Functional Capabilities TLV MAY be followed by optional - TLVs that further specify a non-OSPF functional capability. In - contrast to the OSPF Router Functional Capabilities TLV, the non-OSPF - functional capabilities advertised in this TLV have no impact on the - OSPF protocol operation. The specifications for non-IGP functional - capabilities advertised in this TLV MUST describe protocol behavior - and address backwards compatibility. +3.1. Advertising ELC Using OSPFv2 -4. Advertising ELC Using OSPF + [RFC7684] defines the OSPFv2 Extended Prefix TLV to advertise + additional attributes associated with the prefix. The OSPFv2 + Extended Prefix TLV includes a one octet Flags field. A new bit in + the Flags field is used to signal the ELC for the prefix: - One bit of the Non-IGP Functional Capability Bits for is used to - indicate the ELC. + 0x20 - E-Flag (ELC Flag): Set by the advertising router to + indicate that the prefix originator is capable of processing ELs - Assignment of a Non-IGP Functional Capability Bit for the ELC is - defined in [I-D.ietf-isis-mpls-elc]. +3.2. Advertising ELC Using OSPFv3 - If a router has multiple line cards, the router MUST NOT announce the - ELC [RFC6790] unless all of its linecards are capable of processing - ELs. + [RFC5340] defines the OSPFv3 PrefixOptions that is advertised along + with the prefix. A new bit in the OSPFV3 PrefixOptions is used to + signal the ELC for the prefix: - How to apply the ELC advertisement to the inter-area, inter-AS and - inter-protocol scenarios is outside the scope of this document. + 0x04 - E-Flag (ELC Flag): Set by the advertising router to + indicate that the prefix originator is capable of processing ELs -5. Advertising ERLD Using OSPF +4. Advertising ERLD Using OSPF A new MSD-type of the Node MSD sub-TLV [I-D.ietf-isis-segment-routing-msd], called ERLD is defined to advertise the ERLD of a given router. The scope of the advertisement depends on the application. Assignment of a MSD-Type for ERLD is defined in [I-D.ietf-isis-mpls-elc]. If a router has multiple linecards with different capabilities of reading the maximum label stack deepth, the router MUST advertise the smallest one. -6. Acknowledgements +5. Acknowledgements The authors would like to thank Yimin Shen, George Swallow, Acee Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura , Bruno Decraene and Carlos Pignataro for their valuable comments. -7. IANA Considerations +6. IANA Considerations - This document requests IANA to allocate one TLV type from the OSPF RI - TLVs registry for the Non-IGP Functional CapabilitiesTLV. + This document requests IANA to allocate one bit from the OSPFv2 + Extended Prefix TLV Flags registry: -8. Security Considerations + 0x20 - E-Flag (ELC Flag) + + This document requests IANA to allocate one bit from the OSPFv3 + Prefix Options registry: + + 0x04 - E-Flag (ELC Flag) + +7. Security Considerations The security considerations as described in [RFC7770] is applicable to this document. This document does not introduce any new security risk. -9. References +8. References -9.1. Normative References +8.1. Normative References [I-D.ietf-isis-mpls-elc] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S. Litkowski, "Signaling Entropy Label Capability and Entropy Readable Label Depth Using IS-IS", draft-ietf-isis-mpls- - elc-05 (work in progress), July 2018. + elc-06 (work in progress), September 2018. [I-D.ietf-isis-segment-routing-msd] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, "Signaling MSD (Maximum SID Depth) using IS-IS", draft- - ietf-isis-segment-routing-msd-16 (work in progress), - September 2018. + ietf-isis-segment-routing-msd-19 (work in progress), + October 2018. [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-25 (work in progress), April 2018. + routing-extensions-27 (work in progress), December 2018. [I-D.ietf-spring-segment-routing-mpls] Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing with MPLS - data plane", draft-ietf-spring-segment-routing-mpls-14 - (work in progress), June 2018. + data plane", draft-ietf-spring-segment-routing-mpls-22 + (work in progress), May 2019. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, DOI 10.17487/RFC5305, October 2008, . + [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF + for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, + . + [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, . + [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., + Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute + Advertisement", RFC 7684, DOI 10.17487/RFC7684, November + 2015, . + [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and S. Shaffer, "Extensions to OSPF for Advertising Optional Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, February 2016, . -9.2. Informative References +8.2. Informative References [I-D.ietf-mpls-spring-entropy-label] Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., Shakir, R., and J. Tantsura, "Entropy label for SPRING tunnels", draft-ietf-mpls-spring-entropy-label-12 (work in progress), July 2018. Authors' Addresses Xiaohu Xu Alibaba Inc Email: xiaohu.xxh@alibaba-inc.com Sriganesh Kini Email: sriganeshkini@gmail.com - Siva Sivabalan + Peter Psenak Cisco - Email: msiva@cisco.com + Email: ppsenak@cisco.com + Clarence Filsfils Cisco Email: cfilsfil@cisco.com - Stephane Litkowski Orange Email: stephane.litkowski@orange.com