IDR Working Group U. Chunduri Internet-Draft P. Pillay-Esnault Intended status: Standards Track Huawei USA Expires: November 18, 2019 M. Nanduri Oracle May 17, 2019 BGP-LS extensions for Preferred Path Routing draft-chunduri-idr-bgp-ls-ppr-ext-00 Abstract This document describe extensions to BGP-LS protocol to include Preferred Path Routing (PPR) information. This document also extends BGP-LS protocol and define new SAFIs and NLRIs for propagating path information from a central entity to a node in the network in the south bound direction. 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 RFC2119 [RFC2119], RFC8174 [RFC8174] when, and only when they appear in all capitals, as shown here. 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 November 18, 2019. Chunduri, et al. Expires November 18, 2019 [Page 1] Internet-DraftBGP-LS extensions for Preferred Path Routing May 2019 Copyright Notice 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 1.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 3 2. PPR-ID TLVs Supported by a Prefix . . . . . . . . . . . . . . 3 2.1. PPR-ID Encoding . . . . . . . . . . . . . . . . . . . . . 4 3. Southbound BGP-LS SAFI and NLRIs . . . . . . . . . . . . . . 5 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 5.1. New BGP-LS Attribute . . . . . . . . . . . . . . . . . . 6 5.2. New BGP-LS SAFIs . . . . . . . . . . . . . . . . . . . . 6 5.3. New BGP-LS NLRIs . . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . 7 7.2. Informative References . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction Preferred Path Routing (PPR) is a path routing mechanism where routing happens on path identifier in the packet as opposed to individual segments in the packet as defined in [RFC8402]. PPRs allow path routing for any underlying data plane with abstracted path identifier to represent the path of the data packet. Definition and usage of PPRs by the link state routing protocols ( IS-IS, OSPFv2 and OSPFv3) within IGP topologies are detailed in [I-D.chunduri-lsr-isis-preferred-path-routing] and [I-D.chunduri-lsr-ospf-preferred-path-routing]. PPR-Identifier (PPR-ID) TLV allows advertisement of multi-hop Traffic Engineered (TE) paths, Fast Re-Route (FRR) or certain chained paths. The flooding scope for the IGP extensions for PPRs is an IGP area/ Chunduri, et al. Expires November 18, 2019 [Page 2] Internet-DraftBGP-LS extensions for Preferred Path Routing May 2019 domain. Consequently, the contents of a Link State Database (LSDB) or a Traffic Engineering Database (TED) has the scope of an IGP area/ domain and therefore by using the IGP alone it is not enough to construct PPRs across multiple IGP Areas or AS boundaries. Even though a central entity provisions the PPRs at one of the network node, not all PPRs are active and advertised in IGPs as these could be subjected to the local policies of the network node. PPRs can also be potentially created locally by operators, it is critical to have a complete view of currently active PPRs in the network for creating end-to-end paths crossing multiple IGP areas and AS boundaries. To take care of the above cases, this document describe extensions to BGP-LS to advertise PPR information in Prefix NLRI as described in Section 2. An external component, which is a BGP-LS [RFC7752] speaker (e.g., a controller) then can collect active PPR information in the network in "north bound" direction across IGP areas or ASes. In some environments, where single protocol is desired for controller communication with the network nodes, new SAFIs and new NLRI types are defined to signal the PPR paths from external BGP-LS speaker to the network nodes in Section 3. This information is subjected to the local policies of the network node and eventually can be signaled in an IGP as defined in IGP PPR extensions. 1.1. Acronyms IGP - Interior Gateway Protocols MTU - Maximum Transferrable Unit PPR - Preferred Path Route/Routing SID - Segment Identifier SR - Segment Routing TE - Traffic Engineering 2. PPR-ID TLVs Supported by a Prefix This section defines a new TLV, PPR-ID TLV in BGP-LS Prefix Attributes of Prefix NLRI and describes the encoding of the same. The BGP-LS Prefix attribute, PPR-ID TLV has the following format: Chunduri, et al. Expires November 18, 2019 [Page 3] Internet-DraftBGP-LS extensions for Preferred Path Routing May 2019 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MT-ID | AF | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix Len | FEC Prefix | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // Prefix (continued, variable) // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // PPR-ID Encoding // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Prefix attribute - PPR-ID TLV Format Type - TBD (Suggested Value 1174, IANA TBD). Length - Total length of the value field in bytes (variable). AF - See Section 2.1. MT-ID - is the multi-topology identifier defined in [RFC5120] with 4 most significant bits reset on transmission and ignored on receive. The remaining 12-bit field contains the MT-ID. For OSPFv2 this is as defined in [RFC4915]. For OSPFv3 it MUST be set to zero. Prefix Len - contains the length of the prefix in bits. Prefix - represents the the tail-end node address of the advertised PPR. Value of this field MUST be encoded as a 32-bit value for IPv4 "Prefix". Value of this field MUST be 16 octets for IPv6 "Prefix", encoded as an even multiple of 32-bit words, padded with zeroed bits as necessary. This encoding consumes ((PrefixLength + 31) / 32) 32-bit words. Flags: 1 octet field of PPR-ID TLV has flags as defined in respective IGP and encoded based on the Protocol-ID field in BGP- LS node NLRI. 2.1. PPR-ID Encoding This TLV can be seen as having 3 logical section viz., encoding of Prefix, encoding of PPR-ID with description of ordered path with sub- TLVs and a set of optional PPR-Attribute Sub-TLVs, which can be used to describe one or more parameters of the PPR. Out of the above only the first logical section i.e., encoding Prefix is described here in Chunduri, et al. Expires November 18, 2019 [Page 4] Internet-DraftBGP-LS extensions for Preferred Path Routing May 2019 IGP agnostic way. The remaining 2 sections MUST be encoded as defined in [I-D.chunduri-lsr-isis-preferred-path-routing] and [I-D.chunduri-lsr-ospf-preferred-path-routing] drafts. This MUST be based on the Protocol-ID field as defined in section 3.2 of [RFC7752] 'The Prefix NLRI Format'. The advertisement of PPR-ID TLV in IS-IS has following semantics: The IS-IS 'PPR-ID Encoding' as defined in Section 2 is encoded in the BGP-LS Prefix Attribute TLV and the format is as defined in [I-D.chunduri-lsr-isis-preferred-path-routing] including PPR-ID, PPR- PDE Sub-TLVs and all possible PPR-Attribute Sub-TLVs. The AF field for IS-IS MUST be set to zero. The flags of the PPR-ID TLV are semantically mapped to the definition in [I-D.chunduri-lsr-isis-preferred-path-routing] section 2. The advertisement of PPR-ID TLV in OSPF has following semantics: The OSPFv2/OSPFv3 "PPR-ID Encoding" as defined in Section 2 is encoded in the BGP-LS Prefix Attribute TLV and the format is as defined in [I-D.chunduri-lsr-ospf-preferred-path-routing] including PPR-ID, PPR-PDE Sub-TLVs and all possible PPR-Attribute Sub-TLVs. The flags and AF of the PPR-ID TLV are semantically mapped to the definition in [I-D.chunduri-lsr-ospf-preferred-path-routing] section 2 for OSPFv2 or section 3 for OSPFv3. 3. Southbound BGP-LS SAFI and NLRIs This document extends the [RFC7752] by defining two new South Bound (SB) SAFIs to be used with BGP-LS AFI 16388. All non-VPN SB prefix information SHALL be encoded using AFI 16388 / SAFI 75 (suggested value for SB-BGP-LS SAFI, IANA TBD). VPN SB prefix information SHALL be encoded using AFI 16388 / SAFI 76 (suggested value for SB-BGP-LS- VPN SAFI, IANA TBD). This document also extends then BGP-LS by defining 2 new south bound NLRI types, one for SB IPv4 Topology Prefix (type 5, suggested value, IANA TBD) and one for SB IPv6 Topology Prefix NLRI (type 6, suggested value, IANA TBD). As with other BGP-LS SAFIs, in order for two BGP speakers to exchange SB Link-State NLRI, they MUST use BGP Capabilities Advertisement to advertise SB SAFIs to ensure that they are both capable of properly processing such NLRI. Encoding for the new SB SAFIs and new SB NLRIs are applicable to [RFC7752], including the parameters as defined in "BGP-LS Protocol- IDs", "BGP-LS Well-Known Instance-IDs" and "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs". Chunduri, et al. Expires November 18, 2019 [Page 5] Internet-DraftBGP-LS extensions for Preferred Path Routing May 2019 PPR-ID Prefix Attribute TLV as defined in Section 2 can be advertised with SB IPv4/IPv6 Topology Prefix NLRIs. When this is done this information is advertised in the corresponding underlying IGP subjected to the local node policy. 4. Acknowledgements TBD. 5. IANA Considerations 5.1. New BGP-LS Attribute This document requests IANA to assign a code point from the "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs" registry as follows: BGP-LS Node Attribute - PPR-ID TLV as described in Section 2. TLV # Name ----- ------------------------------ TBD PPR-ID TLV in Prefix attribute 5.2. New BGP-LS SAFIs This document defines a new SAFIs in the registry "Subsequent Address Family Identifiers (SAFI) Parameters" that has been assigned by IANA: SAFI # Description Reference ----- -------------------- ------------ 75 SB-BGP-LS SAFI This Document 76 SB-BGP-LS-VPN SAFI This Document 5.3. New BGP-LS NLRIs This document requests IANA to assign a code point from the"BGP-LS NLRI-Types" registry as follows: NLRI # Description Reference ----- ------------------------ --------------- 5 SB IPv4 Topology Prefix This Document 6 SB IPv6 Topology Prefix This Document Chunduri, et al. Expires November 18, 2019 [Page 6] Internet-DraftBGP-LS extensions for Preferred Path Routing May 2019 6. Security Considerations This document does not introduce security issues beyond those discussed in [RFC7752] 7. References 7.1. Normative References [I-D.chunduri-lsr-isis-preferred-path-routing] Chunduri, U., Li, R., White, R., Tantsura, J., Contreras, L., and Y. Qu, "Preferred Path Routing (PPR) in IS-IS", draft-chunduri-lsr-isis-preferred-path-routing-03 (work in progress), May 2019. [I-D.chunduri-lsr-ospf-preferred-path-routing] Chunduri, U., Qu, Y., White, R., Tantsura, J., and L. Contreras, "Preferred Path Routing (PPR) in OSPF", draft- chunduri-lsr-ospf-preferred-path-routing-03 (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, . [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and S. Ray, "North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP", RFC 7752, DOI 10.17487/RFC7752, March 2016, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 7.2. Informative References [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", RFC 4915, DOI 10.17487/RFC4915, June 2007, . [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi Topology (MT) Routing in Intermediate System to Intermediate Systems (IS-ISs)", RFC 5120, DOI 10.17487/RFC5120, February 2008, . Chunduri, et al. Expires November 18, 2019 [Page 7] Internet-DraftBGP-LS extensions for Preferred Path Routing May 2019 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, July 2018, . Authors' Addresses Uma Chunduri Huawei USA 2330 Central Expressway Santa Clara, CA 95050 USA Email: uma.chunduri@huawei.com Padma Pillay-Esnault Huawei USA 2330 Central Expressway Santa Clara, CA 95050 USA Email: padma@huawei.com Mohan Nanduri Oracle USA Email: mohan.nanduri@oracle.com Chunduri, et al. Expires November 18, 2019 [Page 8]