Network Work group P. Psenak, Ed. Internet-Draft N. Nainar, Ed. Intended status: Standards Track I. Wijnands Expires: May 3, 2018 Cisco Systems, Inc. October 30, 2017 OSPFv3 Extensions for BIER draft-psenak-bier-ospfv3-extensions-00 Abstract Bit Index Explicit Replication (BIER) is an architecture that provides optimal multicast forwarding through a "BIER domain" without requiring intermediate routers to maintain any multicast related per- flow state. BIER also does not require any explicit tree-building protocol for its operation. A multicast data packet enters a BIER domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). The BFIR router adds a BIER header to the packet. The BIER header contains a bit-string in which each bit represents exactly one BFER to forward the packet to. The set of BFERs to which the multicast packet needs to be forwarded is expressed by setting the bits that correspond to those routers in the BIER header. This document describes the OSPFv3 protocol extensions required for BIER. 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 May 3, 2018. Psenak, et al. Expires May 3, 2018 [Page 1] Internet-Draft OSPFv3 Extensions for BIER October 2017 Copyright Notice Copyright (c) 2017 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. Conventions used in this document . . . . . . . . . . . . . . 3 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Requirements notation . . . . . . . . . . . . . . . . . . 3 3. Flooding of BIER information in OSPFv3 . . . . . . . . . . . 3 3.1. BIER Sub-TLV . . . . . . . . . . . . . . . . . . . . . . 4 3.2. BIER MPLS Encapsulation Sub-TLV . . . . . . . . . . . . . 5 3.3. Flooding scope of BIER Information . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 8 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 7.1. Normative References . . . . . . . . . . . . . . . . . . 8 7.2. Informative References . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction [I-D.ietf-bier-architecture] introduces and explains BIER architecture that provides optimal multicast forwarding through a "BIER domain" without requiring intermediate routers to maintain any multicast related per-flow state. BIER also does not require any explicit tree-building protocol for its operation. A multicast data packet enters a BIER domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). The BFIR router adds a BIER header to the packet. The BIER header contains a bit-string in which each bit represents exactly one BFER to forward the packet to. The set of BFERs to which the multicast packet needs to be forwarded is expressed by setting the bits that correspond to those routers in the BIER header. Psenak, et al. Expires May 3, 2018 [Page 2] Internet-Draft OSPFv3 Extensions for BIER October 2017 BIER architecture requires the distribution of BIER specific information among the routers participating within a BIER domain. BIER architecture permits link-state routing protocol to perform the distribution of such information. [I-D.ietf-bier-ospf-bier-extensions] proposes the OSPFv2 protocol extensions to distribute BIER specific information. This document describes the OSPFv3 protocol extensions required to advertise BIER specific information. 2. Conventions used in this document 2.1. Terminology BFER - Bit Forwarding Egress Router BFIR - Bit Forwarding Ingress Router BFR - Bit-Forwarding Router BIER - Bit Index Explicit Replication ECMP - Equal Cost Multi-Path SI - Set Identifier 2.2. Requirements notation 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 [RFC2119]. 3. Flooding of BIER information in OSPFv3 All BIER specific information that a Bit-Forwarding Router (BFR) needs to advertise to other BFRs is associated with a BFR-Prefix. A BFR prefix is a unique (within a given BIER domain) routable IPv4 or IPv6 address that is assigned to each BFR as described in more detail in [I-D.ietf-bier-architecture]. [I-D.ietf-ospf-ospfv3-lsa-extend] defines the encoding of OSPFv3 LSA in TLV format that allows to carry additional informations. This section defines the required Sub-TLVs to carry BIER information that is associated with the BFR-Prefix. The Sub-TLV defined in this section MAY be carried in the below OSPFv3 Extended LSA TLVs [I-D.ietf-ospf-ospfv3-lsa-extend]: Intra-Area-Prefix TLV Psenak, et al. Expires May 3, 2018 [Page 3] Internet-Draft OSPFv3 Extensions for BIER October 2017 Inter-Area-Prefix TLV 3.1. BIER Sub-TLV A Sub-TLV of the above mentioned Prefix TLVs is defined for distributing BIER information. The Sub-TLV is called the BIER Sub- TLV. Multiple BIER Sub-TLVs MAY be included in any of the above mentioned Prefix TLV. The BIER Sub-TLV has the following format: 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 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sub-domain-ID | BAR | BFR-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |C| Flags | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sub-TLVs (variable) | +- -+ | | Type Set to TBD1 Length Variable, dependent on sub-TLVs. Sub-domain-ID Unique value identifying the BIER sub-domain within the BIER domain, as described in [I-D.ietf-bier-architecture] BAR Single octet BIER Algorithm. 0 is the only supported value defined in this document and represents Shortest Path First (SPF) algorithm based on IGP link metric. This is the standard shortest path algorithm as computed by the OSPF protocol. Other values may be defined in the future. BFR-id Psenak, et al. Expires May 3, 2018 [Page 4] Internet-Draft OSPFv3 Extensions for BIER October 2017 A 2 octet field encoding the BFR-id, as documented in [I-D.ietf-bier-architecture]. If the BFR is not locally configured with a valid BFR-id, the value of this field is set to invalid BFR-id per [[I-D.ietf-bier-architecture]. Flags The C flag (BSL Conversion flag) is set to 1 if the node is capable of imposing a different BSL than the one it received in a BIER encapsulated packet. More details about the usage of this conversion is discussed in Section 2.3 of [I-D.ietf-bier-ospf-bier-extensions]. Other flags MUST be set to 0 and receiver MUST ignore the other flags. New flags may be defined in future. If a BFR advertises the same Sub-domain-ID in multiple BIER sub-TLVs, the BRF MUST be treated as if it did not advertise a BIER sub-TLV for such sub-domain. All BFRs MUST detect advertisement of duplicate valid BFR-IDs for a given Sub-domain-ID. When such duplication is detected all BFRs advertising duplicates MUST be treated as if they did not advertise a valid BFR-id. The supported algorithm MUST be consistent for all routers supporting a given BFR sub-domain. A router receiving BIER Sub-TLV advertisement with a BAR which does not match the locally configured value MUST report a misconfiguration for the given BIER sub-domain and MUST ignore such BIER sub-TLV. 3.2. BIER MPLS Encapsulation Sub-TLV The BIER MPLS Encapsulation Sub-TLV is a Sub-TLV of the BIER Sub-TLV defined in Section 3.1. This Sub-TLV is used to carry MPLS encapsulation specific information for BIER in MPLS networks. The BIER MPLS Encapsulation Sub-TLV has the following format: Psenak, et al. Expires May 3, 2018 [Page 5] Internet-Draft OSPFv3 Extensions for BIER October 2017 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 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Lbl Range Size | Label Range Base | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |BS Len | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: Set to TBD2. Length: 8 octets Label Range Size: A 1 octet field encoding the label range size of the label range. It MUST be greater then 0, otherwise the advertising router MUST be treated as if it did not advertise a BIER sub-TLV. Label Range Base: A 3 octet field, where the 20 rightmost bits represent the first label in the label range. The 4 leftmost bits MUST be ignored. Bit String Length: A 4 bits field encoding the supported BitString length associated with this BFR-prefix. The values allowed in this field are specified in section 2 of [I-D.ietf-bier-mpls-encapsulation]. The "label range" is the set of labels beginning with the label range base and ending with ((label range base)+(label range size)- 1). A unique label range is allocated for each BitStream length and Sub-domain-ID. These labels are used for BIER forwarding as described in [I-D.ietf-bier-architecture] and [I-D.ietf-bier-mpls-encapsulation]. The size of the label range is determined by the number of Set Identifiers (SI) (section 1 of [I-D.ietf-bier-architecture]) that are used in the network. Each SI maps to a single label in the label range. The first label is for SI=0, the second label is for SI=1, etc. If same BS length is repeated in multiple BIER MPLS Encapsulation Sub-TLV inside the same BIER Sub-TLV, the BIER sub-TLV MUST be ignored. Psenak, et al. Expires May 3, 2018 [Page 6] Internet-Draft OSPFv3 Extensions for BIER October 2017 Label ranges within all BIER MPLS Encapsulation Sub-TLV inside the same BIER Sub-TLV MUST NOT overlap. If the overlap is detected, the advertising router MUST be treated as if it did not advertise a BIER sub-TLV. All advertised labels MUST be valid, otherwise the BIER sub-TLV MUST be ignored. 3.3. Flooding scope of BIER Information The BIER Sub-TLV is included as part of OSPFv3 Extended LSAs as defined in Section 3. The flooding scope of the BIER Sub-TLV is decided by the flooding scope of the Extended LSA carrying the Sub- TLV. Any OSPFv3 router SHOULD include the local BIER information in BIER Sub-TLV and advertise it using Intra-Area-Prefix LSA. When an OSPFv3 Area Border Router (ABR) originates E-Inter-Area- Prefix-LSA for a Prefix P, it follows the below procedure to propagate the BIER information between areas: o Examine if the Prefix P is a BFR-Prefix. This could be done by checking the presence of BIER Sub-TLV in Intra-Area-Prefix-TLV of E-Intra-Area-Prefix-LSA for Prefix P. o If the above is TRUE, copy the BIER Sub-TLV to Inter-Area-Prefix TLV. 4. IANA Considerations The document requests two new allocations from the OSPFv3 Extended- LSA sub-TLV registry as defined in [I-D.ietf-ospf-ospfv3-lsa-extend]. BIER Sub-TLV: TBD1 BIER MPLS Encapsulation Sub-TLV: TBD2 5. Security Considerations This document defines additional Sub-TLVs for OSPFv3 Extended-LSAs and does not impose any changes in flooding scope or Path computation. Implementations must assure that any malformed TLVs or Sub-TLVs must not result in errors that causes hard OSPFv3 failures. Psenak, et al. Expires May 3, 2018 [Page 7] Internet-Draft OSPFv3 Extensions for BIER October 2017 6. Acknowledgement TBD 7. References 7.1. Normative References [I-D.ietf-bier-architecture] Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and S. Aldrin, "Multicast using Bit Index Explicit Replication", draft-ietf-bier-architecture-08 (work in progress), September 2017. [I-D.ietf-bier-mpls-encapsulation] Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation for Bit Index Explicit Replication in MPLS and non-MPLS Networks", draft-ietf-bier-mpls-encapsulation-12 (work in progress), October 2017. [I-D.ietf-ospf-ospfv3-lsa-extend] Lindem, A., Roy, A., Goethals, D., Vallem, V., and F. Baker, "OSPFv3 LSA Extendibility", draft-ietf-ospf-ospfv3- lsa-extend-16 (work in progress), October 2017. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, . 7.2. Informative References [I-D.ietf-bier-ospf-bier-extensions] Psenak, P., Kumar, N., Wijnands, I., Dolganow, A., Przygienda, T., Zhang, Z., and S. Aldrin, "OSPF Extensions for BIER", draft-ietf-bier-ospf-bier-extensions-09 (work in progress), October 2017. Authors' Addresses Psenak, et al. Expires May 3, 2018 [Page 8] Internet-Draft OSPFv3 Extensions for BIER October 2017 Peter Psenak (editor) Cisco Systems, Inc. Apollo Business Center Mlynske nivy 43, Bratislava 821 09 Slovakia Email: ppsenak@cisco.com Nagendra Kumar Nainar (editor) Cisco Systems, Inc. 7200 Kit Creek Road Research Triangle Park, NC 27709 US Email: naikumar@cisco.com IJsbrand Wijnands Cisco Systems, Inc. De Kleetlaan 6a Diegem 1831 Belgium Email: ice@cisco.com Psenak, et al. Expires May 3, 2018 [Page 9]