--- 1/draft-ietf-lsr-ospf-prefix-originator-05.txt 2020-06-30 02:13:29.519191805 -0700 +++ 2/draft-ietf-lsr-ospf-prefix-originator-06.txt 2020-06-30 02:13:29.551192621 -0700 @@ -1,476 +1,443 @@ LSR Working Group A. Wang Internet-Draft China Telecom Intended status: Standards Track A. Lindem -Expires: May 28, 2020 Cisco Systems +Expires: January 1, 2021 Cisco Systems J. Dong Huawei Technologies P. Psenak K. Talaulikar Cisco Systems - November 25, 2019 + June 30, 2020 - OSPF Prefix Originator Extension - draft-ietf-lsr-ospf-prefix-originator-05 + OSPF Prefix Originator Extensions + draft-ietf-lsr-ospf-prefix-originator-06 Abstract - This document defines Open Shortest Path First (OSPF) encodings to - advertise the router-id of the originator of inter-area prefixes for - OSPFv2 and OSPFv3 Link-State Advertisements (LSAs). The source - originator is needed in several multi-area OSPF use cases. + This document defines OSPF extensions to include information + associated with the node originating a prefix along with the prefix + advertisement. 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 28, 2020. + This Internet-Draft will expire on January 1, 2021. Copyright Notice - Copyright (c) 2019 IETF Trust and the persons identified as the + 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 - 2. Conventions used in this document . . . . . . . . . . . . . . 3 - 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 4. Inter-Area Prefix Source Advertisement Use Cases . . . . . . 4 - 5. External Prefix Source Advertisement Use Cases . . . . . . . 5 - 6. Prefix Source Router-ID sub-TLV . . . . . . . . . . . . . . . 6 - 7. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 7 - 7.1. Inter-Area Prefixes . . . . . . . . . . . . . . . . . . . 7 - 7.2. External Prefixes . . . . . . . . . . . . . . . . . . . . 7 - 8. Security Considerations . . . . . . . . . . . . . . . . . . . 7 - 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 - 10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 8 - 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 11.1. Normative References . . . . . . . . . . . . . . . . . . 9 - 11.2. Informative References . . . . . . . . . . . . . . . . . 10 - Appendix A. Inter-Area Topology Retrieval Process . . . . . . . 10 + 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 + 2. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 3 + 2.1. Prefix Source Router-ID Sub-TLV . . . . . . . . . . . . . 4 + 2.2. Prefix Originator Sub-TLV . . . . . . . . . . . . . . . . 4 + 3. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 5 + 4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 + 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 + 6. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 7 + 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 + 7.1. Normative References . . . . . . . . . . . . . . . . . . 7 + 7.2. Informative References . . . . . . . . . . . . . . . . . 8 + Appendix A. Inter-Area Topology Retrieval Process . . . . . . . 9 Appendix B. Special Considerations on Inter-Area Topology - Retrieval . . . . . . . . . . . . . . . . . . . . . 11 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 + Retrieval . . . . . . . . . . . . . . . . . . . . . 10 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction - [I-D.ietf-ospf-mpls-elc] defines mechanisms to advertise Entropy - Readable Label Depth (ERLD) for ingress Label Switching Routers (LSR) - to discover other LSR's capability of performing Entropy Label based - load-balancing in MPLS networks. The ingress LSR can use this - information to construct the appropriate label stack for specific - traffic requirements, especially in segment routed networks and other - deployments requiring stacked LSPs. - - However, in inter-area scenarios, the Area Border Router (ABR) does - not advertise the originating OSPF router-id for inter-area prefixes. - An OSPF router in one area doesn't know the origin area of inter-area - prefixes and can't determine the router that originated these - prefixes or the ERLD capabilities of the destination. Therefore, it - is necessary to advertise the originator of these inter-area prefixes - to ensure the ingress LSR can construct the appropriate label stack. + Prefix attributes are advertised in OSPFv2 [RFC2328] using the + Extended Prefix Opaque Link State Advertisement (LSA) [RFC7684] and + in OSPFv3 [RFC5340] using the various Extended Prefix LSA types + [RFC8362]. - More generally, [RFC8476] defines a mechanism to advertise multiple - types of supported Maximum SID Depths (MSD) at node and/or link - granularity. This information will be referred when the head-end - router starts to send traffic to destination prefixes. In inter-area - scenario, it is also necessary for the sender to learn the - capabilities of the receivers associated with the inter-area - prefixes. + The identification of the originating router for a prefix in OSPF + varies by the type of the prefix and is currently not always + possible. For intra-area prefixes, the originating router is + identified by the advertising Router ID field of the area-scoped LSA + used for those prefix advertisements. However, for the inter-area + prefixes advertised by the Area Border Router (ABR), the advertising + Router ID field of their area-scoped LSAs is set to the ABR itself + and the information about the router originating the prefix + advertisement is lost in this process of prefix propagation across + areas. For Autonomous System (AS) external prefixes, the originating + router may be considered as the Autonomous System Border Router + (ASBR) and is identified by the advertising Router ID field of the + AS-scoped LSA used. However, the actual originating router for the + prefix may be a remote router outside the OSPF domain. Similarly, + when an ABR performs translation of Not-So-Stubby Area (NSSA) + [RFC3101] LSAs to AS-external LSAs, the information associated with + the NSSA ASBR (or the router outside the OSPF domain) is not conveyed + across the OSPF domain. - There is another scenario where knowing the originator of inter-area - prefixes is useful. For example, Border Gateway Protocol Link-State - (BGP-LS) [RFC7752] describes mechanisms using the BGP protocol to - advertise Link-State information. This information can enable a - Software Definition Network (SDN) controller to automatically - determine the underlay network topology. + While typically the originator of information in OSPF is identified + by its OSPF Router ID, it does not necessarily represent a reachable + address for the router. The IPv4/IPv6 Router Address as defined in + [RFC3630] and [RFC5329] for OSPFv2 and OSPFv3 respectively provide an + address to reach that router. - However, if the underlay network is partitioned into multiple areas - and running the OSPF protocol, it is not easy for the SDN controller - to rebuild the multi-area topology since ABR that connects multiple - areas will normally hide the detailed topology for these non-backbone - areas. If only the internal routers within backbone area run the - BGP-LS protocol, they just learn and report the summary network - information from the non-backbone areas. If the SDN controller can - learn the originator of the inter-area prefixes, it is possible to - rebuild the inter-area topology. + The primary use case for the extensions proposed in this document is + to be able to identify the originator of the prefix in the network. + In cases where multiple prefixes are advertised by a given router, it + is also useful to be able to associate all these prefixes with a + single router even when prefixes are advertised outside of the area + in which they originated. It also helps to determine when the same + prefix is being originated by multiple routers across areas. - [RFC7794] introduces the Intermediate System to Intermediate System - (IS-IS) "IPv4/IPv6 Source Router IDs" Type-Length-Value (TLV) to - advertise the source of prefixes leaked from a different IS-IS level. - This TLV can be used in the above scenarios. Such solution can also - be applied in networks that run the OSPF protocol, but existing OSPF - LSAs TLVs must be extended to include the router originating the - prefix. + This document proposes extensions to the OSPF protocol for inclusion + of information associated with the router originating the prefix + along with the prefix advertisement. These extensions do not change + the core OSPF route computation functionality. They provide useful + information for topology analysis and traffic engineering, especially + on a controller when this information is advertised as an attribute + of the prefixes via mechanisms such as Border Gateway Protocol Link- + State (BGP-LS) [RFC7752]. - This draft provides such solution for the OSPFv2 [RFC2328] and OSPFv3 - [RFC5340] protocols. + Applications related to use of the prefix originating node + information for topology reconstruction process on a controller and + the associated limitations are described in Appendix A and + Appendix B. -2. Conventions used in this document +1.1. 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. Terminology - - The following terms are used in this document: - - o ABR: Area Border Router - o ASBR: Autonomous System Border Router - - o ERLD: Entropy Readable Label Depth - - o EL: Entropy Label - - o IS-IS: Intermediate System to Intermediate System - - o LSA: Link-State Advertisement - - o MSD: Maximum SID Depths - - o NLRI: Network Layer Reachability Information - - o OSPF: Open Shortest Path First - - o SID: Segment IDentifier - - o SDN: Software Definition Network +2. Protocol Extensions -4. Inter-Area Prefix Source Advertisement Use Cases + This document defines the Prefix Source Router-ID and the Prefix + Originator Sub-TLVs for inclusion of the Router ID and a reachable + address information for the router originating the prefix as a prefix + attribute. - Figure 1 illustrates a topology where OSPF is running in multiple - areas. R0-R4 are routers in the backbone area, S1-S4 are internal - routers in area 1, and T1-T4 are internal routers in area 2. R1 and - R3 are ABRs between area 0 and area 1. R2 and R4 are ABRs between - area 0 and area 2. N1 is the network between router S1 and S2 and N2 - is the network between router T1 and T2. Ls1 is the loopback address - of Node S1 and Lt1 is the loopback address of Node T1. +2.1. Prefix Source Router-ID Sub-TLV - +-----------------+ - |IP SDN Controller| - +--------+--------+ - | - | BGP-LS - | - +---------------------+------+--------+-----+--------------+ - | +--+ +--+ ++-+ ++-+ +-++ + -+ +--+| - | |S1+--------+S2+---+R1+---|R0+----+R2+---+T1+--------+T2|| - | +-++ N1 +-++ ++-+ +--+ +-++ ++++ N2 +-++| - | | | | | || | | - | | | | | || | | - | +-++ +-++ ++-+ +-++ ++++ +-++| - | |S4+--------+S3+---+R3+-----------+R4+---+T3+--------+T4|| - | +--+ +--+ ++-+ +-++ ++-+ +--+| - | | | | - | | | | - | Area 1 | Area 0 | Area 2 | - +---------------------+---------------+--------------------+ + For OSPFv2, the Prefix Source Router-ID Sub-TLV is an optional Sub- + TLV of the OSPFv2 Extended Prefix TLV [RFC7684]. For OSPFv3, the + Prefix Source Router-ID Sub-TLV is an optional Sub-TLV of the Intra- + Area-Prefix TLV, Inter-Area-Prefix TLV, and External-Prefix TLV + [RFC8362] when originating either an IPv4 [RFC5838] or an IPv6 prefix + advertisement. - Figure 1: OSPF Inter-Area Prefix Originator Scenario + The Prefix Source Router-ID Sub-TLV has the following format: - If S1 wants to send traffic to prefix Lt1 that is connected to T1 in - another area, it should know the ERLD and MSD values associated with - the node T1, and then construct the right label stack at the ingress - node for traffic destined to prefix Lt1. + 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 | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | OSPF Router ID | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - In another scenario, If R0 has some method to learn the originator of - network N1 and reports such information to IP SDN controller, then it - is possible for the controller to reconstruct the topology in the - non-backbone areas. The topology reconstruction process and its - limitations are described in the Appendix A and Appendix B. + Figure 1: Prefix Source Router-ID Sub-TLV Format -5. External Prefix Source Advertisement Use Cases + Where: - Figure 2 illustrates a topology where OSPF is running in different - domain that is connected by an Autonomous System Border Router - (ASBR). A, B, and C are routers in the Domain 1; C, D, and E are - routers in Domain 2. Router C is the ASBR between the two domains. + o Type: 4 for OSPFv2 and 27 for OSPFv3 - When router E receives an external prefix, it will redistribute it as - an AS-External LSA within domain 2. When C receives such LSA, the - originator information for such external prefix will be lost when it - encodes the prefix information with the current LSA format field. In - some situations, it will be helpful if C can advertise such - originator information. + o Length: 4 - +-------------------------------------------------------------------+ - | | External Prefix | - | +---+ +---+ +---+ +---+ +-|-+ | - | | A +-------+ B +----------| C +---------+ D +---------+ E |------| - | +---+ +---+ +---+ +---+ +---+ | - | Domain 1 | Domain 2 | - +-------------------------------------------------------------------+ + o OSPF Router ID : the OSPF Router ID of the OSPF router that + originated the prefix advertisement in the OSPF domain. - Figure 2: OSPF External Prefix Originator Scenario + A prefix advertisement MAY include more than one Prefix Source + Router-ID sub-TLV, one corresponding to each of the Equal-Cost Multi- + Path (ECMP) nodes that originated the given prefix. - From the above scenarios, we can conclude that it is useful to define - the OSPF prefix originator sub TLV . + A received Prefix Source Router-ID Sub-TLV with OSPF Router ID set to + 0 MUST be considered invalid and ignored. Additionally, reception of + such Sub-TLV SHOULD be logged as an error (subject to rate-limiting). -6. Prefix Source Router-ID sub-TLV +2.2. Prefix Originator Sub-TLV - [RFC7684] and [RFC8362] respectively define TLV-based LSAs for OSPFv2 - and OSPFv3. These documents facilitate addition of new attributes - for prefixes and provide the basis for a sub-TLV to advertise the - "Prefix Source Router ID". For OSPFv2, this sub-TLV is a sub-TLV of - OSPFv2 Extended Prefix TLV which SHOULD be included in the "OSPFv2 - Extended Prefix Opaque LSA" [RFC7684] for inter-area prefixes. For - OSPFv3, this sub-TLV is a sub-TLV of "Inter-Area-Prefix TLV", which - SHOULD be included in the "E-Inter-Area-Prefix-LSA" [RFC8362]. + For OSPFv2, the Prefix Originator Sub-TLV is an optional Sub-TLV of + the OSPFv2 Extended Prefix TLV [RFC7684]. For OSPFv3, the Prefix + Originator Sub-TLV is an optional Sub-TLV of the Intra-Area-Prefix + TLV, Inter-Area-Prefix TLV, and External-Prefix TLV [RFC8362] when + originating either an IPv4 [RFC5838] or an IPv6 prefix advertisement. - The "Prefix Source Router-ID" sub-TLV has the following format: + The Prefix Originator 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Prefix Source Router-ID | - +---------------------------------------------------------------+ - Figure 3: Prefix Source Router-ID sub-TLV Format + | Router Address (4 or 16 octects) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - o Source Router-ID Sub-TLV Type: 4 (IANA TEMPORARY allocation) - [RFC7684] or 27 (IANA TEMPORARY allocation) [RFC8362] + Figure 2: Prefix Originator Sub-TLV Format - o Length: 4 + Where: - o Value: Router-ID of OSPFv2/OSPFv3 router that is the source of the - prefix. + o Type: TBD1 for OSPFv2 and TBD2 for OSPFv3 - This sub-TLV provides the same functionality as the IS-IS "IPv4/IPv6 - Source Router" TLV defined in [RFC7794]. + o Length: 4 or 16 -7. Elements of Procedure + o Router Address: A reachable IPv4 or IPv6 router address for the + router that originated the IPv4 or IPv6 prefix advertisement. + Such an address would be semantically equivalent to what may be + advertised in the OSPFv2 Router Address TLV [RFC3630] or in the + OSPFv3 Router IPv6 Address TLV [RFC5329]. - The following sections describe the procedure to include the newly - defined "Source Router-ID Sub-TLV" in the related LSA for inter-area - prefixes and external prefixes respectively. + A prefix advertisement MAY include more than one Prefix Originator + sub-TLV, one corresponding to each of the Equal-Cost Multi-Path + (ECMP) nodes that originated the given prefix. -7.1. Inter-Area Prefixes + A received Prefix Originator Sub-TLV that has an invalid length (not + 4 or 16) or a Reachable Address containing an invalid IPv4 or IPv6 + address (dependent on address family of the associated prefix) MUST + be considered invalid and ignored. Additionally, reception of such + Sub-TLV SHOULD be logged as an error (subject to rate-limiting). - When an ABR, for example R2 in Figure 1, receives a Router-LSA - advertisement in area 2, it SHOULD originate the corresponding - "OSPFv2 Extended Prefix Opaque LSA" for OSPFv2 or "E-Inter-Area- - Prefix-LSA" for OSPFv3 that includes the Source Router-ID sub-TLV for - the network prefixes. For example, to identify the source router - prefix Lt1 and other inter-area prefixes in Figure 1. + [RFC7794] provides similar functionality for the Intermediate System + to Intermediate System (IS-IS) protocol. - When a router in another area, e.g., S1, receives such LSA, it then - can ascertain that prefix Lt1 is associated with node T1 and obtain - the ERLD or MSD value from T1's Router-Information LSA [RFC7770] and - construct the right label stack at the ingress node S1 for traffic - destined to prefix Lt1. +3. Elements of Procedure - When a router in another area, e.g., R0, receives such LSA, it learns - the Prefix Source Router-id and includes it in the prefix information - advertised to an SDN controller as described in - [I-D.ietf-idr-bgp-ls-segment-routing-ext]. The SDN controller can - then use such information to build the inter-area topology according - to the process described in the Appendix A. The topology retrieval - process may not suitable for some environments as stated in - Appendix B. + This section describes the procedure for advertisement of the Prefix + Source Router-ID and Prefix Originator Sub-TLVs along with the prefix + advertisement. -7.2. External Prefixes + The OSPF Router ID of the Prefix Source Router-ID is set to the OSPF + Router ID of the node originating the prefix in the OSPF domain. - When an ASBR, for example C in Figure 2, receives an AS-External LSA - for an external prefix in domain 2, it SHOULD extract the originator - information from the "Advertising Router" field from the LSA header. - When the prefix is advertised into domain 1 as an AS-External LSA, - router C may also advertise the Source Router-ID using a AS-scoped - OSPFv2 Extended Prefix Opaque LSA or as a Sub-TLV in the OSPFv3 AS- - External LSA. + If the originating node is advertising an OSPFv2 Router Address TLV + [RFC3630] or an OSPFv3 Router IPv6 Address TLV [RFC5329], then that + value is set in the Router Address field of the Prefix Originator + Sub-TLV. When the orignating node is not advertising such an + address, implementations MAY support mechanisms to determine a + reachable address belonging to the originating node to set in the + Router Address field. Such mechanisms are outside the scope of this + document. -8. Security Considerations + Implementations MAY support the selection of specific prefixes for + which the originating node information needs to be included with + their prefix advertisements. - Since this document extends the "OSPFv2 Extended Prefix LSA" and - "OSPFv3 E-Inter-Area-Prefix LSA", the security considerations for - [RFC7684] and [RFC8362] are applicable. + When an ABR generates inter-area prefix advertisements into its non- + backbone areas corresponding to an inter-area prefix advertisement + from the backbone area, the only way to determine the originating + node information is based on the Prefix Source Router-ID and Prefix + Originator Sub-TLVs present in the inter-area prefix advertisement + originated into the backbone area by an ABR for another non-backbone + area. The ABR performs its prefix calculation to determine the set + of nodes that contribute to the best prefix reachability. It MUST + use the prefix originator information only from this set of nodes. + The ABR MUST NOT include the Prefix Source Router-ID or the Prefix + Originator Sub-TLVs when it is unable to determine the information of + the best originating node. - Modification of the "Prefix Source Sub-TLV" could be used for a - Denial-of-Service attack and could inhibit the use cases described in - Section 4. If the OSPF domain is vulnerable to such attacks, OSPF - authentication should be used as defined for OSPFv2 in [RFC5709] and - [RFC7474] and for OSPFv3 in [RFC7166]. + Implementations MAY provide control on ABRs to selectively disable + the propagation of the originating node information across area + boundaries. - Additionally, advertisement of the prefix source for inter-area - prefixes facilitates reconstruction of the OSPF topology for other - areas. Network operators may consider their topologies to be - sensitive confidential data. For OSPFv3, IPsec can be used to - provide confidentiality [RFC4552]. Since there is no standard - defined for native OSPFv2 IPsec, some form of secure tunnel is - required to provide confidentiality. + Implementations MAY support the propagation of the originating node + information along with a redistributed prefix into the OSPF domain + from another routing domain. The details of such mechanisms are + outside the scope of this document. Such implementations MAY also + provide control on whether the Router Address in the Prefix + Originator Sub-TLV is set as the ABSR node address or as the address + of the actual node outside the OSPF domain that owns the prefix. -9. IANA Considerations + When translating the NSSA prefix advertisements [RFC3101] to the AS + external prefix advertisements, the NSSA ABR, follows the same + procedures as an ABR generating inter-area prefix advertisements for + the propagation of the originating node information. - This specification defines the Prefix Source Router-ID sub-TLV as - described in Section 6. This value should be added to the both - existing "OSPFv2 Extended Prefix TLV Sub-TLVs" and "OSPFv3 Extended- - LSA Sub-TLVs" registries. +4. Security Considerations - The following sub-TLV is added to the "OSPFv2 Extended Prefix TLV - Sub-TLVs" registry. The allocation policy is IETF Review as defined - in [RFC7684] + Since this document extends the OSPFv2 Extended Prefix LSA, the + security considerations for [RFC7684] are applicable. Similarly, + since this document extends the OSPFv3 E-Intra-Area-Prefix-LSA, E- + Inter-Area-Prefix-LSA, E-AS-External LSA and E-NSSA-LSA, the security + considerations for [RFC8362] are applicable. - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Code Point | Description | Status | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | 4 | Prefix Source Sub-TLV | Allocation from IANA | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 4: Code Point in "OSPFv2 Extended Prefix TLV Sub-TLVs" +5. IANA Considerations - The following sub-TLV is added to the "OSPFv3 Extended-LSA Sub-TLVs" - registry. The allocation policy is IETF Review as defined in - [RFC8362] + This document requests IANA for the allocation of the codepoint from + the "OSPFv2 Extended Prefix TLV Sub-TLVs" registry under the "Open + Shortest Path First v2 (OSPFv2) Parameters" registry. - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Code Point | Description | Status | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | 27 | Prefix Source Sub-TLV | Allocation from IANA | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 5: Code Point in "OSPFv3 Extended-LSA Sub-TLVs" + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Code | Description | IANA Allocation | + | Point | | Status | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | 4 | Prefix Source Router-ID Sub-TLV | early allocation done | + | TBD1 | Prefix Originator Sub-TLV | pending | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -10. Acknowledgement + Figure 3: Code Points in OSPFv2 Extended Prefix TLV Sub-TLVs + + This document requests IANA for the allocation of the codepoint from + the "OSPFv3 Extended Prefix TLV Sub-TLVs" registry under the "Open + Shortest Path First v3 (OSPFv3) Parameters" registry. + + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Code | Description | IANA Allocation | + | Point | | Status | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | 27 | Prefix Source Router-ID Sub-TLV | early allocation done | + | TBD2 | Prefix Originator Sub-TLV | pending | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Figure 4: Code Points in OSPFv3 Extended-LSA Sub-TLVs + +6. Acknowledgement Many thanks to Les Ginsberg for his suggestions on this draft. Also thanks to Jeff Tantsura, Rob Shakir, Gunter Van De Velde, Goethals Dirk, Smita Selot, Shaofu Peng, and John E Drake for their valuable comments. -11. References +7. References -11.1. Normative References +7.1. Normative References [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, . - [RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality - for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006, - . + [RFC3101] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option", + RFC 3101, DOI 10.17487/RFC3101, January 2003, + . [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, . - [RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M., - Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic - Authentication", RFC 5709, DOI 10.17487/RFC5709, October - 2009, . - - [RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting - Authentication Trailer for OSPFv3", RFC 7166, - DOI 10.17487/RFC7166, March 2014, - . - - [RFC7474] Bhatia, M., Hartman, S., Zhang, D., and A. Lindem, Ed., - "Security Extension for OSPFv2 When Using Manual Key - Management", RFC 7474, DOI 10.17487/RFC7474, April 2015, - . - [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 2015, . - [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and - S. Shaffer, "Extensions to OSPF for Advertising Optional - Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, - February 2016, . - [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, 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, . [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, . - [RFC8476] Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak, - "Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476, - DOI 10.17487/RFC8476, December 2018, - . +7.2. Informative References -11.2. Informative References + [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering + (TE) Extensions to OSPF Version 2", RFC 3630, + DOI 10.17487/RFC3630, September 2003, + . - [I-D.ietf-idr-bgp-ls-segment-routing-ext] - Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H., - and M. Chen, "BGP Link-State extensions for Segment - Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-16 - (work in progress), June 2019. + [RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed., + "Traffic Engineering Extensions to OSPF Version 3", + RFC 5329, DOI 10.17487/RFC5329, September 2008, + . - [I-D.ietf-ospf-mpls-elc] - Xu, X., Kini, S., Psenak, P., Filsfils, C., Litkowski, S., - and M. Bocci, "Signaling Entropy Label Capability and - Entropy Readable Label-stack Depth Using OSPF", draft- - ietf-ospf-mpls-elc-12 (work in progress), October 2019. + [RFC5838] Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and + R. Aggarwal, "Support of Address Families in OSPFv3", + RFC 5838, DOI 10.17487/RFC5838, April 2010, + . [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, . Appendix A. Inter-Area Topology Retrieval Process When an IP SDN Controller receives BGP-LS [RFC7752] information, it should compare the prefix Network Layer Reachability Information (NLRI) that is included in the BGP-LS NLRI. When it encounters the same prefix but with different source router ID, it should extract the corresponding area-ID, rebuild the link between these two source routers in the non-backbone area. Below is one example that based on - the Figure 1: + the Figure 5 which illustrates a topology where OSPF is running in + multiple areas. + + +-----------------+ + |IP SDN Controller| + +--------+--------+ + | + | BGP-LS + | + +---------------------+------+--------+-----+--------------+ + | +--+ +--+ ++-+ ++-+ +-++ + -+ +--+| + | |S1+--------+S2+---+R1+---|R0+----+R2+---+T1+--------+T2|| + | +-++ N1 +-++ ++-+ +--+ +-++ ++++ N2 +-++| + | | | | | || | | + | | | | | || | | + | +-++ +-++ ++-+ +-++ ++++ +-++| + | |S4+--------+S3+---+R3+-----------+R4+---+T3+--------+T4|| + | +--+ +--+ ++-+ +-++ ++-+ +--+| + | | | | + | | | | + | Area 1 | Area 0 | Area 2 | + +---------------------+---------------+--------------------+ + + Figure 5: OSPF Inter-Area Prefix Originator Scenario + + R0-R4 are routers in the backbone area, S1-S4 are internal routers in + area 1, and T1-T4 are internal routers in area 2. R1 and R3 are ABRs + between area 0 and area 1. R2 and R4 are ABRs between area 0 and + area 2. N1 is the network between router S1 and S2 and N2 is the + network between router T1 and T2. Ls1 is the loopback address of + Node S1 and Lt1 is the loopback address of Node T1. Assuming we want to rebuild the connection between router S1 and router S2 located in area 1: a. Normally, router S1 will advertise prefix N1 within its router- LSA. b. When this router-LSA reaches the ABR router R1, it will convert - it into summary-LSA, add the Prefix Source Router-ID sub-TLV, - which is router id of S1 in this example. + it into summary-LSA, add the Source Router-ID Sub-TLV and the + Prefix Originator Sub-TLV, as described in Section 3. c. R1 then floods this extension summary-LSA to R0, which is using the BGP-LS protocol with IP SDN Controller. The controller then knows the prefix for N1 is from S1. d. Router S2 will perform a similar process, and the controller will also learn that prefix N1 is also from S2. e. Then it can reconstruct the link between S1 and S2, using the prefix N1. The topology within Area 1 can then be reconstructed @@ -522,15 +489,13 @@ Peter Psenak Cisco Systems Pribinova Street 10 Bratislava, Eurovea Centre, Central 3 81109 Slovakia Email: ppsenak@cisco.com Ketan Talaulikar Cisco Systems - S.No. 154/6, Phase I, Hinjawadi - Pune 411 057 India Email: ketant@cisco.com