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diff --git a/doc/rfc/rfc8986.txt b/doc/rfc/rfc8986.txt new file mode 100644 index 0000000..238a00d --- /dev/null +++ b/doc/rfc/rfc8986.txt @@ -0,0 +1,2124 @@ + + + + +Internet Engineering Task Force (IETF) C. Filsfils, Ed. +Request for Comments: 8986 P. Camarillo, Ed. +Category: Standards Track Cisco Systems, Inc. +ISSN: 2070-1721 J. Leddy + Akamai Technologies + D. Voyer + Bell Canada + S. Matsushima + SoftBank + Z. Li + Huawei Technologies + February 2021 + + + Segment Routing over IPv6 (SRv6) Network Programming + +Abstract + + The Segment Routing over IPv6 (SRv6) Network Programming framework + enables a network operator or an application to specify a packet + processing program by encoding a sequence of instructions in the IPv6 + packet header. + + Each instruction is implemented on one or several nodes in the + network and identified by an SRv6 Segment Identifier in the packet. + + This document defines the SRv6 Network Programming concept and + specifies the base set of SRv6 behaviors that enables the creation of + interoperable overlays with underlay optimization. + +Status of This Memo + + This is an Internet Standards Track document. + + This document is a product of the Internet Engineering Task Force + (IETF). It represents the consensus of the IETF community. It has + received public review and has been approved for publication by the + Internet Engineering Steering Group (IESG). Further information on + Internet Standards is available in Section 2 of RFC 7841. + + Information about the current status of this document, any errata, + and how to provide feedback on it may be obtained at + https://www.rfc-editor.org/info/rfc8986. + +Copyright Notice + + Copyright (c) 2021 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. Terminology + 2.1. Requirements Language + 3. SRv6 SID + 3.1. SID Format + 3.2. SID Allocation within an SR Domain + 3.3. SID Reachability + 4. SR Endpoint Behaviors + 4.1. End: Endpoint + 4.1.1. Upper-Layer Header + 4.2. End.X: L3 Cross-Connect + 4.3. End.T: Specific IPv6 Table Lookup + 4.4. End.DX6: Decapsulation and IPv6 Cross-Connect + 4.5. End.DX4: Decapsulation and IPv4 Cross-Connect + 4.6. End.DT6: Decapsulation and Specific IPv6 Table Lookup + 4.7. End.DT4: Decapsulation and Specific IPv4 Table Lookup + 4.8. End.DT46: Decapsulation and Specific IP Table Lookup + 4.9. End.DX2: Decapsulation and L2 Cross-Connect + 4.10. End.DX2V: Decapsulation and VLAN L2 Table Lookup + 4.11. End.DT2U: Decapsulation and Unicast MAC L2 Table Lookup + 4.12. End.DT2M: Decapsulation and L2 Table Flooding + 4.13. End.B6.Encaps: Endpoint Bound to an SRv6 Policy with + Encapsulation + 4.14. End.B6.Encaps.Red: End.B6.Encaps with Reduced SRH + 4.15. End.BM: Endpoint Bound to an SR-MPLS Policy + 4.16. Flavors + 4.16.1. PSP: Penultimate Segment Pop of the SRH + 4.16.2. USP: Ultimate Segment Pop of the SRH + 4.16.3. USD: Ultimate Segment Decapsulation + 5. SR Policy Headend Behaviors + 5.1. H.Encaps: SR Headend with Encapsulation in an SR Policy + 5.2. H.Encaps.Red: H.Encaps with Reduced Encapsulation + 5.3. H.Encaps.L2: H.Encaps Applied to Received L2 Frames + 5.4. H.Encaps.L2.Red: H.Encaps.Red Applied to Received L2 Frames + 6. Counters + 7. Flow-Based Hash Computation + 8. Control Plane + 8.1. IGP + 8.2. BGP-LS + 8.3. BGP IP/VPN/EVPN + 8.4. Summary + 9. Security Considerations + 10. IANA Considerations + 10.1. Ethernet Next Header Type + 10.2. SRv6 Endpoint Behaviors Registry + 10.2.1. Registration Procedures + 10.2.2. Initial Registrations + 11. References + 11.1. Normative References + 11.2. Informative References + Acknowledgements + Contributors + Authors' Addresses + +1. Introduction + + Segment Routing [RFC8402] leverages the source routing paradigm. An + ingress node steers a packet through an ordered list of instructions, + called "segments". Each one of these instructions represents a + function to be called at a specific location in the network. A + function is locally defined on the node where it is executed and may + range from simply moving forward in the segment list to any complex + user-defined behavior. Network Programming combines Segment Routing + functions, both simple and complex, to achieve a networking objective + that goes beyond mere packet routing. + + This document defines the SRv6 Network Programming concept and + specifies the main Segment Routing behaviors to enable the creation + of interoperable overlays with underlay optimization. + + [SRV6-NET-PGM-ILLUST] illustrates the concepts defined in this + document. + + Familiarity with the Segment Routing Header [RFC8754] is expected. + +2. Terminology + + The following terms used within this document are defined in + [RFC8402]: Segment Routing (SR), SR Domain, Segment ID (SID), SRv6, + SRv6 SID, SR Policy, Prefix-SID, and Adj-SID. + + The following terms used within this document are defined in + [RFC8754]: Segment Routing Header (SRH), SR source node, transit + node, SR Segment Endpoint Node, Reduced SRH, Segments Left, and Last + Entry. + + The following terms are used in this document as defined below: + + FIB: Forwarding Information Base. A FIB lookup is a lookup in the + forwarding table. + + SA: Source Address + + DA: Destination Address + + L3: Layer 3 + + L2: Layer 2 + + MAC: Media Access Control + + EVPN: Ethernet VPN + + ESI: Ethernet Segment Identifier + + Per-CE VPN label: A single label for each attachment circuit that is + shared by all routes with the same "outgoing attachment circuit" + (Section 4.3.2 of [RFC4364]) + + Per-VRF VPN label: A single label for the entire VPN Routing and + Forwarding (VRF) table that is shared by all routes from that VRF + (Section 4.3.2 of [RFC4364]) + + SL: The Segments Left field of the SRH + + SRv6 SID function: The function part of the SID is an opaque + identification of a local behavior bound to the SID. It is + formally defined in Section 3.1 of this document. + + SRv6 Endpoint behavior: A packet processing behavior executed at an + SRv6 Segment Endpoint Node. Section 4 of this document defines + SRv6 Endpoint behaviors related to traffic-engineering and overlay + use cases. Other behaviors (e.g., service programming) are + outside the scope of this document. + + An SR Policy is resolved to a SID list. A SID list is represented as + <S1, S2, S3> where S1 is the first SID to visit, S2 is the second SID + to visit, and S3 is the last SID to visit along the SR path. + + (SA,DA) (S3, S2, S1; SL) represents an IPv6 packet with: + + * Source Address (SA), Destination Address (DA), and next header + (SRH). + + * SRH with SID list <S1, S2, S3> with Segments Left = SL. + + Note the difference between the <> and () symbols: <S1, S2, S3> + represents a SID list where S1 is the first SID and S3 is the last + SID to traverse. (S3, S2, S1; SL) represents the same SID list + but encoded in the SRH format where the rightmost SID in the SRH + is the first SID and the leftmost SID in the SRH is the last SID. + When referring to an SR Policy in a high-level use case, it is + simpler to use the <S1, S2, S3> notation. When referring to an + illustration of the detailed packet behavior, the (S3, S2, S1; SL) + notation is more convenient. + + * The payload of the packet is omitted. + +2.1. 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. SRv6 SID + + [RFC8402] defines an SRv6 Segment Identifier as an IPv6 address + explicitly associated with the segment. + + When an SRv6 SID is in the Destination Address field of an IPv6 + header of a packet, it is routed through transit nodes in an IPv6 + network as an IPv6 address. + + Its processing is defined in Section 4.3 of [RFC8754] and reproduced + here as a reminder: + + | Without constraining the details of an implementation, the SR + | segment endpoint node creates Forwarding Information Base (FIB) + | entries for its local SIDs. + | + | When an SRv6-capable node receives an IPv6 packet, it performs a + | longest-prefix-match lookup on the packet's destination address. + | This lookup can return any of the following: + | * A FIB entry that represents a locally instantiated SRv6 SID + | + | * A FIB entry that represents a local interface, not locally + | instantiated as an SRv6 SID + | + | * A FIB entry that represents a nonlocal route + | + | * No Match + + Section 4 of this document defines a new set of SRv6 SID behaviors in + addition to that defined in Section 4.3.1 of [RFC8754]. + +3.1. SID Format + + This document defines an SRv6 SID as consisting of LOC:FUNCT:ARG, + where a locator (LOC) is encoded in the L most significant bits of + the SID, followed by F bits of function (FUNCT) and A bits of + arguments (ARG). L, the locator length, is flexible, and an operator + is free to use the locator length of their choice. F and A may be + any value as long as L+F+A <= 128. When L+F+A is less than 128, then + the remaining bits of the SID MUST be zero. + + A locator may be represented as B:N where B is the SRv6 SID block + (IPv6 prefix allocated for SRv6 SIDs by the operator) and N is the + identifier of the parent node instantiating the SID. + + When the LOC part of the SRv6 SIDs is routable, it leads to the node, + which instantiates the SID. + + The FUNCT is an opaque identification of a local behavior bound to + the SID. + + The term "function" refers to the bit string in the SRv6 SID. The + term "behavior" identifies the behavior bound to the SID. Some + behaviors are defined in Section 4 of this document. + + An SRv6 Endpoint behavior may require additional information for its + processing (e.g., related to the flow or service). This information + may be encoded in the ARG bits of the SID. + + In such a case, the semantics and format of the ARG bits are defined + as part of the SRv6 Endpoint behavior specification. + + The ARG value of a routed SID SHOULD remain constant among packets in + a given flow. Varying ARG values among packets in a flow may result + in different ECMP hashing and cause reordering. + +3.2. SID Allocation within an SR Domain + + Locators are assigned consistent with IPv6 infrastructure allocation. + For example, a network operator may: + + * Assign block B::/48 to the SR domain + + * Assign a unique B:N::/64 block to each SRv6-enabled node in the + domain + + As an example, one mobile service provider has commercially deployed + SRv6 across more than 1000 commercial routers and 1800 whitebox + routers. All these devices are enabled for SRv6 and advertise SRv6 + SIDs. The provider historically deployed IPv6 and assigned + infrastructure addresses from the Unique Local Address (ULA) space + [RFC4193]. They specifically allocated three /48 prefixes (Country + X, Country Y, Country Z) to support their SRv6 infrastructure. From + those /48 prefixes, each router was assigned a /64 prefix from which + all SIDs of that router are allocated. + + In another example, a large mobile and fixed-line service provider + has commercially deployed SRv6 in their country-wide network. This + provider is assigned a /20 prefix by a Regional Internet Registry + (RIR). They sub-allocated a few /48 prefixes to their infrastructure + to deploy SRv6. Each router is assigned a /64 prefix from which all + SIDs of that router are allocated. + + IPv6 address consumption in both these examples is minimal, + representing less than one billionth and one millionth of the + available address space, respectively. + + A service provider receiving the current minimum allocation of a /32 + prefix from an RIR may assign a /48 prefix to their infrastructure + deploying SRv6 and subsequently allocate /64 prefixes for SIDs at + each SRv6 node. The /48 assignment is one sixty-five thousandth + (1/2^16) of the usable IPv6 address space available for assignment by + the provider. + + When an operator instantiates a SID at a node, they specify a SID + value B:N:FUNCT and the behavior bound to the SID using one of the + SRv6 Endpoint Behavior codepoints of the registry defined in this + document (see Table 6). + + The node advertises the SID, B:N:FUNCT, in the control plane (see + Section 8) together with the SRv6 Endpoint Behavior codepoint + identifying the behavior of the SID. + + An SR source node cannot infer the behavior by examination of the + FUNCT value of a SID. + + Therefore, the SRv6 Endpoint Behavior codepoint is advertised along + with the SID in the control plane. + + An SR source node uses the SRv6 Endpoint Behavior codepoint to map + the received SID (B:N:FUNCT) to a behavior. + + An SR source node selects a desired behavior at an advertising node + by selecting the SID (B:N:FUNCT) advertised with the desired + behavior. + + As an example: + + * A network operator may assign an SRv6 SID block 2001:db8:bbbb::/48 + from their in-house operation block for their SRv6 infrastructure. + + * A network operator may assign an SRv6 Locator 2001:db8:bbbb:3::/64 + to one particular router, for example Router 3, in their SR + Domain. + + * At Router 3, within the locator 2001:db8:bbbb:3::/64, the network + operator or the router performs dynamic assignment for: + + - Function 0x0100 associated with the behavior End.X (Endpoint + with L3 cross-connect) between router 3 and its connected + neighbor router (e.g., Router 4). This function is encoded as + a 16-bit value and has no arguments (F=16, A=0). + + This SID is advertised in the control plane as + 2001:db8:bbbb:3:100:: with an SRv6 Endpoint Behavior codepoint + value of 5. + + - Function 0x0101 associated with the behavior End.X (Endpoint + with L3 cross-connect) between router 3 and its connected + neighbor router (e.g., Router 2). This function is encoded as + a 16-bit value and has no arguments (F=16, A=0). + + This SID is advertised in the control plane as + 2001:db8:bbbb:3:101:: with an SRv6 Endpoint Behavior codepoint + value of 5. + + These examples do not preclude any other IPv6 addressing allocation + scheme. + +3.3. SID Reachability + + Most often, the node N would advertise IPv6 prefix(es) matching the + LOC parts covering its SIDs or shorter-mask prefix. The distribution + of these advertisements and calculation of their reachability are + specific to the routing protocol and are outside of the scope of this + document. + + An SRv6 SID is said to be routed if its SID belongs to an IPv6 prefix + advertised via a routing protocol. An SRv6 SID that does not fulfill + this condition is non-routed. + + Let's provide a classic illustration: + + Node N is configured explicitly with two SIDs: 2001:db8:b:1:100:: and + 2001:db8:b:2:101::. + + The network learns about a path to 2001:db8:b:1::/64 via the IGP; + hence, a packet destined to 2001:db8:b:1:100:: would be routed up to + N. The network does not learn about a path to 2001:db8:b:2::/64 via + the IGP; hence, a packet destined to 2001:db8:b:2:101:: would not be + routed up to N. + + A packet could be steered through a non-routed SID 2001:db8:b:2:101:: + by using a SID list <...,2001:db8:b:1:100::,2001:db8:b:2:101::,...> + where the non-routed SID is preceded by a routed SID to the same + node. A packet could also be steered to a node instantiating a non- + routed SID by preceding it in the SID list with an Adj-SID to that + node. Routed and non-routed SRv6 SIDs are the SRv6 instantiation of + global and local segments, respectively [RFC8402]. + +4. SR Endpoint Behaviors + + The following is a set of well-known behaviors that can be associated + with a SID. + + +-------------------+---------------------------------------------+ + | End | Endpoint | + | | | + | | The SRv6 instantiation of a Prefix-SID | + | | [RFC8402] | + +-------------------+---------------------------------------------+ + | End.X | Endpoint with L3 cross-connect | + | | | + | | The SRv6 instantiation of an Adj-SID | + | | [RFC8402] | + +-------------------+---------------------------------------------+ + | End.T | Endpoint with specific IPv6 table lookup | + +-------------------+---------------------------------------------+ + | End.DX6 | Endpoint with decapsulation and IPv6 cross- | + | | connect | + | | | + | | e.g., IPv6-L3VPN (equivalent to per-CE VPN | + | | label) | + +-------------------+---------------------------------------------+ + | End.DX4 | Endpoint with decapsulation and IPv4 cross- | + | | connect | + | | | + | | e.g., IPv4-L3VPN (equivalent to per-CE VPN | + | | label) | + +-------------------+---------------------------------------------+ + | End.DT6 | Endpoint with decapsulation and specific | + | | IPv6 table lookup | + | | | + | | e.g., IPv6-L3VPN (equivalent to per-VRF VPN | + | | label) | + +-------------------+---------------------------------------------+ + | End.DT4 | Endpoint with decapsulation and specific | + | | IPv4 table lookup | + | | | + | | e.g., IPv4-L3VPN (equivalent to per-VRF VPN | + | | label) | + +-------------------+---------------------------------------------+ + | End.DT46 | Endpoint with decapsulation and specific IP | + | | table lookup | + | | | + | | e.g., IP-L3VPN (equivalent to per-VRF VPN | + | | label) | + +-------------------+---------------------------------------------+ + | End.DX2 | Endpoint with decapsulation and L2 cross- | + | | connect | + | | | + | | e.g., L2VPN use case | + +-------------------+---------------------------------------------+ + | End.DX2V | Endpoint with decapsulation and VLAN L2 | + | | table lookup | + | | | + | | e.g., EVPN Flexible Cross-connect use case | + +-------------------+---------------------------------------------+ + | End.DT2U | Endpoint with decapsulation and unicast MAC | + | | L2 table lookup | + | | | + | | e.g., EVPN Bridging Unicast use case | + +-------------------+---------------------------------------------+ + | End.DT2M | Endpoint with decapsulation and L2 table | + | | flooding | + | | | + | | e.g., EVPN Bridging Broadcast, Unknown | + | | Unicast, and Multicast (BUM) use case with | + | | Ethernet Segment Identifier (ESI) filtering | + +-------------------+---------------------------------------------+ + | End.B6.Encaps | Endpoint bound to an SRv6 Policy with | + | | encapsulation | + | | | + | | SRv6 instantiation of a Binding SID | + +-------------------+---------------------------------------------+ + | End.B6.Encaps.Red | End.B6.Encaps with reduced SRH | + | | | + | | SRv6 instantiation of a Binding SID | + +-------------------+---------------------------------------------+ + | End.BM | Endpoint bound to an SR-MPLS Policy | + | | | + | | SRv6 instantiation of an SR-MPLS Binding | + | | SID | + +-------------------+---------------------------------------------+ + + Table 1: Endpoint Behaviors + + The list is not exhaustive. In practice, any behavior can be + attached to a local SID; for example, a node N can bind a SID to a + local Virtual Machine (VM) or container that can apply any complex + processing on the packet, provided there is an SRv6 Endpoint Behavior + codepoint allocated for the processing. + + When an SRv6-capable node (N) receives an IPv6 packet whose + destination address matches a FIB entry that represents a locally + instantiated SRv6 SID (S), the IPv6 header chain is processed as + defined in Section 4 of [RFC8200]. For SRv6 SIDs associated with an + Endpoint behavior defined in this document, the SRH and Upper-Layer + header are processed as defined in the following subsections. + + The pseudocode describing these behaviors details local processing at + a node. An implementation of the pseudocode is compliant as long as + the externally observable wire protocol is as described by the + pseudocode. + + Section 4.16 defines flavors of some of these behaviors. + + Section 10.2 of this document defines the IANA registry used to + maintain all these behaviors as well as future ones defined in other + documents. + +4.1. End: Endpoint + + The Endpoint behavior ("End" for short) is the most basic behavior. + It is the instantiation of a Prefix-SID [RFC8402]. + + When N receives a packet whose IPv6 DA is S and S is a local End SID, + N does the following: + + S01. When an SRH is processed { + S02. If (Segments Left == 0) { + S03. Stop processing the SRH, and proceed to process the next + header in the packet, whose type is identified by + the Next Header field in the routing header. + S04. } + S05. If (IPv6 Hop Limit <= 1) { + S06. Send an ICMP Time Exceeded message to the Source Address + with Code 0 (Hop limit exceeded in transit), + interrupt packet processing, and discard the packet. + S07. } + S08. max_LE = (Hdr Ext Len / 2) - 1 + S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) { + S10. Send an ICMP Parameter Problem to the Source Address + with Code 0 (Erroneous header field encountered) + and Pointer set to the Segments Left field, + interrupt packet processing, and discard the packet. + + S11. } + S12. Decrement IPv6 Hop Limit by 1 + S13. Decrement Segments Left by 1 + S14. Update IPv6 DA with Segment List[Segments Left] + S15. Submit the packet to the egress IPv6 FIB lookup for + transmission to the new destination + S16. } + + | Note: + | + | The End behavior operates on the same FIB table (i.e., + | identified by VRF or L3 relay ID) associated to the packet. + | Hence, the FIB lookup on line S15 is done in the same FIB table + | as the ingress interface. + +4.1.1. Upper-Layer Header + + When processing the Upper-Layer header of a packet matching a FIB + entry locally instantiated as an End SID, N does the following: + + S01. If (Upper-Layer header type is allowed by local configuration) { + S02. Proceed to process the Upper-Layer header + S03. } Else { + S04. Send an ICMP Parameter Problem to the Source Address + with Code 4 (SR Upper-layer Header Error) + and Pointer set to the offset of the Upper-Layer header, + interrupt packet processing, and discard the packet. + S05 } + + Allowing the processing of specific Upper-Layer header types is + useful for Operations, Administration, and Maintenance (OAM). As an + example, an operator might permit pinging of SIDs. To do this, they + may enable local configuration to allow Upper-Layer header type 58 + (ICMPv6). + + It is RECOMMENDED that an implementation of local configuration only + allows Upper-Layer header processing of types that do not result in + the packet being forwarded (e.g., ICMPv6). + +4.2. End.X: L3 Cross-Connect + + The "Endpoint with L3 cross-connect" behavior ("End.X" for short) is + a variant of the End behavior. + + It is the SRv6 instantiation of an Adj-SID [RFC8402], and its main + use is for traffic-engineering policies. + + Any SID instance of this behavior is associated with a set, J, of one + or more L3 adjacencies. + + When N receives a packet destined to S and S is a local End.X SID, + the line S15 from the End processing is replaced by the following: + + S15. Submit the packet to the IPv6 module for transmission + to the new destination via a member of J + + | Note: + | + | S15. If the set J contains several L3 adjacencies, then one + | element of the set is selected based on a hash of the packet's + | header (see Section 7). + + If a node N has 30 outgoing interfaces to 30 neighbors, usually the + operator would explicitly instantiate 30 End.X SIDs at N: one per L3 + adjacency to a neighbor. Potentially, more End.X could be explicitly + defined (groups of L3 adjacencies to the same neighbor or to + different neighbors). + + Note that if N has an outgoing interface bundle I to a neighbor Q + made of 10 member links, N might allocate up to 11 End.X local SIDs: + one for the bundle itself and then up to one for each L2 member link. + The flows steered using the End.X SID corresponding to the bundle + itself get load-balanced across the member links via hashing while + the flows steered using the End.X SID corresponding to a member link + get steered over that specific member link alone. + + When the End.X behavior is associated with a BGP Next-Hop, it is the + SRv6 instantiation of the BGP peering segments [RFC8402]. + + When processing the Upper-Layer header of a packet matching a FIB + entry locally instantiated as an End.X SID, process the packet as per + Section 4.1.1. + +4.3. End.T: Specific IPv6 Table Lookup + + The "Endpoint with specific IPv6 table lookup" behavior ("End.T" for + short) is a variant of the End behavior. + + The End.T behavior is used for multi-table operation in the core. + For this reason, an instance of the End.T behavior is associated with + an IPv6 FIB table T. + + When N receives a packet destined to S and S is a local End.T SID, + the line S15 from the End processing is replaced by the following: + + S15.1. Set the packet's associated FIB table to T + S15.2. Submit the packet to the egress IPv6 FIB lookup for + transmission to the new destination + + When processing the Upper-Layer header of a packet matching a FIB + entry locally instantiated as an End.T SID, process the packet as per + Section 4.1.1. + +4.4. End.DX6: Decapsulation and IPv6 Cross-Connect + + The "Endpoint with decapsulation and IPv6 cross-connect" behavior + ("End.DX6" for short) is a variant of the End.X behavior. + + One of the applications of the End.DX6 behavior is the L3VPNv6 use + case where a FIB lookup in a specific tenant table at the egress + Provider Edge (PE) is not required. This is equivalent to the per-CE + VPN label in MPLS [RFC4364]. + + The End.DX6 SID MUST be the last segment in an SR Policy, and it is + associated with one or more L3 IPv6 adjacencies J. + + When N receives a packet destined to S and S is a local End.DX6 SID, + N does the following: + + S01. When an SRH is processed { + S02. If (Segments Left != 0) { + S03. Send an ICMP Parameter Problem to the Source Address + with Code 0 (Erroneous header field encountered) + and Pointer set to the Segments Left field, + interrupt packet processing, and discard the packet. + S04. } + S05. Proceed to process the next header in the packet + S06. } + + When processing the Upper-Layer header of a packet matching a FIB + entry locally instantiated as an End.DX6 SID, N does the following: + + S01. If (Upper-Layer header type == 41(IPv6) ) { + S02. Remove the outer IPv6 header with all its extension headers + S03. Forward the exposed IPv6 packet to the L3 adjacency J + S04. } Else { + S05. Process as per Section 4.1.1 + S06. } + + | Note: + | + | S01. "41" refers to "IPv6 encapsulation" as defined in the IANA + | "Assigned Internet Protocol Numbers" registry. + | + | S03. If the End.DX6 SID is bound to an array of L3 + | adjacencies, then one entry of the array is selected based on + | the hash of the packet's header (see Section 7). + +4.5. End.DX4: Decapsulation and IPv4 Cross-Connect + + The "Endpoint with decapsulation and IPv4 cross-connect" behavior + ("End.DX4" for short) is a variant of the End.X behavior. + + One of the applications of the End.DX4 behavior is the L3VPNv4 use + case where a FIB lookup in a specific tenant table at the egress PE + is not required. This is equivalent to the per-CE VPN label in MPLS + [RFC4364]. + + The End.DX4 SID MUST be the last segment in an SR Policy, and it is + associated with one or more L3 IPv4 adjacencies J. + + When N receives a packet destined to S and S is a local End.DX4 SID, + N does the following: + + S01. When an SRH is processed { + S02. If (Segments Left != 0) { + S03. Send an ICMP Parameter Problem to the Source Address + with Code 0 (Erroneous header field encountered) + and Pointer set to the Segments Left field, + interrupt packet processing, and discard the packet. + S04. } + S05. Proceed to process the next header in the packet + S06. } + + When processing the Upper-Layer header of a packet matching a FIB + entry locally instantiated as an End.DX4 SID, N does the following: + + S01. If (Upper-Layer header type == 4(IPv4) ) { + S02. Remove the outer IPv6 header with all its extension headers + S03. Forward the exposed IPv4 packet to the L3 adjacency J + S04. } Else { + S05. Process as per Section 4.1.1 + S06. } + + | Note: + | + | S01. "4" refers to "IPv4 encapsulation" as defined in the IANA + | "Assigned Internet Protocol Numbers" registry. + | + | S03. If the End.DX4 SID is bound to an array of L3 + | adjacencies, then one entry of the array is selected based on + | the hash of the packet's header (see Section 7). + +4.6. End.DT6: Decapsulation and Specific IPv6 Table Lookup + + The "Endpoint with decapsulation and specific IPv6 table lookup" + behavior ("End.DT6" for short) is a variant of the End.T behavior. + + One of the applications of the End.DT6 behavior is the L3VPNv6 use + case where a FIB lookup in a specific tenant table at the egress PE + is required. This is equivalent to the per-VRF VPN label in MPLS + [RFC4364]. + + Note that an End.DT6 may be defined for the main IPv6 table, in which + case an End.DT6 supports the equivalent of an IPv6-in-IPv6 + decapsulation (without VPN/tenant implication). + + The End.DT6 SID MUST be the last segment in an SR Policy, and a SID + instance is associated with an IPv6 FIB table T. + + When N receives a packet destined to S and S is a local End.DT6 SID, + N does the following: + + S01. When an SRH is processed { + S02. If (Segments Left != 0) { + S03. Send an ICMP Parameter Problem to the Source Address + with Code 0 (Erroneous header field encountered) + and Pointer set to the Segments Left field, + interrupt packet processing, and discard the packet. + S04. } + S05. Proceed to process the next header in the packet + S06. } + + When processing the Upper-Layer header of a packet matching a FIB + entry locally instantiated as an End.DT6 SID, N does the following: + + S01. If (Upper-Layer header type == 41(IPv6) ) { + S02. Remove the outer IPv6 header with all its extension headers + S03. Set the packet's associated FIB table to T + S04. Submit the packet to the egress IPv6 FIB lookup for + transmission to the new destination + S05. } Else { + S06. Process as per Section 4.1.1 + S07. } + +4.7. End.DT4: Decapsulation and Specific IPv4 Table Lookup + + The "Endpoint with decapsulation and specific IPv4 table lookup" + behavior ("End.DT4" for short) is a variant of the End.T behavior. + + One of the applications of the End.DT4 behavior is the L3VPNv4 use + case where a FIB lookup in a specific tenant table at the egress PE + is required. This is equivalent to the per-VRF VPN label in MPLS + [RFC4364]. + + Note that an End.DT4 may be defined for the main IPv4 table, in which + case an End.DT4 supports the equivalent of an IPv4-in-IPv6 + decapsulation (without VPN/tenant implication). + + The End.DT4 SID MUST be the last segment in an SR Policy, and a SID + instance is associated with an IPv4 FIB table T. + + When N receives a packet destined to S and S is a local End.DT4 SID, + N does the following: + + S01. When an SRH is processed { + S02. If (Segments Left != 0) { + S03. Send an ICMP Parameter Problem to the Source Address + with Code 0 (Erroneous header field encountered) + and Pointer set to the Segments Left field, + interrupt packet processing, and discard the packet. + S04. } + S05. Proceed to process the next header in the packet + S06. } + + When processing the Upper-Layer header of a packet matching a FIB + entry locally instantiated as an End.DT4 SID, N does the following: + + S01. If (Upper-Layer header type == 4(IPv4) ) { + S02. Remove the outer IPv6 header with all its extension headers + S03. Set the packet's associated FIB table to T + S04. Submit the packet to the egress IPv4 FIB lookup for + transmission to the new destination + S05. } Else { + S06. Process as per Section 4.1.1 + S07. } + +4.8. End.DT46: Decapsulation and Specific IP Table Lookup + + The "Endpoint with decapsulation and specific IP table lookup" + behavior ("End.DT46" for short) is a variant of the End.DT4 and + End.DT6 behavior. + + One of the applications of the End.DT46 behavior is the L3VPN use + case where a FIB lookup in a specific IP tenant table at the egress + PE is required. This is equivalent to the single per-VRF VPN label + (for IPv4 and IPv6) in MPLS [RFC4364]. + + Note that an End.DT46 may be defined for the main IP table, in which + case an End.DT46 supports the equivalent of an IP-in-IPv6 + decapsulation (without VPN/tenant implication). + + The End.DT46 SID MUST be the last segment in an SR Policy, and a SID + instance is associated with an IPv4 FIB table T4 and an IPv6 FIB + table T6. + + When N receives a packet destined to S and S is a local End.DT46 SID, + N does the following: + + S01. When an SRH is processed { + S02. If (Segments Left != 0) { + S03. Send an ICMP Parameter Problem to the Source Address + with Code 0 (Erroneous header field encountered) + and Pointer set to the Segments Left field, + interrupt packet processing, and discard the packet. + S04. } + S05. Proceed to process the next header in the packet + S06. } + + When processing the Upper-Layer header of a packet matching a FIB + entry locally instantiated as an End.DT46 SID, N does the following: + + S01. If (Upper-Layer header type == 4(IPv4) ) { + S02. Remove the outer IPv6 header with all its extension headers + S03. Set the packet's associated FIB table to T4 + S04. Submit the packet to the egress IPv4 FIB lookup for + transmission to the new destination + S05. } Else if (Upper-Layer header type == 41(IPv6) ) { + S06. Remove the outer IPv6 header with all its extension headers + S07. Set the packet's associated FIB table to T6 + S08. Submit the packet to the egress IPv6 FIB lookup for + transmission to the new destination + S09. } Else { + S10. Process as per Section 4.1.1 + S11. } + +4.9. End.DX2: Decapsulation and L2 Cross-Connect + + The "Endpoint with decapsulation and L2 cross-connect" behavior + ("End.DX2" for short) is a variant of the Endpoint behavior. + + One of the applications of the End.DX2 behavior is the L2VPN + [RFC4664] / EVPN Virtual Private Wire Service (VPWS) [RFC7432] + [RFC8214] use case. + + The End.DX2 SID MUST be the last segment in an SR Policy, and it is + associated with one outgoing interface I. + + When N receives a packet destined to S and S is a local End.DX2 SID, + N does the following: + + S01. When an SRH is processed { + S02. If (Segments Left != 0) { + S03. Send an ICMP Parameter Problem to the Source Address + with Code 0 (Erroneous header field encountered) + and Pointer set to the Segments Left field, + interrupt packet processing, and discard the packet. + S04. } + S05. Proceed to process the next header in the packet + S06. } + + When processing the Upper-Layer header of a packet matching a FIB + entry locally instantiated as an End.DX2 SID, N does the following: + + S01. If (Upper-Layer header type == 143(Ethernet) ) { + S02. Remove the outer IPv6 header with all its extension headers + S03. Forward the Ethernet frame to the OIF I + S04. } Else { + S05. Process as per Section 4.1.1 + S06. } + + | Note: + | + | S01. IANA has allocated value "143" for "Ethernet" + | [IEEE.802.3_2018] in the "Assigned Internet Protocol Numbers" + | registry (see Section 10.1). + | + | S03. An End.DX2 behavior could be customized to expect a + | specific IEEE header (e.g., VLAN tag) and rewrite the egress + | IEEE header before forwarding on the outgoing interface. + + Note that an End.DX2 SID may also be associated with a bundle of + outgoing interfaces. + +4.10. End.DX2V: Decapsulation and VLAN L2 Table Lookup + + The "Endpoint with decapsulation and VLAN L2 table lookup" behavior + ("End.DX2V" for short) is a variant of the End.DX2 behavior. + + One of the applications of the End.DX2V behavior is the EVPN Flexible + Cross-connect use case. The End.DX2V behavior is used to perform a + lookup of the Ethernet frame VLANs in a particular L2 table. Any SID + instance of this behavior is associated with an L2 table T. + + When N receives a packet whose IPv6 DA is S and S is a local End.DX2 + SID, the processing is identical to the End.DX2 behavior except for + the Upper-Layer header processing, which is modified as follows: + + S03. Look up the exposed VLANs in L2 table T, and forward + via the matched table entry. + + | Note: + | + | S03. An End.DX2V behavior could be customized to expect a + | specific VLAN format and rewrite the egress VLAN header before + | forwarding on the outgoing interface. + +4.11. End.DT2U: Decapsulation and Unicast MAC L2 Table Lookup + + The "Endpoint with decapsulation and unicast MAC L2 table lookup" + behavior ("End.DT2U" for short) is a variant of the End behavior. + + One of the applications of the End.DT2U behavior is the EVPN Bridging + Unicast [RFC7432]. Any SID instance of the End.DT2U behavior is + associated with an L2 table T. + + When N receives a packet whose IPv6 DA is S and S is a local End.DT2U + SID, the processing is identical to the End.DX2 behavior except for + the Upper-Layer header processing, which is as follows: + + S01. If (Upper-Layer header type == 143(Ethernet) ) { + S02. Remove the outer IPv6 header with all its extension headers + S03. Learn the exposed MAC Source Address in L2 table T + S04. Look up the exposed MAC Destination Address in L2 table T + S05. If (matched entry in T) { + S06. Forward via the matched table T entry + S07. } Else { + S08. Forward via all L2 OIFs in table T + S09. } + S10. } Else { + S11. Process as per Section 4.1.1 + S12. } + + | Note: + | + | S01. IANA has allocated value "143" for "Ethernet" in the + | "Assigned Internet Protocol Numbers" registry (see + | Section 10.1). + | + | S03. In EVPN [RFC7432], the learning of the exposed MAC Source + | Address is done via the control plane. In L2VPN Virtual + | Private LAN Service (VPLS) [RFC4761] [RFC4762], reachability is + | obtained by standard learning bridge functions in the data + | plane. + +4.12. End.DT2M: Decapsulation and L2 Table Flooding + + The "Endpoint with decapsulation and L2 table flooding" behavior + ("End.DT2M" for short) is a variant of the End.DT2U behavior. + + Two of the applications of the End.DT2M behavior are the EVPN + Bridging of Broadcast, Unknown Unicast, and Multicast (BUM) traffic + with Ethernet Segment Identifier (ESI) filtering [RFC7432] and the + EVPN Ethernet-Tree (E-Tree) [RFC8317] use cases. + + Any SID instance of this behavior is associated with an L2 table T. + The behavior also takes an argument: "Arg.FE2". This argument + provides a local mapping to ESI for split-horizon filtering of the + received traffic to exclude a specific OIF (or set of OIFs) from L2 + table T flooding. The allocation of the argument values is local to + the SR Segment Endpoint Node instantiating this behavior, and the + signaling of the argument to other nodes for the EVPN functionality + occurs via the control plane. + + When N receives a packet whose IPv6 DA is S and S is a local End.DT2M + SID, the processing is identical to the End.DX2 behavior except for + the Upper-Layer header processing, which is as follows: + + S01. If (Upper-Layer header type == 143(Ethernet) ) { + S02. Remove the outer IPv6 header with all its extension headers + S03. Learn the exposed MAC Source Address in L2 table T + S04. Forward via all L2 OIFs excluding those associated with the + identifier Arg.FE2 + S05. } Else { + S06. Process as per Section 4.1.1 + S07. } + + | Note: + | + | S01. IANA has allocated value "143" for "Ethernet" in the + | "Assigned Internet Protocol Numbers" registry (see + | Section 10.1). + | + | S03. In EVPN [RFC7432], the learning of the exposed MAC Source + | Address is done via the control plane. In L2VPN VPLS [RFC4761] + | [RFC4762], reachability is obtained by standard learning bridge + | functions in the data plane. + +4.13. End.B6.Encaps: Endpoint Bound to an SRv6 Policy with + Encapsulation + + This is a variation of the End behavior. + + One of its applications is to express scalable traffic-engineering + policies across multiple domains. It is one of the SRv6 + instantiations of a Binding SID [RFC8402]. + + Any SID instance of this behavior is associated with an SR Policy B + and a source address A. + + When N receives a packet whose IPv6 DA is S and S is a local + End.B6.Encaps SID, N does the following: + + S01. When an SRH is processed { + S02. If (Segments Left == 0) { + S03. Stop processing the SRH, and proceed to process the next + header in the packet, whose type is identified by + the Next Header field in the routing header. + S04. } + S05. If (IPv6 Hop Limit <= 1) { + S06. Send an ICMP Time Exceeded message to the Source Address + with Code 0 (Hop limit exceeded in transit), + interrupt packet processing, and discard the packet. + S07. } + S08. max_LE = (Hdr Ext Len / 2) - 1 + S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) { + S10. Send an ICMP Parameter Problem to the Source Address + with Code 0 (Erroneous header field encountered) + and Pointer set to the Segments Left field, + interrupt packet processing, and discard the packet. + S11. } + S12. Decrement IPv6 Hop Limit by 1 + S13. Decrement Segments Left by 1 + S14. Update IPv6 DA with Segment List[Segments Left] + S15. Push a new IPv6 header with its own SRH containing B + S16. Set the outer IPv6 SA to A + S17. Set the outer IPv6 DA to the first SID of B + S18. Set the outer Payload Length, Traffic Class, Flow Label, + Hop Limit, and Next Header fields + S19. Submit the packet to the egress IPv6 FIB lookup for + transmission to the new destination + S20. } + + | Note: + | + | S15. The SRH MAY be omitted when the SRv6 Policy B only + | contains one SID and there is no need to use any flag, tag, or + | TLV. + | + | S18. The Payload Length, Traffic Class, Hop Limit, and Next + | Header fields are set as per [RFC2473]. The Flow Label is + | computed as per [RFC6437]. + + When processing the Upper-Layer header of a packet matching a FIB + entry locally instantiated as an End.B6.Encaps SID, process the + packet as per Section 4.1.1. + +4.14. End.B6.Encaps.Red: End.B6.Encaps with Reduced SRH + + This is an optimization of the End.B6.Encaps behavior. + + End.B6.Encaps.Red reduces the size of the SRH by one SID by excluding + the first SID in the SRH of the new IPv6 header. Thus, the first + segment is only placed in the IPv6 Destination Address of the new + IPv6 header, and the packet is forwarded according to it. + + The SRH Last Entry field is set as defined in Section 4.1.1 of + [RFC8754]. + + The SRH MAY be omitted when the SRv6 Policy only contains one SID and + there is no need to use any flag, tag, or TLV. + +4.15. End.BM: Endpoint Bound to an SR-MPLS Policy + + The "Endpoint bound to an SR-MPLS Policy" behavior ("End.BM" for + short) is a variant of the End behavior. + + The End.BM behavior is required to express scalable traffic- + engineering policies across multiple domains where some domains + support the MPLS instantiation of Segment Routing. This is an SRv6 + instantiation of an SR-MPLS Binding SID [RFC8402]. + + Any SID instance of this behavior is associated with an SR-MPLS + Policy B. + + When N receives a packet whose IPv6 DA is S and S is a local End.BM + SID, N does the following: + + S01. When an SRH is processed { + S02. If (Segments Left == 0) { + S03. Stop processing the SRH, and proceed to process the next + header in the packet, whose type is identified by + the Next Header field in the routing header. + S04. } + S05. If (IPv6 Hop Limit <= 1) { + S06. Send an ICMP Time Exceeded message to the Source Address + with Code 0 (Hop limit exceeded in transit), + interrupt packet processing, and discard the packet. + S07. } + S08. max_LE = (Hdr Ext Len / 2) - 1 + S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) { + S10. Send an ICMP Parameter Problem to the Source Address + with Code 0 (Erroneous header field encountered) + and Pointer set to the Segments Left field, + interrupt packet processing, and discard the packet. + + S11. } + S12. Decrement IPv6 Hop Limit by 1 + S13. Decrement Segments Left by 1 + S14. Update IPv6 DA with Segment List[Segments Left] + S15. Push the MPLS label stack for B + S16. Submit the packet to the MPLS engine for transmission + S17. } + + When processing the Upper-Layer header of a packet matching a FIB + entry locally instantiated as an End.BM SID, process the packet as + per Section 4.1.1. + +4.16. Flavors + + The Penultimate Segment Pop (PSP) of the SRH, Ultimate Segment Pop + (USP) of the SRH, and Ultimate Segment Decapsulation (USD) flavors + are variants of the End, End.X, and End.T behaviors. The End, End.X, + and End.T behaviors can support these flavors either individually or + in combinations. + +4.16.1. PSP: Penultimate Segment Pop of the SRH + +4.16.1.1. Guidelines + + SR Segment Endpoint Nodes advertise the SIDs instantiated on them via + control-plane protocols as described in Section 8. Different + behavior IDs are allocated for flavored and unflavored SIDs (see + Table 6). + + An SR Segment Endpoint Node that offers both PSP- and non-PSP- + flavored behavior advertises them as two different SIDs. + + The SR Segment Endpoint Node only advertises the PSP flavor if the + operator enables this capability at the node. + + The PSP operation is deterministically controlled by the SR source + node. + + A PSP-flavored SID is used by the SR source node when it needs to + instruct the penultimate SR Segment Endpoint Node listed in the SRH + to remove the SRH from the IPv6 header. + +4.16.1.2. Definition + + SR Segment Endpoint Nodes receive the IPv6 packet with the + Destination Address field of the IPv6 header equal to its SID + address. + + A penultimate SR Segment Endpoint Node is one that, as part of the + SID processing, copies the last SID from the SRH into the IPv6 + Destination Address and decrements the Segments Left value from one + to zero. + + The PSP operation only takes place at a penultimate SR Segment + Endpoint Node and does not happen at any transit node. When a SID of + PSP flavor is processed at a non-penultimate SR Segment Endpoint + Node, the PSP behavior is not performed as described in the + pseudocode below since Segments Left would not be zero. + + The SRH processing of the End, End.X, and End.T behaviors are + modified: after the instruction "S14. Update IPv6 DA with Segment + List[Segments Left]" is executed, the following instructions must be + executed as well: + + S14.1. If (Segments Left == 0) { + S14.2. Update the Next Header field in the preceding header to + the Next Header value from the SRH + S14.3. Decrease the IPv6 header Payload Length by + 8*(Hdr Ext Len+1) + S14.4. Remove the SRH from the IPv6 extension header chain + S14.5. } + + The usage of PSP does not increase the MTU of the IPv6 packet and + hence does not have any impact on the Path MTU (PMTU) discovery + mechanism. + + As a reminder, Section 5 of [RFC8754] defines the SR Deployment Model + within the SR Domain [RFC8402]. Within this framework, the + Authentication Header (AH) is not used to secure the SRH as described + in Section 7.5 of [RFC8754]. Hence, the discussion of applicability + of PSP along with AH usage is beyond the scope of this document. + + In the context of this specification, the End, End.X, and End.T + behaviors with PSP do not contravene Section 4 of [RFC8200] because + the destination address of the incoming packet is the address of the + node executing the behavior. + +4.16.1.3. Use Case + + One use case for the PSP functionality is streamlining the operation + of an egress border router. + + +----------------------------------------------------+ + | | + +-+-+ +--+ +--+ +--+ +-+-+ + |iPE+-------->+R2+-------->+R3+-------->+R4+-------->+ePE| + | R1| +--+ +--+ +--+ |R5 | + +-+-+ +-----+ +-----+ +-----+ +-----+ +-+-+ + | |IPv6 | |IPv6 | |IPv6 | |IPv6 | | + | |DA=R3| |DA=R3| |DA=R5| |DA=R5| | + | +-----+ +-----+ +-----+ +-----+ | + | | SRH | | SRH | | IP | | IP | | + | |SL=1 | |SL=1 | +-----+ +-----+ | + | | R5 | | R5 | | + | +-----+ +-----+ | + | | IP | | IP | | + | +-----+ +-----+ | + | | + +----------------------------------------------------+ + + Figure 1: PSP Use Case Topology + + In the above illustration, for a packet sent from the ingress + provider edge (iPE) to the egress provider edge (ePE), node R3 is an + intermediate traffic-engineering waypoint and is the penultimate + segment endpoint router; this node copies the last segment from the + SRH into the IPv6 Destination Address and decrements Segments Left to + 0. The Software-Defined Networking (SDN) controller knows that no + other node after R3 needs to inspect the SRH, and it instructs R3 to + remove the exhausted SRH from the packet by using a PSP-flavored SID. + + The benefits for the egress PE are straightforward: + + * As part of the decapsulation process, the egress PE is required to + parse and remove fewer bytes from the packet. + + * If a lookup on an upper-layer IP header is required (e.g., per-VRF + VPN), the header is more likely to be within the memory accessible + to the lookup engine in the forwarding ASIC (Application-Specific + Integrated Circuit). + +4.16.2. USP: Ultimate Segment Pop of the SRH + + The SRH processing of the End, End.X, and End.T behaviors are + modified; the instructions S02-S04 are substituted by the following + ones: + + S02. If (Segments Left == 0) { + S03.1. Update the Next Header field in the preceding header to + the Next Header value of the SRH + S03.2. Decrease the IPv6 header Payload Length by + 8*(Hdr Ext Len+1) + S03.3. Remove the SRH from the IPv6 extension header chain + S03.4. Proceed to process the next header in the packet + S04. } + + One of the applications of the USP flavor is when a packet with an + SRH is destined to an application on hosts with smartNICs ("Smart + Network Interface Cards") implementing SRv6. The USP flavor is used + to remove the consumed SRH from the extension header chain before + sending the packet to the host. + +4.16.3. USD: Ultimate Segment Decapsulation + + The Upper-Layer header processing of the End, End.X, and End.T + behaviors are modified as follows: + + End: + + S01. If (Upper-Layer header type == 41(IPv6) ) { + S02. Remove the outer IPv6 header with all its extension headers + S03. Submit the packet to the egress IPv6 FIB lookup for + transmission to the new destination + S04. } Else if (Upper-Layer header type == 4(IPv4) ) { + S05. Remove the outer IPv6 header with all its extension headers + S06. Submit the packet to the egress IPv4 FIB lookup for + transmission to the new destination + S07. Else { + S08. Process as per Section 4.1.1 + S09. } + + End.T: + + S01. If (Upper-Layer header type == 41(IPv6) ) { + S02. Remove the outer IPv6 header with all its extension headers + S03. Set the packet's associated FIB table to T + S04. Submit the packet to the egress IPv6 FIB lookup for + transmission to the new destination + S05. } Else if (Upper-Layer header type == 4(IPv4) ) { + S06. Remove the outer IPv6 header with all its extension headers + S07. Set the packet's associated FIB table to T + S08. Submit the packet to the egress IPv4 FIB lookup for + transmission to the new destination + S09. Else { + S10. Process as per Section 4.1.1 + S11. } + + End.X: + + S01. If (Upper-Layer header type == 41(IPv6) || + Upper-Layer header type == 4(IPv4) ) { + S02. Remove the outer IPv6 header with all its extension headers + S03. Forward the exposed IP packet to the L3 adjacency J + S04. } Else { + S05. Process as per Section 4.1.1 + S06. } + + One of the applications of the USD flavor is the case of a Topology + Independent Loop-Free Alternate (TI-LFA) in P routers with + encapsulation. The USD flavor allows the last SR Segment Endpoint + Node in the repair path list to decapsulate the IPv6 header added at + the TI-LFA Point of Local Repair and forward the inner packet. + +5. SR Policy Headend Behaviors + + This section describes a set of SRv6 Policy Headend [RFC8402] + behaviors. + + +-----------------+-----------------------------------------------+ + | H.Encaps | SR Headend with Encapsulation in an SR Policy | + +-----------------+-----------------------------------------------+ + | H.Encaps.Red | H.Encaps with Reduced Encapsulation | + +-----------------+-----------------------------------------------+ + | H.Encaps.L2 | H.Encaps Applied to Received L2 Frames | + +-----------------+-----------------------------------------------+ + | H.Encaps.L2.Red | H.Encaps.Red Applied to Received L2 Frames | + +-----------------+-----------------------------------------------+ + + Table 2: SR Policy Headend Behaviors + + This list is not exhaustive, and future documents may define + additional behaviors. + +5.1. H.Encaps: SR Headend with Encapsulation in an SR Policy + + Node N receives two packets P1=(A, B2) and P2=(A,B2)(B3, B2, B1; + SL=1). B2 is neither a local address nor SID of N. + + Node N is configured with an IPv6 address T (e.g., assigned to its + loopback). + + N steers the transit packets P1 and P2 into an SRv6 Policy with a + Source Address T and a segment list <S1, S2, S3>. + + The H.Encaps encapsulation behavior is defined as follows: + + S01. Push an IPv6 header with its own SRH + S02. Set outer IPv6 SA = T and outer IPv6 DA to the first SID + in the segment list + S03. Set outer Payload Length, Traffic Class, Hop Limit, and + Flow Label fields + S04. Set the outer Next Header value + S05. Decrement inner IPv6 Hop Limit or IPv4 TTL + S06. Submit the packet to the IPv6 module for transmission to S1 + + | Note: + | + | S03: As described in [RFC2473] and [RFC6437]. + + After the H.Encaps behavior, P1' and P2' respectively look like: + + * (T, S1) (S3, S2, S1; SL=2) (A, B2) + + * (T, S1) (S3, S2, S1; SL=2) (A, B2) (B3, B2, B1; SL=1) + + The received packet is encapsulated unmodified (with the exception of + the IPv4 TTL or IPv6 Hop Limit that is decremented as described in + [RFC2473]). + + The H.Encaps behavior is valid for any kind of L3 traffic. This + behavior is commonly used for L3VPN with IPv4 and IPv6 deployments. + It may be also used for TI-LFA [SR-TI-LFA] at the Point of Local + Repair. + + The push of the SRH MAY be omitted when the SRv6 Policy only contains + one segment and there is no need to use any flag, tag, or TLV. + +5.2. H.Encaps.Red: H.Encaps with Reduced Encapsulation + + The H.Encaps.Red behavior is an optimization of the H.Encaps + behavior. + + H.Encaps.Red reduces the length of the SRH by excluding the first SID + in the SRH of the pushed IPv6 header. The first SID is only placed + in the Destination Address field of the pushed IPv6 header. + + After the H.Encaps.Red behavior, P1' and P2' respectively look like: + + * (T, S1) (S3, S2; SL=2) (A, B2) + + * (T, S1) (S3, S2; SL=2) (A, B2) (B3, B2, B1; SL=1) + + The push of the SRH MAY be omitted when the SRv6 Policy only contains + one segment and there is no need to use any flag, tag, or TLV. + +5.3. H.Encaps.L2: H.Encaps Applied to Received L2 Frames + + The H.Encaps.L2 behavior encapsulates a received Ethernet + [IEEE.802.3_2018] frame and its attached VLAN header, if present, in + an IPv6 packet with an SRH. The Ethernet frame becomes the payload + of the new IPv6 packet. + + The Next Header field of the SRH MUST be set to 143. + + The push of the SRH MAY be omitted when the SRv6 Policy only contains + one segment and there is no need to use any flag, tag, or TLV. + + The encapsulating node MUST remove the preamble (if any) and frame + check sequence (FCS) from the Ethernet frame upon encapsulation, and + the decapsulating node MUST regenerate, as required, the preamble and + FCS before forwarding the Ethernet frame. + +5.4. H.Encaps.L2.Red: H.Encaps.Red Applied to Received L2 Frames + + The H.Encaps.L2.Red behavior is an optimization of the H.Encaps.L2 + behavior. + + H.Encaps.L2.Red reduces the length of the SRH by excluding the first + SID in the SRH of the pushed IPv6 header. The first SID is only + placed in the Destination Address field of the pushed IPv6 header. + + The push of the SRH MAY be omitted when the SRv6 Policy only contains + one segment and there is no need to use any flag, tag, or TLV. + +6. Counters + + A node supporting this document SHOULD implement a pair of traffic + counters (one for packets and one for bytes) per local SID entry, for + traffic that matched that SID and was processed successfully (i.e., + packets that generate ICMP Error Messages or are dropped are not + counted). The retrieval of these counters from MIB, NETCONF/YANG, or + any other data structure is outside the scope of this document. + +7. Flow-Based Hash Computation + + When a flow-based selection within a set needs to be performed, the + IPv6 Source Address, the IPv6 Destination Address, and the IPv6 Flow + Label of the outer IPv6 header MUST be included in the flow-based + hash. + + This may occur in any of the following scenarios: + + * A FIB lookup is performed and multiple ECMP paths exist to the + updated destination address. + + * End.X, End.DX4, or End.DX6 is bound to an array of adjacencies. + + * The packet is steered in an SR Policy whose selected path has + multiple SID lists. + + Additionally, any transit router in an SRv6 domain includes the outer + flow label in its ECMP flow-based hash [RFC6437]. + +8. Control Plane + + In an SDN environment, one expects the controller to explicitly + provision the SIDs and/or discover them as part of a service + discovery function. Applications residing on top of the controller + could then discover the required SIDs and combine them to form a + distributed network program. + + The concept of "SRv6 Network Programming" refers to the capability of + an application to encode any complex program as a set of individual + functions distributed through the network. Some functions relate to + underlay SLA, others to overlay/tenant, and others to complex + applications residing in VMs and containers. + + While not necessary for an SDN control plane, the remainder of this + section provides a high-level illustrative overview of how control- + plane protocols may be involved with SRv6. Their specification is + outside the scope of this document. + +8.1. IGP + + The End, End.T, and End.X SIDs express topological behaviors and + hence are expected to be signaled in the IGP together with the + flavors PSP, USP, and USD. The IGP should also advertise the Maximum + SID Depth (MSD) capability of the node for each type of SRv6 + operation -- in particular, the SR source (e.g., H.Encaps), + intermediate endpoint (e.g., End and End.X), and final endpoint + (e.g., End.DX4 and End.DT6) behaviors. These capabilities are + factored in by an SR source node (or a controller) during the SR + Policy computation. + + The presence of SIDs in the IGP does not imply any routing semantics + to the addresses represented by these SIDs. The routing reachability + to an IPv6 address is solely governed by the non-SID-related IGP + prefix reachability information that includes locators. Routing is + neither governed nor influenced in any way by a SID advertisement in + the IGP. + + These SIDs provide important topological behaviors for the IGP to + build Fast Reroute (FRR) solutions based on TI-LFA [SR-TI-LFA] and + for TE processes relying on an IGP topology database to build SR + Policies. + +8.2. BGP-LS + + BGP-LS provides the functionality for topology discovery that + includes the SRv6 capabilities of the nodes, their locators, and + locally instantiated SIDs. This enables controllers or applications + to build an inter-domain topology that can be used for computation of + SR Policies using the SRv6 SIDs. + +8.3. BGP IP/VPN/EVPN + + The End.DX4, End.DX6, End.DT4, End.DT6, End.DT46, End.DX2, End.DX2V, + End.DT2U, and End.DT2M SIDs can be signaled in BGP. + + In some scenarios, an egress PE advertising a VPN route might wish to + abstract the specific behavior bound to the SID from the ingress PE + and other routers in the network. In such case, the SID may be + advertised using the Opaque SRv6 Endpoint Behavior codepoint defined + in Table 6. The details of such control-plane signaling mechanisms + are out of the scope of this document. + +8.4. Summary + + The following table summarizes which SID behaviors may be signaled in + which control-plane protocol. + + +=======================+=====+========+=================+ + | | IGP | BGP-LS | BGP IP/VPN/EVPN | + +=======================+=====+========+=================+ + | End (PSP, USP, USD) | X | X | | + +-----------------------+-----+--------+-----------------+ + | End.X (PSP, USP, USD) | X | X | | + +-----------------------+-----+--------+-----------------+ + | End.T (PSP, USP, USD) | X | X | | + +-----------------------+-----+--------+-----------------+ + | End.DX6 | X | X | X | + +-----------------------+-----+--------+-----------------+ + | End.DX4 | X | X | X | + +-----------------------+-----+--------+-----------------+ + | End.DT6 | X | X | X | + +-----------------------+-----+--------+-----------------+ + | End.DT4 | X | X | X | + +-----------------------+-----+--------+-----------------+ + | End.DT46 | X | X | X | + +-----------------------+-----+--------+-----------------+ + | End.DX2 | | X | X | + +-----------------------+-----+--------+-----------------+ + | End.DX2V | | X | X | + +-----------------------+-----+--------+-----------------+ + | End.DT2U | | X | X | + +-----------------------+-----+--------+-----------------+ + | End.DT2M | | X | X | + +-----------------------+-----+--------+-----------------+ + | End.B6.Encaps | | X | | + +-----------------------+-----+--------+-----------------+ + | End.B6.Encaps.Red | | X | | + +-----------------------+-----+--------+-----------------+ + | End.B6.BM | | X | | + +-----------------------+-----+--------+-----------------+ + + Table 3: SRv6 Locally Instantiated SIDs Signaling + + The following table summarizes which SR Policy Headend capabilities + may be signaled in which control-plane protocol. + + +=================+=====+========+=================+ + | | IGP | BGP-LS | BGP IP/VPN/EVPN | + +=================+=====+========+=================+ + | H.Encaps | X | X | | + +-----------------+-----+--------+-----------------+ + | H.Encaps.Red | X | X | | + +-----------------+-----+--------+-----------------+ + | H.Encaps.L2 | | X | | + +-----------------+-----+--------+-----------------+ + | H.Encaps.L2.Red | | X | | + +-----------------+-----+--------+-----------------+ + + Table 4: SRv6 Policy Headend Behaviors Signaling + + The previous table describes generic capabilities. It does not + describe specific instantiated SR Policies. + + For example, a BGP-LS advertisement of H.Encaps behavior would + describe the capability of node N to perform H.Encaps behavior. + Specifically, it would describe how many SIDs could be pushed by N + without significant performance degradation. + + + As a reminder, an SR Policy is always assigned a Binding SID + [RFC8402]. Binding SIDs are also advertised in BGP-LS as shown in + Table 3. Hence, Table 4 only focuses on the generic capabilities + related to H.Encaps. + +9. Security Considerations + + The security considerations for Segment Routing are discussed in + [RFC8402]. Section 5 of [RFC8754] describes the SR Deployment Model + and the requirements for securing the SR Domain. The security + considerations of [RFC8754] also cover topics such as attack vectors + and their mitigation mechanisms that also apply the behaviors + introduced in this document. Together, they describe the required + security mechanisms that allow establishment of an SR domain of + trust. Having such a well-defined trust boundary is necessary in + order to operate SRv6-based services for internal traffic while + preventing any external traffic from accessing or exploiting the + SRv6-based services. Care and rigor in IPv6 address allocation for + use for SRv6 SID allocations and network infrastructure addresses, as + distinct from IPv6 addresses allocated for end users and systems (as + illustrated in Section 5.1 of [RFC8754]), can provide the clear + distinction between internal and external address space that is + required to maintain the integrity and security of the SRv6 Domain. + Additionally, [RFC8754] defines a Hashed Message Authentication Code + (HMAC) TLV permitting SR Segment Endpoint Nodes in the SR domain to + verify that the SRH applied to a packet was selected by an authorized + party and to ensure that the segment list is not modified after + generation, regardless of the number of segments in the segment list. + When enabled by local configuration, HMAC processing occurs at the + beginning of SRH processing as defined in Section 2.1.2.1 of + [RFC8754]. + + This document introduces SRv6 Endpoint and SR Policy Headend + behaviors for implementation on SRv6-capable nodes in the network. + The definition of the SR Policy Headend should be consistent with the + specific behavior used and any local configuration (as specified in + Section 4.1.1). As such, this document does not introduce any new + security considerations. + + The SID behaviors specified in this document have the same HMAC TLV + handling and mutability properties with regard to the Flags, Tag, and + Segment List field as the SID behavior specified in [RFC8754]. + +10. IANA Considerations + +10.1. Ethernet Next Header Type + + IANA has allocated "Ethernet" (value 143) in the "Assigned Internet + Protocol Numbers" registry (see <https://www.iana.org/assignments/ + protocol-numbers/>). Value 143 in the Next Header field of an IPv6 + header or any extension header indicates that the payload is an + Ethernet frame [IEEE.802.3_2018]. + +10.2. SRv6 Endpoint Behaviors Registry + + IANA has created a new top-level registry called "Segment Routing" + (see <https://www.iana.org/assignments/segment-routing/>). This + registry serves as a top-level registry for all Segment Routing + subregistries. + + Additionally, IANA has created a new subregistry called "SRv6 + Endpoint Behaviors" under the top-level "Segment Routing" registry. + This subregistry maintains 16-bit identifiers for the SRv6 Endpoint + behaviors. This registry is established to provide consistency for + control-plane protocols that need to refer to these behaviors. These + values are not encoded in the function bits within a SID. + +10.2.1. Registration Procedures + + The range of the registry is 0-65535 (0x0000-0xFFFF). The table + below contains the allocation ranges and registration policies + [RFC8126] for each: + + +=============+===============+=========================+===========+ + | Range | Range (Hex) | Registration | Note | + | | | Procedures | | + +=============+===============+=========================+===========+ + | 0 | 0x0000 | Reserved | Not to be | + | | | | allocated | + +-------------+---------------+-------------------------+-----------+ + | 1-32767 | 0x0001-0x7FFF | First Come | | + | | | First Served | | + +-------------+---------------+-------------------------+-----------+ + | 32768-34815 | 0x8000-0x87FF | Private Use | | + +-------------+---------------+-------------------------+-----------+ + | 34816-65534 | 0x8800-0xFFFE | Reserved | | + +-------------+---------------+-------------------------+-----------+ + | 65535 | 0xFFFF | Reserved | Opaque | + +-------------+---------------+-------------------------+-----------+ + + Table 5: Registration Procedures + +10.2.2. Initial Registrations + + The initial registrations for the subregistry are as follows: + + +=============+===============+=========================+===========+ + | Value | Hex | Endpoint Behavior | Reference | + +=============+===============+=========================+===========+ + | 0 | 0x0000 | Reserved | | + +-------------+---------------+-------------------------+-----------+ + | 1 | 0x0001 | End | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 2 | 0x0002 | End with PSP | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 3 | 0x0003 | End with USP | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 4 | 0x0004 | End with PSP & USP | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 5 | 0x0005 | End.X | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 6 | 0x0006 | End.X with PSP | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 7 | 0x0007 | End.X with USP | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 8 | 0x0008 | End.X with PSP & USP | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 9 | 0x0009 | End.T | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 10 | 0x000A | End.T with PSP | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 11 | 0x000B | End.T with USP | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 12 | 0x000C | End.T with PSP & USP | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 13 | 0x000D | Unassigned | | + +-------------+---------------+-------------------------+-----------+ + | 14 | 0x000E | End.B6.Encaps | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 15 | 0x000F | End.BM | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 16 | 0x0010 | End.DX6 | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 17 | 0x0011 | End.DX4 | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 18 | 0x0012 | End.DT6 | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 19 | 0x0013 | End.DT4 | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 20 | 0x0014 | End.DT46 | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 21 | 0x0015 | End.DX2 | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 22 | 0x0016 | End.DX2V | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 23 | 0x0017 | End.DT2U | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 24 | 0x0018 | End.DT2M | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 25 | 0x0019 | Reserved | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 26 | 0x001A | Unassigned | | + +-------------+---------------+-------------------------+-----------+ + | 27 | 0x001B | End.B6.Encaps.Red | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 28 | 0x001C | End with USD | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 29 | 0x001D | End with PSP & USD | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 30 | 0x001E | End with USP & USD | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 31 | 0x001F | End with PSP, USP & | RFC 8986 | + | | | USD | | + +-------------+---------------+-------------------------+-----------+ + | 32 | 0x0020 | End.X with USD | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 33 | 0x0021 | End.X with PSP & USD | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 34 | 0x0022 | End.X with USP & USD | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 35 | 0x0023 | End.X with PSP, USP | RFC 8986 | + | | | & USD | | + +-------------+---------------+-------------------------+-----------+ + | 36 | 0x0024 | End.T with USD | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 37 | 0x0025 | End.T with PSP & USD | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 38 | 0x0026 | End.T with USP & USD | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 39 | 0x0027 | End.T with PSP, USP | RFC 8986 | + | | | & USD | | + +-------------+---------------+-------------------------+-----------+ + | 40-32766 | 0x0028-0x7FFE | Unassigned | | + +-------------+---------------+-------------------------+-----------+ + | 32767 | 0x7FFF | The SID defined in | RFC 8986, | + | | | RFC 8754 | RFC 8754 | + +-------------+---------------+-------------------------+-----------+ + | 32768-34815 | 0x8000-0x87FF | Reserved for Private | RFC 8986 | + | | | Use | | + +-------------+---------------+-------------------------+-----------+ + | 34816-65534 | 0x8800-0xFFFE | Reserved | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + | 65535 | 0xFFFF | Opaque | RFC 8986 | + +-------------+---------------+-------------------------+-----------+ + + Table 6: Initial Registrations + +11. References + +11.1. Normative References + + [IEEE.802.3_2018] + IEEE, "IEEE Standard for Ethernet", IEEE 802.3-2018, + DOI 10.1109/IEEESTD.2018.8457469, 31 August 2018, + <https://ieeexplore.ieee.org/document/8457469>. + + [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels", BCP 14, RFC 2119, + DOI 10.17487/RFC2119, March 1997, + <https://www.rfc-editor.org/info/rfc2119>. + + [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in + IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, + December 1998, <https://www.rfc-editor.org/info/rfc2473>. + + [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, + "IPv6 Flow Label Specification", RFC 6437, + DOI 10.17487/RFC6437, November 2011, + <https://www.rfc-editor.org/info/rfc6437>. + + [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC + 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, + May 2017, <https://www.rfc-editor.org/info/rfc8174>. + + [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 + (IPv6) Specification", STD 86, RFC 8200, + DOI 10.17487/RFC8200, July 2017, + <https://www.rfc-editor.org/info/rfc8200>. + + [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., + Decraene, B., Litkowski, S., and R. Shakir, "Segment + Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, + July 2018, <https://www.rfc-editor.org/info/rfc8402>. + + [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., + Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header + (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, + <https://www.rfc-editor.org/info/rfc8754>. + +11.2. Informative References + + [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast + Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005, + <https://www.rfc-editor.org/info/rfc4193>. + + [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private + Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February + 2006, <https://www.rfc-editor.org/info/rfc4364>. + + [RFC4664] Andersson, L., Ed. and E. Rosen, Ed., "Framework for Layer + 2 Virtual Private Networks (L2VPNs)", RFC 4664, + DOI 10.17487/RFC4664, September 2006, + <https://www.rfc-editor.org/info/rfc4664>. + + [RFC4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private + LAN Service (VPLS) Using BGP for Auto-Discovery and + Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007, + <https://www.rfc-editor.org/info/rfc4761>. + + [RFC4762] Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private + LAN Service (VPLS) Using Label Distribution Protocol (LDP) + Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007, + <https://www.rfc-editor.org/info/rfc4762>. + + [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., + Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based + Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February + 2015, <https://www.rfc-editor.org/info/rfc7432>. + + [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for + Writing an IANA Considerations Section in RFCs", BCP 26, + RFC 8126, DOI 10.17487/RFC8126, June 2017, + <https://www.rfc-editor.org/info/rfc8126>. + + [RFC8214] Boutros, S., Sajassi, A., Salam, S., Drake, J., and J. + Rabadan, "Virtual Private Wire Service Support in Ethernet + VPN", RFC 8214, DOI 10.17487/RFC8214, August 2017, + <https://www.rfc-editor.org/info/rfc8214>. + + [RFC8317] Sajassi, A., Ed., Salam, S., Drake, J., Uttaro, J., + Boutros, S., and J. Rabadan, "Ethernet-Tree (E-Tree) + Support in Ethernet VPN (EVPN) and Provider Backbone + Bridging EVPN (PBB-EVPN)", RFC 8317, DOI 10.17487/RFC8317, + January 2018, <https://www.rfc-editor.org/info/rfc8317>. + + [SR-TI-LFA] + Litkowski, S., Bashandy, A., Filsfils, C., Francois, P., + Decraene, B., and D. Voyer, "Topology Independent Fast + Reroute using Segment Routing", Work in Progress, + Internet-Draft, draft-ietf-rtgwg-segment-routing-ti-lfa- + 06, 1 February 2021, <https://tools.ietf.org/html/draft- + ietf-rtgwg-segment-routing-ti-lfa-06>. + + [SRV6-NET-PGM-ILLUST] + Filsfils, C., Camarillo, P., Ed., Li, Z., Matsushima, S., + Decraene, B., Steinberg, D., Lebrun, D., Raszuk, R., and + J. Leddy, "Illustrations for SRv6 Network Programming", + Work in Progress, Internet-Draft, draft-filsfils-spring- + srv6-net-pgm-illustration-03, 25 September 2020, + <https://tools.ietf.org/html/draft-filsfils-spring-srv6- + net-pgm-illustration-03>. + +Acknowledgements + + The authors would like to acknowledge Stefano Previdi, Dave Barach, + Mark Townsley, Peter Psenak, Thierry Couture, Kris Michielsen, Paul + Wells, Robert Hanzl, Dan Ye, Gaurav Dawra, Faisal Iqbal, Jaganbabu + Rajamanickam, David Toscano, Asif Islam, Jianda Liu, Yunpeng Zhang, + Jiaoming Li, Narendra A.K, Mike Mc Gourty, Bhupendra Yadav, Sherif + Toulan, Satish Damodaran, John Bettink, Kishore Nandyala Veera Venk, + Jisu Bhattacharya, Saleem Hafeez, and Brian Carpenter. + +Contributors + + Daniel Bernier + Bell Canada + Canada + + Email: daniel.bernier@bell.ca + + + Dirk Steinberg + Lapishills Consulting Limited + Cyprus + + Email: dirk@lapishills.com + + + Robert Raszuk + Bloomberg LP + United States of America + + Email: robert@raszuk.net + + + Bruno Decraene + Orange + France + + Email: bruno.decraene@orange.com + + + Bart Peirens + Proximus + Belgium + + Email: bart.peirens@proximus.com + + + Hani Elmalky + Google + United States of America + + Email: helmalky@google.com + + + Prem Jonnalagadda + Barefoot Networks + United States of America + + Email: prem@barefootnetworks.com + + + Milad Sharif + SambaNova Systems + United States of America + + Email: milad.sharif@sambanova.ai + + + David Lebrun + Google + Belgium + + Email: dlebrun@google.com + + + Stefano Salsano + Universita di Roma "Tor Vergata" + Italy + + Email: stefano.salsano@uniroma2.it + + + Ahmed AbdelSalam + Gran Sasso Science Institute + Italy + + Email: ahmed.abdelsalam@gssi.it + + + Gaurav Naik + Drexel University + United States of America + + Email: gn@drexel.edu + + + Arthi Ayyangar + Arrcus, Inc + United States of America + + Email: arthi@arrcus.com + + + Satish Mynam + Arrcus, Inc + United States of America + + Email: satishm@arrcus.com + + + Wim Henderickx + Nokia + Belgium + + Email: wim.henderickx@nokia.com + + + Shaowen Ma + Juniper + Singapore + + Email: mashao@juniper.net + + + Ahmed Bashandy + Individual + United States of America + + Email: abashandy.ietf@gmail.com + + + Francois Clad + Cisco Systems, Inc. + France + + Email: fclad@cisco.com + + + Kamran Raza + Cisco Systems, Inc. + Canada + + Email: skraza@cisco.com + + + Darren Dukes + Cisco Systems, Inc. + Canada + + Email: ddukes@cisco.com + + + Patrice Brissete + Cisco Systems, Inc. + Canada + + Email: pbrisset@cisco.com + + + Zafar Ali + Cisco Systems, Inc. + United States of America + + Email: zali@cisco.com + + + Ketan Talaulikar + Cisco Systems, Inc. + India + + Email: ketant@cisco.com + + +Authors' Addresses + + Clarence Filsfils (editor) + Cisco Systems, Inc. + Belgium + + Email: cf@cisco.com + + + Pablo Camarillo Garvia (editor) + Cisco Systems, Inc. + Spain + + Email: pcamaril@cisco.com + + + John Leddy + Akamai Technologies + United States of America + + Email: john@leddy.net + + + Daniel Voyer + Bell Canada + Canada + + Email: daniel.voyer@bell.ca + + + Satoru Matsushima + SoftBank + Japan + + Email: satoru.matsushima@g.softbank.co.jp + + + Zhenbin Li + Huawei Technologies + China + + Email: lizhenbin@huawei.com |