LSR Workgroup A. Lindem Internet-Draft Cisco Systems Intended status: Standards Track Y. Qu Expires: 22 November 2022 Futurewei A. Roy Arrcus, Inc. S. Mirtorabi Cisco Systems 21 May 2022 OSPF Transport Instance Extensions draft-ietf-lsr-ospf-transport-instance-02 Abstract OSPFv2 and OSPFv3 include a reliable flooding mechanism to disseminate routing topology and Traffic Engineering (TE) information within a routing domain. Given the effectiveness of these mechanisms, it is convenient to envision using the same mechanism for dissemination of other types of information within the domain. However, burdening OSPF with this additional information will impact intra-domain routing convergence and possibly jeopardize the stability of the OSPF routing domain. This document presents mechanism to relegate this ancillary information to a separate OSPF instance and minimize the impact. 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 22 November 2022. Copyright Notice Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved. Lindem, et al. Expires 22 November 2022 [Page 1] Internet-Draft OSPF Transport Instance May 2022 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 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 3. Possible Use Cases . . . . . . . . . . . . . . . . . . . . . 3 3.1. MEC Service Discovery . . . . . . . . . . . . . . . . . . 3 3.2. Application Data Dissemination . . . . . . . . . . . . . 4 3.3. Intra-Area Topology for BGP-LS Distribution . . . . . . . 4 4. OSPF Transport Instance . . . . . . . . . . . . . . . . . . . 4 4.1. OSPFv2 Transport Instance Packet Differentiation . . . . 5 4.2. OSPFv3 Transport Instance Packet Differentiation . . . . 5 4.3. Instance Relationship to Normal OSPF Instances . . . . . 5 4.4. Network Prioritization . . . . . . . . . . . . . . . . . 5 4.5. OSPF Transport Instance Omission of Routing Calculation . . . . . . . . . . . . . . . . . . . . . . . 6 4.6. Non-routing Instance Separation . . . . . . . . . . . . . 6 4.7. Non-Routing Sparse Topologies . . . . . . . . . . . . . . 7 4.7.1. Remote OSPF Neighbor . . . . . . . . . . . . . . . . 8 4.8. Multiple Topologies . . . . . . . . . . . . . . . . . . . 8 5. OSPF Transport Instance Information (TII) Encoding . . . . . 8 5.1. OSPFv2 Transport Instance Information Encoding . . . . . 8 5.2. OSPFv3 Transport Instance Information Encoding . . . . . 9 5.3. Transport Instance Information (TII) TLV Encoding . . . . 10 5.3.1. Top-Level TII Application TLV . . . . . . . . . . . . 11 6. Manageability Considerations . . . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 8.1. OSPFv2 Opaque LSA Type Assignment . . . . . . . . . . . . 12 8.2. OSPFv3 LSA Function Code Assignment . . . . . . . . . . . 12 8.3. OSPF Transport Instance Information Top-Level TLV Registry . . . . . . . . . . . . . . . . . . . . . . . . 12 9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 12 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 10.1. Normative References . . . . . . . . . . . . . . . . . . 12 10.2. Informative References . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 Lindem, et al. Expires 22 November 2022 [Page 2] Internet-Draft OSPF Transport Instance May 2022 1. Introduction OSPFv2 [RFC2328] and OSPFv3 [RFC5340] include a reliable flooding mechanism to disseminate routing topology and Traffic Engineering (TE) information within a routing domain. Given the effectiveness of these mechanisms, it is convenient to envision using the same mechanism for dissemination of other types of information within the domain. However, burdening OSPF with this additional information will impact intra-domain routing convergence and possibly jeopardize the stability of the OSPF routing domain. This document presents mechanism to relegate this ancillary information to a separate OSPF instance and minimize the impact. This OSPF protocol extension provides functionality similar to "Advertising Generic Information in IS-IS" [RFC6823]. Additionally, OSPF is extended to support sparse non-routing overlay topologies Section 4.7. 2. Requirements Language 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. 3. Possible Use Cases 3.1. MEC Service Discovery Multi-Access Edge Computing (MEC) plays an important role in 5G architecture. MEC optimizes the performance for ultra-low latency and high bandwidth services by providing networking and computing at the edge of the network [ETSI-WP28-MEC]. To achieve this goal, it's important to expose the network capabilities and services of a MEC device to 5G User Equipment UE, i.e. UEs. The followings are an incomplete list of the kind of information that OSPF transport instance can help to disseminate: * A network service is realized using one or more physical or virtualized hosts in MEC, and the locations of these service points might change. The auto-discovery of these service locations can be achieved using an OSPF transport instance. Lindem, et al. Expires 22 November 2022 [Page 3] Internet-Draft OSPF Transport Instance May 2022 * UEs might be mobile, and MEC should support service continuity and application mobility. This may require service state transferring and synchronization. OSPF transport instance can be used to synchronize these states. * Network resources are limited, such as computing power, storage. The availability of such resources is dynamic, and OSPF transport instance can be used to populate such information, so applications can pick the right location of such resources, hence improve user experience and resource utilization. 3.2. Application Data Dissemination Typically a network consists of routers from different vendors with different capabilities, and some applications may want to know whether a router supports certain functionality or where to find a router supports a functionality, so it will be ideal if such kind of information is known to all routers or a group of routers in the network. For example, an ingress router needs to find an egress router that supports In-situ Flow Information Telemetry (IFIT) [I-D.wang-lsr-igp-extensions-ifit] and obtain IFIT parameters. OSPF transport instance can be used to populate such router capabilities/functionalities without impacting the performance or convergence of the base OSPF protocol. 3.3. Intra-Area Topology for BGP-LS Distribution In some cases, it is desirable to limit the number of BGP-LS [RFC5572] sessions with a controller to the a one or two routers in an OSPF domain. However, many times those router(s) do not have full visibility to the complete topology of all the areas. To solve this problem without extended the BGP-LS domain, the OSPF LSAs for non- local area could be flooded over the OSPF transport instance topology using remote neighbors Section 4.7.1. 4. OSPF Transport Instance In order to isolate the effects of flooding and processing of non- routing information, it will be relegated to a separate protocol instance. This instance should be given lower priority when contending for router resources including processing, backplane bandwidth, and line card bandwidth. How that is realized is an implementation issue and is outside the scope of this document. Lindem, et al. Expires 22 November 2022 [Page 4] Internet-Draft OSPF Transport Instance May 2022 Throughout the document, non-routing refers to routing information that is not used for IP or IPv6 routing calculations. The OSPF transport instance is ideally suited for dissemination of routing information for other protocols and layers. 4.1. OSPFv2 Transport Instance Packet Differentiation OSPFv2 currently does not offer a mechanism to differentiate Transport instance packets from normal instance packets sent and received on the same interface. However, the [RFC6549] provides the necessary packet encoding to support multiple OSPF protocol instances. 4.2. OSPFv3 Transport Instance Packet Differentiation Fortunately, OSPFv3 already supports separate instances within the packet encodings. The existing OSPFv3 packet header instance ID field will be used to differentiate packets received on the same link (refer to section 2.4 in [RFC5340]). 4.3. Instance Relationship to Normal OSPF Instances In OSPF transport instance, we must guarantee that any information we've received is treated as valid if and only if the router sending it is reachable. We'll refer to this as the "condition of reachability" in this document. The OSPF transport instance is not dependent on any other OSPF instance. It does, however, have much of the same as topology information must be advertised to satisfy the "condition of reachability". Further optimizations and coupling between an OSPF transport instance and a normal OSPF instance are beyond the scope of this document. This is an area for future study. 4.4. Network Prioritization While OSPFv2 (section 4.3 in [RFC2328]) are normally sent with IP precedence Internetwork Control, any packets sent by an OSPF transport instance will be sent with IP precedence Flash (B'011'). This is only appropriate given that this is a pretty flashy mechanism. Similarly, OSPFv3 transport instance packets will be sent with the traffic class mapped to flash (B'011') as specified in ([RFC5340]). Lindem, et al. Expires 22 November 2022 [Page 5] Internet-Draft OSPF Transport Instance May 2022 By setting the IP/IPv6 precedence differently for OSPF transport instance packets, normal OSPF routing instances can be given priority during both packet transmission and reception. In fact, some router implementations map the IP precedence directly to their internal packet priority. However, internal router implementation decisions are beyond the scope of this document. 4.5. OSPF Transport Instance Omission of Routing Calculation Since the whole point of the transport instance is to separate the routing and non-routing processing and fate sharing, a transport instance SHOULD NOT install any IP or IPv6 routes. OSPF routers SHOULD NOT advertise any transport instance LSAs containing IP or IPv6 prefixes and OSPF routers receiving LSAs advertising IP or IPv6 prefixes SHOULD ignore them. This implies that an OSPF transport instance Link State Database should not include any of the LSAs as shown in Table 1. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OSPFv2 | summary-LSAs (type 3) | | | AS-external-LSAs (type 5) | | | NSSA-LSAs (type 7) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OSPFv3 | inter-area-prefix-LSAs (type 2003) | | | AS-external-LSAs (type 0x4005) | | | NSSA-LSAs (type 0x2007) | | | intra-area-prefix-LSAs (type 0x2009) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OSPFv3 Extended LSA | E-inter-area-prefix-LSAs (type 0xA023) | | | E-as-external-LSAs (type 0xC025) | | | E-Type-7-NSSA (type 0xA027) | | | E-intra-area-prefix-LSA (type 0xA029) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: LSAs not included in OSPF transport instance If these LSAs are erroneously advertised, they will be flooded as per standard OSPF but MUST be ignored by OSPF routers supporting this specification. 4.6. Non-routing Instance Separation It has been suggested that an implementation could obtain the same level of separation between IP routing information and non-routing information in a single instance with slight modifications to the OSPF protocol. The authors refute this contention for the following reasons: Lindem, et al. Expires 22 November 2022 [Page 6] Internet-Draft OSPF Transport Instance May 2022 * Adding internal and external mechanisms to prioritize routing information over non-routing information are much more complex than simply relegating the non-routing information to a separate instance as proposed in this specification. * The instance boundary offers much better separation for allocation of finite resources such as buffers, memory, processor cores, sockets, and bandwidth. * The instance boundary decreases the level of fate sharing for failures. Each instance may be implemented as a separate process or task. * With non-routing information, many times not every router in the OSPF routing domain requires knowledge of every piece of non- routing information. In these cases, groups of routers which need to share information can be segregated into sparse topologies greatly reducing the amount of non-routing information any single router needs to maintain. 4.7. Non-Routing Sparse Topologies With non-routing information, many times not every router in the OSPF routing domain requires knowledge of every piece of non-routing information. In these cases, groups of routers which need to share information can be segregated into sparse topologies. This will greatly reduce the amount of information any single router needs to maintain with the core routers possibly not requiring any non-routing information at all. With normal OSPF, every router in an OSPF area must have every piece of topological information and every intra-area IP or IPv6 prefix. With non-routing information, only the routers needing to share a set of information need be part of the corresponding sparse topology. For directly attached routers, one only needs to configure the desired topologies on the interfaces with routers requiring the non- routing information. When the routers making up the sparse topology are not part of a uniconnected graph, two alternatives exist. The first alternative is configuring tunnels to form a fully connected graph including only those routers in the sparse topology. The second alternative is use remote neighbors as described in Section 4.7.1. Lindem, et al. Expires 22 November 2022 [Page 7] Internet-Draft OSPF Transport Instance May 2022 4.7.1. Remote OSPF Neighbor With sparse topologies, OSPF routers sharing non-routing information may not be directly connected. OSPF adjacencies with remote neighbors are formed exactly as they are with regular OSPF neighbors. The main difference is that a remote OSPF neighbor's address is configured and IP routing is used to deliver OSPF protocol packets to the remote neighbor. Other salient feature of the remote neighbor include: * All OSPF packets have the remote neighbor's configured IP address as the IP destination address. This address has be to reachable usig the unicast topology. * The adjacency is represented in the router Router-LSA as a router (type-1) link with the link data set to the remote neighbor's configured IP address. * Similar to NBMA networks, a poll-interval is configured to determine if the remote neighbor is reachable. This value is normally much higher than the hello interval with 40 seconds RECOMMENDED as the default. 4.8. Multiple Topologies For some applications, the information need to be flooded only to a topology which is a subset of routers of the transport instance. This allows the application specific information only to be flooded to routers that support the application. A transport instance may support multiple topologies as defined in [RFC4915]. But as pointed out in Section 4.5, a transport instance or topology SHOULD NOT install any IP or IPv6 routes. Each topology associated with the transport instance MUST be fully connected in order for the LSAs to be successfully flooded to all routers in the topology. 5. OSPF Transport Instance Information (TII) Encoding 5.1. OSPFv2 Transport Instance Information Encoding Application specific information will be flooded in opaque LSAs as specified in [RFC5250]. An Opaque LSA option code will be reserved for Transport Instance Information (TII) as described in Section 8. The TII LSA can be advertised at any of the defined flooding scopes (link, area, or autonomous system (AS)). Lindem, et al. Expires 22 November 2022 [Page 8] Internet-Draft OSPF Transport Instance May 2022 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS age | Options | 9, 10, or 11 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TBD1 | Opaque ID (Instance ID) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Advertising Router | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS sequence number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS checksum | length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +- TLVs -+ | ... | g Figure 2: OSPFv2 Transport Instance Information Opaque LSA The format of the TLVs within the body of an TII LSA is as defined in Section 5.3. 5.2. OSPFv3 Transport Instance Information Encoding Application specific information will be flooded in separate LSAs with a separate function code. Refer to section A.4.2.1 of [RFC5340]. for information on the LS Type encoding in OSPFv3, and section 2 of [RFC8362] for OSPFv3 extended LSA types. An OSPFv3 function code will be reserved for Transport Instance Information (TII) as described in Section 8. Same as OSPFv2, the TII LSA can be advertised at any of the defined flooding scopes (link, area, or autonomous system (AS)). The U bit will be set indicating that OSPFv3 TTI LSAs should be flooded even if it is not understood. Lindem, et al. Expires 22 November 2022 [Page 9] Internet-Draft OSPF Transport Instance May 2022 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS age |1|S12| TBD2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link State ID (Instance ID) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Advertising Router | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS sequence number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS checksum | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +- TLVs -+ | ... | Figure 3: OSPFv3 Transport Instance Information LSA The format of the TLVs within the body of an TII LSA is as defined in Section 5.3. 5.3. Transport Instance Information (TII) TLV Encoding The format of the TLVs within the body of the LSAs containing non- routing information is the same as the format used by the Traffic Engineering Extensions to OSPF [RFC3630]. The LSA payload consists of one or more nested Type/Length/Value (TLV) triplets. The format of each TLV is: 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: TLV Format Lindem, et al. Expires 22 November 2022 [Page 10] Internet-Draft OSPF Transport Instance May 2022 5.3.1. Top-Level TII Application TLV An Application top-level TLV will be used to encapsulate application data advertised within TII LSAs. This top-level TLV may be used to handle the local publication/subscription for application specific data. The details of such a publication/subscription mechanism are beyond the scope of this document. An Application ID is used in the top-level application TLV and shares the same code point with IS-IS as defined in [RFC6823]. 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 (1) | Length - Variable | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Application ID | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . Sub-TLVs . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Application ID: An identifier assigned to this application via the IANA registry, as defined in RFC 6823. Each unique application will have a unique ID. Additional Application-Specific Sub-TLVs: Additional information defined by applications can be encoded as Sub-TLVs. Definition of such information is beyond the scope of this document. Figure 5: Top-Level TLV The specific TLVs and sub-TLVs relating to a given application and the corresponding IANA considerations MUST be specified in the document corresponding to that application. 6. Manageability Considerations 7. Security Considerations The security considerations for the Transport Instance will not be different for those for OSPFv2 [RFC2328] and OSPFv3 [RFC5340]. 8. IANA Considerations Lindem, et al. Expires 22 November 2022 [Page 11] Internet-Draft OSPF Transport Instance May 2022 8.1. OSPFv2 Opaque LSA Type Assignment IANA is requested to assign an option type, TBD1, for Transport Instance Information (TII) LSA from the "Opaque Link-State Advertisements (LSA) Option Types" registry. 8.2. OSPFv3 LSA Function Code Assignment IANA is requested to assign a function code, TBD2, for Transport Instance Information (TII) LSAs from the "OSPFv3 LSA Function Codes" registry. 8.3. OSPF Transport Instance Information Top-Level TLV Registry IANA is requested to create a registry for OSPF Transport Instance Information (TII) Top-Level TLVs. The first available TLV (1) is assigned to the Application TLV Section 5.3.1. The allocation of the unsigned 16-bit TLV type are defined in the table below. +-------------+-----------------------------------+ | Range | Assignment Policy | +-------------+-----------------------------------+ | 0 | Reserved (Not to be assigned) | | | | | 1 | Application TLV | | | | | 2-16383 | Unassigned (IETF Review) | | | | | 16383-32767 | Unassigned (FCFS) | | | | | 32768-32777 | Experimentation (No assignements) | | | | | 32778-65535 | Reserved (Not to be assigned) | +-----------+-------------------------------------+ Figure 6: TII Top-Level TLV Registry Assignments 9. Acknowledgement The authors would like to thank Les Ginsberg for review and comments. 10. References 10.1. Normative References Lindem, et al. Expires 22 November 2022 [Page 12] Internet-Draft OSPF Transport Instance May 2022 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, DOI 10.17487/RFC2328, April 1998, . [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, DOI 10.17487/RFC3630, September 2003, . [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, . [RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The OSPF Opaque LSA Option", RFC 5250, DOI 10.17487/RFC5250, July 2008, . [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, . [RFC6549] Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi- Instance Extensions", RFC 6549, DOI 10.17487/RFC6549, March 2012, . [RFC6823] Ginsberg, L., Previdi, S., and M. Shand, "Advertising Generic Information in IS-IS", RFC 6823, DOI 10.17487/RFC6823, December 2012, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and F. Baker, "OSPFv3 Link State Advertisement (LSA) Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 2018, . 10.2. Informative References Lindem, et al. Expires 22 November 2022 [Page 13] Internet-Draft OSPF Transport Instance May 2022 [ETSI-WP28-MEC] Sami Kekki, etc., "MEC in 5G Networks", 2018, . [I-D.wang-lsr-igp-extensions-ifit] Wang, Y., Zhou, T., Qin, F., Chen, H., and R. Pang, "IGP Extensions for In-situ Flow Information Telemetry (IFIT) Capability Advertisement", Work in Progress, Internet- Draft, draft-wang-lsr-igp-extensions-ifit-01, 28 July 2020, . [RFC5572] Blanchet, M. and F. Parent, "IPv6 Tunnel Broker with the Tunnel Setup Protocol (TSP)", RFC 5572, DOI 10.17487/RFC5572, February 2010, . Authors' Addresses Acee Lindem Cisco Systems 301 Midenhall Way CARY, NC 27513 United States Email: acee@cisco.com Yingzhen Qu Futurewei 2330 Central Expressway Santa Clara, CA 95050 United States of America Email: yingzhen.qu@futurewei.com Abhay Roy Arrcus, Inc. Email: abhay@arrcus.com Sina Mirtorabi Cisco Systems 170 West Tasman Drive San Jose, CA 95134 United States of America Email: smirtora@cisco.com Lindem, et al. Expires 22 November 2022 [Page 14]