IDR Working Group J. Zhou Internet-Draft Shaofu. Peng Intended status: Standards Track ZTE Corp. Expires: August 21, 2020 Feb 18, 2020 BGP Extension for SR-MPLS Entropy Label Position draft-zhou-idr-bgp-srmpls-elp-00 Abstract This document proposed an extension for BGP to configure the entropy label position for SR-MPLS networks. 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 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 August 21, 2020. Copyright Notice Copyright (c) 2020 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. Zhou & Peng Expires August 21, 2020 [Page 1] Internet-DraBGP Extension for SR-MPLS Entropy Label Position Feb 2020 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. BGP Extensions of Segment Flags . . . . . . . . . . . . . . . 2 3. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 5. Normative References . . . . . . . . . . . . . . . . . . . . 3 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction Entropy Label(EL)[RFC6790] is a technology that can be used for load- balancing in Segment Routing (SR) MPLS. [I-D.ietf-mpls-spring-entropy-label] discusses in detail the factors to be considered when inserting EL in SR, analyzes the possible insertion positions of entropy labels, and gives a specific algorithm for calculating the position of entropy labels. An MPLS label stack can contain multiple ELs, so multiple EL insertion positions may be calculated. When calculating the position, it is necessary to consider the Maximum SID Depth(MSD) capability of the head node and Entropy Readable Label Depth(ERLD) capability of the intermediate node in combination with the algorithm. The position calculation of EL is usually completed by the controller, which is issued by the controller to the head node. [I-D.ietf-idr-segment-routing-te-policy] defines the specific process of how the controller in the SR network passes the path calculation result of the SR-TE policy to the head node of the network through BGP. In this document, the EL position information is transmitted by extending the flags of Segment List Sub-TLV in the BGP. 2. BGP Extensions of Segment Flags The Segment Flags is defined in Section 2.4.3.2.12 of [I-D.ietf-idr-segment-routing-te-policy]. 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |V|A|E| | +-+-+-+-+-+-+-+-+ E-Flag: This flag indicates that presence of label pairs are inserted after this segment. It is applicable to all Segment Types. Zhou & Peng Expires August 21, 2020 [Page 2] Internet-DraBGP Extension for SR-MPLS Entropy Label Position Feb 2020 3. Operations Supposed the head end had received a SR-TE path from the controller with multiple Segment List Sub-TLVs, for example, , especially S3 and S6 with E-flag. It indicates that two pairs SHOULD be inserted into the label stack of the SR-TE forwarding entry, respectively after the Label for S3 and Label for S6. With EL information, the label stack for SR-MPLS would be . 4. IANA Considerations This document requests bit 2 for Entropy Label Flag. Bit Description Reference ------------------------------------------------------------------ 2 Entropy Label Flag(E-Flag) This document 5. Normative References [I-D.ietf-idr-segment-routing-te-policy] Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P., Rosen, E., Jain, D., and S. Lin, "Advertising Segment Routing Policies in BGP", draft-ietf-idr-segment-routing- te-policy-08 (work in progress), November 2019. [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. [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 Jin Zhou ZTE Corp. Email: zhou.jin6@zte.com.cn Zhou & Peng Expires August 21, 2020 [Page 3] Internet-DraBGP Extension for SR-MPLS Entropy Label Position Feb 2020 Shaofu Peng ZTE Corp. Email: peng.shaofu@zte.com.cn Zhou & Peng Expires August 21, 2020 [Page 4]