Network Working Group H. Bidgoli, Ed. Internet-Draft Nokia Intended status: Standards Track S. Venaas Expires: 26 January 2023 Cisco System, Inc. M. Mishra Cisco System Z. Zhang Juniper Networks M. McBride Futurewei Technologies Inc. 25 July 2022 PIM Light draft-hb-pim-light-02 Abstract This document specifies a new Protocol Independent Multicast interface which does not need PIM Hello to accept PIM Join/Prunes or PIM Asserts. 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 26 January 2023. Copyright Notice Copyright (c) 2022 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 Bidgoli, et al. Expires 26 January 2023 [Page 1] Internet-Draft PIM Light July 2022 and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions used in this document . . . . . . . . . . . . . . 2 2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 2 3. PIM Light Interface . . . . . . . . . . . . . . . . . . . . . 3 3.1. PLI Configuration . . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 7.2. Informative References . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction It might be desirable to create a PIM interface between routers where only PIM Join/Prunes packets are triggered over it without having a full PIM neighbor discovery. As an example, this type of PIM interface can be useful in some scenarios where the multicast state needs to be signaled over a network or medium which is not capable of or has no need for creating full PIM neighborship between its Peer Routers. These type of PIM interfaces are called PIM Light Interfaces (PLI). 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 2.1. Definitions This draft uses definitions used in [RFC7761] Bidgoli, et al. Expires 26 January 2023 [Page 2] Internet-Draft PIM Light July 2022 3. PIM Light Interface RFC [RFC7761] section 4.3.1 describes the PIM neighbor discovery via Hello messages. It also describes that PIM Join/Prune are not accepted from a router unless a Hello message has been heard from that router. In some scenarios it is desired to communicate and build multicast states between two directly or non directly attach routers without establishing a PIM neighborship. There could be many reasons for this desired, but one example is the desired to signal multicast states upstream, between two or more PIM Domains via a network or medium that is not optimized for PIM or does not require PIM Neighbor establishment. An example is a BIER network connecting multiple PIM domains. In these BIER networks PIM Join/prune messages are tunneled via bier as per [draft-ietf-bier-pim-signaling]. A PIM Light Interface (PLI) does ONLY accept Join/Prune messages from an unknown PIM router and it accepts it without receiving a PIM Hello message form the router. Lack of Hello Messages on a PLI means there is no mechanism to learn about the neighboring PIM routers on each interface and there is no DR Priority options communicated between Routers either. As such the router doesn't create any General- Purpose state for neighboring PIM routers and it accepts and installs each Join message from upstream routers in its multicast routing table. Because of this a PLI needs to be created in very especial cases and the application that is using these PLIs should ensure there is no multicast duplication of packets. As an example, multiple upstream routers sending the same multicast stream to a single downstream router. As an example, in a BIER domain which is connecting 2 PIM networks a PLI can be used between the BIER edge routers. The PLI will be used for only multicast states communicated via by transmitting ONLY PIM Join/prunes over the BIER domain. In this case to ensure there is no multicast stream duplication the PIM routers attached on each side of the BIER domain might want to establish PIM Adjacency via [RFC7761] to ensure DR selection on the edge of the BIER router, while PLI is used in the BIER Domain between BIER edge routers. When the Join or Prune message arrives from a PIM domain to the down stream BIER edge router, it can be send over the BIER tunnel to the upstream BIER edge router. These BIER edge routers have PLI established between them hence PIM Join/Prunes can be accepted on these routers to build their multicast state. After the multicast states are build the traffic will flow as per [draft-ietf-bier-pim-signaling] Bidgoli, et al. Expires 26 January 2023 [Page 3] Internet-Draft PIM Light July 2022 3.1. PLI Configuration Since a PLI doesn't require PIM Hello Messages and PIM neighbor adjacency is not checked for join/prune messages, there needs to be a mechanism to enable PLI on interfaces for security purpose, while on some other interfaces this may be enabled automatically. An example of the latter is the logical interface for a BIER sub-domain [draft-ietf-bier-pim-signaling]. If a system explicitly needs a PLI to be configured, then this system should not accepts the Join/Prune messages on interfaces that the PLI is not configured on, and it should drop these messages on a non PLI interface. If the system automatically enables PLI on some special interfaces, as an example interfaces facing a BIER domain, then it should accept Join/Prune messages on these interfaces only. 4. IANA Considerations 5. Security Considerations 6. Acknowledgments 7. References 7.1. Normative References [draft-ietf-bier-pim-signaling] "H.Bidgoli, F.XU, J. Kotalwar, I. Wijnands, M.Mishra, Z. Zhang, "PIM Signaling Through BIER Core"", July 2021. [RFC2119] "S. Brandner, "Key words for use in RFCs to Indicate Requirement Levels"", March 1997. [RFC7761] "B.Fenner, M.Handley, H. Holbrook, I. Kouvelas, R. Parekh, Z.Zhang "PIM Sparse Mode"", March 2016. [RFC8174] "B. Leiba, "ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words"", May 2017. 7.2. Informative References [RFC8279] "Wijnands, IJ., Rosen, E., Dolganow, A., Przygienda, T. and S. Aldrin, "Multicast using Bit Index Explicit Replication"", October 2016. Bidgoli, et al. Expires 26 January 2023 [Page 4] Internet-Draft PIM Light July 2022 Authors' Addresses Hooman Bidgoli (editor) Nokia Ottawa Canada Email: hooman.bidgoli@nokia.com Stig Cisco System, Inc. San Jose, United States of America Email: stig@cisco.com Mankamana Mishra Cisco System Milpitas, United States of America Email: mankamis@cisco.com Zhaohui Zhang Juniper Networks Boston, United States of America Email: zzhang@juniper.com Mike Futurewei Technologies Inc. Santa Clara, United States of America Email: michael.mcbride@futurewei.com Bidgoli, et al. Expires 26 January 2023 [Page 5]