<?xmlversion="1.0" encoding="US-ASCII"?>version='1.0' encoding='utf-8'?> <!DOCTYPE rfc SYSTEM"rfc2629.dtd"> <?rfc toc="yes"?> <?rfc tocompact="yes"?> <?rfc tocdepth="3"?> <?rfc tocindent="yes"?> <?rfc symrefs="yes"?> <?rfc sortrefs="yes"?> <?rfc comments="yes"?> <?rfc inline="yes"?> <?rfc compact="yes"?> <?rfc subcompact="no"?>"rfc2629-xhtml.ent"> <rfccategory="std"xmlns:xi="http://www.w3.org/2001/XInclude" number="8666" docName="draft-ietf-ospf-ospfv3-segment-routing-extensions-23"ipr="trust200902">category="std" submissionType="IETF" consensus="true" ipr="trust200902" obsoletes="" updates="" xml:lang="en" tocInclude="true" symRefs="true" sortRefs="true" version="3"> <front> <title abbrev="OSPFv3 Extensions for Segment Routing">OSPFv3 Extensions for Segment Routing</title> <seriesInfo name="RFC" value="8666"/> <author fullname="Peter Psenak" initials="P." role="editor" surname="Psenak"> <organization>Cisco Systems, Inc.</organization> <address> <postal> <street>Eurovea Centre, Central 3</street> <street>Pribinova Street 10</street> <city>Bratislava</city> <code>81109</code> <country>Slovakia</country> </postal> <email>ppsenak@cisco.com</email> </address> </author> <author fullname="Stefano Previdi" initials="S." role="editor" surname="Previdi"><organization>Individual</organization><organization>Cisco Systems, Inc.</organization> <address> <postal><street></street> <city></city> <code></code> <country></country><street/> <city/> <code/> <country/> </postal><email>stefano.previdi@net</email><email>stefano@previdi.net</email> </address> </author> <dateyear=""/>month="December" year="2019"/> <area>Routing</area> <workgroup>Open Shortest Path First IGP</workgroup><keyword>MPLS</keyword> <keyword>SID</keyword> <keyword>IGP</keyword> <keyword>OSPF</keyword> <keyword>Label advertisement</keyword> <keyword>Segment<keyword>MPLS, SID, IGP, OSPF, Label advertisement, Segment Routing</keyword> <abstract> <t>Segment Routing (SR) allows a flexible definition of end-to-end paths within IGP topologies by encoding paths as sequences of topologicalsub-paths,subpaths called "segments". These segments are advertised by the link-state routing protocols (IS-IS and OSPF).</t> <t>Thisdraftdocument describes the OSPFv3 extensions required for Segment Routing with the MPLS data plane.</t> </abstract><note title="Requirements Language"> <t>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 BCP14 <xref target="RFC2119"/> <xref target="RFC8174"/> when, and only when, they appear in all capitals, as shown here.</t> </note></front> <middle> <sectiontitle="Introduction">numbered="true" toc="default"> <name>Introduction</name> <t>Segment Routing (SR) allows a flexible definition of end-to-end paths within IGP topologies by encoding paths as sequences of topologicalsub-paths,subpaths called "segments". These segments are advertised by the link-state routing protocols (IS-IS and OSPF). Prefix segments represent an ECMP-awareshortest-pathshortest path to a prefix (or anode),node) as per the state of the IGP topology. Adjacency segments represent a hop over a specific adjacency between two nodes in the IGP. A prefix segment is typically a multi-hop path while an adjacency segment, in most cases, is a one-hop path. SR'scontrol-planecontrol plane can be applied to both IPv6 and MPLSdata-planes,data planes, and it does not require any additionalsignallingsignaling (other than IGP extensions). The IPv6 data plane is out of the scope of thisspecification -specification; the OSPFv3 extension for SR with the IPv6 data plane will be specified in a separate document. When used in MPLS networks, SR paths do not require any LDP or RSVP-TEsignalling.signaling. However, SR can interoperate in the presence ofLSPsLabel Switched Paths (LSPs) established with RSVP or LDP.</t> <t>Thisdraftdocument describes the OSPFv3 extensions required for Segment Routing with the MPLS data plane.</t> <t>Segment Routing architecture is described in <xreftarget="RFC8402"/>.</t>target="RFC8402" format="default"/>.</t> <t>Segment Routing use cases are described in <xreftarget="RFC7855"/>.</t>target="RFC7855" format="default"/>.</t> </section> <sectiontitle="Terminology">numbered="true" toc="default"> <name>Terminology</name> <t>This section lists some of the terminology used in this document:<list style="hanging"> <t>ABR - Area</t> <dl newline="false" spacing="normal" indent="12"> <dt>ABR:</dt> <dd>Area BorderRouter</t> <t>Adj-SID - AdjacencyRouter</dd> <dt>Adj-SID:</dt> <dd>Adjacency SegmentIdentifier</t> <t>AS - Autonomous System</t> <t>ASBR - AutonomousIdentifier</dd> <dt>AS:</dt> <dd>Autonomous System</dd> <dt>ASBR:</dt> <dd>Autonomous System BoundaryRouter</t> <t>DR - Designated Router</t> <t>IS-IS - IntermediateRouter</dd> <dt>DR:</dt> <dd>Designated Router</dd> <dt>IS-IS:</dt> <dd>Intermediate System to IntermediateSystem</t> <t>LDP - LabelSystem</dd> <dt>LDP:</dt> <dd>Label DistributionProtocol</t> <t>LSP - LabelProtocol</dd> <dt>LSP:</dt> <dd>Label SwitchedPath</t> <t>MPLS - Multi ProtocolPath</dd> <dt>MPLS:</dt> <dd>Multiprotocol LabelSwitching</t> <t>OSPF - OpenSwitching</dd> <dt>OSPF:</dt> <dd>Open Shortest PathFirst</t> <t>SPF - ShortestFirst</dd> <dt>SPF:</dt> <dd>Shortest PathFirst</t> <t>RSVP - ResourceFirst</dd> <dt>RSVP:</dt> <dd>Resource ReservationProtocol</t> <t>SID - Segment Identifier</t> <t>SR - Segment Routing</t> <t>SRGB - SegmentProtocol</dd> <dt>SID:</dt> <dd>Segment Identifier</dd> <dt>SR:</dt> <dd>Segment Routing</dd> <dt>SRGB:</dt> <dd>Segment Routing GlobalBlock</t> <t>SRLB - SegmentBlock</dd> <dt>SRLB:</dt> <dd>Segment Routing LocalBlock</t> <t>SRMS - SegmentBlock</dd> <dt>SRMS:</dt> <dd>Segment Routing MappingServer</t> <t>TLV - TypeServer</dd> <dt>TLV:</dt> <dd>Type LengthValue</t> </list></t>Value</dd> </dl> <t> The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>", "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as described in BCP 14 <xref target="RFC2119" format="default"/> <xref target="RFC8174" format="default"/> when, and only when, they appear in all capitals, as shown here. </t> </section> <sectiontitle="Segmentnumbered="true" toc="default"> <name>Segment RoutingIdentifiers">Identifiers</name> <t>Segment Routing defines various types of Segment Identifiers (SIDs): Prefix-SID,Adjacency-SID,Adjacency SID, and LAN Adjacency SID.</t> <section anchor="SIDLABEL"title="SID/Label Sub-TLV">numbered="true" toc="default"> <name>SID/Label Sub-TLV</name> <t>The SID/LabelSub-TLVsub-TLV appears in multiple TLVs orSub-TLVssub-TLVs defined later in this document. It is used to advertise the SID or label associated with a prefix or adjacency. The SID/LabelSub-TLVsub-TLV has the followingformat:<figure> <artwork>format:</t> <artwork name="" type="" align="left" alt=""><![CDATA[ 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SID/Label (variable) |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where: </artwork> </figure><list style="hanging"> <t>Type: 7</t> <t>Length: Either 3+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork><t>where:</t> <ul empty="true"><li><dl newline="false" spacing="normal"> <dt>Type:</dt> <dd>7</dd> <dt>Length:</dt> <dd>3 or 4octets</t> <t>SID/Label: Ifoctets.</dd> <dt>SID/Label:</dt> <dd>If the length is set to 3, then the 20 rightmost bits represent a label. If the length is set to 4, then the value represents a 32-bitSID.</t> <t>The receiving router MUST ignore the SID/Label Sub-TLV if the length is other than 3 or 4.</t> </list></t>SID.</dd> </dl></li></ul> </section> </section> <section anchor="SRCAP"title="Segmentnumbered="true" toc="default"> <name>Segment RoutingCapabilities">Capabilities</name> <t>Segment Routing requires some additional router capabilities to be advertised to other routers in the area.</t> <t>These SR capabilities are advertised in the OSPFv3 Router Information Opaque LSA (defined in <xreftarget="RFC7770"/>)target="RFC7770" format="default"/>) and specified in <xreftarget="I-D.ietf-ospf-segment-routing-extensions"/>.</t>target="RFC8665" format="default"/>.</t> </section> <section anchor="PFXRANGE"title="OSPFv3numbered="true" toc="default"> <name>OSPFv3 Extended Prefix RangeTLV">TLV</name> <t>In somecasescases, it is useful to advertise attributes for a range of prefixes in a single advertisement. TheSegment RoutingSR Mapping Server, which is described in <xreftarget="I-D.ietf-spring-segment-routing-ldp-interop"/>,target="RFC8661" format="default"/>, is an example of where SIDs for multiple prefixes can be advertised. To optimize such advertisement in case of multiple prefixes from a contiguous address range, OSPFv3 Extended Prefix Range TLV isdefined."</t>defined.</t> <t>The OSPFv3 Extended Prefix Range TLV is a top-level TLV of the following LSAs defined in <xreftarget="RFC8362"/>: <list style="hanging"> <t>E-Intra-Area-Prefix-LSA</t> <t>E-Inter-Area-Prefix-LSA</t> <t>E-AS-External-LSA</t> <t>E-Type-7-LSA</t> </list></t>target="RFC8362" format="default"/>: </t> <ul empty="true" spacing="normal"> <li>E-Intra-Area-Prefix-LSA</li> <li>E-Inter-Area-Prefix-LSA</li> <li>E-AS-External-LSA</li> <li>E-Type-7-LSA</li> </ul> <t>Multiple OSPFv3 Extended Prefix Range TLVsMAY<bcp14>MAY</bcp14> be advertised in each LSA mentioned above. The OSPFv3 Extended Prefix Range TLV has the following format:<figure> <artwork></t> <artwork name="" type="" align="left" alt=""><![CDATA[ 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 Length | AF | Range Size | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Address Prefix (variable) | | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sub-TLVs (variable) | +- -+ || where: </artwork> </figure><list style="hanging"> <t>Type: 9</t> <t>Length: Variable,|]]></artwork> <t>where:</t><ul empty="true"><li><dl newline="false" spacing="normal"> <dt>Type:</dt> <dd>9</dd> <dt>Length:</dt> <dd>Variable, in octets,dependentdepending onSub-TLVs.</t> <t>Prefix length: Lengththe sub-TLVs.</dd> <dt>Prefix Length:</dt> <dd>Length of prefix inbits.</t> <t>AF: Addressbits.</dd> <dt>AF:</dt> <dd> <t>Address family for the prefix.<list style="hanging"> <t>AF: 0</t> <dl newline="false" spacing="normal"> <dt>AF:</dt> <dd>0 - IPv4unicast</t> <t>AF: 1unicast</dd> <dt>AF:</dt> <dd>1 - IPv6unicast</t> </list></t> <t>Range size: Representsunicast</dd> </dl> </dd> <dt>Range Size:</dt> <dd> <t>Represents the number of prefixes that are covered by the advertisement. The Range SizeMUST NOT<bcp14>MUST NOT</bcp14> exceed the number of prefixes that could be satisfied by theprefix lengthPrefix Length without including:<list style="hanging"> <t>Addresses</t> <ul empty="true" spacing="normal"> <li>Addresses from the IPv4 multicast address range (224.0.0.0/3), if the AF is IPv4unicast</t> <t>Addressesunicast.</li> <li>Addresses other than the IPv6 unicast addresses, if the AF is IPv6unicast</t> </list></t> <t>Flags: Reserved. MUSTunicast.</li> </ul> </dd> <dt>Flags:</dt> <dd>Reserved. <bcp14>MUST</bcp14> be zero when sent and are ignored whenreceived.</t> <t>Reserved: SHOULDreceived.</dd> <dt>Reserved:</dt> <dd><bcp14>SHOULD</bcp14> be set to 0 on transmission andMUST<bcp14>MUST</bcp14> be ignored onreception.</t> <t>Address Prefix: <list style="hanging"> <t>Forreception.</dd> <dt>Address Prefix:</dt> <dd> <ul empty="true" spacing="normal"> <li>For the address family IPv4 unicast, the prefix itself is encoded as a 32-bit value. The default route is represented by a prefix of length0.</t> <t>For0.</li> <li>For the address family IPv6 unicast, theprefix,prefix is encoded as an even multiple of 32-bitwords,words and padded with zeroed bits as necessary. This encoding consumes ((PrefixLength + 31) / 32) 32-bit words.</t> <t>Prefix</li> <li>Prefix encoding for other address families is beyond the scope of this specification. Prefix encoding for other address families can be defined inthefuturestandard-trackStandards Track specifications from the IETFspecifications.</t> </list></t> </list></t>stream.</li> </ul> </dd> </dl></li></ul> <t>The range represents the contiguous set of prefixes with the same prefix length as specified by the Prefix Length field. The set starts with the prefix that is specified by the Address Prefix field. The number of prefixes in the range is equal to the Rangesize.</t>Size.</t> <t>If the OSPFv3 Extended Prefix Range TLVs advertising the exact same range appears in multiple LSAs of the same type, originated by the same OSPFv3 router, the LSA with the numerically smallest Instance IDMUST<bcp14>MUST</bcp14> beusedused, and subsequent instances of the OSPFv3 Extended Prefix Range TLVsMUST<bcp14>MUST</bcp14> be ignored.</t> </section> <section anchor="PREFIXSID"title="Prefix SID Sub-TLV">numbered="true" toc="default"> <name>Prefix-SID Sub-TLV</name> <t>ThePrefix SID Sub-TLVPrefix-SID sub-TLV is aSub-TLVsub-TLV of the following OSPFv3 TLVs as defined in <xreftarget="RFC8362"/>target="RFC8362" format="default"/> and in <xreftarget="PFXRANGE"/>: <list style="hanging"> <t>Intra-Areatarget="PFXRANGE" format="default"/>: </t> <ul empty="true" spacing="normal"> <li>Intra-Area PrefixTLV</t> <t>Inter-AreaTLV</li> <li>Inter-Area PrefixTLV</t> <t>ExternalTLV</li> <li>External PrefixTLV</t> <t>OSPFv3TLV</li> <li>OSPFv3 Extended Prefix RangeTLV</t> </list></t>TLV</li> </ul> <t>ItMAY<bcp14>MAY</bcp14> appear more than once in the parent TLV and has the following format:<figure> <artwork></t> <artwork name="" type="" align="left" alt=""><![CDATA[ 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | Algorithm | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SID/Index/Label (variable) |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where:</artwork> </figure><list style="hanging"> <t>Type: 4</t> <t>Length: 7+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork><t>where:</t> <ul empty="true"><li><dl newline="false" spacing="normal"> <dt>Type:</dt> <dd>4</dd> <dt>Length:</dt> <dd>7 or 8 octets,dependentdepending on theV-flag</t> <t>Flags: Single octetV-Flag.</dd> <dt>Flags:</dt> <dd> <t>Single-octet field. The following flags are defined:<figure align="center"> <artwork></t> <artwork name="" type="" align="left" alt=""><![CDATA[ 0 1 2 3 4 5 6 7 +--+--+--+--+--+--+--+--+ | |NP|M |E |V |L | | |+--+--+--+--+--+--+--+--+ where:</artwork> </figure><list style="hanging"> <t>NP-Flag: No-PHP flag.+--+--+--+--+--+--+--+--+]]></artwork> <t>where:</t> <dl newline="false" spacing="normal"> <dt>NP-Flag:</dt> <dd>No-PHP (Penultimate Hop Popping) Flag. If set, then the penultimate hopMUST NOT<bcp14>MUST NOT</bcp14> pop the Prefix-SID before delivering packets to the node that advertised thePrefix-SID.</t> <t>M-Flag: MappingPrefix-SID.</dd> <dt>M-Flag:</dt> <dd>Mapping Server Flag. If set, the SID was advertised bya Segment Routingan SR Mapping Server as described in <xreftarget="I-D.ietf-spring-segment-routing-ldp-interop"/>.</t> <t>E-Flag: Explicit-Nulltarget="RFC8661" format="default"/>.</dd> <dt>E-Flag:</dt> <dd>Explicit Null Flag. If set, any upstream neighbor of the Prefix-SID originatorMUST<bcp14>MUST</bcp14> replace the Prefix-SID with theExplicit-NULLExplicit NULL label (0 for IPv4, 2 for IPv6) before forwarding thepacket.</t> <t>V-Flag: Value/Indexpacket.</dd> <dt>V-Flag:</dt> <dd>Value/Index Flag. If set, then the Prefix-SID carries an absolute value. If not set, then the Prefix-SID carries anindex.</t> <t>L-Flag: Local/Globalindex.</dd> <dt>L-Flag:</dt> <dd>Local/Global Flag. If set, then the value/index carried by the Prefix-SID has local significance. If not set, then the value/index carried by thisSub-TLVsub-TLV has globalsignificance.</t> <t>Other bits: Reserved.significance.</dd> <dt>Other bits:</dt> <dd>Reserved. TheseMUST<bcp14>MUST</bcp14> be zero when sent and are ignored whenreceived.</t> </list></t> <t>Reserved: SHOULDreceived.</dd> </dl> </dd> <dt>Reserved:</dt> <dd><bcp14>SHOULD</bcp14> be set to 0 on transmission andMUST<bcp14>MUST</bcp14> be ignored onreception.</t> <t>Algorithm: Singlereception.</dd> <dt>Algorithm:</dt> <dd><t>Single octet identifying the algorithm the Prefix-SID is associated with as defined in the IGP Algorithm Types registry <xreftarget="I-D.ietf-ospf-segment-routing-extensions"/>.</t>target="ALGOREG" format="default"/>.</t> <t>A router receiving a Prefix-SID from a remote node and with an algorithm value thatsuchthe remote node has not advertised in the SR-Algorithm TLV <xreftarget="I-D.ietf-ospf-segment-routing-extensions"/> MUSTtarget="RFC8665" format="default"/> <bcp14>MUST</bcp14> ignore the Prefix-SIDSub-TLV.</t> <t>SID/Index/Label: Accordingsub-TLV.</t></dd> <dt>SID/Index/Label:</dt> <dd> <t>According to the V-Flag and L-Flag, it contains:<list style="hanging"> <t>V-flag</t> <ul empty="true" spacing="normal"> <li>V-Flag is set to 0 andL-flagL-Flag is set to 0: The SID/Index/Label field is a4 octet4-octet index defining the offset in the SID/Label space advertised by thisrouter</t> <t>V-flagrouter.</li> <li>V-Flag is set to 1 andL-flagL-Flag is set to 1: The SID/Index/Label field is a3 octet3-octet local label where the 20 rightmost bits are used for encoding the labelvalue.</t> <t>Allvalue.</li> <li>All other combinations ofV-flagV-Flag andL-flagL-Flag are invalid and any SIDadvertisementAdvertisement received with an invalid setting forVV- andL flags MUSTL-Flags <bcp14>MUST</bcp14> beignored.</t> </list></t> </list></t>ignored.</li> </ul> </dd> </dl></li></ul> <t>If an OSPFv3 router advertises multiple Prefix-SIDs for the same prefix, topology, and algorithm, all of themMUST<bcp14>MUST</bcp14> be ignored.</t> <t>When calculating the outgoing label for the prefix, the routerMUST<bcp14>MUST</bcp14> take into account, as described below, theE, NP,E-, NP-, andM flagsM-Flags advertised by the next-hop router if that router advertised the SID for the prefix. ThisMUST<bcp14>MUST</bcp14> be done regardless of whether the next-hop router contributes to the best path to the prefix.</t> <t>The NP-Flag (No-PHP)MUST<bcp14>MUST</bcp14> be set and theE-flag MUSTE-Flag <bcp14>MUST</bcp14> be clear for Prefix-SIDs allocated to prefixes that are propagated between areas by an ABR based on intra-area or inter-area reachability, unless the advertised prefix is directly attached to such ABR.</t> <t>The NP-Flag (No-PHP)MUST<bcp14>MUST</bcp14> be set and theE-flag MUSTE-Flag <bcp14>MUST</bcp14> be clear for Prefix-SIDs allocated to redistributed prefixes, unless the redistributed prefix is directly attached to the advertising ASBR.</t> <t>If the NP-Flag is not set,then anythen:</t> <ul empty="true" spacing="normal"> <li>Any upstream neighbor of the Prefix-SID originatorMUST<bcp14>MUST</bcp14> pop the Prefix-SID. This is equivalent to the penultimatehop poppinghop-popping mechanism used in the MPLSdataplane. If the NP-flag is not set, then thedata plane.</li> <li>The receivedE-flagE-Flag isignored.</t>ignored.</li> </ul> <t>If theNP-flagNP-Flag is setthen:<list style="hanging"> <t> Ifand theE-flagE-Flag is not set,then anythen:</t> <ul empty="true" spacing="normal"> <li>Any upstream neighbor of the Prefix-SID originatorMUST<bcp14>MUST</bcp14> keep the Prefix-SID on top of the stack. This is useful when the originator of the Prefix-SID needs to stitch the incoming packet into a continuing MPLS LSP to the final destination. This could occur at an ABR (prefix propagation from one area to another) or at an ASBR (prefix propagation from one domain toanother).</t>another). </li> </ul> <t>If both theE-flag isNP-Flag and E-Flag are set,then anythen:</t> <ul empty="true" spacing="normal"> <li>Any upstream neighbor of the Prefix-SID originatorMUST<bcp14>MUST</bcp14> replace the Prefix-SID with anExplicit-NULLExplicit NULL label. This is useful, e.g., when the originator of the Prefix-SID is the final destination for the related prefix and the originator wishes to receive the packet with the original Traffic Class field <xreftarget="RFC5462"/>.</t> </list></t>target="RFC5462" format="default"/>.</li> </ul> <t>When the M-Flag is set, theNP-flagNP-Flag and theE-flag MUSTE-Flag <bcp14>MUST</bcp14> be ignored on reception.</t> <t>As the Mapping Server does not specify the originator of a prefix advertisement, it is not possible to determine PHP behavior solely based on the Mapping Serveradvertisement.Advertisement. However, PHP behaviorSHOULD<bcp14>SHOULD</bcp14> be done in the following cases:<list style="hanging"> <t>The</t> <ul empty="true" spacing="normal"> <li>The Prefix is intra-area type and the downstream neighbor is the originator of theprefix.</t> <t>Theprefix.</li> <li>The Prefix is inter-area type and the downstream neighbor is an ABR, which is advertising prefix reachability and is setting the LA-bit in the Prefix Options as described in <xreftarget="RFC8362"/>.</t> <t>Thetarget="RFC8362" format="default"/>.</li> <li>The Prefix is external type and the downstream neighbor is an ASBR, which is advertising prefix reachability and is setting the LA-bit in the Prefix Options as described in <xreftarget="RFC8362"/>.</t> </list></t>target="RFC8362" format="default"/>.</li> </ul> <t>When a Prefix-SID is advertised in the OSPFv3 Extended Prefix Range TLV, then the value advertised in thePrefix SID Sub-TLVPrefix-SID sub-TLV is interpreted as a starting SID/Label value.</t> <t>Example 1: If the following router addresses (loopback addresses) need to be mapped into the correspondingPrefix SIDPrefix-SID indexes:<figure suppress-title="true"> <artwork></t> <artwork name="" type="" align="left" alt=""><![CDATA[ Router-A: 2001:DB8::1/128, Prefix-SID: Index 1 Router-B: 2001:DB8::2/128, Prefix-SID: Index 2 Router-C: 2001:DB8::3/128, Prefix-SID: Index 3 Router-D: 2001:DB8::4/128, Prefix-SID: Index4 </artwork> </figure></t>4]]></artwork> <t>then the Address Prefix field in the OSPFv3 Extended Prefix Range TLV would be set to 2001:DB8::1, the Prefix Length would be set to 128, the Range Size would be set to 4, and the Index value in the Prefix-SIDSub-TLVsub-TLV would be set to 1.</t> <t>Example 2: If the following prefixes need to be mapped into the corresponding Prefix-SID indexes:<figure suppress-title="true"> <artwork></t> <artwork name="" type="" align="left" alt=""><![CDATA[ 2001:DB8:1::0/120, Prefix-SID: Index 51 2001:DB8:1::100/120, Prefix-SID: Index 52 2001:DB8:1::200/120, Prefix-SID: Index 53 2001:DB8:1::300/120, Prefix-SID: Index 54 2001:DB8:1::400/120, Prefix-SID: Index 55 2001:DB8:1::500/120, Prefix-SID: Index 56 2001:DB8:1::600/120, Prefix-SID: Index57 </artwork> </figure></t>57]]></artwork> <t>then the Prefix field in the OSPFv3 Extended Prefix Range TLV would be set to 2001:DB8:1::0, the Prefix Length would be set to 120, the Range Size would be set to 7, and the Index value in the Prefix-SIDSub-TLVsub-TLV would be set to 51.</t> </section> <section anchor="ADJSID"title="Adjacencynumbered="true" toc="default"> <name>Adjacency Segment Identifier(Adj-SID)">(Adj-SID)</name> <t>An Adjacency Segment Identifier (Adj-SID) represents a router adjacency in Segment Routing.</t> <section anchor="ADJSIDSUBTLV"title="Adj-SID Sub-TLV">numbered="true" toc="default"> <name>Adj-SID Sub-TLV</name> <t>The Adj-SIDSub-TLVsub-TLV is an optionalSub-TLVsub-TLV of the Router-Link TLV as defined in <xreftarget="RFC8362"/>.target="RFC8362" format="default"/>. ItMAY<bcp14>MAY</bcp14> appear multiple times in the Router-Link TLV. The Adj-SIDSub-TLVsub-TLV has the followingformat:<figure> <artwork>format:</t> <artwork name="" type="" align="left" alt=""><![CDATA[ 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | Weight | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SID/Label/Index (variable) |+---------------------------------------------------------------+ where:</artwork> </figure><list style="hanging"> <t>Type: 5</t> <t>Length: 7+---------------------------------------------------------------+]]></artwork><t>where:</t> <ul empty="true"><li><dl newline="false" spacing="normal"> <dt>Type:</dt> <dd>5</dd> <dt>Length:</dt> <dd>7 or 8 octets,dependentdepending on theV flag.</t> <t>Flags: Single octetV-Flag.</dd> <dt>Flags:</dt> <dd> <t>Single-octet field containing the followingflags:<figure align="center"> <artwork>flags:</t> <artwork name="" type="" align="left" alt=""><![CDATA[ 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |B|V|L|G|P| |+-+-+-+-+-+-+-+-+ where:</artwork> </figure><list style="hanging"> <t>B-Flag: Backup+-+-+-+-+-+-+-+-+]]></artwork><t>where:</t> <dl newline="false" spacing="normal"> <dt>B-Flag:</dt> <dd>Backup Flag. If set, the Adj-SID refers to an adjacency that is eligible for protection (e.g., usingIPFRRIP Fast Reroute (IPFRR) orMPLS-FRR)MPLS-FRR (MPLS Fast Reroute)) as described insection 3.5 of<xreftarget="RFC8402"/>.</t> <t>The V-Flag: Value/Indextarget="RFC8402" sectionFormat="of" section="3.4"/>.</dd> <dt>V-Flag:</dt> <dd>Value/Index Flag. If set, then the Adj-SID carries an absolute value. If not set, then the Adj-SID carries anindex.</t> <t>The L-Flag: Local/Globalindex.</dd> <dt>L-Flag:</dt> <dd>Local/Global Flag. If set, then the value/index carried by the Adj-SID has local significance. If not set, then the value/index carried by thisSub-TLVsub-TLV has globalsignificance.</t> <t>The G-Flag: Groupsignificance.</dd> <dt>G-Flag:</dt> <dd>Group Flag. When set, the G-Flag indicates that the Adj-SID refers to a group of adjacencies (and thereforeMAY<bcp14>MAY</bcp14> be assigned to other adjacencies aswell).</t> <t>P-Flag. Persistent flag.well).</dd> <dt>P-Flag.</dt> <dd>Persistent Flag. When set, the P-Flag indicates that the Adj-SID is persistently allocated, i.e., the Adj-SID value remains the same across router restart and/or interfaceflap.</t> <t>Other bits: Reserved.flap.</dd> <dt>Other bits:</dt> <dd>Reserved. TheseMUST<bcp14>MUST</bcp14> be zero when sent and are ignored whenreceived.</t> </list></t> <t>Reserved: SHOULDreceived.</dd> </dl> </dd> <dt>Reserved:</dt> <dd><bcp14>SHOULD</bcp14> be set to 0 on transmission andMUST<bcp14>MUST</bcp14> be ignored onreception.</t> <t>Weight: Weightreception.</dd> <dt>Weight:</dt> <dd>Weight used for load-balancing purposes. The use of the weight is defined in <xreftarget="RFC8402"/>.</t> <t>SID/Index/Label: astarget="RFC8402" format="default"/>.</dd> <dt>SID/Index/Label:</dt> <dd>As described in <xreftarget="PREFIXSID"/>.</t> </list></t>target="PREFIXSID" format="default"/>.</dd> </dl></li></ul> <t>An SR-capable routerMAY<bcp14>MAY</bcp14> allocate an Adj-SID for each of its adjacencies and set the B-Flag when the adjacency is eligible for protection by an FRR mechanism (IP or MPLS) as described in <xreftarget="RFC8402"/>.</t>target="RFC8402" format="default"/>.</t> <t>An SR-capable routerMAY<bcp14>MAY</bcp14> allocate more than one Adj-SID to an adjacency.</t> <t>An SR-capable routerMAY<bcp14>MAY</bcp14> allocate the same Adj-SID to different adjacencies.</t> <t>When theP-flagP-Flag is not set, the Adj-SIDMAY<bcp14>MAY</bcp14> be persistent. When theP-flagP-Flag is set, the Adj-SIDMUST<bcp14>MUST</bcp14> be persistent.</t> </section> <section anchor="LANADJSIDSUBTLV"title="LANnumbered="true" toc="default"> <name>LAN Adj-SIDSub-TLV">Sub-TLV</name> <t>The LANAdj-SID Sub-TLVAdjacency SID is an optionalSub-TLVsub-TLV of the Router-Link TLV. ItMAY<bcp14>MAY</bcp14> appear multiple times in the Router-Link TLV. It is used to advertise a SID/Label for an adjacency to a non-DR router on a broadcast,NBMA,Non-Broadcast Multi-Access (NBMA), or hybrid <xreftarget="RFC6845"/>target="RFC6845" format="default"/> network.<figure> <artwork></t> <artwork name="" type="" align="left" alt=""><![CDATA[ 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | Weight | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Neighbor ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SID/Label/Index (variable) |+---------------------------------------------------------------+ where:</artwork> </figure><list style="hanging"> <t>Type: 6</t> <t>Length: 11+---------------------------------------------------------------+]]></artwork><t>where:</t> <ul empty="true"><li><dl newline="false" spacing="normal"> <dt>Type:</dt> <dd>6</dd> <dt>Length:</dt> <dd>11 or 12 octets,dependentdepending onV-flag.</t> <t>Flags: samethe V-Flag.</dd> <dt>Flags:</dt> <dd>Same as in <xreftarget="ADJSIDSUBTLV"/></t> <t>Weight: Weighttarget="ADJSIDSUBTLV" format="default"/>.</dd> <dt>Weight:</dt> <dd>Weight used for load-balancing purposes. The use of the weight is defined in <xreftarget="RFC8402"/>.</t> <t>Reserved: SHOULDtarget="RFC8402" format="default"/>.</dd> <dt>Reserved:</dt> <dd><bcp14>SHOULD</bcp14> be set to 0 on transmission andMUST<bcp14>MUST</bcp14> be ignored onreception.</t> <t>Neighbor ID: Thereception.</dd> <dt>Neighbor ID:</dt> <dd>The Router ID of the neighbor for which theLAN-Adj-SIDLAN Adjacency SID isadvertised.</t> <t>SID/Index/Label: asadvertised.</dd> <dt>SID/Index/Label:</dt> <dd><t>As described in <xreftarget="PREFIXSID"/>.</t>target="PREFIXSID" format="default"/>.</t> <t>When theP-flagP-Flag is not set, the LANAdj-SID MAYAdjacency SID <bcp14>MAY</bcp14> be persistent. When theP-flagP-Flag is set, the LANAdj-SID MUSTAdjacency SID <bcp14>MUST</bcp14> bepersistent.</t> </list></t>persistent.</t></dd> </dl></li></ul> </section> </section> <sectiontitle="Elementsnumbered="true" toc="default"> <name>Elements ofProcedure">Procedure</name> <sectiontitle="Intra-areanumbered="true" toc="default"> <name>Intra-area SegmentroutingRouting inOSPFv3 ">OSPFv3</name> <t>An OSPFv3 router that supportssegment routing MAYSegment Routing <bcp14>MAY</bcp14> advertise Prefix- SIDs for any prefix to which it is advertising reachability (e.g., a loopback IP address as described in <xreftarget="PREFIXSID"/>).</t>target="PREFIXSID" format="default"/>).</t> <t>A Prefix-SID can also be advertised by SR Mapping Servers (as described in <xreftarget="I-D.ietf-spring-segment-routing-ldp-interop"/>).target="RFC8661" format="default"/>). A Mapping Server advertises Prefix-SIDs for remote prefixes that exist in the OSPFv3 routing domain. Multiple Mapping Servers can advertise Prefix-SIDs for the same prefix, in which case the same Prefix-SIDMUST<bcp14>MUST</bcp14> be advertised by all of them. The SR Mapping Server could use either area flooding scope or autonomous system flooding scope when advertisingPrefix SIDsPrefix-SIDs for prefixes, based on the configuration of the SR Mapping Server. Depending on the flooding scope used, the SR Mapping Server chooses the OSPFv3 LSA type that will be used. If the area flooding scope is needed, an E-Intra-Area-Prefix-LSA <xreftarget="RFC8362"/>target="RFC8362" format="default"/> is used. If autonomous system flooding scope is needed, an E-AS-External-LSA <xreftarget="RFC8362"/>target="RFC8362" format="default"/> is used.</t> <t>When a Prefix-SID is advertised by the Mapping Server, which is indicated by theM-flagM-Flag in the Prefix-SIDSub-TLVsub-TLV (<xreftarget="PREFIXSID"/>),target="PREFIXSID" format="default"/>), the route type as implied by the LSA type is ignored and the Prefix-SID is bound to the corresponding prefix independent of the route type.</t> <t>Advertisement of the Prefix-SID by the Mapping Server using an Inter-Area Prefix TLV, External-Prefix TLV, or Intra-Area-Prefix TLV <xreftarget="RFC8362"/>target="RFC8362" format="default"/> does not itself contribute to the prefix reachability. The NU-bit <xreftarget="RFC5340"/> MUSTtarget="RFC5340" format="default"/> <bcp14>MUST</bcp14> be set in the PrefixOptions field of theLSALSA, which is used by the Mapping Server to advertise SID or SID Range, which prevents the advertisement from contributing to prefix reachability.</t> <t>An SR Mapping ServerMUST<bcp14>MUST</bcp14> use the OSPFv3 Extended Prefix Range TLVs when advertising SIDs for prefixes. Prefixes of differentroute-typesroute types can be combined in a single OSPFv3 Extended Prefix Range TLV advertised by an SR Mapping Server.</t> <t>Area-scoped OSPFv3 Extended Prefix Range TLVs are propagated between areas, similar to propagation of prefixes between areas. Same rules that are used for propagating prefixes between areas <xreftarget="RFC5340"/>target="RFC5340" format="default"/> are used for the propagation of the prefix ranges.</t> </section> <sectiontitle="Inter-areanumbered="true" toc="default"> <name>Inter-area SegmentroutingRouting inOSPFv3">OSPFv3</name> <t>In order to support SR in amulti-areamultiarea environment, OSPFv3MUST<bcp14>MUST</bcp14> propagate Prefix-SID information between areas. The following procedure is used to propagatePrefix SIDsPrefix-SIDs between areas.</t> <t>When an OSPFv3 ABR advertises an Inter-Area-Prefix-LSA from an intra-area prefix to all its connected areas, it will also include the Prefix-SIDSub-TLV,sub-TLV as described in <xreftarget="PREFIXSID"/>.target="PREFIXSID" format="default"/>. The Prefix-SID value will be set as follows:<list style="hanging"> <t>The</t> <ul empty="true" spacing="normal"> <li>The ABR will look at its best path to the prefix in the source area and find the advertising router associated with the best path to thatprefix.</t> <t>Theprefix.</li> <li>The ABR will then determine ifsuchthis router advertised a Prefix-SID for the prefix and use it when advertising the Prefix-SID to other connectedareas.</t> <t>Ifareas.</li> <li>If no Prefix-SID was advertised for the prefix in the source area by the router that contributes to the best path to the prefix, the originating ABR will use the Prefix-SID advertised by any other router when propagating the Prefix-SID for the prefix to otherareas.</t> </list></t>areas.</li> </ul> <t>When an OSPFv3 ABR advertises an Inter-Area-Prefix-LSALSAsfrom an inter-area route to all its connected areas, it will also include the Prefix-SIDSub-TLV,sub-TLV as described in <xreftarget="PREFIXSID"/>.target="PREFIXSID" format="default"/>. The Prefix-SID value will be set as follows:<list style="hanging"> <t>The</t> <ul empty="true" spacing="normal"> <li>The ABR will look at its best path to the prefix in the backbone area and find the advertising router associated with the best path to thatprefix.</t> <t>Theprefix.</li> <li>The ABR will then determine ifsuchthis router advertised a Prefix-SID for the prefix and use it when advertising the Prefix-SID to other connectedareas.</t> <t>Ifareas.</li> <li>If no Prefix-SID was advertised for the prefix in the backbone area by the ABR that contributes to the best path to the prefix, the originating ABR will use the Prefix-SID advertised by any other router when propagating the Prefix-SID for the prefix to otherareas.</t> </list></t>areas.</li> </ul> </section> <sectiontitle="Segmentnumbered="true" toc="default"> <name>Segment Routing for ExternalPrefixes">Prefixes</name> <t>AS-External-LSAs are flooded domain wide. When an ASBR, which supports SR, originates an E-AS-External-LSA, itSHOULD<bcp14>SHOULD</bcp14> also include a Prefix-SIDSub-TLV,sub-TLV as described in <xreftarget="PREFIXSID"/>.target="PREFIXSID" format="default"/>. The Prefix-SID value will be set to the SID that has been reserved for that prefix.</t> <t>Whenan NSSAa Not-So-Stubby Area (NSSA) <xreftarget="RFC3101"/>target="RFC3101" format="default"/> ABR translates an E-NSSA-LSA into an E-AS-External-LSA, itSHOULD<bcp14>SHOULD</bcp14> also advertise the Prefix-SID for the prefix. The NSSA ABR determines its best path to the prefix advertised in the translated E-NSSA-LSA and finds the advertising router associated with that path. If the advertising router has advertised a Prefix-SID for the prefix, then the NSSA ABR uses it when advertising the Prefix-SID for the E-AS-External-LSA. Otherwise, the Prefix-SID advertised by any other router will be used.</t> </section> <sectiontitle="Advertisementnumbered="true" toc="default"> <name>Advertisement ofAdj-SID">Adj-SID</name> <t>The Adjacency Segment Routing Identifier (Adj-SID) is advertised using the Adj-SIDSub-TLVsub-TLV as described in <xreftarget="ADJSID"/>.</t>target="ADJSID" format="default"/>.</t> <sectiontitle="Advertisementnumbered="true" toc="default"> <name>Advertisement of Adj-SID on Point-to-PointLinks">Links</name> <t>An Adj-SIDMAY<bcp14>MAY</bcp14> be advertised for any adjacency on aP2Ppoint-to-point (P2P) link that is in neighbor state 2-Way or higher. If the adjacency on a P2P link transitions from the FULL state, then the Adj-SID for that adjacencyMAY<bcp14>MAY</bcp14> be removed from the area. If the adjacency transitions to a state lower than 2-Way, then the Adj-SIDadvertisement MUSTAdvertisement <bcp14>MUST</bcp14> be withdrawn from the area.</t> </section> <sectiontitle="Adjacencynumbered="true" toc="default"> <name>Adjacency SID on Broadcast or NBMAInterfaces">Interfaces</name> <t>Broadcast, NBMA, or hybrid <xreftarget="RFC6845"/>target="RFC6845" format="default"/> networks in OSPFv3 are represented by a star topology where the DR is the central point to which all other routers on the broadcast, NBMA, or hybrid network connect. As a result, routers on the broadcast, NBMA, or hybrid network advertise only their adjacency to the DR. Routers that do not act as DR do not form or advertise adjacencies with each other. They do, however, maintain 2-Way adjacency state with each other and are directly reachable.</t> <t>When Segment Routing is used, each router on the broadcast, NBMA, or hybrid networkMAY<bcp14>MAY</bcp14> advertise the Adj-SID for its adjacency to the DR using the Adj-SIDSub-TLVsub-TLV as described in <xreftarget="ADJSIDSUBTLV"/>.</t>target="ADJSIDSUBTLV" format="default"/>.</t> <t>SR-capable routersMAY<bcp14>MAY</bcp14> also advertise aLAN-Adj-SIDLAN Adjacency SID for other neighbors (e.g.,BDR, DR-OTHER)Backup Designated Router (BDR), DR-OTHER, etc.) on the broadcast, NBMA, or hybrid network using theLAN-Adj-SID Sub-TLVLAN Adj-SID sub-TLV as described in <xreftarget="LANADJSIDSUBTLV"/>.</t>target="LANADJSIDSUBTLV" format="default"/>.</t> </section> </section> </section> <section anchor="IANA"title="IANA Considerations">numbered="true" toc="default"> <name>IANA Considerations</name> <t>This specification updatesseveraltwo existing OSPFv3 registries.</t> <section anchor="EPLTLVREG"title="OSPFv3numbered="true" toc="default"> <name>"OSPFv3 Extended-LSATLV Registry"> <t>FollowingTLVs" Registry</name> <t>The following valuesarehave been allocated:</t><t>o 9 - OSPFv3<table anchor="IANA1" align="left"> <name>OSPFv3 Extended-LSA TLVs</name> <thead> <tr> <th>Value</th> <th>Description</th> <th>Reference</th> </tr> </thead> <tbody> <tr> <td>9</td> <td>OSPFv3 Extended Prefix RangeTLV</t>TLV</td> <td>This document</td> </tr> </tbody> </table> </section> <section anchor="EXTLSAREG"title="OSPFv3numbered="true" toc="default"> <name>"OSPFv3 Extended-LSASub-TLV registry"> <t>o 4 - Prefix SID Sub-TLV</t> <t>o 5 - Adj-SID Sub-TLV</t> <t>o 6 - LANSub-TLVs" Registry</name> <t>The following values have been allocated:</t> <table anchor="IANA2" align="left"> <name>OSPFv3 Extended-LSA Sub-TLVs</name> <thead> <tr> <th>Value</th> <th>Description</th> <th>Reference</th> </tr> </thead> <tbody> <tr> <td>4</td> <td>Prefix-SID sub-TLV</td> <td>This document</td> </tr> <tr> <td>5</td> <td>Adj-SID sub-TLV</td> <td>This document</td> </tr> <tr> <td>6</td> <td>LAN Adj-SIDSub-TLV</t> <t>o 7 - SID/Label Sub-TLV</t>sub-TLV</td> <td>This document</td> </tr> <tr> <td>7</td> <td>SID/Label sub-TLV</td> <td>This document</td> </tr> </tbody> </table> </section> </section> <section anchor="Error-handling" numbered="true" toc="default"> <name>TLV/Sub-TLV Error Handling </name> <t>For any new TLVs/sub-TLVs defined in this document, if the length is invalid, the LSA in which it is advertised is considered malformed and <bcp14>MUST</bcp14> be ignored. Errors <bcp14>SHOULD</bcp14> be logged subject to rate limiting. </t> </section> <section anchor="Security"title="Security Considerations">numbered="true" toc="default"> <name>Security Considerations</name> <t>With the OSPFv3segment routingSegment Routing extensions defined herein, OSPFv3 will now program the MPLS data plane <xreftarget="RFC3031"></xref>.target="RFC3031" format="default"/>. Previously, LDP <xreftarget="RFC5036"></xref>target="RFC5036" format="default"/> or another label distribution mechanism was required to advertise MPLS labels and program the MPLS data plane.</t> <t>In general, the same types of attacks that can be carried out on the IP control plane can be carried out on the MPLS control plane resulting in traffic being misrouted in the respective data planes. However, the latter can be more difficult to detect and isolate.</t> <t>Existing securityextensionsextensions, as described in <xreftarget="RFC5340"></xref>target="RFC5340" format="default"/> and <xreftarget="RFC8362"/>target="RFC8362" format="default"/>, apply to thesesegment routingSegment Routing extensions. While OSPFv3 is under a single administrative domain, there can be deployments where potential attackers have access to one or more networks in the OSPFv3 routing domain. In these deployments, stronger authenticationmechanismsmechanisms, such as those specified in <xreftarget="RFC4552"></xref>target="RFC4552" format="default"/> or <xreftarget="RFC7166"></xref> SHOULDtarget="RFC7166" format="default"/>, <bcp14>SHOULD</bcp14> be used.</t> <t>ImplementationsMUST assure<bcp14>MUST</bcp14> ensure that malformedTLVTLVs andSub-TLVsub-TLVs defined in this document are detected and that they do not provide a vulnerability for attackers to crash the OSPFv3 router or routing process. Reception of a malformed TLV orSub-TLV SHOULDsub-TLV <bcp14>SHOULD</bcp14> be counted and/or logged for further analysis. Logging of malformed TLVs andSub-TLVs SHOULDsub-TLVs <bcp14>SHOULD</bcp14> berate-limitedrate limited to prevent aDenial of ServiceDenial-of-Service (DoS) attack (distributed or otherwise) from overloading the OSPFv3 control plane.</t> </section> </middle> <back> <references> <name>References</name> <references> <name>Normative References</name> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.5340.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.7770.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.6845.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.3101.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.5036.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.3031.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.8362.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.8402.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.5462.xml"/> <!-- I-D.ietf-spring-segment-routing-ldp-interop: Companion document --> <reference anchor='RFC8661' target="https://www.rfc-editor.org/info/rfc8661"> <front> <title>Segment Routing MPLS Interworking with LDP</title> <author initials='A' surname='Bashandy' fullname='Ahmed Bashandy' role="editor"> <organization /> </author> <author initials='C' surname='Filsfils' fullname='Clarence Filsfils' role="editor"> <organization /> </author> <author initials='S' surname='Previdi' fullname='Stefano Previdi'> <organization /> </author> <author initials='B' surname='Decraene' fullname='Bruno Decraene'> <organization /> </author> <author initials='S' surname='Litkowski' fullname='Stephane Litkowski'> <organization /> </author> <date month='December' year='2019' /> </front> <seriesInfo name="RFC" value="8661"/> <seriesInfo name="DOI" value="10.17487/RFC8661"/> </reference> <reference anchor="ALGOREG" target="https://www.iana.org/assignments/igp-parameters"> <front> <title>Interior Gateway Protocol (IGP) Parameters</title> <author><organization>IANA</organization> </author> </front> </reference> <!-- I-D.ietf-ospf-segment-routing-extensions: I-D exists--> <reference anchor="RFC8665" target="https://www.rfc-editor.org/info/rfc8665"> <front> <title>OSPF Extensions for Segment Routing</title> <author initials='P' surname='Psenak' fullname='Peter Psenak' role="editor"> <organization/> </author> <author initials='S' surname='Previdi' fullname='Stefano Previdi' role="editor"> <organization/> </author> <author initials='C' surname='Filfils' fullname='Clarence Filsfils'> <organization/> </author> <author initials='H' surname='Gredler' fullname='Hannes Gredler'> <organization/> </author> <author initials='R' surname='Shakir' fullname='Rob Shakir'> <organization/> </author> <author initials='W' surname='Henderickx' fullname='Wim Henderickx'> <organization/> </author> <author initials='J' surname='Tantsura' fullname='Jeff Tantsura'> <organization/> </author> <date month='December' year='2019'/> </front> <seriesInfo name="RFC" value="8665"/> <seriesInfo name="DOI" value="10.17487/RFC8665"/> </reference> </references> <references> <name>Informative References</name> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.7855.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.4552.xml"/> <xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.7166.xml"/> </references> </references> <section anchor="Acknowledgements"title="Contributors">numbered="false" toc="default"> <name>Contributors</name> <t>The following people gave a substantial contribution to the content of this document and should be consideredas co-authors:</t> <t><figure> <artwork><![CDATA[coauthors:</t> <artwork name="" type="" align="left" alt=""><![CDATA[ Clarence Filsfils Cisco Systems, Inc. Brussels Belgium Email:cfilsfil@cisco.comcfilsfil@cisco.com]]></artwork> <artwork name="" type="" align="left" alt=""><![CDATA[ Hannes Gredler RtBrick Inc. Austria Email:hannes@rtbrick.comhannes@rtbrick.com]]></artwork> <artwork name="" type="" align="left" alt=""><![CDATA[ Rob Shakir Google, Inc.1600 Amphitheatre Parkway Mountain View, CA 94043 USUnited States of America Email:robjs@google.comrobjs@google.com]]></artwork> <artwork name="" type="" align="left" alt=""><![CDATA[ Wim Henderickx NokiaCopernicuslaan 50 Antwerp 2018 BEBelgium Email:wim.henderickx@nokia.comwim.henderickx@nokia.com]]></artwork> <artwork name="" type="" align="left" alt=""><![CDATA[ Jeff TantsuraNuage Networks USApstra, Inc. United States of America Email:jefftant.ietf@gmail.com ]]></artwork> </figure></t>jefftant.ietf@gmail.com]]></artwork> <t>Thanks to Acee Lindem for his substantial contribution to the content of this document.</t> <t>We would like to thank Anton Smirnov for his contribution as well.</t> </section></middle> <back> <references title="Normative References"> <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml"?> <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.5340.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.7770.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.6845.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.3101.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.5036.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.3031.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.8362.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.8402.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.5462.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-spring-segment-routing-ldp-interop.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-spring-segment-routing-mpls.xml"?> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-ospf-segment-routing-extensions.xml"?> <reference anchor="ALGOREG" target="https://www.iana.org/assignments/igp-parameters/igp-parameters.xhtml#igp-algorithm-types"> <front> <title>IGP Algorithm Types</title> <author> </author> <date/> </front> </reference> </references> <references title="Informative References"> <?rfc include="http://xml2rfc.tools.ietf.org/public/rfc/bibxml/reference.RFC.7855.xml"?> <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.4552.xml"?> <?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.7166.xml"?> </references></back> </rfc>